The Burden of Disease among the Global Poor · 2016. 7. 17. · The Burden of Disease among the Global Poor. Current Situation, Future Trends, and Implications for Strategy. The World

HUMAN DEVELOPMENT NETWORK Health Nutrition and Population

The Burden of Disease among the Global Poor Current Situation, Future Trends, and Implications for Strategy David R. Gwatkin Michel Guillot Global Forum for Health Reasearch Promoting Research to Improve the Health of Poor People

GLOBAL FORUM FOR HEALTH RESEARCH c/o World Health Organization 20 avenue Appia 1211 Geneva 27 Switzerland Telephone: 41-22- 791-4260 Facsimile: 41-22- 791-4394 Internet: www.globalforumhealth.org E-mail: [email protected] THE WORLD BANK 1818 H Street, N.W. Washington, D.C. 20433 USA Telephone: 202-477-1234 Facsimile: 202-477-6391 Telex: MCI 64145 WORLDBANK MCI 248423 WORLDBANK Internet: www.worldbank.org E-mail: [email protected]

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Administrator29182

This publication was prepared by the Health, Nutrition, andPopulation division (HNP) of the World Bank’s HumanDevelopment Network. HNP publications provide information onthe Bank’s work in the sectors of health, population, and nutrition.They consolidate previous papers in these areas, and improve thestandard for quality control, peer review, and dissemination of HNPresearch.

The publications expand our knowledge of HNP policy and strategyissues through thematic reviews, analyses, case studies, and exam-ples of best practice. They focus on material of global and regionalrelevance.

The broad strategic themes of the publications are proposed by aneditorial committee, which is coordinated by Alexander S. Preker.The other members of this committee are A. Edward Elmendorf,Mariam Claeson, Armin H. Fidler, Charles C. Griffin, Peter F.Heywood, Prabhat K. Jha, Jack Langenbrunner, Maureen A. Lewis,Samuel S. Lieberman, Milla McLachlan, Judith Snavely McGuire,Akiko Maeda, Thomas W. Merrick, Philip Musgrove, David H.Peters, Oscar Picazo, George Schieber, and Michael Walton.

Hea l th , Nu t r i t i on , and Popu la t i on Se r ies

The Burden of Diseaseamong the Global PoorCurrent Situation, Future Trends, andImplications for Strategy

The World BankWashington, D.C.

Davidson R. Gwatkin andMichel Guillot

H U M A N D E V E L O P M E N T N E T W O R KH e a l t h , N u t r i t i o n , a n d P o p u l a t i o n

© 2000 The International Bank for Reconstructionand Development / THE WORLD BANK1818 H Street, N.W. Washington, D.C. 20433, U.S.A.

All rights reservedManufactured in the United States of AmericaFirst printing November 1999

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Library of Congress Cataloging-in-Publication Data

Gwatkin, Davidson R.The burden of disease among the global poor : current situation, future trends,

and implications for strategy / Davidson R. Gwatkin and Michel Guillot.p. cm.

ISBN 0-8213-4619-91. Poor—Diseases. 2. Poor—Diseases—Forecasting. 3. Poor—Health and

hygiene—Forecasting. 4. World health—Forecasting. I. Guillot, Michel. II. Title.

RA418.5.P6 G93 1999362.1'086'942—dc21

99–055249

iii

Foreword v

Abstract vi

Acknowledgments vii

Overview 1

1 Introduction: The Importance of Burden of Disease InformationSpecific to the Poor 3

The Earlier Focus of Research and Policy on Disease Conditions among the Poor 3The Recent Shift of Research Attention to Global Disease Conditions 4Implications of the Resulting Lack of Congruity 4

2 The Burden of Disease among the Poor and Rich in 1990 6Method of Assessment 6Findings 8Interpretation 13

3 Changes in the Burden of Disease among the Poor and Rich between 1990 and 2020 16Method of Assessment 16Findings 18Interpretation 22

4 Implications for Strategy 25

Notes 27

Annex A. Summary of Methodology 31

Annex B. 1990 Statistical Tables 37

Figures1 Causes of Death and Disability, 1990 82a Causes of Death by Gender, 1990 102b Causes of DALY Loss by Gender, 1990 103 Causes of Poor-Rich Health Status Gap, 1990 124 Concentration of Deaths and Disability, 1990 135 Poor-Rich Differences in Death Rates from Communicable

and Noncommunicable Diseases, 1990 156 Additional 1990–2020 Life Expectancy Gain Produced in a Given

Population Group by Different Disease-Reduction Strategies 21

Contents

iv The Burden of Disease Among the Global Poor

7 Additional 1990–2020 Life Expectancy Gain Produced by a GivenDisease-Reduction Strategy in Different Population Groups 21

8 Life Expectancy Difference Between Global Rich and Global Poorin 2020 Under Different Disease-Reduction Scenarios 21

Tables1a Leading Causes of Death in Different Population Groups, 1990 91b Leading Causes of DALY Loss in Different Population Groups, 1990 92a Mortality Gap between the Global Poor and the Global Rich, 1990 122b DALY Gap between the Global Poor and the Global Rich, 1990 123 Impact of Alternative Global Disease-Reduction Scenarios on

the Health of the Poor and Rich 20

v

Foreword

The World Bank and the Global Forum for HealthResearch share a central concern for improving thehealth of the world’s poor. At present, of the US$ 60 bil-lion spent worldwide annually on health research byboth the public and private sectors, only about 10 per-cent is devoted to 90 percent of the world’s health prob-lems (as measured by DALYs or similar indicators). Theeconomic and social costs to society as a whole of suchmisallocation of resources are enormous, both directlyand indirectly. The direct costs are particularly high forthe poorer population, given the vicious circle betweenpoverty and poor health.

This so-called 10/90 Gap is, at least in part, due to thefact that decisionmakers do not have enough informa-tion. One important type of information which is lack-ing concerns the pattern of diseases from which the poorsuffer the most. Not until we have this information canwe be certain that our efforts to deal with diseases arefocused correctly on those ailments that are most impor-tant among those most in need. The objective of the pre-sent study is to contribute to shedding more light on thiskey topic so that decisions can be based on more andbetter information.

The past decade has seen a promising beginning inthe collation of this critical information, with increas-

ingly sophisticated estimates of the burden of disease inthe world as a whole and in its major geographic regions.The material presented here takes the next step: to buildon that beginning in order to provide estimates of thedisease burden among the global poor, wherever theymay live.

The importance of this step will become apparentfrom the findings put forward in these pages. These find-ings show that the pattern of diseases experienced by thepoor differs significantly from the pattern shown by theglobal averages that have attracted the most attention ofresearchers and policymakers. It must be concludedfrom these findings that the development of interven-tions suited to the needs of the poor cannot rely on soci-etal averages, but should instead draw upon informationbased on research and data specifically of the disadvan-taged population groups those interventions wouldaddress.

