UNIVERSIDADE FEDERAL DE PERNAMBUCO … · examinador as medidas foram realizadas por dois fisioterapeutas e para testar a reprodutibilidade intra-examinador, um deles

_________________________________________________________________________________________ LIMA, P.O.P. Propriedades Clinimétricas da UBP

UNIVERSIDADE FEDERAL DE PERNAMBUCO

CENTRO DE CIÊNCIAS DA SAÚDE

DEPARTAMENTO DE FISIOTERAPIA

PROGRAMA DE PÓS-GRADUAÇÃO EM FISIOTERAPIA

PEDRO OLAVO DE PAULA LIMA

PROPRIEDADES CLINIMÉTRICAS DA UNIDADE DE BIOFEEDBACK

PRESSÓRICO NA AVALIAÇÃO DA ATIVIDADE MUSCULAR DO TRANSVERSO

ABDOMINAL EM PACIENTES COM DOR LOMBAR CRÔNICA INESPECÍFICA.

RECIFE

2010


PEDRO OLAVO DE PAULA LIMA

PROPRIEDADES CLINIMÉTRICAS DA UNIDADE DE BIOFEEDBACK

PRESSÓRICO NA AVALIAÇÃO DA ATIVIDADE MUSCULAR DO TRANSVERSO

ABDOMINAL EM PACIENTES COM DOR LOMBAR CRÔNICA INESPECÍFICA.

Dissertação apresentada ao Programa de Pós-Graduação em Fisioterapia do Centro de Ciências da Saúde da Universidade Federal de Pernambuco, para obtenção do Grau de Mestre em Fisioterapia.

Linha de Pesquisa: Instrumentação e Intervenção Fisioterapêutica - Aplicabilidade e confiabilidade de métodos de avaliação em Fisioterapia.

Orientadora: Glória Elizabeth Carneiro Laurentino.

Co-orientadora: Maria Cristina Falcão Raposo.

RECIFE

2010


Lima, Pedro Olavo de Paula

Propriedades clinimétricas da unidade de biofeedback pressórico na avaliação da atividade muscular do transverso abdominal em pacientes com dor lombar crônica inespecífica / Pedro Olavo de Paula Lima. – Recife: O Autor, 2010.

91 folhas: il., fig., tab.

Dissertação (mestrado) – Universidade Federal de Pernambuco. CCS. Fisioterapia, 2010.

Inclui bibliografia, anexos e apêndice.

1. Unidade de biofeedback pressórico. 2. Dor lombar. 3. Músculo transverso abdominal. 4. Reprodutibilidade. 5. Validade. I. Título.

615.8-7 CDU (2.ed.) UFPE 615.82 CDD (20.ed.) CCS2010-142



ORIENTADORA

Glória Elizabeth Carneiro Laurentino

Professora Adjunto do Departamento de Fisioterapia do Centro de Ciências da Saúde da

Universidade Federal de Pernambuco

Doutora em Nutrição pela Universidade Federal de Pernambuco

CO-ORIENTADORA

Maria Cristina Falcão Raposo

Professora Adjunto do Departamento de Estatística do Centro de Ciências Exatas e da

Natureza da Universidade Federal de Pernambuco

Doutora em Economia pela Universidade Federal de Pernambuco


DEDICATÓRIA

Ao Senhor: Deus

À minha Mãe: Idée Maria

Ao meu pai: Pedro Olegário

À minha noiva: Flávia Botelho

Aos meus irmãos: Lílian, Jonathan, Ronaldo e Maria Clara

Ao meu sobrinho: Davi Lima Maia

Às minhas avós: Margarida e Carmelita

Aos meus avôs: Olavo e Moiséis “In Memoriam”


AGRADECIMENTOS ESPECIAIS

À Profª. Drª. Glória Elizabeth Carneiro Laurentino,

que aceitou a orientação deste trabalho e sempre se conduziu de maneira dedicada e

competente durante toda sua elaboração. Muito obrigado por sua dedicação e apoio em todos

os momentos, sempre disponível quando precisava.

À Profª. Drª. Maria Cristina Falcão Raposo,

pelo empenho na elaboração deste trabalho, supervisão estatística detalhada e tranquilidade

nas explicações;

Ao amigo e colega de trabalho, Rodrigo Ribeiro de Oliveira,

pela valiosa participação na coleta de dados e elaboração deste trabalho, seu apoio foi

fundamental;

Ao Prof°. Dr. Leonardo Oliveira Pena Costa

pela disponibilidade e atenção que sempre me dispensou, apesar da distância, em responder

dúvidas e revisar os manuscritos deste trabalho com máxima prontidão.


AGRADECIMENTOS

• Ao Departamento de Fisioterapia da UFPE, especialmente ao Laboratório de

Cinesiologia e Avaliação Funcional, pela acolhida e pelo apoio desde o início das

atividades do mestrado;

• Aos meus companheiros de moradia, Thales Henrique de Araújo Sales e Rodrigo

Ribeiro de Oliveira, pela parceira/companheirismo e por toda paciência com minha

pessoa durante o período do mestrado;

• A todos os meus colegas de mestrado, Alana Elza; Thaysa Oliveira; Emanuela

Cavalcante; Leila Barbosa; Antônio Francisco; João Danyell; Jacqueline Barcelar;

Silvana Uchôa; Dinalva Lacerda; Roberta Machado e Adriana Sarmento, pelos

estudos e debates que tanto promoveram o conhecimento da primeira turma do curso

(2009), assim como pelos encontros sociais realizados;

• Ao Prof°. Dr. Alberto Galvão de Moura Filho, pela acolhida no laboratório e

disponibilização da sala de eletromiografia para as coletas de dados;

• A todos os professores que participaram de minha formação profissional no mestrado.

Aos funcionários do Departamento de Fisioterapia pela atenção e ajuda;

• Aos sujeitos, que participaram de forma voluntária das avaliações, pela paciência e

pela disponibilização de tempo para contribuir nesse estudo;

• À amiga Elda Madruga e família, pela acolhida calorosa em seu lar e por todo apoio

despendido durante minha estadia em Recife-PE;


• Ao meu amigo de infância de Belém-PA, Bruno Brasil e a toda sua família, por me

receberem tão bem em sua cidade;

• À tia Anália Paranhos e a toda sua família por me receberem em sua casa tão bem;

• Agradeço a toda minha família e aos meus amigos pela torcida, constantes incentivos e

orações. Obrigado por acreditarem no meu esforço.


LISTA DE ABREVEATURAS, SIGLAS E SÍMBOLOS

DP Desvio Padrão

SD Standard Deviation

p Probabilidade de significância estatística

ICC Intraclass Correlation Coeficient

IC Intervalo de Confiança

CI Confidence Interval

r Coeficiente de Correlação de Pearson

CV Coeficiente de Variação

SEM Standard Error of the Measurement

SDC Smallest Detectable Change

LOA Limits of Agreement

PPV Positive Predictive Value

NPV Negative Predictive Value

SPSS Statistical Package for Social Sciences

UFPE Universidade Federal de Pernambuco

UFC Universidade Federal do Ceará

UNICID Universidade Cidade de são Paulo

CINAHL Cumulative Index to Nursing and Allied Health Literature

PRISMA Preferred Reporting Items for Systematic Reviews and Meta-Analyses

UBP Unidade de Biofeedback Pressórico

PBU Pressure Biofeedback Unit

EMG Eletromiografia (Electromyography)

SENIAM Surface Electromyography for Non Invasive Assessment of Muscles


CIVM Contração Isométrica Voluntária Máxima

MVIC Maximal Voluntary Isometric Contraction

RMS Root Means Square

Ag/AgCl Cloreto de Prata

TrA Transverso Abdominal [Transversus Abdominis]

OI Oblíquo Interno [Internal Oblique]

LBP Low Back Pain

IMC Índice de Massa Corpórea

BMI Body Mass Index

JCR Journal Citation Reports


LISTA DE TABELAS

Referentes ao primeiro artigo - Measurement properties of the pressure biofeedback unit in

the evaluation of transversus abdominis muscle activity: a

systematic review.

Tabela 1. Checklist used to evaluate the clinimetric properties of the studies included in

the review. (p.32)

Tabela 2. Description of eligible studies. (p.34)

Tabela 3. Results and limitations of the studies included in the review. (p.36)

Tabela 4. Summary of assessment of the quality criteria of studies included in the review.

(p.37)

Referentes ao segundo artigo - Reproducibility of pressure biofeedback unit in the transversus

abdominis muscle activity in patients with chronic

nonspecific low back pain.

Tabela 1. Sample characteristics. (p.52)

Tabela 2. Reliability and agreement for pressure measures. (p.53)


Referentes ao terceiro artigo - Validity of pressure biofeedback unit in the transversus



Tabela 1. Sample characteristics. (p.70)

Tabela 2. Description of the pressure measures and electromyographic measures in the

transversus abdominis muscle activity. (p.71)

Tabela 3. 2x2 Table between the pressure biofeedback unit ratings and the surface

electromyography ratings. (p.72)


LISTA DE FIGURAS

Referentes ao primeiro artigo - Measurement properties of the pressure biofeedback unit in

the evaluation of transversus abdominis muscle activity: a

systematic review.

Figura 1. PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-

Analyses) flow diagram of the literature search. (p.33)

Referentes ao segundo artigo - Reproducibility of pressure biofeedback unit in the transversus



Figura 1. Pressure Biofeedback Unit (STABILIZER®). (p.50)

Figura 2. Bland and Altman plots for pressure measures of Examiner A (test 1 – test 2).

(p.53)

Figura 3. Bland and Altman plots for pressure measures of Examiner A and Examiner B.

(p.54)


Referentes ao terceiro artigo - Validity of pressure biofeedback unit in the transversus



Figura 1. Pressure Biofeedback Unit (STABILIZER®). (p.69)


SUMÁRIO

LISTA DE ABREVEATURAS, SIGLAS E SÍMBOLOS

LISTA DE TABELAS

LISTA DE FIGURAS

RESUMO 18

ABSTRACT 19

1. APRESENTAÇÃO................................................................................................ 20

INTRODUÇÃO 23

2. PRIMEIRO ARTIGO…………………………….………………………....... 24

ABSTRACT 26

INTRODUCTION 28

METHODS 29

Data Sources and Searches 29

Study Selection and Eligibility Criteria 30

Data Extraction and Quality Assessment 30

RESULTS 31


DISCUSSION 37

REFERENCES 41

3. SEGUNDO ARTIGO…………………………………………………………… 43

ABSTRACT 45

INTRODUCTION 47

METHODS 48

RESULTS 51

DISCUSSION 54

CONCLUSION 58

REFERENCES 59

4. TERCEIRO ARTIGO………………………...………………………………… 61

ABSTRACT 63

INTRODUCTION 64

METHODS 66

RESULTS 70

DISCUSSION 72

CONCLUSION 75


REFERENCES 76

5. CONCLUSÕES……………………………..…………………………………… 79

APÊNDICE 81

APÊNDICE A: Termo de Consentimento Livre e Esclarecido 82

ANEXOS 84

ANEXO 1: Termo de Submissão para a Physiotherapy 85

ANEXO 2: Termo de Submissão para a Physiotherapy Research

International

86

ANEXO 3: Termo de Submissão para a Physiotherapy Theory and Practice 87

ANEXO 4: Pain Numerical Rating Scale 88

ANEXO 5: Roland Morris Disability Questionnaire 89

ANEXO 6: Aprovação do Comitê de Ética em Pesquisa 91

18


RESUMO

Introdução: A Unidade de Biofeedback Pressórico (UBP) é, frequentemente, usada por

clínicos e pesquisadores para avaliar a atividade muscular do transverso abdominal (TrA) em

pacientes com dor lombar crônica inespecífica, entretanto pouco se sabe sobre suas

propriedades clinimétricas. Objetivos: Avaliar a reprodutibilidade e a validade da UBP na

atividade do músculo TrA em pacientes com dor lombar crônica inespecífica. Métodos: A

amostra foi composta por cinquenta participantes. Para testar a reprodutibilidade inter-

examinador as medidas foram realizadas por dois fisioterapeutas e para testar a

reprodutibilidade intra-examinador, um deles realizou duas medidas em ocasiões diferentes

com um intervalo de sete dias entre os testes. Para testar a validade foram correlacionadas as

medidas da UBP (teste índice) e da eletromiografia de superfície (teste padrão-referência).

