9789241596657_eng anemia

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    Worldwide

    prevalence of anaemia19932005who Gb db

    ai

    Editors

    Bruno de Benoist

    w h ogizi

    G, siz

    Erin McLean

    w h ogizi

    G, siz

    Ines Egli

    Ii si nii,

    eth Zi, siz

    Mary Cogswellc di c pi

    a, Ggi

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    World Health Organization 2008

    All rights reserved. Publications o the World Health Organization can be obtained rom WHO Press, World Health Organization, 20 Avenue Appia,1211 Geneva 27, Switzerland (tel.: +41 22 791 3264; ax: +41 22 791 4857; e-mail: [email protected]). Requests or permission to reproduce ortranslate WHO publications whether or sale or or noncommercial distribution should be addressed to WHO Press, at the above address (ax: +41

    22 791 4806; e-mail: [email protected]).The designations employed and the presentation o the material in this publication do not imply the expression o any opinion whatsoever on the part othe World Health Organization concerning the legal status o any country, territory, city or area or o its authorities, or concerning the delimitation o itsrontiers or boundaries. Dotted lines on maps represent approximate border lines or which there may not yet be ull agreement.

    The mention o specic companies or o certain manuacturers products does not imply that they are endorsed or recommended by the World HealthOrganization in preerence to others o a similar nature that are not mentioned. Errors and omissions excepted, the names o proprietary products aredistinguished by initial capital letters.

    All reasonable precautions have been taken by the World Health Organization to veriy the inormation contained in this publication. However, thepublished material is being distributed without warranty o any kind, either expressed or implied. The responsibility or the interpretation and use o thematerial lies with the reader. In no event shall the World Health Organization be liable or damages arising rom its use.

    The named authors alone are responsible or the views expressed in this publication.

    Cover photographs by Virot Pierre, Armando Waak, Carlos Gaggero

    Designed by minimum graphicsPrinted in Spain

    WHO Library Cataloguing-in-Publication Data

    Worldwide prevalence o anaemia 19932005 : WHO global database on anaemia / Edited by Bruno de Benoist,Erin McLean, Ines Egli and Mary Cogswell.

    1.Anemia prevention and control. 2.Anemia epidemiology. 3.Prevalence. I.World Health Organization.

    ISBN 978 92 4 159665 7 (NLM classication: WH 155)

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    Contents

    Preace v Acknowledgements Abbreviations

    1. Introduction 1

    1.1 Anaemia: a public health problem 1

    1.1.1 Etiology 11.1.2 Health consequences 11.1.3 Assessing anaemia 1

    1.2 Control o anaemia 11.2.1 Correcting anaemia 1

    2. Methods 3

    2.1 Data sources The WHO Global Database on Anaemia 32.2 Selection o survey data 3

    2.2.1 Administrative level 32.2.2 Population groups 4

    2.3 Dening anaemia 4

    2.3.1 Haemoglobin threshold 42.3.2 Estimated anaemia prevalence or countries with no survey data 52.3.3 Uncertainty o estimates 52.3.4 Combining national estimates 52.3.5 Global anaemia prevalence 52.3.6 Classication o anaemia as a problem o public health signicance 6

    2.4 Population coverage, proportion o population, and the number o individuals with anaemia 62.4.1 Population coverage 62.4.2 Proportion o population and the number o individuals aected 6

    3. Results and Discussion 7

    3.1 Results 7

    3.1.1. Population coverage 73.1.2 Proportion o population and number o individuals with anaemia 73.1.3 Classication o countries by degree o public health signicance o anaemia 8

    3.2 Discussion 83.2.1 Population coverage 83.2.2 Strengths o estimates 83.2.3 Limitations o estimates 83.2.4 Proportion o population and the number o individuals with anaemia 123.2.5 Classication o countries by degree o public health signicance o anaemia, based on

    haemoglobin concentration 123.2.6 Comparison to previous estimates 12

    3.3 Conclusion 12

    References 14

    iiicontents

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    Annexes

    Annex 1 WHO Member States grouped by WHO and UN regions 15Table A1.1 WHO Member States grouped by WHO regions 15Table A1.2 WHO Member States grouped by UN regions and subregions 16