The work presented here is intended only as a start inthis direction. Much more research will be required toproduce an understanding of the disease burden amongthe poor that is fully adequate for policy and programdevelopment purposes. We hope that readers of this paperwill join with the Global Forum for Health Research andthe World Bank in working toward this end.

Louis Currat J. Christopher LovelaceExecutive Secretary Chair, Health, Nutrition, and Population Sector BoardGlobal Forum for Health Research The World Bank

This paper provides information about the burden ofdisease among the poor members of society. It isdesigned to complement the data about society as awhole that have been the principal focus of most bur-den of disease work to date. The information present-ed here deals with the 1990 situation and with pro-jected trends between 1990 and 2020.

The 1990 Situation. Communicable diseases are con-siderably more important for the world’s poor thanglobal averages suggest. Noncommunicable diseasesare correspondingly less important. For example:

• Communicable diseases cause 59 percent of deathsand 64 percent of DALY (disability-adjusted lifeyear) loss among the 20 percent of the global pop-ulation living in countries with the lowest per capi-ta incomes, compared with 34 percent of deaths and44 percent of DALY loss among the entire globalpopulation.

• Communicable diseases are responsible for 77 per-cent of the mortality gap and 79 percent of the DALYgap between the world’s poorest and richest 20 per-cent, compared with 15 percent and 9 percentattributable to noncommunicable diseases.

The Projected 1990–2020 Trend. An acceleratedoverall decline in communicable diseases would ben-efit the world’s poor more than a faster global reduc-tion in noncommunicable disorders. A faster reductionin deaths from communicable diseases would also ben-efit the poor much more than it would the rich, andwould thereby reduce global poor-rich differences in

longevity. In contrast, the leading beneficiaries of afaster global reduction in deaths from noncommuni-cable disorders would be the rich. For instance:

• A doubling in the currently projected 1990–2020rate of decline in mortality from communicable dis-eases, distributed evenly across all social classes,would produce a year 2020 life expectancy amongthe global poor that would be 4.1 years higher thanunder the baseline projection. A doubling of the rateof decline in mortality from noncommunicable dis-eases would produce a comparable figure of 1.4years for the same group.

• The 4.1-year gain that the global poor would achievefrom a doubled, evenly distributed rate of progressagainst communicable diseases would be more than10 times greater than the 0.4-year increment thatwouldbeproducedamong theglobal rich.Adoubledrate of decline in mortality from noncommunicableconditions, in contrast, would benefit the rich near-ly four times as much as it would the poor.

• A doubling of the rate of progress against commu-nicable diseases would reduce the currently pro-jected year 2020 poor-rich life expectancy gap by3.7 years. The same acceleration in progress againstnoncommunicable conditions would achieve theopposite effect, widening the gap by 3.9 years.

Implications. Such findings illustrate the importanceof giving high priority to communicable diseases instrategies to improve the health of the poor and lessenpoor-rich health differences.

vi

Abstract

The authors acknowledge with thanks the supportfrom the Global Forum for Health Research that madepossible the preparation of an earlier version of thisreport. They also thank the several agencies that pro-vided support for the work on which the report isbased and for preparing the report in its present form:the World Bank, with resources provided by the Swiss

and Norwegian Governments; and the UNDP/WorldBank/WHO Special Programme for Research andTraining in Topical Diseases. Further thanks go to Drs.David Evans, Christopher Murray, and Derek Yach fortheir advice, comments, and suggestions.

The authors accept sole responsibility for any flawsthat may exist in the figures and arguments presented.

vii

Acknowledgments

1

Overview

This paper deals with the burden of disease among theglobal poor, as distinct from the burden of disease inthe global population as a whole, which has been theprincipal focus of most burden of disease work to date.The purpose of the paper is to provide estimates of dis-ease levels and trends, in order to assist in identifyingthe diseases that are most important for the needy.

The paper consists of four parts:

Introduction.

Examination of the global situation in 1990. Thissection presents a series of estimates of the burden of

disease among the global poor and, for comparativepurposes, among the global rich.

Projection of global trends between 1990 and2020. This section opens with a presentation of abaseline scenario for the poor and the rich, thenexamines the implications for the poor of altering thatscenario by pursuing reductions in different types ofdisease.

Summary of the paper’s findings and their implica-tions for those concerned with the health dimension ofpoverty alleviation.

3

The recent estimates of the global disease burden thathave attracted the attention of epidemiologicalresearchers and policy makers represent a quantumleap in both the sophistication and the coverage of ear-lier work on disease patterns. The newer estimates alsohave a different focus: the population of the world as awhole, rich as well as poor, rather than the global pooralone.

This shift in focus has produced a lack of congruitybetween burden of disease estimates and the globalhealth policy statements that they are intended to sup-port. While the focus of epidemiological analysis isshifting toward the population of the world as a whole,most prominent global health policy statements con-tinue to emphasize the importance of improving thehealth of the global poor.

This lack of congruity is of much more than simplyacademic interest, because, as will be seen, disease pat-terns vary systematically across social class. The pat-tern of diseases prevalent among the global poor dif-fers from that of the population of the world as a whole,and global averages are therefore unreliable guides forprograms directed at this specific sector of the popula-tion. Instead of relying on global averages, policy mak-ers wishing to undertake programs oriented toward theneeds of the global poor need information specific tothe poor.

The Earlier Focus of Research and Policy onDisease Conditions among the Poor

The lack of congruity just described is relatively recent.From the 1970s until the late 1980s, a concern for thehealth of the world’s poor dominated both the policyand research domains. International health policies

were oriented primarily toward improving the healthof the disadvantaged, and the focus of research into thecauses of death and disability was congruent with thisorientation.