Resultados: Foram observados valores do coeficiente de correlação intraclasse de 0,74 e 0,76

para a reprodutibilidade intra e inter-examinador, respectivamente. A concordância intra-

examinador e inter-examinador estiveram dentro dos limites de concordância em 95% das

ocasiões. Foi observado fraco valor do coeficiente de correlação de Pearson (r=0,2; p<0,20)

para a validade. Os testes diagnósticos mostraram baixa sensibilidade (60%) e especificidade

(40%) da UBP. O valor preditivo positivo foi igual a 0,8 e o valor preditivo negativo igual a

0,2. Conclusões: A reprodutibilidade da UBP variou de satisfatória a excelente e a validade

apresentou baixa correlação entre os dados pressóricos e eletromiográficos. Conclui-se que

um paciente com dor lombar crônica inespecífica pode ser avaliado por um único

fisioterapeuta em momentos distintos, assim como, esse mesmo paciente pode ser avaliado

por fisioterapeutas diferentes e obter o mesmo diagnóstico cinesiológico. Entretanto, os

achados eletromiográficos sugerem que a aplicabilidade clínica da UBP em pacientes com dor

lombar crônica inespecífica não é indicada.

Palavras-chave: unidade de biofeedback pressórico, dor lombar, músculo transverso

abdominal, reprodutibilidade, confiabilidade, concordância, validade.

19


ABSTRACT

Introduction: Pressure Biofeedback Unit (PBU) is often used by clinicians and researchers to

evaluate the muscular activity of transversus abdominis (TrA) in patients with chronic

nonspecific low back pain, however little is known about its clinimetric properties.

Objectives: To assess the reliability and validity of PBU in the TrA muscle activity in patients

with chronic nonspecific low back pain. Methods: The sample consisted of fifty participants.

To test the inter-examiner reliability measurements were performed by two physiotherapists

and to test the intra-examiner reliability, one of them performed two measures on different

occasions with an interval of seven days between the tests. To test the validity were correlated

PBU (index test) measures and surface electromyography (reference-standard test) measures.

Results: We observed values of the intraclass correlation coefficient of 0.74 and 0.76 for

intra-examiner reproducibility and inter-examiner, respectively. Intra-examiner and inter-

examiner agremeent were within the limits of agreement in 95% of occasions. We observed

low value of the Pearson correlation coefficient (r = 0.2, p <0.20) for validity. Diagnostic

tests showed low sensitivity (60%) and specificity (40%) of the PBU. The positive predictive

value was equal to 0.8 and negative predictive value equal to 0.2. Conclusions: The

reproducibility of PBU ranged from satisfactory to excellent and the validity shown poor

correlation between pressure data and electromyographic data. We conclude that a patient

with chronic nonspecific low back pain can be assessed by a single physiotherapist at

different times and, that same patient can be evaluated by different physiotherapists and get

the same kinesiology diagnostic. However, electromyographic findings suggest that the

clinical applicability of the PBU in patients with chronic nonspecific low back pain is not

indicated.

Keywords: pressure biofeedback unit, low back pain, transversus abdominis muscle,

reproducibility, reliability, agreement, validity.

20


1. APRESENTAÇÃO

A maioria dos estudos sobre propriedades clinimétricas da unidade de

biofeedback pressórico (UBP) enfoca, em geral, indivíduos saudáveis, sendo escassos os

estudos objetivando testar clinimetricamente o instrumento em uma amostra relevante para a

prática clínica, isto é, composta por pacientes com dor lombar crônica inespecífica.

Para o desenvolvimento do estudo, inicialmente, foi realizada uma revisão

sistemática com o intuito de se fazer um levantando crítico da literatura. A partir das

conclusões extraídas dessa revisão, foram realizados ajustes no projeto de pesquisa inicial

com o objetivo de se reduzir possíveis vieses metodológicos no transcorrer da coleta e

análises dos dados. As etapas pré-definidas, dentro da metodologia estabelecida, foram

obedecidas e seguidas rigorosamente e, por fim, os resultados obtidos geraram dois artigos

originais, de acordo com seus principais desfechos. Um artigo teve como objeto principal

investigar a reprodutibilidade da UBP, enquanto o outro abordou a sua validade.

Com base na literatura especializada e após reflexão sobre o tema, foram

construídas as seguintes hipóteses:

• A UBP apresenta valores aceitáveis de reprodutibilidade intra-examinador da

atividade do músculo TrA em pacientes com dor lombar crônica inespecífica;

• A UBP apresenta valores aceitáveis de reprodutibilidade inter-examinador da

atividade do músculo TrA em pacientes com dor lombar crônica inespecífica;

• A UBP apresenta valores aceitáveis de validade da atividade do músculo TrA em

pacientes com dor lombar crônica inespecífica quando comparada a eletromiografia de

superfície;

21


Para consecução da proposta e, como forma de aceitar ou rejeitar as hipóteses

formuladas, foram definidos os seguintes objetivos:

• Avaliar a confiabilidade intra-examinador da UBP, por intermédio de medidas

repetidas da atividade do músculo transverso abdominal em pacientes com dor lombar

crônica inespecífica;

• Avaliar a confiabilidade inter-examinador da UBP, por intermédio de medidas



• Avaliar a concordância intra-examinador da UBP, por intermédio de medidas



• Avaliar a concordância inter-examinador da UBP, por intermédio de medidas



• Avaliar a validade da UBP, por intermédio de análise comparativa com a

eletromiografia de superfície em pacientes com dor lombar crônica inespecífica.

Seguindo recomendações do Programa de Pós-graduação em Fisioterapia da

UFPE, o trabalho de dissertação, aqui apresentado, inclui na sua estruturação três artigos

científicos enviados para publicação em revistas especializadas e, por esta razão, seguem as

normas dessas revistas no que diz respeito à formatação e escrita do manuscrito.

O primeiro artigo, intitulado – Measurement properties of the pressure

biofeedback unit in the evaluation of transversus abdominis muscle activity: a systematic

22


review – constitui uma revisão sistemática da literatura sobre propriedades clinimétricas da

UBP. Esse manuscrito foi submetido para publicação no periódico Physiotherapy (conceito

B1 na área 21 da CAPES, com fator de impacto igual a 0,773 JCR-2009) no dia 21 de Janeiro

de 2010 (ANEXO 1) e foi aceito para publicação no dia 27 de Julho de 2010.

Este artigo, por constituir uma revisão da literatura sobre o tema central aqui

abordado, está sendo usado como a introdução desta dissertação e os principais tópicos

abordados foram: propriedades clinimétricas (reprodutibilidade e validade); unidade de

biofeedback pressórico; músculo transverso abdominal e dor lombar crônica inespecífica.

O segundo artigo, intitulado – Reproducibility of pressure biofeedback unit in

the transversus abdominis muscle activity in patients with chronic nonspecific low back

pain – foi submetido ao periódico Physiotherapy Research International (conceito B1 na área

21 da CAPES) no dia 15 de Julho de 2010 (ANEXO 2), na qualidade de artigo original. Este

artigo enfoca, principalmente, a reprodutibilidade da UBP em pacientes com dor lombar

crônica inespecífica. Como desfechos primários foram abordadas a confiabilidade e

concordância intra-examinador e inter-examinador.

O terceiro artigo, intitulado – Validity of pressure biofeedback unit in the

transversus abdominis muscle activity in patients with chronic nonspecific low back pain –

foi submetido à Physiotherapy Theory and Practice (conceito B1 na área 21 da CAPES) no

dia 15 de Julho de 2010 (ANEXO 3), na qualidade de artigo original. O principal objeto desse

estudo foi investigar a validade da UBP em pacientes com dor lombar crônica inespecífica.

Como desfechos primários foram abordados a correlação entre dados pressóricos e

eletromiográficos, assim como análise de testes diagnósticos.

23


INTRODUÇÃO

24


2. PRIMEIRO ARTIGO

MEASUREMENT PROPERTIES OF THE PRESSURE BIOFEEDBACK UNIT IN THE

EVALUATION OF TRANSVERSUS ABDOMINIS MUSCLE ACTIVITY: A

SYSTEMATIC REVIEW.

Revisão sistemática submetida para publicação na Physiotherapy (ANEXO 1).

25


MEASUREMENT PROPERTIES OF THE PRESSURE BIOFEEDBACK UNIT IN

THE EVALUATION OF TRANSVERSUS ABDOMINIS MUSCLE ACTIVITY: A

SYSTEMATIC REVIEW.

Pedro Olavo de Paula Limaa*, Rodrigo Ribeiro de Oliveiraa, Leonardo Oliveira Pena Costab, Glória Elizabeth

Carneiro Laurentinoc.

a Master's Program in Physical Therapy, Universidade Federal de Pernambuco, Brazil

b Master's Program in Physical Therapy, Universidade Cidade de São Paulo, Brazil

c Department of Physical Therapy, Universidade Federal de Pernambuco, Brazil

* Corresponding Author: Laboratory of Kinesiology and Functional Assessment.

Address: Anibal Fernandes Street, Recife, PE, 50740-560, Brazil.

Telephone: +55 81 21268811 Facsimile: +55 81 21268491

Email: [email protected]

26


ABSTRACT

Background: Measurements of pressure biofeedback unit (PBU) are used to indirectly

evaluate the activity of the transversus abdominis (TrA) muscle. These measures can be used

to classify patients or to monitor progress of treatment programs for people with low back

pain.

Objective: The purpose of this study was to systematically review studies on the

measurement properties of the PBU for the activity of the TrA muscle.

Data Sources: Eligible studies were identified through searches on PUBMED, CINAHL and

BIREME (1990-2009). Additionally, hand searches of journals and citation tracking were

performed.

Study Selection: Studies published in full text involving any type of clinimetric tests of the

PBU measurement for TrA muscle were selected.

Data Extraction: Two independent reviewers selected the studies, extracted the data and

assessed the methodological quality.

Data Synthesis: Due to the heterogeneity of study designs and statistical analysis, pooling the

data for a meta-analysis was not possible. Six studies met our inclusion criteria. These studies

were of low quality and recruited healthy subjects rather than patients with low back pain.

Results:The studies found moderate to good reproducibility with ICC values ranging from

0.47 to 0.82 and acceptable construct validity with correlations values ranging from 0.48 to

0.90.

Conclusions: The current evidence of the measurement properties of the PBU for evaluating

the muscle activity of TrA is mainly based on studies with suboptimal designs and the

findings from these studies are likely to be overly optimistic. The most important clinical

27


questions about the measurement properties of the PBU on the TrA muscle are yet to be

answered.

Key-words: pressure biofeedback unit, transversus abdominis, reproducibility, validity

systematic review.