    Annex 2 Results by UN region 18Table A2.1 Population coverage by anaemia prevalence surveys (national or subnational)

    conducted between 1993 and 2005 by UN region 18Table A2.2 Anaemia prevalence by UN region 18

    Annex 3 National estimates o anaemia 20Table A3.1 Country estimates o anaemia prevalence in preschool-age children 20Table A3.2 Country estimates o anaemia prevalence in pregnant women 25Table A3.3 Country estimates o anaemia prevalence in non-pregnant women o reproductive age 30Table A3.4 Country reerences 35

    Tables

    Table 2.1 Haemoglobin thresholds used to dene anaemia 4Table 2.2 Prediction equations used to generate anaemia estimates or countries without survey data 5Table 2.3 Classication o anaemia as a problem o public health signicance 6

    Table 3.1 Population coverage (%) by anaemia prevalence surveys (national or subnational) conductedbetween 1993 and 2005 7

    Table 3.2 Global anaemia prevalence and number o individuals aected 7Table 3.3 Anaemia prevalence and number o individuals aected in preschool-age children, non-pregnant

    women and pregnant women in each WHO region 8Table 3.4 Number o countries categorized by public health signicance o anaemia 8

    Figures

    Figure 3.1 Anaemia as a public health problem by country(a) Preschool-age children 9(b) Pregnant women 10(c) Non-pregnant women o reproductive age 11

    worldwIde prevalence o anaemIa 19932005iv

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    Preface

    Anaemia is a public health problem that aects populationsin both rich and poor countries. Although the primarycause is iron deciency, it is seldom present in isolation.More requently it coexists with a number o other causes,such as malaria, parasitic inection, nutritional deciencies,

    and haemoglobinopathies.Given the importance o this pathology in the world, nu-

    merous countries conduct interventions to reduce anaemia;particularly in the groups most susceptible to its devastat-ing eects: pregnant women and young children. In orderto assess the impact o these interventions, the adequacyo the strategies implemented, and the progress made inthe ght against anaemia, inormation on anaemia preva-lence must be collected. This is the primary objective o theWHO Global Database on Anaemia. However, estimateso anaemia prevalence by themselves are only useul i they

    are associated with a picture o the various causal actorsthat contribute to the development o anaemia in specicsettings. Indeed these actors are multiple and complex, andit is critical to collect accurate inormation about them toprovide the basis or developing the best interventions oranaemia control.

    In the last three decades, there have been various at-tempts to produce estimates o the prevalence o anaemiaat dierent levels including at the global level, but untilthe present time, there has never been a systematic reviewo all o the data collected and published with the objec-tive o deriving regional and global estimates. The WHO

    Global Database on Anaemia has lled this gap: data rom93 countries, representing as much as 76% o the popula-tion in the case o preschool-age children, were analysedand used to develop statistical models to generate nationalprevalence estimates or countries with no data within thetime rame specied.

    It is surprising that given the public health importanceo anaemia, there are numerous countries lacking nationalprevalence data. Moreover, most survey data are relatedto the three population groups: preschool-age children,pregnant women, and non-pregnant women o reproduc-

    tive age, which is why the report ocuses on these groups.

    The data available or school-age children, men, and theelderly were not sucient to generate regional or country-level estimates or these groups, and thereore only globalestimates or these groups are presented.

    In addition, despite the act that iron deciency is con-

    sidered to be the primary cause o anaemia, there are ewdata on the prevalence o this deciency. The likely reasonis that iron assessment is dicult because the available in-dicators o iron status do not provide sucient inormationalone and must be used in combination to obtain reliableinormation on the existence o iron deciency. Further-more, there is no real consensus on the best combination oindicators to use. Another reason is that the role o actorsother than iron deciency in the development o anaemiahas been underestimated by public health ocials, becauseor a long time anaemia has been conused with iron de-

    ciency anaemia, and this has infuenced the development ostrategies and programmes designed to control anaemia.In this report, the prevalence o anaemia is presented by

    country and by WHO regions. Because these prevalencedata may be used to identiy programme needs by otherUnited Nations agencies, we have presented the estimatesclassied by United Nations regions in the annexes. In ad-dition, one chapter is dedicated to the criteria used to iden-tiy, revise, and select the surveys, and the methodologydeveloped to generate national, regional, and global esti-mates.

    A lesson learned rom producing this report is that in

    order or the database to reach its ull potentia l, data s