The prevailing policy climate was typified by initia-tives developed at the World Health Organization(WHO) and the United Nations Children’s Fund(UNICEF). For example, participants in a 1978 inter-national conference organized by these two agencies inAlma-Ata, USSR (now Almaty, Kazakhstan) made cleartheir concern for poverty by beginning their reportwith a declaration that “ . . . the health status of hun-dreds of millions in the world today is unacceptable,especially in developing countries.”1 To deal with this,the participants advocated “a new approach to healthcare, to close the gap between the ‘haves’ and ‘have-nots.’”2 Similarly, the first major UNICEF “State of theWorld’s Children” report for 1981–82 started by advo-cating more and wiser spending on activities to helpthe poorest 500 million mothers and young childrenin the world.3

The principal epidemiological assessments of thatera were also oriented toward poor countries and peo-ple. A noted 1979 work focused primarily on infectiousdiseases “because these infections tend to flourish at thepoverty level.”4 The 1980 policy paper that announcedthe World Bank’s decision to begin lending to healthprograms indicated a particular concern for fecallyrelated diseases, airborne diseases, and malnutrition,because “these three major disease groups account forthe majority of deaths among the poorest people in poorcountries.”5 And a classic 1968 study of the synergybetween malnutrition and infection was undertakenbecause the authors felt that this synergy “is responsi-ble for much of the excess mortality among infants andpreschool children in less developed regions.”6

1 Introduction: The Importance of Burden of Disease Information Specific to the Poor

4 The Burden of Disease Among the Global Poor

These and other studies identified a complex of gas-trointestinal infections, ailments of the lower respira-tory tract, and malnutrition as the principal causes ofdeath and disability among the poor. Their conclusionstriggered a concerted effort to find cost-effective meansof dealing with these and related problems, such asimmunization against major infectious diseases, oralrehydration therapy for diarrhea, and growth monitor-ing to counter malnutrition. These interventionsbecame the principal components of the leading inter-national health initiatives of the time, such as theWHO-led primary health care movement and theUNICEF child survival revolution. Along with themany similar movements of the time, they were devel-oped as a response to empirical assessments of theprincipal disease problems of the target population—that is, assessments of the disease problems of theworld’s poor.

The Recent Shift of Research Attention to GlobalDisease Conditions

This emphasis on the problems of the world’s poor hascontinued to figure prominently in leading public doc-uments dealing with international health. For example,a concern about equity and poverty is central to themajor reports of the 1990s. The 1990 report by theCommission of Health Research for Developmentstates its concern clearly, in its title, “Health Research:Essential Link to Equity in Development.”7 The WorldBank’s 1993 World Development Report8 makesnumerous references to the health problems of thepoor, and prominently includes a package of clinicalservices designed explicitly for the poor.9 A third majorreport, the 1996 WHO Ad Hoc Committee Report,10

resulted in the establishment of the Global Forum forHealth Research, whose letterhead describes it as an“Initiative for Health Research and Development forthe Poor.”

However, the focus of the epidemiological evidencegathered in connection with these reports has beenshifting away from the global poor toward the entireglobal population, which includes people of all incomelevels, high as well as low. The beginning of this trendcan be seen in the 1990 Commission Report, which

incorporated the first in the current generation of dis-ease burden estimates. These estimates provided infor-mation about the causes of death in the world as awhole, and separately for industrialized and develop-ing countries.11 The 1993 World Development Reportcontained more refined versions of the 1990 diseasedata, covering disability as well as death.12 While itincluded a careful discussion of regional variations, italso gave the data a global flavor by introducing andfrequently employing the expression “global burden ofdisease.” In the 1996 Ad Hoc Committee report, thedata were still more refined, and included projectionsto 2020 as well as figures for 1990.13 Again, regionalas well as global data were presented in the report itself;but the expression “global burden” appeared evenmore prominently than in 1993, and the overall glob-al conditions dominated the Committee’s media out-reach and the extensive press coverage that itreceived.14

Such movement toward an overall global outlook inthe epidemiological data, implicitly including high- aswell as low-income people, means that the data havebegun to refer increasingly to a population group thatdiffers from the global poor who merit such high pri-ority in the report texts. The magnitude of this differ-ence will obviously vary according to the definition ofpoverty used, but is potentially quite significant. Forexample, under the current World Bank definition ofthe international poverty line, 1.3 billion or around 24percent of the world’s population is classified as poor.15

Acceptance of this definition would mean that theremaining 76 percent of the world’s people—overthree-quarters of the total—included in global burdenof disease estimates lie outside the poverty group thatis of concern.

Implications of the Resulting Lack of Congruity

The resulting lack of congruence between the focus ofthe reports and the epidemiological analysis underly-ing them would not matter if disease patterns were dis-tributed equally across different socioeconomicgroups, but they almost certainly are not. A long tradi-tion of empirical analysis has shown a systematic rela-tionship between a population group’s overall longevi-

Introduction 5

ty or mortality level and the pattern of diseases pre-vailing within it.16

Specifically, empirical research has indicated clearlythat, in general, the lower the overall level of mortali-ty in a society, the greater the importance of noncom-municable diseases relative to communicable ailments.Conversely, the higher the level of all-cause mortality,the more important are communicable disorders rela-tive to noncommunicable illnesses.

Of the several implications that flow from this gen-eralization, one has attracted particular attention. Thisimplication follows from the generalization’s temporaldimension—that is, from an appreciation of what hap-pens to disease patterns within a society over time.Since mortality in almost all societies has been falling,the generalization provides strong support for what hasbecome known as the “epidemiological transition,”17

during which the importance of communicable illnessrecedes in importance relative to noncommunicabledisease. This transition, frequently cited in the recentglobal epidemiological analyses and policy reportsreferred to earlier, is typically invoked to call attentionto the rising importance of noncommunicable ailmentsin the world as a whole and in the great majority ofcountries.

Less frequently recognized, at least in print, is thefact that the generalization also has an important cross-sectional dimension. That is, just as the generalizationcan be employed to describe trends over time within asociety as a whole, so too can it be applied to assess dif-ferences among groups within a society at a singlepoint in time.

When used for this latter purpose, the generaliza-tion suggests that the higher the overall mortality levelprevailing among any group, the greater the impor-tance of communicable ailments. Conversely, the lowera group’s overall mortality, the higher the proportion ofthat group’s mortality that is attributable to noncom-municable illness.

Given the clear existence of a strong direct relationshipbetween income level and health status,18 the general-ization can also be readily reformulated in economicterms to state that communicable diseases matter muchmore than noncommunicable conditions for poor groupswithin society. Conversely, the groups for whom non-communicable disorders matter most tend to be rich.

To the extent that this is the case, any shift in atten-tion from communicable diseases toward noncommu-nicable ailments would have important distributionalimplications. Although such a shift might well be jus-tifiable on the basis of trends in a society as a whole, itwould work to the detriment of the poor, for whomcommunicable diseases are relatively more importantthan they are for richer groups. The shift’s principalbeneficiaries would be the rich, who would thereforegain at the expense of the poor.

This is obviously a disconcerting possibility. Butidentification of a possibility on the basis of generalconsiderations is not an adequate basis for policy for-mulation. Policy makers are much better served byempirical evidence as directly and immediately rele-vant as possible to the particular situations with whichthey are dealing. Thus the need for the assessment ofdisease conditions specific to the poor that follow.

6

Method of Assessment

Starting PointThe starting point for assessing the burden of diseaseamong the poor is the well-known set of global esti-mates prepared by Christopher Murray and AlanLopez.19 These estimates provide information aboutthe cause of death and disability for the world as awhole, for the developing world as a whole, for each ofeight geographical regions, for each of seven agegroups, and for each gender. The Murray-Lopez com-pilations do not, however, break down the data in themanner that would have greatest relevance for thepoor—that is, by socioeconomic status.