28


INTRODUCTION

Specific stabilization exercises (also known as motor control exercises) in treatment programs

for patients with low back pain (LBP) have become increasingly popular in clinical practice.

The biological rationale for use of these exercises is that stability and control of the spine is

altered in patients with low back pain. Previous studies have also demonstrated that patients

who recovered from a period of acute low back pain are more vulnerable to recurrence and

chronicity if these changes on the deep abdominal wall muscles, were not treated with motor

control exercise.[1-3] Most researchers have assessed the activity of the transversus abdominis

(TrA) through direct and indirect measures such as fine wire electromyography and

rehabilitative ultrasound imaging. However, these methods have limitations such as high cost

and have the risk of being painful or causing infection which limits the use these equipments

in clinical practice.[4-6] An alternative approach may be the use of an indirect measurement of

muscle activity of TrA by measuring the abdominal wall pressure changes using a specific

instrument known as the pressure biofeedback unit (Stabilizer®, Chattanooga Group Inc.,

Hixson, USA).[7]

It is important that clinical measurements should have acceptable measurement properties.[8]

The most important measurement properties are criterion validity, construct validity,

reproducibility and responsiveness. Criterion validity refers to the extent that scores on an

instrument relate to a gold standard. Construct validity refers to the extent that scores on a

particular instrument relate to other measures that measure the same construct; regardless the

comparator is not a gold standard.[9] Reproducibility could be defined as the degree to which

repeated measurements can provide similar results, and thus is a broad term that includes two

properties: agreement and reliability. Agreement can be defined as the degree to which scores

on repeated measurements are close to each other (absolute measurement error) and reliability

29


can be defined as the degree to which individuals can be distinguished from each other,

despite the measurement error (relative measurement error). Reproducibility can be further

divided into two types: intra-examiner which is associated with repeated measurements taken

by the same examiner at different time points and inter-examiner which evaluates the

repetitive measurements taken by different examiners.[9, 10] Finally responsiveness refers to the

ability of an instrument to detect clinically important changes over time, even if these changes

are small.[11]

Although there are some studies[12-17] evaluating the clinimetric properties of measures of

PBU in the muscle activity of the TrA, there is no comprehensive systematic review

summarizing this. The aim of this study was to systematically review studies that evaluated

the measurement properties of the PBU in the activity of the TrA muscle.

METHODS

Data Sources and Searches

We performed systematic searches on PUBMED, CINAHL and BIREME (a comprehensive

database of medical journals published in Portuguese and Spanish languages) over the period

from January 1990 to July 2009. Additionally, hand searches of journals and citation tracking

of reference lists related to PBU were performed. There were no language restrictions and

when necessary non-English papers were translated. The last search was performed on 31st of

July 2009.

The search terms used are described as it follows:

30


1. Reliability OR agreement OR validity OR test-retest OR assessment OR evaluation

OR examination OR activation OR contraction OR responsiveness OR sensitivity to

change;

2. Pressure biofeedback unit OR pressure biofeedback OR clinical tests;

3. Transversus abdominis OR abdominal muscle$;

4. 1 AND 2 AND 3.

Study Selection and Eligibility Criteria

Studies were considered eligible for inclusion if they met the following criteria:

1. Used the PBU as a tool for evaluation of muscle activity;

2. Evaluated the activity of the transversus abdominal muscle;

3. Analyzed measurement properties of the PBU;

4. Described the characteristics of the sample;

5. Published in full text in a peer-reviewed journal.

We excluded studies that used the PBU as visual feedback to patients (i.e. we only included

studies that used the PBU as a testing/screening instrument).

Data Extraction and Quality Assessment

The selection of studies, data extraction and quality assessment were performed by two

independent reviewers (P.O.P.L. and R.R.O.), disagreements between reviewers were

resolved by a third reviewer (G.E.C.L.). The items that were extracted from eligible studies

were: (1) description of the sample, (2) presence of LBP, (3) study design, (4) description of

the examiners, (5) the time interval between tests, (6) assessment measures, (7) results and (8)

limitations of the studies. The measurement properties were extracted from the measures of

activity of the TrA muscle.

31


The quality of the studies was classified by the items 3, 4 and 5 of the Quality Criteria for

Measurement Properties of Health Status Questionnaires (Table 1).[9] These items evaluate

the study design, as well as the measurement properties values. Although this quality criterion

was developed for the evaluation of measurement properties of questionnaires we considered

it applicable to be used for the current study. This approach has been used in previous reviews

that analyzed not only measurement properties of questionnaires[18, 19], but it was also used by

studies that analyzed the clinimetric properties of measurement instruments such as

rehabilitative ultrasound imaging[20, 21]. We are unaware of a better criterion to evaluate

measurement properties of instruments such as the PBU.

RESULTS

From the search strategy, 193 potentially relevant studies were found. Of these, only 6 studies

were eligible for data analysis (Figure 1).[12-17] Five studies calculated the intra-examiner

reliability,[13-17] two also calculated the inter-examiner reliability,[16, 17] one estimated the

construct validity[13] and one study calculated the criterion validity.[12] It is noteworthy that

one of the studies, in addition to assessing the intra and inter-examiner reliability, also

calculated agreement.[16] Important measurement properties such as responsiveness and

ceiling and floor effects were not evaluated in any study. Due to the heterogeneity of the

eligible studies with regards to the study design and statistical analysis, the pooling of data in

a meta-analysis was not possible. Thus, the results are presented descriptively.

32


Table 1: Checklist used to evaluate the clinimetric properties the studies included in the review (adapted from Costa et al. [6] and de Koning et al. [22]).

Clinimetric Properties Definition Quality Criteriaa,b

Reproducibility

(Intra-examiner agreement)

The extent to which the scores on repeated measures are

close to each other (absolute measurement error).

Repeated measures performed by the same examiner.

+ MIC** < SDC OR MIC outside the LOA OR convincing arguments that agreement is acceptable;

? Doubtful design or method OR (MIC not defined AND no convincing arguments that agreement is acceptable);

− MIC > SDC OR MIC equals or inside LOA, despite adequate design and method;

0 No information found on agreement.

Reproducibility

(Inter-examiner agreement)

The extent to which the scores on repeated measures are

close to each other (absolute measurement error).

Repeated measures performed by two or more

examiners.

Reproducibility

(Intra-examiner reliability)

Repeated measures made by the same examiner at

different times, ie refers to the ability of the examiner to

measure the same construct repeatedly.

+ ICC or weighted Kappa > 0.70; ? Doubtful design or method (eg, interval between tests not given,

inadequate description of the ICC); − ICC or weighted Kappa < 0.70, despite adequate design and

method; 0 No information found on reliability.

Reproducibility

(Inter-examiner reliability)

Repeated measures made by different examiners, ie, the

ability of different examiners measuring the same

construct repeatedly.

Criterion Validity The extent to which scores on a particular instrument

relate to a gold standard

+ Convincing arguments that gold standard is ‘‘gold’’ AND correlation with gold standard >0.70;

? No convincing arguments that gold standard is ‘‘gold’’ OR doubtful design or method;

− Correlation with gold standard < 0.70, despite adequate design and method;

0 No information found on criterion validity.

Construct Validity

The extent to which scores on a particular instrument relate to other measures in a manner that is consistent with theoretically derived hypotheses concerning the

concepts that are being measured

+ Specific hypotheses were formulated AND at least 75% of the results are in accordance with these hypotheses;

? Doubtful design or method (e.g., no hypotheses); − Less than 75% of hypotheses were confirmed, despite adequate

design and methods; 0 No information found on construct validity.

a + positive rating, ? indeterminate rating, - negative rating e 0 no information available. b MIC = minimal important change; SDC = smallest detectable change; LOA = limits of agreement; ICC = intraclass correlation coefficient; kappa = kappa coefficient. ** MIC was not considered in the ratings of agreement as MIC is more related to self-report patient outcome measures than physiological measures as PBU.

33


Table 2 describes the data that were extracted from eligible studies.

Screening

Included

Eligibility

Iden

tification

Records identified through database searching: PUBMED (n=137), CINAHL

(n=41) and BIREME (n=14)

Additional records identified through other sources

(n=1)

Records after duplicates removed (n=6)

Records screened (n=187)

Records excluded, title (n=173) and abstract (n=5)

Full-text articles assessed for eligibility (n =9)

Full-text articles excluded, because used the PBU as a

feedback tool (n=3)

Studies included in qualitative synthesis

(n =6)

Figure 1: PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flow diagram of the literature search.

34


Table 2: Description of eligible studies.

Eligible studies Description of the sample Presence of low

back pain Clinimetric properties

tested Description of examiners

Time interval between tests

Assessment measures

Hodges et al., 1996 [12]

15 subjects (age 20-24 years, height 1.58-1.91 m, weight 58-85 kg. 9 men and 6

women)

6 subjects with LBP and 9 without LBP

Criterion validity No information No

information

EMG (measured latency TrA-DAa and

peak in 10 sec.) PBU (abdominal

hollowingb

maintained for 10 sec.)

Storheim et al., 2002 [15]

15 subjects (age 22.1 ± 2.45 years and body mass index 22.12 ± 2.1 kg/m2. 7 men

and 8 women)

No Reproducibility (intra-examiner reliability)

A single trained investigator blinded

to the previous measures

7 days Abdominal hollowing (maintained for 8-10

sec.)

Costa et al., 2004 [13] 29 subjects (age 22.7 ± 1.64 years and body mass index

22.82 ± 2.61 kg/m2) No

Reproducibility (intra-examiner reliability) and

Construct Validity

A single trained investigator blinded

to the previous measures

7 days

PBU (Abdominal hollowing maintained

for 8-10 sec.) Palpation test (deep tension maintained

for 10 sec.)

Figueiredo et al., 2005 [17]

31 subjects (age 23 ± 2.87 years, height 1.69 ± 10.4 m and weight 62.5 ± 13 kg)

No Reproducibility (intra and inter-examiner reliability)

2 trained examiners blinded to the

previous measures 7 days

Abdominal hollowing (reference value was obtained at the peak of contraction for 10

sec.)

Costa et al., 2006 [14]

29 subjects (age 22.7 ± 1.64 years, height 1.72 ± 0.09 m and weight 68.09 ± 1.13 kg)

No Reproducibility (intra-examiner reliability)

A single trained examiners blinded to

the previous measures

7 days Abdominal hollowing (maintained for 8-10

sec.)

von Garnier et al., 2009 [16]

40 subjects (age 44 ranging 24-62 years and body mass index 26 ranging 19-45

kg/m2)

Group with individuals who have had LBP

Reproducibility (intra and inter-examiner reliability

and agreement)

3 trained examiners, which are blind to the previous measures

Unclear

Abdominal hollowing (decrease of at least 1 mmHg maintained

for 4-10 sec.) a TrA-AD = transversus abdominal and anterior deltoid muscles; b Abdominal hollowing = voluntary contraction of the TrA muscle in the prone position.

35


The results and considerations differed among the eligible studies (Table 3). The ICC

(intraclass correlation coefficient), the kappa (coefficient) and the coefficient of variation

(CV%) were used to analyze the intra and inter-examiner reliability. Agreement was analyzed

by calculating the limits of agreement through Bland and Altman plots. Pearson’s r and

Spearman’s correlation coefficients were used to assess construct and criterion validity. In

regards to intra-examiner reliability, the ICC values ranged from 0.50 to 0.81 and the ICC

values to inter-examiner reliability ranged from 0.47 to 0.82. Correlation values assessing

validity ranged from 0.48 to 0.90.[12, 16] All studies used small sample sizes (ranging from 15

to 40 subjects) and only a pilot study was conducted prior to the main study for the sample

size calculation.[16]

36


Table 3: Results and limitations of the studies included in the review.