The work presented here is designed to beginextending the work of Murray and Lopez in this direc-tion, by applying their techniques and data to estimatethe burden of disease among the world’s poorest andrichest population groups. The Murray-Lopez tech-nique and data were not designed for such a disaggre-gation, however, and cannot support precise estima-tion of the burden of disease in any particularsocioeconomic group; nor are the data necessary forthis purpose available from any other known source.This clearly constrains the development of accurateestimates for the poor. It is nonetheless possible to pro-duce crude estimates that at least provide a notably bet-ter basis for developing poverty- and equity-orientedhealth strategies than do the global averages that are incurrent widespread use.

The estimate produced is of the burden of diseaseprevalent among the 20 percent of the global popula-tion living in countries that have the world’s lowestaverage per capita incomes. For comparative purpos-es, an estimate was also prepared for a group repre-

senting the 20 percent of the global population livingin the richest countries. The estimates permit a com-parison of the high and low quintiles, a measure com-monly used by poverty analysts.20

Estimation ProcedureThe procedure used to develop the estimates for thesetwo groups is described fully in Annex A1. It consistsof six steps:

Step One: Identification of the poor and rich popu-lation groups of interest. This was done through acountry-based approach. Countries were listed inascending order on the basis of their average per capi-ta incomes, adjusted for purchasing power, and a linewas drawn at that point on the list above which thecumulative population of the countries listed equaled20 percent of the world’s population. The rich popula-tion group of interest was identified through an analo-gous procedure, starting at the bottom of the list andworking upward.21,22

For convenience, the population groups thusidentified are henceforth referred to as the globalpoor and the global rich. Because not everybody ina poor country is poor and rich countries containsome people who are poor, the global poorest andrichest 20 percent as defined in the manner justdescribed differ to at least some degree from groupsconsisting of the poorest and richest 20 percent ofthe world’s individuals. Given the limitations of theavailable data, however, any attempt to develop anapproximation of the poorest and richest 20 percentof the world’s individuals would have required somany additional assumptions that the results wouldhave had dubious validity.

Also, as will be seen later, statistical considerationsmake it almost certain that findings of a study based on

2 The Burden of Disease among the Poorand Rich in 1990

The Burden of Disease among the Poor and Rich in 1990 7

the poorest and richest 20 percent of individuals wouldsimply reinforce the findings made with the definitionused here. This being the case, the extra benefit ofworking with population groups defined in terms ofthe poorest and richest individuals, rather than interms of inhabitants of the poorest and richest coun-tries, was deemed not worth the additional cost of pro-ducing the necessary figures.

Step Two: Estimation of the total number of deathsfrom all causes, for each population group of interest.This was done by obtaining, for each country aboveand below the lines described in the preceding para-graph, information from standard United Nations andWorld Bank data sources about (a) the number of peo-ple in each age/gender group, and (b) the overall, all-causes death rates applicable to those age/gendergroups.23 Multiplying the number of people in eachgroup by the death rate applicable to that group yield-ed a figure for the number of deaths in the group. Thesegroup-specific numbers were then aggregated to pro-duce total numbers of deaths for the poorest and rich-est 20 percent of the global population.

Step Three: Disaggregation of the total number ofdeaths from all causes by each of the three principaldisease groups employed by Murray and Lopez:

Group I (communicable, maternal, perinatal, andnutritional)Group II (noncommunicable)Group III (accidents and injuries)24

This was achieved using the same technique appliedby Murray and Lopez for this purpose, whereby initialestimates were established by using the observed rela-tionship between total and disease-specific mortality inthose countries with reliable data; these estimates werethen refined through careful examination of the resultsand adjustment of the data as necessary.

Step Four: Conversion of the data for deaths intocombined figures for death and disability, expressed interms of the disability-adjusted life year (DALY) indexdeveloped by Murray and Lopez.25 This was donethrough proration: The number of deaths in eachage/gender group for the countries identified in stepone and located in a given region was multiplied by theratio of deaths to DALYs in that region as calculated in

the previously cited Murray-Lopez volume, and theresults aggregated.

Steps Five and Six: Disaggregation of the deathinformation (step five) and the DALY information (stepsix) for the three principal disease groups to provideillustrative estimates for 25 specific diseases and con-ditions, 22 that are the leading causes of global deathand disability and three that are of special interest toparticular audiences. The procedure used was analo-gous to that of step four: The number of deaths orDALY loss attributable to a specific disease in each pooror rich age/gender-specific group for a given region wasmultiplied by the ratio of deaths caused by the specif-ic disease to total deaths caused by the larger group (I,II, or III, as described in step three) to which the dis-ease in question belongs. The resulting group-specificfigures were then aggregated.

Taken together, the 22 leading causes covered instep five are responsible for around 90 percent ofdeaths and disability among the global rich and poor,as well as among the population of the world as awhole. As greater specificity reduces the reliability ofestimates, no attempt was made to prepare compara-ble figures for the additional 75 to 80 disease condi-tions identified by Murray and Lopez as being respon-sible for the remaining 10 percent of deaths anddisability.

Types of Assessment The resulting estimates were organized in a mannerdesigned to permit two types of assessment:

The health of the poor alone. This involvesintrapopulation group disease comparisons: in thiscase, assessment of the relative importance of differentdiseases among the people within the global poorgroup. This assessment is of greatest relevance forimproving the health of the people within a specificpopulation group, independently of any other popula-tion group. It is thus the approach most relevant to apoverty alleviation strategy—that is, a strategy con-cerned with improving the health status of the pooralone, without regard to the impact that such animprovement might have on the differences betweenpoor and rich.26

Differences between the health of the poor and thehealth of others. This involves interpopulation group


comparisons; that is, comparisons of the importance ofa given disease between one population group andanother—between the global poor and the global rich,for example, or between the global poor and the rest ofthe world. This is the approach employed in what issometimes called an equity enhancement strategy, ormore precisely, an inequality reduction strategy,27

which focuses primarily upon the reduction of differ-ences between groups rather than on the conditionsprevailing in any one group.28,29

Findings

Health of the Poor Alone

Overview. Figure 1 provides a summary of the burdenof disease among the global poor, the global rich, andthe entire global population. Part A presents figures forthe numbers of deaths; Part B provides comparableinformation for DALY loss.

The most notable features of Figure 1 are the inverserelationship between economic status and communi-

cable diseases, and the opposite relationship betweeneconomic status and noncommunicable conditions.The lower one’s economic status, in other words, thegreater the significance of communicable diseases butlesser the significance of noncommunicable condi-tions. Specifically:

• Communicable diseases are concentrated amongand are thus most important for the global poor.Among this group, communicable illnesses areresponsible for a clear majority of deaths (58.6 per-cent) and DALY loss (63.6 percent). This is anotably higher percentage than for the populationof the world as a whole, in which communicablediseases cause 34.2 percent of all deaths and 43.9percent of DALY loss, and higher still than for theglobal rich, among whom communicable diseasesresult in 7.7 percent of all deaths and 10.9 percentof DALY loss.

• Noncommunicable conditions are distinctly lessimportant for the global poor than are communica-ble conditions. They are also much less importantfor the global poor than for the global rich. Amongthe poor, noncommunicable conditions cause 32.0percent of deaths and 23.3 percent of DALY loss,compared with the 58.6 percent and 63.6 percentattributable to communicable conditions. In theworld as a whole, noncommunicable diseases areconsiderably more important, being responsible formore than half of all deaths (55.7 percent) andalmost half of DALY loss (41.0 percent). Among theglobal rich, noncommunicable ailments are moreimportant still, causing more than three-quarters ofdeaths (85.2 percent) and DALY loss (75.8 percent).

• Injuries are less important for the global poor thaneither communicable or noncommunicable dis-eases. They are also more evenly distributed acrosssocial class. Among the poor, injuries cause 9.4 per-cent of all deaths and 13.1 percent of DALY loss—slightly less than in the world as a whole, whereinjuries are responsible for 10.1 percent of deathsand 15.1 percent of DALY loss. Among the globalrich, 7.1 percent of deaths and 13.3 percent of DALYloss are attributable to injuries.

Figure 1 Causes of Death and Disability, 1990

0102030405060708090

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Global Poor World Average Global Rich

% o

f Tot

al D

ALY

Los

s

Communicable Diseases Noncommunicable Diseases Injuries

A. Death

B. DALY Loss

0102030405060708090

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Global Poor World Average Global Rich

% o

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ALY

Los

s


Specific Diseases. Table 1 provides figures for the fiveleading causes of poor health: Section A deals withdeaths, and Section B with DALYs. Annex B1 providesa fuller list, covering all 25 of the specific diseases forwhich estimates have been prepared. These figures arefar from precise and should be interpreted with cau-tion, but the general orders of magnitude presented arenonetheless of interest.

In light of what was said in the preceding section,Table 1 contains few surprises. The figures in it showthat:

• Among the global poor, the leading causes of deathare communicable diseases. Respiratory infectionsand diarrheal diseases each cause more than 10 per-cent of total deaths, and perinatal conditions and thechildhood cluster of diseases30 are each responsiblefor almost 8 percent of deaths. A noncommunicabledisease, ischaemic heart disease, is in fifth place, andis responsible for 7.3 percent of deaths.

Respiratory infections and diarrhea remain the lead-ing problems when ill health is assessed in terms ofDALY loss instead of death. Ischaemic heart diseasedrops out of the top five causes and is replaced by unin-tentional injuries, which occupies third place.

• Among the global rich, all of the top five causes ofdeath and of DALY loss are noncommunicable dis-eases, with ischaemic heart disease and malignantneoplasms at or near the top. The principal differ-ence when using DALY loss rather than deaths as themetric of health status occurs with respect to neu-ropsychiatric conditions, which are responsible foronly about around 1 percent of deaths but consti-tute the leading cause of DALY loss, accountable fornearly one-fourth of the total.

Gender Differences. Figure 2 provides estimates ofthe relative importance of the three principal groups ofdiseases for men and for women. As in the previous fig-

Table 1A. Leading Causes of Death in Different Population Groups, 1990

Global poor Global rich Entire global populationCause Percent of total deaths Cause Percent of total deaths Cause Percent of total deaths

Respiratory Infections 13.4 Ischaemic Heart Disease 23.4 Ischaemic Heart Disease 12.4(Group I) (Group II) (Group II)

Diarrheal Diseases 11.3 Malignant Neoplasms 22.6 Malignant Neoplasms 11.9(Group I) (Group II) (Group II)

Perinatal Conditions 7.9 Cerebrovascular Diseases 12.0 Cerebrovascular Diseases 8.7(Group I) (Group II) (Group II)

Childhood Cluster 7.8 Other Cardiovascular 10.2 Respiratory Infections 8.7Diseases (Group I) Diseases (Group II) (Group I)

Ischaemic Heart Disease 7.3 Respiratory Diseases 4.8 Other Cardiovascular 7.3(Group II) (Group II) Diseases (Group II)

Table 1B. Leading Causes of DALY Loss in Different Population Groups, 1990

Global poor Global rich Entire global populationCause Percent of total deaths Cause Percent of total deaths Cause Percent of total deaths

Respiratory Infections 11.8 Neuropsychiatric 22.1 Unintentional Injuries 11.0(Group I) Conditions (Group II) (Group III)

Diarrheal Diseases 11.0 Malignant Neoplasms 13.2 Neuropsychiatric 10.5(Group I) (Group II) Conditions (Group II)

Unintentional Injuries 10.0 Unintentional Injuries 9.5 Respiratory Infections 8.5(Group III) (Group III) (Group I)

Perinatal Conditions 8.8 Ischaemic Heart Disease 8.8 Diarrheal Disease 7.2(Group I) (Group II) (Group I)

Childhood Cluster 8.1 Cerebrovascular Disease 5.2 Perinatal Conditions 6.7Diseases (Group I) (Group II) (Group I)

ures and tables, Section A deals with deaths, Section Bwith DALY loss.

Two patterns emerge:First, ailments in the communicable diseases group

are relatively more important for poor women than forpoor men. Part of the reason is that, as noted earlier, the

communicable diseases group includes maternal health,which obviously affects women only. But there is moreto the story than this, since communicable diseasesaccount for a higher proportion of death and disabilityamong poor women than among poor men even aftermaternal conditions are removed from consideration.


Figure 2A Causes of Death by Gender, 1990

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Among the rich, these differences disappear. If any-thing, communicable diseases appear to cause a some-what lower percentage of female than of male deathsand disability, while noncommunicable conditionsbecome more important for women than for men.

Specifically, when maternal conditions are included,diseases in the communicable conditions group areresponsible for about 7.5 percentage points more oftotal deaths and 11.4 percentage points more of DALYloss among poor women than among poor men. Whenmaternal conditions are excluded, those figures fall to6.3 percentage points more for deaths and 7.5 per-centage points for DALY loss. Among the rich, com-municable diseases cause less death and disabilityamong women than among men, by 0.6 percentagepoints for deaths and 0.9 percentage points for DALYloss. Noncommunicable diseases, in contrast, areresponsible for more deaths and disability amongwomen than men, by 5.4 percentage points for deathsand 7.8 percentage points for DALY loss.