Eligible studies Results Limitations

Hodges et al., 1996 [12] Spearman's coefficient (r = 0.48 / p <0.07) Fisher's exact test (p <0.006)

Underpowered.


Wilcoxon test (p <0.09) Coefficient of variation (21%) Spearman's coefficient (r = 0.59)

Underpowered.

Costa et al., 2004 [13]

Intra-examiner reliability: ICC2,1 = 0.5 Pearson correlation coefficient (r = 0.5 / p <0.01) Adjusted correlation (r = 0.9 / p <0.01)

The categorizations of the palpation test and of the PBU were not

referenced. Underpowered.

Figueiredo et al., 2005 [17] Intra-examiner reliability: ICC2,1 = 0.71 Inter-examiner reliability: ICC2,1 = 0.82

Lack of CI (95%) for the ICC values Underpowered.

Costa et al., 2006 [14] Intra-examiner reliability: ICC2,1 = 0.58 (95% CI 0.28 to 0.78)

Underpowered.


Intra-examiner reliability: ICC = 0.81 (95% CI 0.67 to 0.90) and kappa = 0.68 (95% CI 0.35 to 1.00) Inter-examiner reliability: ICC = 0.47 (95% CI 0.20 to 0.68) and kappa = 0.38 (95% CI 0.03 to 0.73) Intra-examiner agreement: no statistical analysis Inter-examiner agreement: differences within the limits of agreement (95% CI)

Underpowered.

* ICC = intraclass correlation coefficient; kappa = kappa coefficient; PBU = pressure biofeedback unit; CI = confidence interval.

Table 4 shows the quality assessment of the 6 eligible studies, summarizing each

as positive; indeterminate; negative or no information. Most of the studies were classified as

negative or indeterminate. All studies classified as negative had insufficient statistical power

(i.e. sample sizes smaller than 50 participants[11, 23]) or had some important methodological

limitations (e.g., inclusion of healthy participants and lack description about examiners).[9, 24]

37


Table 4: Summary of assessment of the quality criteria of studies included in the review.a

Eligible studies Intra-examiner Agreement

Inter-examiner Agreement

Intra-examiner Reliability

Inter-examiner Reliability

Criterion Validity

Construct Validity

Hodges et al., 1996

[12]

0 0 0 0 - 0


0 0 - 0 0 0

Costa et al., 2004 [13]

0 0 - 0 0 +

Figueiredo et al., 2005 [17]

0 0 ? ? 0 0

Costa et al., 2006 [14]

0 0 - 0 0 0


? ? - - 0 0 a + = positive rating, ? = indeterminate rating, - = negative rating, 0 = no information available.

DISCUSSION

This review emphasizes the limitations of existing studies that analyzed the measurement

properties of the PBU as a measurement of the activity of the TrA muscle. Most studies have

assessed the intra-examiner reliability and few have evaluated the inter-examiner reliability

and agreement. This scenario is similar for validity studies; where there are only 2 published

articles: one comparing the PBU with fine wire electromyography and other with palpation

tests.[12, 13] No studies examined responsiveness or ceiling and floor effects.

In general, the quality assessments of the studies were classified as negative, since the

statistical values pre-established as criteria were not met. In relation to methodological

38


quality, can be highlighted as weaknesses the inclusion of healthy subjects in most of the

studies and small sample sizes.

The complete process of evaluation of the muscle activity of TrA muscle with the PBU has

several sources of error such as proper positioning of the patient in a prone position on a hard

surface (to minimize deformation of the mattress), the correct positioning of the PBU in the

lower abdomen, the uniform distribution of air in the 3 inflatable bags of the PBU and the

standardization of the verbal command to request the voluntary contraction of the TrA

muscle. It is also questioned whether the material of the bag would be totally inelastic and the

connection between the valve and the bag would be fully adequate to maintain an even

pressure without leakage. Furthermore, it should be acknowledged that normal variations in

the test and retest process can influence the performance of evaluation of muscle activity.

Because of this, it would be useful to examine whether changes in the assessment protocol

could increase the levels of reproducibility of pressure measurements of the PBU. Previous

studies on the reproducibility of measurement instruments for LBP patients have shown that

standardization of the protocol is likely to improve the reliability. [25, 26]

Methodological limitations in the studies may be focused in the sample and the evaluation

protocol. The studies used very small samples and only one study had performed a previous

pilot study.[16] To analyze the clinimetric properties of assessment tools, it is recommended

that a sample of at least 50 individuals[23] or carrying out a pilot study for posterior sample

size calculation.[9] The generalization of the findings from the study samples included in this

systematic review is critically limited because most studies recruited healthy subjects and

39


only one selected a mixed sample of patients with LBP and asymptomatic subjects.[12] Future

studies must attempt to these issues rather than testing an equipment in healthy

participants.[27]

The time interval between tests was mentioned in 4 studies as 7 days.[13-15, 17] The time period

between repetitions of the measures should be long enough to avoid the memorization of data

by examiners, but short enough to ensure that there were no clinical changes in the

participants. It is recommended that one or two weeks would be ideal, but there may be

reasons for the choice of another interval.[9]

The most used statistical test for reliability was the Intraclass Correlation Coefficient (ICC) (4

in 6 studies), which is the most appropriate choice to analyze the reliability for continuous

scales.[28] Choosing the best type of ICC depends on several factors, for example, if the

authors want to generalize their results to different examiners or not.[29] Only three studies

described the type of ICC used (type 2,1)[13, 14, 17] One of the studies did not provided the 95%

confidence intervals.[17] Another study used the coefficient of variation (CV%) to assess

reliability,[15] however, this statistical calculation is likely to provide overly optimistic

estimates for reliability, since it does not consider all aspects of the variance.[28, 29]

One study[16] evaluating agreement used Bland and Altman plots, and it was classified as

doubtful because lack of statistical power.[9, 10] The differences between the means of the

examiners were within the limits of agreement in 95% of cases, but as the differences between

repeated measurements (test-retest) were not normally distributed, the limits of agreement

could not be calculated.

40


One question that needs to be discussed is that many of the studies reported the reliability of

the average of repeated measurements. Even being an acceptable way to evaluate the

reliability of a measure, ultimately makes the measuring protocol longer. Similarly, it is worth

remembering that some studies used trained examiners, strict control of patient positioning

and selective isolation of the TrA muscle contraction. Although these elements are justifiable

and necessary for the purposes of scientific research, they limit the generalization of data for

clinical practice.[27]

This systematic review provided valuable information for researchers and clinicians on the

use of the PBU as a tool for assessing the activity of the TrA muscle. It is important to

clinicians understand that the current evidence of reproducibility and validity of

measurements taken from the PBU is limited. In addition, researchers must acknowledge that

the most important clinical questions about the measurement properties of the PBU for the

TrA muscle are yet to be answered, and further studies are needed.

Ethical Approval: Not applicable

Conflict of Interest: There are not conflicts of interests.

41


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14. Costa LOP, Costa Lda C, Cancado RL, Oliveira Wde M, Ferreira PH. Short report: intra-tester reliability

of two clinical tests of transversus abdominis muscle recruitment. Physiother Res Int. 2006 Mar;11(1):48-50.

15. Storheim K, Bo K, Pederstad O, Jahnsen R. Intra-tester reproducibility of pressure biofeedback in

measurement of transversus abdominis function. Physiother Res Int. 2002;7(4):239-49.

16. von Garnier K, Koveker K, Rackwitz B, Kober U, Wilke S, Ewert T, et al. Reliability of a test measuring

transversus abdominis muscle recruitment with a pressure biofeedback unit. Physiotherapy. 2009 Mar;95(1):8-

14.

17. Figueiredo MK, Chaves Júnior IP, Figueiredo VGC, Costa LOP, Costa LCM. Estudo da confiabilidade intra

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abdominal. Rev Bras Cienc Mov. 2005;13(4):93-100.

18. Costa LCM, Maher CG, McAuley J, Costa LOP. Systematic review of cross-cultural adaptations of McGill

pain questionnaire reveals a paucity of clinimetric testing. J Clin Epidemiol. 2009;62(9):934-43.

19. Costa LOP, Maher CG, Latimer J. Self-report outcome measures for low back pain - Searching for

international cross-cultural adaptations. Spine. 2007;32(9):1028-37.

20. Costa LOP, Maher CG, Latimer J, Smeets RJEM. Reproducibility of rehabilitative ultrasound imaging for

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22. Altman DG. Practical statistics for medical research. London: Chapman and Hall; 1991.

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24. Chiradejnant A, Maher CG, Latimer J. Objective manual assessment of lumbar posteroanterior stiffness

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25. Maher CG, Latimer J, Adams R. An investigation of the reliability and validity of posteroanterior spinal

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28. Armstrong GD. The intraclass correlation as a measure of interrater reliability of subjective judgments.

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29. de Koning CH, van den Heuvel SP, Staal JB, Smits-Engelsman BC, Hendriks EJ. Clinimetric evaluation of

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Musculoskelet Disord. 2008;9:142.

43


3. SEGUNDO ARTIGO

REPRODUCIBILITY OF PRESSURE BIOFEEDBACK UNIT IN THE TRANSVERSUS

ABDOMINIS MUSCLE ACTIVITY IN PATIENTS WITH CHRONIC NONSPECIFIC

LOW BACK PAIN

Artigo original foi submetido para publicação na Physiotherapy Research International

(ANEXO 2).

44


REPRODUCIBILITY OF PRESSURE BIOFEEDBACK UNIT IN THE

TRANSVERSUS ABDOMINIS MUSCLE ACTIVITY IN PATIENTS WITH

CHRONIC NONSPECIFIC LOW BACK PAIN

Pedro Olavo de Paula Limaa*, Rodrigo Ribeiro de Oliveiraa, Alberto Galvão de Moura Filhob, Maria Cristina

Falcão Raposoc, Leonardo Oliveira Pena Costad, Glória Elizabeth Carneiro Laurentinob.

a Master's Program in Physical Therapy, Federal University of Pernambuco and Department of

Physiotherapy, Federal University of Ceará, Brazil

b Department of Physiotherapy, Federal University of Pernambuco, Brazil

c Department of Statistic, Federal University of Pernambuco, Brazil

d Master's Program in Physiotherapy, University City of São Paulo, Brazil





Short title: Reproducibility of pressure biofeedback unit.

Word count: 3.238

45


ABSTRACT

Background: Pressure Biofeedback Units (PBU) are often used by clinicians and researchers

to indirectly evaluate the transversus abdominis (TrA) muscle activity in patients with low

back pain. Previous studies evaluating the reproducibility of PBU have provided important

information, however some clinically relevant questions have not been fully clarified. Little is

known about the reproducibility of PBU in a clinically relevant sample, with an adequate

sample size and using a standardized assessment protocol.

Objectives: The purpose of this study was to evaluate the reproducibility of PBU in the TrA

muscle activity in patients with chronic nonspecific low back pain.

Methods: Fifty patients with chronic nonspecific low back pain were recruited for this study.

Participants were on average 22 years old, weighed 63.7 kilos, 1.70 meters height and mean

low back pain duration was 1.9 years. To test the inter-examiner reproducibility,

measurements were performed by two physiotherapists and to test the intra-examiner

reproducibility, one of them performed two measures of the TrA muscle activity on two

different occasions with a seven-day interval between tests.