Second, injuries are much less important forwomen than for men among both the global poor andthe global rich. In each group, the percentage of deathsand of DALY loss among women attributable toinjuries is only of the order of one-half of the figure formen. Specifically, 6.7 percent of deaths and 9.1 per-cent of DALY loss among poor women are attributableto injuries, compared to 12.0 percent of deaths and17.2 percent of DALY loss among poor men. For theglobal rich, the figures are 4.6 percent of deaths and8.3 percent of DALY loss among women, compared to9.4 percent of deaths and 17.3 percent of DALY lossamong men.

Differences between the Health of the Poor and theHealth of Others

Introduction. The differences between the health ofthe poor and the health of others in society have beenpresented in two different ways:

• Poor-Rich Gap: The health of the global poor com-pared with that of the global rich. This comparisonis expressed in terms of excess death and disability,where excess is defined as the difference betweenthe number of deaths (or amount of DALY loss)

experienced by the poor and the number of deaths(or amount of DALY loss) that they would haveexperienced had they suffered from the same rate ofdeath (or DALY loss) as the rich in each age and gen-der group. The number of excess deaths (or amountof excess DALY loss) can be seen a measure of thegap in health status between poor and rich.

• Concentration among the Poor: The health of theglobal poor compared with that of the entire glob-al population. This comparison is expressed as thepercentage of total global deaths (or DALY loss) thatis experienced by the global poor, and indicates theextent to which the effects of a given disease areconcentrated among the poor. If a given diseasewere evenly distributed across all populationgroups, the world’s poorest 20 percent would suf-fer 20 percent of the death and disability caused bythat disease. Should the poor suffer more than 20percent of all the worldwide deaths and disabilitycaused by the disease, the disease can be said to bedisproportionately concentrated in that poor pop-ulation group.

The Poor-Rich Gap. Table 2 records the amount ofexcess death and disability suffered by the world’spoorest 20 percent, illustrating the poor-rich gap.

Section A of Table 2 deals with deaths; section B cov-ers DALY loss. Each section presents the findings intwo different ways:

Column 5 indicates the excess deaths/DALY loss suf-fered by the global poor that is attributable to a givengroup of diseases, expressed as a percentage of the totalloss caused among the poor by that group of diseases.This percentage represents the extent to which mortal-ity or morbidity from the disease could be reduced bylowering the age/gender-specific rates suffered by thepoor to those suffered by the rich.

Column 6 indicates the percentage of total excessdeaths/DALY loss suffered by the global poor that isattributable to each disease group—i.e., the percentageof the total poor-rich gap that is attributable to that dis-ease. Data from this column are summarized graphi-cally in Figure 3.

The numbers given in Table 2 and Figure 3 showthat:



Table 2A. Mortality Gap between the Global Poor and the Global Rich, 1990

(1) (2) (3) (4) (5) (6)Number of Percentage

deaths at death Number of reduction needed to PercentageActual rates of excess eliminate excess of total

number of deaths global rich deaths deaths poor-richCause (000) (000) (col. 2–col. 3, 000) (col. 4/col. 2 x 100) gap

Communicablediseases 8,159 642 7,517 92.1 % 77.0 %

Noncommunicablediseaeses 4,449 3,011 1,438 32.3 % 14.7 %

Injuries 1,315 510 805 61.2 % 8.3 %

Total 13,923 4,163 9,760 70.1 % 100.0 %

Table 2B. DALY Gap between the Global Poor and the Global Rich, 1990

(1) (2) (3) (4) (5) (6)Number of ProportionDALYs lost Number of of DALYs lost Percentage

Actual number at rates of excess DALYs that is of totalof DALYs lost global rich lost excessive poor-rich

Cause (000) (000) (col. 2–col. 3, 000) (col. 4/col. 2 x 100) gap

Communicablediseases 301.719 23,920 277,799 92.1 % 78.9 %

Noncommunicablediseaeses 110,486 31,750 78,736 28.7 % 9.0 %

Injuries 62,301 42,635 19,666 68.4 % 12.1 %

Total 474,506 122,322 352,184 74.2 % 100.0 %

Figure 3 Causes of Poor-Rich Health Status Gap, 1990

A. Deaths B. DALY LossInjuries

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The great majority of deaths and disability causedby communicable disease—92.1 percent of deaths and92.1 percent of DALY loss—among the poor is exces-sive, or directly attributable to differences between richand poor.

Noncommunicable diseases also cause excess deathand disability among the poor, reflecting the fact thatage/gender-specific death/disability rates from non-communicable as well as from communicable diseasesare higher for the poor than for the rich. Compared tocommunicable diseases, however, the proportion oftotal loss from noncommunicable diseases among thepoor that is excessive is relatively small, at 32.3 percentof deaths and 28.7 percent of DALY loss.

Excess death and disability from communicable dis-eases among the poor is responsible for nearly four-fifthsof the total poor-rich gap in health status (77.0 percentwith respect to deaths and 78.9 percent with respect toDALYs). Noncommunicable diseases account for lessthan one-fifth of the gap (14.7 percent with respect todeaths, 9.0 percent with respect to DALY loss).

Concentration among the Poor. Figure 4 shows thepercentage of global death and disability attributable toeach of the three disease groups that is suffered by theworld’s poorest 20 percent. Section A indicates deathsand Section B DALY loss. Comparable figures for theworld’s richest 20 percent are also provided.

The principal findings of this assessment are that:Communicable diseases are heavily concentrated

among the poor. Almost half of all worldwide death anddisability caused by communicable disease occursamong the global poor (47.3 percent of deaths and 49.8percent of DALY loss). In contrast, the rich bear only 4.2percent of the global burden of death caused by com-municable disease, and 2.6 percent of the DALY loss.

Injuries also affect the poor disproportionately,although to a lesser degree. The world’s poor suffer 25.9percent of the deaths and 29.8 percent of the DALY lossattributable to injuries worldwide. The richest 20 per-cent bears 13.1 percent of the global burden of death toinjuries, and 9.1 percent of the burden of DALY loss.

The burden of noncommunicable diseases, by con-trast, is somewhat more concentrated among the richthan among the poor. The global richest 20 percent expe-riences 28.5 percent of all deaths and 19.2 percent of total

global DALY loss from noncommunicable disease. Thepoor suffer notably fewer deaths (15.8 percent of theglobal total), but slightly more DALY loss (19.6 percent).

Interpretation

These findings suggest that global averages significant-ly understate the importance of communicable dis-eases and overstate the role of noncommunicable dis-eases among the world’s poor. It is important torecognize, however, that while the estimates presentedhere represent closer approximations of the burden ofdisease on the poor than do the global averages in cur-rent use, they are far from precise. In addition to theuncertainties inherent in the Murray-Lopez data onwhich the estimates are based, there are two technicalconsiderations that deserve careful attention:

Country Basis of EstimatesAs noted earlier, the estimates for the global poorestand richest 20 percent are constructed from the 20 per-cent of the world’s people who live in those countrieswith the world’s lowest and highest average per capita


Figure 4 Concentration of Deaths and Disability, 1990

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incomes, as distinct from the poorest and richest 20percent of individuals in the world. This means boththat some rich people are included in the estimates ofthe global poor and that some poor people are count-ed among the global rich.

The population groups identified through a coun-try-based procedure are therefore less purely poor orrich than would be the case were it feasible to identifythe groups individual by individual. This raises thequestion of how much difference there might bebetween a country-based and an individual-basedgroup, and of how that difference would affect theresults that have been reported.

Assessment of the likely magnitude of the differencelies far beyond the scope of this paper. However, thedirection of the difference can be confidently assessed:Individual-based estimates of the global poor and richwould almost certainly reveal larger poor-rich differ-ences in disease patterns than the country-basedapproximations presented here.

One way of demonstrating this is by noting that ashift from a country to an individual basis for definingthe global poor would involve transferring out of thegroup people who are relatively rich but living in poorcountries. Their places would be taken by individualswho are poorer than they, but who reside in placeswhere average incomes are higher. The result of thisprocess would be to reduce the average income of peo-ple in the group of global poor.

As shown in the technical literature cited earlier (en.16) and in the country-based estimates presented ear-lier, there is a systematic relationship between incomeand disease patterns. The poorer a population group is,the more important are communicable diseases and theless significant are noncommunicable conditions as aproportion of the total disease burden. A reduction inthe average income of the group of global poor wouldtherefore be likely to raise the significance of commu-nicable ailments and lower the importance of non-communicable conditions in that group.

In other words, communicable diseases could beexpected to figure even more prominently in individ-ual-based definitions of the global poor than they dowhen that population group is defined in terms ofcountries, as in the example provided here. The role ofnoncommunicable conditions would be comparably

reduced. The reverse would be true for the global rich:that is, noncommunicable conditions would be evenmore important and communicable ailments lessimportant when that group is determined with refer-ence to individuals.

Comprehensiveness of ApproachThe findings reported here, showing that noncommu-nicable diseases are less important for the poor than forthe rich, differ from those of earlier studies based onsimilar data. The reason for the difference lies in thecomprehensiveness of the approach taken.

The earlier findings were based primarily on poor-rich comparisons of age-specific death rates from non-communicable diseases among adults, which showedthe existence of higher rates among the poor thanamong the rich. The approach used here goes beyondsuch comparisons by incorporating two additionalconsiderations. One is a focus not on the simple exis-tence of a higher death rate among the poor for a sin-gle type of disease, but rather on a comparison of thesize of the poor-rich differences associated with differ-ent types of disease. The objective is to identify thosediseases where the poor-rich differences are greatest—from which the poor suffer the greatest comparativedisadvantage. The second additional consideration isthe difference in the age structure of the poor and richpopulation groups.

The Principle of Comparative Disadvantage. Whenthe Murray-Lopez data used here are examined withrespect only to age-specific death rates of noncommu-nicable diseases, they, like data from other sources,show that noncommunicable diseases are more impor-tant for the poor than for the rich. This is true at allages, as can be seen from Figure 5. At ages 0–4, thedeath rate from noncommunicable diseases among theworld’s poor is 1.7 times as high as among the globalrich; this ratio peaks at 5.0 for the age group 5–14, thendeclines more or less steadily toward a value of 1.2 forpeople over 70 years of age.

While such figures are important, they tell only partof the story. There is also need to compare the magni-tude of the poor-rich differences that they reveal withthe size of the poor-rich differences in suffering fromother types of disease.


Application of this comparative approach to theMurray-Lopez data presented in Figure 5 indicate thatthe global poor suffer a higher death rate than the glob-al rich not only from noncommunicable diseases, butalso from communicable diseases. In every case, thepoor-rich gaps are larger for these other causes of deaththan for noncommunicable diseases.

In general, the poor-rich differences in the rate ofdeath from communicable diseases are from four to 12times as great as they are for noncommunicable dis-eases. For example, in the 5–14 age category, as citedabove, the death rate from noncommunicable diseasesamong the global poor is 5.0 times as high as it isamong the global rich. In that same age category, thedeath rate from communicable diseases is 56.2 timesas high for the poor as for the rich. This being the case,it makes most sense from a poverty and burden of dis-ease perspective to focus health strategies on commu-nicable diseases, since it is the disease group for whichthe poor-rich gap is greatest.

As such figures illustrate, the establishment of “pro-poor” health policies requires the application of whatmight be called the “principle of comparative disad-vantage.”31 In a setting where, on an age/gender-specif-ic basis, every disease represents more of a problem forthe poor than for the rich, the mere fact that a specificdisease displays this characteristic is insufficientgrounds for singling it out for attention. What mattersfrom a poverty perspective is the magnitude of the dis-advantage associated with that disease relative to the

magnitude of the disadvantage associated with otherdiseases.

The Magnifying Influence of Age Structure. The dif-ference in the composition of the global poor and glob-al rich by age is also important, because of the tenden-cy of communicable diseases to congregate in theyounger age categories. For example, nearly 70 percentof all deaths from communicable diseases in the worldoccur to people younger than 14 years of age; less than10 percent of deaths from noncommunicable diseasesare suffered by the same age group. The correspondingDALY figures are more than 75 percent for communi-cable diseases and less than 20 percent for noncom-municable diseases. Death and disability from com-municable diseases can therefore be expected to play amuch more important role in a younger than in anolder population, even when cause/age-specific deathrates in both populations are the same.

This factor is significant here because the global poorare on average far younger than the global rich, primari-ly because of the higher fertility that poor groups experi-ence. For instance, 41.2 percent of the poor populationis under 15 years of age, compared with only 20.9 per-cent of the rich population. For some analytical purpos-es, it is useful to even out such differences by standard-izing for age—but not for public policy. Standardizationin the public policy context would lead to a policy suit-able for a population in which the age structures of poorand rich groups are similar, when in fact the age struc-ture of the groups is very different. The importance ofgrounding public policy in reality means these differ-ences in age structure must be taken fully into account.32

SummaryThe two technical considerations discussed here areclearly important for an understanding of the results, butthey also reinforce the basic conclusions drawn fromthose results. The first consideration, concerning the esti-mation bias, suggests that the conclusions if anythingunderstate the degree to which reliance on global aver-ages misrepresents the problems of the poor. The secondconsideration, of the comprehensiveness of the approachused, increases in the conclusions’ validity made byexplaining how they can be reconciled with the seem-ingly contradictory findings reported in other studies.