Results: It was observed a Intraclass Correlation Coefficients (ICC2,1) of 0.74 (95%

Confidence Intervals - CI 0.54 to 0.85) and 0.76 (95% CI 0.58 to 0.86) for the intra and inter-

examiner reproducibility, respectively. The intra-examiner agreement (Limits of Agreement -

LOA = 2.1 to -1.8 mmHg) and the inter-examiner agreement (LOA = 2.0 to -1.9 mmHg) were

within the limits of agreement in 95% of occasions. The standard error of measurement

(SEM) was 1.62 mmHg and smallest detectable change (SDC) was 4.49 mmHg.

46


Conclusion: The reproducibility of PBU in the TrA muscle activity in patients with chronic

nonspecific low back pain ranged from satisfactory to excellent. Other clinimetric properties

(such as validity) of PBU should be an important topic for future investigations

Keywords: pressure biofeedback unit, transversus abdominis muscle, reproducibility,

reliability, agreement.

47


INTRODUCTION

The use of motor control exercises (also known as specific stabilization exercises)

has became very popular in clinical practice for the treatment of nonspecific low back pain(1-

4). The rationale for the use of motor control exercises is that the deep muscles of the

abdominal wall have a key role in dynamic control of the lumbar spine(5,6), being observed a

delay in onset of activation of the transversus abdominis (TrA) muscle in patients with

recurrent low back pain compared to asymptomatic controls(5,7).

Most studies that measured the muscle activity of the deep abdominal wall

muscles used fine-wire electromyography(8). However, this type of exam is invasive, painful,

uncomfortable, expensive and may present risks of infection(9,10). Thus, the pressure

biofeedback unit (PBU) has been used as an alternative approach to indirectly measure the

muscle activity(9,11,12). In physiotherapy, PBU is usually used to evaluate the activity of the

abdominal and neck muscles as well as serves as biofeedback tool for patients undertaking

motor control exercise interventions(13).

In order to be useful, PBU measures need to have acceptable clinimetric

properties such as reproducibility. Reproducibility is the degree to which repeated

measurements provide similar results in clinically stable patients and serves as an umbrella

term for reliability and agreement(14). Agreement can be defined as the degree to which scores

on repeated measurements are close to each other (absolute measurement error). Reliability

can be defined as the degree to which individuals can be distinguished from each other,

despite the measurement error (relative measurement error)(14,15).

Previous studies(8,9,16-19) that evaluated the reproducibility of PBU in the TrA

muscle activity answered some, but not all questions about the use of this test to guide the

48


clinical management of low back pain, being most of them sampled solely healthy

individuals(9,16-18). Only the studies conducted by Hodges; Richardson and Jull(8) and von

Garnier(19) recruited volunteers with a previous history of back pain. Although some authors

have concluded that PBU provides reproducible measures of the TrA muscle activity, their

results are questionable due to the suboptimal methodological quality, such as small sample

sizes; lack of standardization of the assessment protocol; recruitment of healthy subjects and

insufficient statistical power(9,16-19). Despite the reproducibility of PBU has already been

evaluated in previous studies, lack of consensus among several authors does not allow us to

consider the results as conclusive. Moreover, just few studies sampled participants with low

back pain, which is one of the target conditions for the use of PBU.

Therefore, this study aimed to evaluate the intra and inter-examiner

reproducibility of PBU in the TrA muscle activity in patients with chronic nonspecific low

back pain.

METHODS

This study was performed in a test-retest design(20), and it was carried out at the

Laboratory of Kinesiology and Functional Assessment of the Department of Physiotherapy of

Federal University of Pernambuco, Brazil in 2009.

The sample was selected among students of Federal University of Pernambuco

with chronic nonspecific low back pain. The sample size was estimated based on the

recommendations of specific guidelines on clinimetric properties that suggest a sample of at

least 50 individuals for reproducibility studies(14).

49


We included participants with chronic nonspecific low back pain for more than

three months. We excluded participants who had acute low back pain (i.e., an episode of low

back pain of less than 6 weeks), were pregnant, previous abdominal wall or spine surgery,

body mass index (BMI) over 25, were menstruation during the tests and suspected or

confirmed neurological and musculoskeletal pathologies in the pelvis and/or spine.

Participants who missed consecutive tests were also excluded.

Measurements were performed by two physiotherapists in order to test the inter-

examiner reproducibility of PBU. In order to avoid exchanging of information between the

examiners, none of them was present during measurements performed by the other examiner.

For the study of intra-examiner reproducibility, one of examiners conducted two

measurements of the TrA muscle activity on two different occasions, with an interval of seven

days between tests to reduce recall. The examiners were previously trained and were blind to

the measures collected from each other(14).

All participants received basic information about anatomy, biomechanics and

functions of the TrA muscle, as well as on the procedure of testing and training of the TrA

muscle contraction. Selected subjects were previously scheduled to the following instructions:

fasting for 2 hours prior to testing (including water), emptying the bladder immediately before

test and not performing abdominal exercises prior to the tests(9). In both tests, participants and

examiners have adopted the same clinical, environmental and temporal conditions to avoid

external influences or internal errors during data collection. Participants were positioned on

prone position on a hard surface, with lower limbs positioned with feet off the plinth and with

the upper limbs along the body.

Thereafter, the inflatable bag was placed between the anterior superior iliac spine

and navel. Before starting of contraction, the bag was inflated to a pressure of 70 mmHg with

50


the valve closed. Participants were instructed to make some deep breaths using mainly the

abdominal wall, then the inflatable bag was adjusted to 70 mmHg again. Patients were

requested to perform three TrA muscle contractions with the following verbal commands

standardized by examiner: "Draw in your abdomen without moving the spine or pelvis".

These contractions were maintained for ten seconds(9) According to the manufacturer of PBU

(Stabilizer®, Chattanooga Group Inc., Hixson, TN, USA), the ability to contract the TrA

muscle results in a pressure reduction from 4 to 10 mmHg, which was recorded by the

pressure gauge of PBU(12) (Figure 1). Thus, based on this information and previous research

on the subject a pressure reduction of at least 4 mmHg was defined as a positive result

(success)(8,9).

Figure 1: Pressure Biofeedback Unit (STABILIZER®).

51


All information were recorded using a digital evaluation form provided by

specific software (Miograph®). Pain intensity was measured by the Pain Numerical Rating

Scale and disability was measured by the Roland Morris Disability Questionnaire, both

adapted and clinimetrically tested for Brazilian-Portuguese speakers(21-23).

The sample characteristics was described by using descriptive statistics(24). To

describe the reliability, we used the Intraclass Correlation Coefficient (ICC2,1), ICC values

lower than 0.4 can be classified as poor, values between 0.4 and 0.7 are classified as

satisfactory and over 0.7 are classified as excellent(15). We used three measures of agreement:

Bland and Altman plots(25), Standard Error of the Measurement (SEM) and Smallest

Detectable Change (SDC). The SEM was calculated by dividing the standard deviation of the

mean differences between two measurements by the square root of 2 (SD differences/√2) and

the SDC was calculated using the formula SDC = 1.96 x √2 x SEM. The SEM reflects the

error of the instrument itself and the SDC reflects the smallest within person change in a score

that can be interpreted as a ‘‘real’’ change, above measurement error one of an individual(15).

Data were analyzed with SPSS software (Statistical Package for Social Sciences) version

15.0.

This study was approved by the Research Ethics Committee (# 00490236000-09).

RESULTS

In total, 57 participants were evaluated, of whom seven were excluded for not

attending on second test day, therefore 50 individuals were analyzed.

52


Sample characteristics are presented in Table 1.

Table 1. Sample characteristics.

VARIABLES Mean (SD)

Gender (N, %) Female 38 (76%)

Male 12 (24%)

Age (years) 22 (2.3)

Low back pain duration (years) 1.9 (3.4)

Weight (kg) 62.7 (12)

Height (m) 1.7 (0.1)

Pain Intensity Numerical Rating Scale (0-10) 5.1 (1.8)

Roland Morris Disability Questionnaire (0-24) 9.1 (5.9)

Examiner A obtained mean pressure values of -4.1 (2.4) mmHg and -4.9 (2.9)

mmHg on first test day (Test 1) and second test day (Test 2), respectively. Examiner B

obtained a mean of -4.7 (3.1) mmHg. The difference between the means of Examiner A (Test

1 - Test 2) was 0.79 (2.3) mmHg with a ICC2,1 = 0.74 (95% CI 0.54 to 0.85). The difference

between the means of two examiners (Examiner A - Examiner B) was -0.14 (2.6) mmHg with

a ICC2,1 = 0.76 (95% CI 0.58 to 0.86). The SEM was 1.62 mmHg and SDC = 4.49 mmHg

(Table 2).

53


Table 2. Reliability and agreement for pressure measures.

Measures Mean (SD)

mmHg ICC (95% CI)

SEM

mmHg

SDC

mmHg

PBU Examiner A (Test 1) -4.1 (2.4) -

PBU Examiner A (Test 2) -4.9 (2.9) -

PBU Examiner B -4.7 (3.1) -

Examiner A (Test 1 – Test 2) 0.79 (2.3) 0.74 (0.54 to 0.85) 1.62 4.49

Examiner A – Examiner B -0.14 (2.6) 0.76 (0.58 to 0.86)

* SD= standard deviation; ICC= intraclass correlation coefficient; SEM= standard error of the measurement; SDC= smallest detectable change.

Bland and Altman plots for intra-examiner agreement of Examiner A (test 1 - test

2) showed limits of agreement ranging between 2.1 and -1.8 mmHg (Figure 2). In the case of

inter-examiner agreement for pressure changes, limits of agreement ranged between 2.0 and -

1.9 mmHg, as shown by the Bland and Altman plots (Figure 3).

Figure 2. Bland and Altman plots for pressure measures of Examiner A (test 1 – test 2).

54


Figure 3. Bland and Altman plots for pressure measures of Examiner A and Examiner B.

DISCUSSION

In this study, the results of measurements of PBU in the TrA muscle activity

during voluntary contraction maneuver in patients with chronic nonspecific low back pain

showed reproducibility indices that ranged from satisfactory to excellent for both the intra-

examiner and inter-examiner.

The use of PBU by physiotherapists as a feedback tool for the evaluation of

patients with chronic nonspecific low back pain has increased over the last decade. In clinical

practice, it is common that a patient is evaluated several times by the same examiner or by

different professionals. Therefore, it is important that measures and instruments used by the

same examiner on different occasions and by different examiners are reproducible(26).

With regards to intra-examiner reliability, the ICC2,1=0.74 reflected an excellent

reliability of the measures of the TrA muscle, similar results were found in most studies in

55


literature about the topic(9,17-19). However, this finding was not consensual, given the results

obtained by Storheim et al.(16) which the intra-examiner reliability was considered poor. This

discrepancy may be related to differences in some methodological aspects used in both

studies, as sample size and sample subjects, standardization of breathing during the

assessment protocol and methods of statistical analysis. Storheim et al.(16) recruited a sample

of 15 healthy subjects, did not standardized the breathing during the assessment protocol and

data analysis was performed by the coefficient of variation, unlike the present study that used

the Intraclass Correlation Coefficient.

Likewise, the inter-examiner reliability of PBU achieved excellent results (ICC2,1

= 0.76), corroborating with findings obtained by Figueireiro et al.(17) that found an ICC of

0.82. However, our results were different with the ones obtained by von Garnier et al.(19) with

ICCs ranging from 0.20 to 0.68 (poor to satisfactory).

Although some precautions have been taken in order to reduce the error of

measurements of PBU (extensive training of examiners and the use of the same equipment in

all measurements), different results were observed when compared with some previously

published studies. Perhaps these differences regarding to the reliability of PBU were related to

the different criteria adopted in each study to define how the pressure data would be collected

in evaluation test with the PBU. While Richardson; Hodges and Hides(27) collected a pressure

reduction of 4 to 10 mmHg for 10 seconds, Costa et al.(18) collected only the peak of pressure

reduction maintained for 2 seconds within a period of 10 seconds. Storheim et al.(16) also

recorded the maximum pressure reduction of at least 2 seconds within a period of 8 to 10

seconds. In contrast, von Garnier et al.(19) performed in their data collection a set of four

criteria that participants would have to fulfill for the correct TrA muscle contraction:

continuous breathing, absence of muscle substitution maneuvers, appropriate muscle

56


contraction checked by palpation test and pressure reduction of at least 1 mmHg for 4 seconds

within a period of 10 seconds. In summary, it was observed that some authors collected only

peak of muscle contraction while others have collected the most stable values for a certain

time. The results of this study showed that approximately 40% of participants were not able to

achieve positive results, similar to previous studies where it was found that people with a

history of chronic nonspecific low back pain have difficulty to perform a correct contraction

of the TrA muscle(28-30). Cairns et al.(31) evaluating two groups (symptomatic and healthy

subjects) with the PBU noted that pressure results obtained for group of patients with low

back pain were different from those obtained for the group with healthy subjects, confirming

the importance of checking clinimetric properties of PBU in a homogeneous sample

composed of patients with chronic nonspecific low back pain.

Adoption of different criteria for pressure data collection in some studies might

cause a tendency to reduce the reliability of PBU. Considering the information provided by

manufacturer of PBU, the literature and different criteria used in previous studies, the most

appropriate criteria to determine success of this test remain unclear. Furthermore, another fact

to consider is the standardization in the assessment protocol, which has shown to improve the

reproducibility of other processes of evaluation in patients with low back pain(32-34).

Most studies about reproducibility of PBU used seven days as interval period

between tests(9,16-18), same time used in our study. Time periods between the repeated

measurements should be long enough to avoid recall of data by the investigators, but short

enough to ensure there are no clinical changes in the participants(14). However, in all analysis

of assessment instruments it is possible that learning effects influence the results on the

second day of tests. The time interval between the first and second test is also an attempt to

limit this bias in this type of research(35).

57


In order to facilitate the comparison of results of this study with the majority of

investigations about clinimetric properties, we decided to estimate the reliability from the

average of three measures. This fact could constitute a potential difficulty in generalizing our

findings because, in clinical practice, is usual to consider simple measures to evaluate with the

PBU. However there is evidence that use of repeated measures is the best way to reduce error

and consequently increase the reproducibility(10,34).

The findings of Bland and Altman plots showed excellent intra-examiner

agreement (Limits of Agreement - LOA = 2.1 to -1.8 mmHg), indicating that measures related

to the first test were in agreement with the second test in 95% of occasions. Similarly, we

found excellent inter-examiner agreement (LOA = 2.0 to -1.9 mmHg), which means that

measures relating to Examiner A were in agreement with the Examiner B in 95% of

occasions. Results showed a SEM of 1.62 mmHg and a SDC of 4.49 mmHg, which means

that the absolute measurement error of PBU is around 1.62 mmHg, and there would need to

be at least an 4.49 mmHg improvement in the TrA muscle activity to make sure that a true

change has occurred(10,15). Although considering agreement values (SEM and SDC) for

pressure measurements, it is important to consider that there is no normative data in the

literature that could allow the determination of the minimal important change (MIC). Ideally

would be that the SDC is smaller than MIC(15), however these values are not available in the

literature.

Influence of breathing in the evaluation of patients with chronic nonspecific low

back pain with PBU was unknown until recently. Lafond et al.(36) investigated this influence

for the clinical assessment of lumbar postural control and concluded that there are significant

differences between pressure measurements collected during breathing and apnea, with higher

values during breathing. They also found that in order to ensure acceptable reliability during

58


apnea with ICC=0.8, this requires at least three repeated measures. Thus, how the breathing

might lead to misinterpretation of performance during the test with the PBU, clinicians should

be alert to standardization of assessment protocol during collections. There is a tendency that

participants without guidance as to breathing correctly, to make a TrA muscle contraction

associated with apnea(31). However, it has been demonstrated that data collection performed at

the end of expiratory time, could reduce contamination of results(37).

CONCLUSION

The intra and inter-examiner reproducibility of measures of PBU in the TrA

muscle activity, during voluntary contraction maneuver in patients with chronic nonspecific

low back pain ranged from satisfactory to excellent. It is suggested that other clinimetric

properties (such as validity) of PBU should be an important topic for future investigations.

Conflict of Interest: There are no conflicts of interests.

59


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4. TERCEIRO ARTIGO

VALIDITY OF PRESSURE BIOFEEDBACK UNIT IN THE TRANSVERSUS


LOW BACK PAIN

Artigo original foi submetido para publicação na Physiotherapy Theory and Practice

(ANEXO 3).

62


VALIDITY OF PRESSURE BIOFEEDBACK UNIT IN THE TRANSVERSUS


LOW BACK PAIN

Pedro Olavo de Paula Limaa*, Rodrigo Ribeiro de Oliveiraa, Alberto Galvão de Moura Filhob, Maria Cristina

Falcão Raposoc, Leonardo Oliveira Pena Costad, Glória Elizabeth Carneiro Laurentinob.

a Master's Program in Physical Therapy, Federal University of Pernambuco and Department of

Physiotherapy, Federal University of Ceará, Brazil

b Department of Physiotherapy, Federal University of Pernambuco, Brazil

c Department of Statistic, Federal University of Pernambuco, Brazil

d Master's Program in Physiotherapy, University City of São Paulo, Brazil





63


ABSTRACT

Background: Pressure biofeedback unit (PBU) is an assessment tool used in clinical practice

and research to indirectly analyze the transversus abdominis (TrA) muscle activity in patients

with low back pain. Studies investigating the validity of PBU are very scarce. The validity of

PBU in a clinically relevant sample is still unclear.

Objectives: To evaluate the validity of PBU in the TrA muscle activity in patients with

chronic nonspecific low back pain.

Methods: Fifty patients with chronic nonspecific low back pain were recruited for this study.

To test the validity both pressure measures (index test) and superficial electromyographic

measures (reference-standard test) were collected by a physiotherapist from a voluntary

contraction maneuver of TrA muscle.

Results: Participants were on average 22 years old, weighed 63.7 kilos, 1.70 meters height

and mean low back pain duration was 1.9 years. It was observed a weak and non-significant

Pearson correlation coefficient (r=0.2, p<0.20) for the validity. With regards to diagnostic

tests, results suggest a low sensitivity (60%) and specificity (40%) of PBU. The positive

predictive value was high (0.8) and negative predictive value was low (0.2).

Conclusion: The validity of PBU in the TrA muscle activity in patients with chronic

nonspecific low back pain is poor, considering that there is no statistically significant

correlation between pressure data and electromyographic data.

Keywords: pressure biofeedback unit, transversus abdominis, diagnostic tests, validity.

64


INTRODUCTION

Low back pain is considered as a major public health problems and is associated

with high socioeconomic costs, work absenteeism and disability(1,2). Usually, acute low back

pain presents a satisfactory outcome and most patients return to their activities between 4-8

weeks, although recurrence is a common finding(3). Approximately 10-40% of cases of low

back pain become chronic and, despite several etiologic factors, most of them (85%) are

classified as nonspecific. Patients who develop chronic nonspecific low back pain (i.e.,

persistent pain and disability for more than three months) are responsible for more than 80%

of health care that are spent for spinal problem(4,5). European guidelines recommend motor

control exercises and spinal manipulative therapy as possible choices for the clinical

management of chronic nonspecific low back pain(6-8).

A delay in the onset of activation of the transversus abdominis (TrA) muscle has

been observed in patients with recurrent low back pain compared to asymptomatic

controls(9,10). In general, one of most used methods for measuring muscle activity of the deep

abdominal wall is fine-wire electromyography. However, some factors such as high cost,

pain, discomfort and risk of infection make the use of this method less accessible in clinical

practice. Thus, other valid instruments that are noninvasive and low cost could be useful to

measure the TrA muscle activity favoring the clinical management of the patients with

chronic nonspecific low back pain(11,12). Accordingly, pressure biofeedback unit (PBU) could

be considered as an alternative approach to indirectly measure the TrA muscle activity(13-15).

It is necessary that pressure measures of the abdominal muscle activity have

minimum validity indices to be useful. Validity is the degree to which the measure represents

the phenomenon of interest, and refers to how much an instrument measures what it would be

supposed to measure(16). Thus, when an instrument undergoes a validation process, in fact is

65


not the instrument itself that is being validated, but the purpose for which the instrument is

being used(17). There are four types of validity described in the literature: face, content,

construct and criterion validity. Validity is observed when it evaluates to how much the score

of a particular instrument correlates to other instrument for the same purpose(17-19).

Clinimetric properties of PBU in the TrA muscle activity have been discussed in

previous studies(13,20-24), but most of them sampled solely healthy individuals(13,21-23). Only the

studies conducted by Hodges; Richardson; Jull(20) and von Garnier(24) recruited subjects with a

history of low back pain. Of the six studies, only one(20) investigated the validity and, despite

the authors have concluded that PBU provides valid measures, their findings are questionable

due to the suboptimal methodological quality, such as small sample size (n=15), use of

different motor tasks to assess the TrA muscle activity and insufficient statistical power(20).

Findings from scientific research are more accepted when different studies investigate

the effects of an intervention or test, obtain similar conclusions(25). Thus, clinimetric

properties of the measures should be studied and presented for that the quality of the results

can be evaluated.

Therefore, considering the importance of the use of validated measures that can

support clinical practice and considering the scarce of studies concerning to validation of the

PBU in a clinically relevant sample, the purpose of this study was to evaluate the validity of

PBU in the TrA muscle activity in patients with chronic nonspecific low back pain.

66


METHODS

This study was performed as a validation design(26), and it was carried out at the

Laboratory of Kinesiology and Functional Assessment of the Department of Physiotherapy of

Federal University of Pernambuco, Brazil in 2009.

The sample was selected among students of Federal University of Pernambuco

with chronic nonspecific low back pain. The sample size was estimated based on the

recommendations of specific guidelines on clinimetric properties that suggest a sample of at

least 50 individuals for validation studies(18).

We included participants with chronic nonspecific low back pain for more than

three months. We excluded participants who had acute low back pain (i.e., an episode of low

back pain of less than 6 weeks), were pregnant, previous abdominal wall or spine surgery,

body mass index (BMI) over 25, were menstruation during the tests and suspected or

confirmed neurological and musculoskeletal pathologies in the pelvis and/or spine.

All participants received basic information about anatomy, biomechanics and

functions of the TrA muscle, as well as on the procedure of testing and training of TrA muscle

contraction. Selected subjects were previously scheduled to the following instructions: fasting

for 2 hours prior to testing (including water), emptying the bladder immediately before test

and not performing abdominal exercises prior to the tests(13). In both tests, participants and

examiners have adopted the same clinical conditions, environmental and temporal to avoid

external influences or internal errors during data collection. Participants were positioned on

prone position on a hard surface to minimize deformation of the foam.

To test the validity of PBU, surface electromyography (EMG) was considered as

the reference-standard test, based on the findings of previous studies on the topic(27-29) and

67


considering the questions of the ethics committees. For all patients, was initially performed

the surface EMG (Miotec® Miotool 400) under the conditions described below. Before

placing the electrodes, detection surfaces were properly cleaned, exfoliated and, when

necessary, a trichotomy was performed following the recommendations of SENIAM (Surface

Electromyography for Non Invasive Assessment of Muscles)(30) to allow a low impedance

between the skin and the electrodes. The bipolar surface electrodes (Ag/AgCl - Meditrace®)

were placed with a distance of 20 mm between their centers, and placed at right side in the

area corresponding to the TrA/OI (transversus abdominis/internal oblique) muscles, located 2

cm the anterior superior iliac spine, following the instructions established by Hodges;

Gandevia; Richardson(29) and adapted by Chanthapetch et al.(28). The reference electrode was

placed in the right lateral epicondyle. Participants were positioned on supine position with

knees flexed to 90°.

The first step was a recording of 30 seconds at rest to detect the parameters of

electromyographic silence (basal tonus). Then, it was performed the protocol of maximal

voluntary isometric contraction (MVIC) in agreement with the standards of SENIAM(30):

three contractions of 5 seconds with intervals of 3 seconds between each contraction, with

three replications (i.e., total of nine contractions). Each individual had one minute of rest

between repetitions. To finish the electromyographic collection was requested a TrA muscle

contraction maintained for 10 seconds. Overall, there were five electromyographic records.

The signs of electrical activity of TrA muscle were collected and transmitted to a monitor that

was connected to the EMG equipment. EMG data were sampled at 1000 Hz over a bandwidth

of 20-450 Hz (band-pass filter). The raw EMG signals generated were analyzed using the root

mean square (RMS). EMG data were normalized by the percentage of MVIC and significant

68


electromyographic activity (positive result - success) was defined as an activity at least 10%

of the MVIC(31,32).

After obtaining EMG recordings and respecting an interval of 15 minutes, was

initiated to measure of the TrA muscle activity through the PBU. Participants were positioned

on prone position and the inflatable bag was placed between the anterior superior iliac spine

and navel. Before starting the contraction, the bag was inflated to a pressure of 70 mmHg with

the valve closed. Participants were instructed to breathe deeply using mainly abdominal wall,

then the inflatable bag was adjusted to 70 mmHg again. Patients were requested to perform

three TrA muscle contractions with following verbal commands standardized by examiner:

"Draw in your abdomen without moving the spine or pelvis". These contractions were

maintained for ten seconds(13). According to manufacturer of PBU (Stabilizer®, Chattanooga

Group Inc., Hixson, USA), the ability to contract the TrA muscle results in a pressure

reduction from 4 to 10 mmHg, which was recorded by pressure gauge of PBU(15). Thus, based

on this information and previous research on the subject was defined as a positive result

(success) a pressure reduction of at least 4 mmHg (Figure 1).

69


Figure1: Pressure Biofeedback Unit (STABILIZER®).

All information was recorded using a digital evaluation form provided by specific

software (Miograph®). Pain intensity was measured by the Numerical Pain Rating Scale and

disability was measured by the Roland Morris Disability Questionnaire, both adapted and

clinimetric tested for Brazilian-Portuguese speakers(33-35).

Description of sample characteristics was performed by using descriptive

statistics(36). To analyze the validity, we used the Pearson Correlation Coefficient, whose

values range from -1 to 1 and if it lower than 0.5 can be classified as weak, values between

0.5 and 0.7 are classified as moderate and over 0.7 are classified as strong correlation(37). The

relationship between the TrA muscle contraction maintained for 10 seconds measured by the

surface EMG (%MVIC) and the scores of pressure reduction measured by the PBU (mmHg)

was the specific hypothesis formulated to analyze the validity. We hypothesized that the PBU

(index test) would have a moderate and positive correlation with the surface EMG (reference-

70


standard test)(18,38). Furthermore, we calculated the values of diagnostic tests, such as

sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV).

Data were analyzed with software SPSS (Statistical Package for Social Sciences) version

15.0, considering the significance level of p<0.05 in all calculations.

This study was approved by the Research Ethics Committee (# 00490236000-09).

RESULTS

Sample characteristics are presented in Table 1.

Table 1. Sample characteristics.

VARIABLES*

Gender (N, %) Female 38 (76%)

Male 12 (24%)

Age (years) 22 (2.3)

Low back pain duration (years) 1.9 (3.4)

Weight (kg) 62.7 (12)

Height (m) 1.7 (0.1)

Pain Intensity Numerical Rating Scale (0-10) 5.1 (1.8)

Roland Morris Disability Questionnaire (0-24) 9.1 (5.9)

* Continuous data are mean (SD).

71


The measures performed through the surface EMG and the PBU are presented in

Table 2.

Table 2. Description of the pressure measures and electromyographic measures in the TrA muscle activity.

VARIABLES Mean (SD)

Pressure Measures

PBU (mmHg) - 4.1 (2.4)

Electromyographic Measures

MVIC* (µV) 127.1 (95.5)

MVIC (%) 100

Rest (µV) 2.3 (1.9)

Rest (%) 2.9

Contraction maintained for 10 seconds (µV) 29.6 (21.8)

Contraction maintained for 10 seconds (%) 24.4 * MVIC: maximal voluntary isometric contraction.

According to predetermined criteria to characterize the results as positive

(success), 31 (62%) patients received similar ratings by the two assessment instruments, but

19 (38%) were classified as false-positive (8%) and false-negative (30%), which shows a

weak and non-significant correlation of r=0.2 (p<0.20) between the ratings of PBU and

surface EMG (Table 3).

72


Table 3. 2x2 Table between the PBU ratings and the surface EMG ratings.

EMG

(reference-standard test)

Positive Negative Total

PBU

(index test)

Positive 25 (50%) 4 (8%) 29 (58%)

Negative 15 (30%) 6 (12%) 21 (42%)

Total 40 (80%) 10 (20%) 50 (100%)*

* Pearson Correlation Coefficient (r=0.2, p<0.20).

Regarding to the diagnostic tests, the results showed low sensitivity (60%), low

specificity (40%), a high PPV (0.8) and a low NPV (0.2) of the PBU.

DISCUSSION

The findings showed a poor validity of PBU in the TrA muscle activity during

voluntary contraction maneuver in patients with nonspecific chronic low back pain. In

scientific research or clinical practice the usefulness of a measure depends on how much we

can rely on the accuracy of your data as indicators of the behavior or the phenomenon

assessed. Ideally, any measurement should be practical, easy to obtain and able to produce

reliable and valid data, since no consistent measures produce unreliable results, leading to

erroneous conclusions(39).

With regards to the correlation between the ratings of PBU and surface EMG, the

high disagreement of 38% showed that the pressure data are not statistically correlated to the

EMG data (r=0.2, p<0.20)(37). Similar results were found by Hodges; Richardson and Jull(20),

73


who preliminarily found a no significant correlation between the absolute magnitudes of PBU

and fine-wire EMG (r=0.48, p<0.07) but subsequently showed that the same data, when

converted into an ordinal scale to classify the two measures had high probability of being

correlated. Methodological differences can be used as a possible explanation for these

conflicting results, since in the study by Hodges; Richardson and Jull(20), while the PBU was

used to evaluate the presence of the TrA muscle activity, EMG was used to evaluate the

latency period between the onset of contraction of the TrA and anterior deltoid muscles (i.e.,

the instruments evaluated distinct phenomena). In this study, the two instruments (PBU and

surface EMG) were used to evaluate the same phenomenon (presence of the TrA muscle

activity).

The scarcity of studies investigating the validity of PBU makes it harder to

perform a detailed analysis of our results. Besides the study of Hodges; Richardson and

Jull(20) other research conducted by Costa et al.(13) tried to estimate the construct validity of

PBU in relation to a palpation test, and showed a positive and significant correlation between

the two tests (r=0.99, p<0.01). However, it is observed that their study compared two clinical

tests and did not take into account any laboratory finding, and its results are questioned by

Richardson et al.(40). In 2003, Falla and other researchers(41) found a correlation of 0.56

(p<0.001) between pressure data and electromyographic data (contact electrodes attached to a

suction catheter), but this study was conducted in individuals with chronic nonspecific neck

pain, unlike our sample of chronic low back pain participants.

The possibility of existence of the phenomenon of cross-talk would be a likely

explanation for the weak correlation observed between the instruments, however the

SENIAM(30) assumes that the placement of the surface electrodes could collect the

electromyographic signals from the TrA and OI muscles.

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Among the many factors that can affect the outcome measure, the lack of

standardization of methodology is often referred to as an important source of error. In this

sense, the definition of certain criteria, which may be adopted as a benchmark to be followed,

is essential for a critical assessment as the best evidence available when different studies

investigating the effects of a test(17,25,26). One finding during the development of this study

was the absence of a benchmark for defining what would be considered "positive result" and

"negative result" of the PBU. There is no guidance in the literature in this direction, so that

different criteria were used by several authors(13,20-24,42). This fact may explain, at least as

likely hypothesis, this lack of consensus among studies on the validity of PBU. Considering

the information provided by manufacturer of PBU, the literature and different criteria used in

previous studies, the most appropriate criteria to determine success of this test remain unclear.

Accordingly, it is necessary to establish the criterion of pressure reduction more appropriately

to standardize the PBU test results(17,26,43,44).

Regarding to the diagnostic tests, the results showed a low sensitivity (60%) with

small ability of PBU detecting the TrA muscle activity when it is present, also showed a low

specificity (40%) with small ability of PBU to rule out the TrA muscle activity when it is

absent. Based on these results we can infer that the pressure measures were not sensitive to

discriminate the presence of the TrA muscle activity and were not specific to identify the

absence of the same muscle activity, making questionable the usefulness of PBU to evaluate

the TrA muscle activity in patients with chronic nonspecific low back pain(44,45). With regards

to diagnostic tests, the high PPV (0.8) found, ensures that if result of PBU is positive, the

chance to be a real TrA muscle activity is 80%. While the low NPV (0.2) does not assume

that the negative tests of PBU represent absence of the TrA muscle activity, since if results of

PBU are negative, the chance that there is no TrA muscle activity is only 20%.

75


CONCLUSION

Therefore, based on the results observed and the literature, it is emphasized that

there was no evidence sufficient to support the validity of PBU in the TrA muscle activity in

patients with chronic nonspecific low back pain.

Conflict of Interest: There are no conflicts of interests.

76


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5. CONCLUSÕES

As evidências encontradas, até a realização da revisão sistemática, sobre as

propriedades clinimétricas da UBP na atividade do músculo TrA eram limitadas. Abordagens

metodológicas questionáveis não permitiam que os achados da literatura fossem considerados

conclusivos. As principais restrições para generalização dos resultados observados eram:

tamanho amostral reduzido, falta de padronização do protocolo de avaliação, recrutamento de

indivíduos saudáveis e poder estatístico insuficiente. Estudos avaliando as propriedades

clinimétricas da UBP têm fornecido informações importantes, entretanto algumas questões

clinicamente relevantes ainda não foram totalmente esclarecidas. Pouco se sabe sobre a

reprodutibilidade e validade da UBP em uma amostra de pacientes com dor lombar crônica

inespecífica, com tamanho adequado e protocolo de avaliação padronizado.

As medidas da UBP na atividade do músculo TrA, durante a manobra de

contração voluntária em pacientes com dor lombar crônica inespecífica, apresentaram

reprodutibilidade intra-examinador e inter-examinador variando de satisfatória a excelente.

Na prática clínica, isso significa que um paciente com dor lombar crônica inespecífica pode

ser avaliado por um único fisioterapeuta em momentos distintos. Assim como, esse mesmo

paciente pode ser avaliado por fisioterapeutas diferentes e obter o mesmo diagnóstico

cinesiológico.

As medidas da UBP na atividade do músculo TrA, mediante comparação com os

dados eletromiográficos em pacientes com dor lombar crônica inespecífica, não apresentaram

evidências suficientes que possam comprovar sua validade. Esse achado sugere que a

aplicabilidade clínica da UBP em pacientes com dor lombar crônica inespecífica não é

80


indicada. Os critérios de redução pressórica mais adequados para determinar o sucesso

(resultado positivo) do teste com a UBP permanecem obscuros.

Sugere-se para futuras investigações, a determinação de um ponto de corte mais

adequado para avaliar e classificar os resultados obtidos pela UBP.

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APÊNDICE

82


APÊNCIDE A

TERMO DE CONSENTIMENTO LIVRE E ESCLARECIDO.

TÍTULO: PROPRIEDADES CLINIMÉTRICAS DA UNIDADE DE BIOFEEDBACK PRESSÓRICO NA AVALIAÇÃO DA ATIVIDADE MUSCULAR DO TRANSVERSO ABDOMINAL EM PACIENTES COM DOR LOMBAR CRÔNICA INESPECÍFICA.

INVESTIGADOR: Drª. Glória Elizabeth Carneiro Laurentino.

Nome completo do local de estudo: Laboratório de Cinesiologia e Avaliação Funcional / Departamento de Fisioterapia / Universidade Federal de Pernambuco - UFPE.

OBS: Este termo de consentimento pode conter palavras que você não entenda. Por favor, pergunte à equipe que o acompanha no estudo a respeito de quaisquer palavras ou informação que você não entenda claramente. Você receberá uma cópia deste termo de consentimento para seu registro.

INTRODUÇÃO: O (A) Senhor (a) está sendo convidado a participar de um estudo de pesquisa, “PROPRIEDADES CLINIMÉTRICAS DA UNIDADE DE BIOFEEDBACK PRESSÓRICO NA AVALIAÇÃO DA ATIVIDADE MUSCULAR DO TRANSVERSO ABDOMINAL EM PACIENTES COM DOR LOMBAR CRÔNICA INESPECÍFICA”.

OBJETIVOS DO ESTUDO: Durante a prática clínica da fisioterapia, a medida da ativação do músculo transverso abdominal, constitui um dos procedimentos mais utilizados, podendo ser aferida por diferentes métodos e instrumentos, não se observado, no entanto, consenso sobre qual deles seria mais confiável e viável ao mesmo tempo. Assim, este objetiva analisar a reprodutibilidade intra e inter-examinadores e a validade de um aparelho utilizado para medir a ativação dessa musculatura: a unidade de biofeedback pressórico e o eletromiógrafo de superfície.

DURAÇÃO DO ESTUDO: O estudo prevê um período de 2 anos para o desenvolvimento de todas as suas etapas.

DESCRIÇÃO DO ESTUDO: este estudo objetiva analisar a reprodutibilidade de medidas realizadas a partir dos seguintes equipamentos para medir a ativação do músculo transverso abdominal: unidade de biofeedback pressórico e eletromiógrafo de superfície. Poderão participar do estudo indivíduos de todas as idades e de ambos os sexos. As medidas serão feitas com os voluntários em decúbito dorsal e ventral. Na primeira etapa será feita a mensuração com a unidade de biofeedback pressórico e com o eletromiógrafo de superfície, e na segunda etapa repeti-se novamente a mensuração com a unidade de biofeedback pressórico.

RISCOS: Levando em consideração que os voluntários que farão parte da presente investigação não devem apresentar nenhuma anomalia ou descompensação grave; considerando que nenhum dos métodos de mensuração que serão investigados produz algum dano ou malefício ao organismo

83


humano e; considerando ainda, que todas as medidas serão feitas a partir de um movimento fisiológico, este trabalho conduz a riscos mínimos aos seus participantes.

BENEFÍCIOS: O fato da medida de ativação do músculo transverso abdominal constituir procedimento usual durante a prática clínica da fisioterapia, os resultados obtidos com a presente investigação poderão melhor nortear os profissionais e as pesquisas científicas na escolha do método ou instrumento a ser empregado.

CONFIDENCIALIDADE: As informações obtidas através desse estudo serão sigilosas, não daremos informações sobre o nome ou outros dados das pessoas que participarem e seus resultados serão divulgados publicamente, sem nenhuma identificação dos voluntários.

PARTICIPAÇÃO VOLUNTÁRIA/RETIRADA: A sua participação nesse estudo é voluntária. Você pode recusar-se a participar ou parar de participar a qualquer momento da pesquisa.

CONSENTIMENTO DO VOLUNTÁRIO: Li e entendi as informações procedentes descrevendo esse estudo, e todas as minhas dúvidas em relação ao estudo e a minha participação nele foram respondidas satisfatoriamente. Dou livremente meu consentimento em participar do estudo até que decida pelo contrário.

Assinando este termo de consentimento, concordo em participar desse estudo e não abro mão, na condição de participante de um estudo de pesquisa, de nenhum dos direitos legais que eu teria de outra forma.

NOME DO VOLUNTÁRIO ASSINATURA DATA

NOME DA TESTEMUNHA ASSINATURA DATA

NOME DA TESTEMUNHA ASSINATURA DATA

NOME DO PESQUISADOR ASSINATURA DATA

Telefones para contato:

Pedro Olavo de Paula Lima: (85) 8864-3219; (81) 9912-1592; (81) 2126-8811

Av: Profº. Moraes Rego, 1235, Cidade Universitária, Departamento de Fisioterapia, CEP: 50670-901

Recife-PE e-mail: [email protected]

84


ANEXOS

85


ANEXO 1

TERMO DE SUBMISSÃO PARA PUBLICAÇÃO NA PHYSIOTHERAPY.

Elsevier Editorial System(tm) for Physiotherapy

Manuscript Draft

Manuscript Number:

Title: MEASUREMENT PROPERTIES OF THE PRESSURE BIOFEEDBACK UNIT IN

THE EVALUATION OF TRANSVERSUS ABDOMINIS MUSCLE ACTIVITY: A

SYSTEMATIC REVIEW

Article Type: Systematic Review

Keywords: pressure biofeedback unit; transversus abdominis, reproducibility; validity;

measurement properties; systematic review

Corresponding Author: Dr Leonardo O P Costa, PhD

Corresponding Author's Institution: The George Institute for International Health

First Author: Pedro O Lima

Order of Authors: Pedro O Lima; Rodrigo R de Oliveira; Leonardo O P Costa, PhD; Glória E

Laurentino,PhD

Manuscript Region of Origin: BRAZIL

86


ANEXO 2

TERMO DE SUBMISSÃO PARA PUBLICAÇÃO NA PHYSIOTHERAPY RESEARCH

INTERNATIONAL.

87


ANEXO 3

TERMO DE SUBMISSÃO PARA PUBLICAÇÃO NA PHYSIOTHERAPY THEORY

AND PRACTICE.

For Peer Review Only

VALIDITY OF PRESSURE BIOFEEDBACK UNIT IN THE

TRANSVERSUS ABDOMINIS MUSCLE ACTIVITY IN PATIENTS

WITH CHRONIC NONSPECIFIC LOW BACK PAIN

Journal: Physiotherapy Theory and Practice

Manuscript ID: Draft

Manuscript Type: Research Report

Keywords:

pressure biofeedback unit, transversus abdominis muscle, validity,

diagnostic tests

88


ANEXO 4

ESCALA NUMÉRICA DE DOR (Pain Numerical Rating Scale)

Instruções: Eu gostaria que você desse uma nota para sua dor numa escala de 0 a 10 onde 0 é

nenhuma dor e 10 é a pior dor possível. Por favor, dê um número para descrever sua média de

dor.

0 1 2 3 4 5 6 7 8 9 10

Nenhuma Pior dor possível

89


ANEXO 5

BRASIL ROLAND MORRIS (Roland Morris Disability Questionnaire)

Instruções: Quando suas costas doem, você pode encontrar dificuldades em fazer algumas

coisas que normalmente faz. Esta lista possui algumas frases que as pessoas tem utilizado

para se descreverem quando sentem dores nas costas. Quando você ler (ou ouvir) estas frases

poderá notar que algumas se destacam por descrever você hoje. Ao ler (ou ouvir) a lista pense

em você hoje. Quando ler ou ouvir uma frase que descreve você hoje, responda sim. Se a

frase não descreve você, então responda não e siga para a próxima frase. Lembre-se, responda

sim apenas à frase que tiver certeza que descreve você hoje.

(sim) (não) 1. Fico em casa a maior parte do tempo por causa de minhas costas.

(sim) (não) 2. Mudo de posição freqüentemente tentando deixar minhas costas confortáveis.

(sim) (não) 3. Ando mais devagar que o habitual por causa de minhas costas.

(sim) (não) 4. Por causa de minhas costas eu não estou fazendo nenhum dos meus trabalhos que geralmente faço em casa.

(sim) (não) 5. Por causa de minhas costas, eu uso o corrimão para subir escadas.

(sim) (não) 6. Por causa de minhas costas, eu me deito para descansar freqüentemente.

(sim) (não) 7. Por causa de minhas costas, eu tenho que me apoiar em alguma coisa para me levantar de uma cadeira normal.

90


(sim) (não) 8. Por causa de minhas costas, tento conseguir com que outras pessoas façam as coisas por mim.

(sim) (não) 9. Eu me visto mais lentamente que o habitual por causa de minhas costas.

(sim) (não) 10. Eu somente fico de pé por períodos curtos de tempo por causa de minhas costas.

(sim) (não) 11. Por causa de minhas costas evito me abaixar ou me ajoelhar.

(sim) (não) 12. Encontro dificuldades em me levantar de uma cadeira por causa de minhas costas.

(sim) (não) 13. As minhas costas doem quase o tempo todo.

(sim) (não) 14. Tenho dificuldade em me virar na cama por causa de minhas costas.

(sim) (não) 15. Meu apetite não é muito bom por causa das dores em minhas costas.

(sim) (não) 16. Tenho problemas para colocar minhas meias (ou meia calça) por causa das dores em minhas costas.

(sim) (não) 17. Caminho apenas curtas distâncias por causa de minhas dores nas costas.

(sim) (não) 18. Não durmo tão bem por causa de minhas costas.

(sim) (não) 19. Por causa de minhas costas, eu me visto com ajuda de outras pessoas.

(sim) (não) 20. Fico sentado a maior parte do dia por causa de minhas costas.

(sim) (não) 21. Evito trabalhos pesados em casa por causa de minhas costas.

(sim) (não) 22. Por causa de minhas dores nas costas, fico mais irritado e mal humorado com as pessoas do que o habitual.

(sim) (não) 23. Por causa de minhas costas, eu subo escadas mais vagarosamente do que o habitual.

(sim) (não) 24. Fico na cama a maior parte do tempo por causa de minhas costas.

91


ANEXO 6

APROVAÇÃO DO COMITÊ DE ÉTICA EM PESQUISA

Documents

UNIVERSIDADE FEDERAL DE PERNAMBUCO … · examinador as medidas foram realizadas por dois fisioterapeutas e para testar a reprodutibilidade intra-examinador, um deles