Figure 5 Poor-Rich Differences in Death Rates from

Communicable and Noncommunicable Diseases, 1990

Communicable Diseases Noncommunicable Diseases

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16

3 Changes in the Burden of Disease amongthe Poor and Rich between 1990 and 2020

As instructive as the discussion of the 1990 situationmay be, it provides only part of the story. Of at leastequal interest are the projected changes in the globalburden of disease situation between 1990 and 2020.According to the Murray-Lopez baseline scenario, dur-ing that 30-year period:

• Deaths from communicable diseases will fall from34 percent to 15 percent of the global total, andDALY loss will decline from 44 percent to 20 per-cent.

• Death and disability from noncommunicable dis-eases will rise; in relative terms, deaths increasingfrom 56 percent to 73 percent of the worldwide totaland DALY loss from 41 percent to 60 percent.

Should this scenario prove accurate, by 2020 therewould be nearly five deaths from noncommunicablediseases for every death from communicable diseases.DALY loss from noncommunicable diseases would benearly three times as great as that attributable to com-municable ailments.

These figures, of course, refer to the world as awhole. What would they mean for the global poor?And to what extent would the global poor share in thebenefits from changes in the baseline scenario withrespect to different types of disease?

These are the questions that the current section willaddress. It will do so through a series of projections oflife expectancy gain between 1990 and 2020 undervarying assumptions about progress against differentdisease groups.

Method of Assessment

Principal FeaturesAs with the 1990 estimates presented in Chapter 2, theprincipal source of data for the 1990–2020 projectionsis the Murray-Lopez analysis of the global disease bur-den. However, the approach to data assessment differsfrom that of Murray and Lopez in two ways:

• As in Chapter 2, the emphasis is not on global orregional trends, but rather on trends affecting thepoor and rich—defined, as before, as the globalpoorest and richest 20 percent.

• The focus of the assessment is on the potential con-sequences for the poor of efforts to influence thosetrends, rather than on the trends themselves. Thetrends, rather than being portrayed as unalterable,are seen as potentially amenable to change throughpolicy intervention. Of special interest is the poten-tial impact of two alternative courses of action:

(a) a commitment to producing the fastest possibledecline in death and disability from communi-cable diseases, and

(b) a shift in attention from communicable to non-communicable diseases.

The projection method features a two-stageapproach. The first stage is the construction of a base-line scenario for the global poor and rich in the year2020. The second stage is a set of simple simulations,

consisting of modifications to the baseline scenario thatare designed to illustrate how the benefits of accelerat-ed progress with respect to a particular disease groupmight affect the poor, the rich, and the gap betweenthem.

Estimation ProcedureThe procedure used in constructing the baseline sce-nario is described more fully in Annex A2. It resemblesclosely the method employed to construct the 1990estimates for the global poor and rich, and consists ofthree steps:

• Step One: Identification of the poorest and richestglobal 20 percent in the year 2020. This was doneby projecting the income and the population of eachcountry in 2020 by applying the annual rates of1990–2020 population and per capita incomegrowth used by Murray and Lopez in constructingtheir baseline scenario. Countries (or, in the cases ofChina and India, provinces and states) were listed inascending order of year 2020 per capita income, anda line was drawn at that point below the top of thelist at which the cumulative population represented20 percent of the global total, in order to define thepoorest 20 percent. An analogous procedure, work-ing from the bottom of the list, was applied to iden-tify the richest 20 percent. As explained earlier, theresulting population groups approximate but do notequal the poorest and richest 20 percent of individ-uals in the world.

• Step Two: Calculation of the total number of deathsfor the poorest and richest global 20 percent. Thiswas achieved using data from standard UnitedNations and World Bank sources about projectedyear 2020 age/gender-specific death rates andage/gender population distributions. Multiplying thenumber of people in each age/gender group by thedeath rate for that group yielded a set of figures rep-resenting the number of deaths in each group fromall causes; and these figures were added together.

• Step Three: Disaggregation of the total number ofdeaths according to the three principal groups as

defined by Murray and Lopez. The techniqueapplied by Murray and Lopez for their 1990 disease-specific estimates was again used, as described pre-viously. The number of DALYs for each of the prin-cipal groups was estimated through proration.33

The technique applied in the second stage—the cre-ation of simulated scenarios—is also presented morefully in Annex A2.34 This technique consisted of sev-eral steps:

• Step One: Selection of two alternative scenarios forpresentation:Scenario I was designed to illustrate the potential

impact of renewed attention to communicable dis-eases. The baseline rate of decline in deaths from non-communicable diseases and injuries was held constant,while the pace of decline in deaths from communica-ble diseases was accelerated.

Scenario II was intended to demonstrate the resultof shifting attention to noncommunicable diseases.The baseline rates of decline in deaths from communi-cable disease and injury reduction were retained, andthe projected baseline rate of decline of deaths fromnoncommunicable diseases was increased.

Variants of each scenario were developed, involvingrates of decline ranging from 1.1 to 2.5 times that ofthe baseline rate in each population group. The rateused obviously affected the size of the differencesbetween the baseline and alternative scenarios, but ithad only a marginal impact on the relative poor-richdifferences that are of principal interest. For ease ofcomprehension, findings from only one of these vari-ants are therefore presented below: those from the vari-ant involving a doubling in the baseline rate of decline,for the disease concerned, in every age/gender catego-ry within the global poor and rich.

• Step Two: Determination of the annual rate ofdecline in age/gender-specific mortality ratesimplied by the Murray-Lopez 1990–2020 baselinescenario. This was done for the global poor and rich,and for each major disease group. The sets ofage/gender/cause-specific mortality rates for 1990that were developed during the work for Chapter 2

Changes in the Burden of Disease among the Poor and Rich between 1990 and 2020 17

were used, along with the rates for 2020 that werecalculated while preparing the baseline scenario justdescribed.

• Step Three: Derivation of the alternative year 2020mortality rates from communicable diseases andfrom noncommunicable diseases. This was achievedsimply by doubling the annual average pace ofdecline estimated in step two.

• Step Four: Aggregation of the baseline and alterna-tive 2020 sets of age/gender-specific mortality ratesfrom the different disease groups. This was done ina manner that produced three sets of all-causeage/gender-specific death rates:

(a) rates for the baseline scenario, being the sum ofthe baseline 2020 rates for each of the three dis-ease groups;

(b) rates for scenario I, being the total of the base-line rates for noncommunicable diseases andinjuries and the alternative rates for communi-cable diseases; and

(c) rates for scenario II, being the sum of the base-line rates for communicable diseases andinjuries and the alternative rates for noncom-municable diseases.

• Step Five: Translation of the three resulting sets ofall-causes age/gender-specific mortality rates intolife expectancies. The life expectancy figures for sce-narios I and II were then compared with those of thebaseline in order to assess the implications of thetwo alternative scenarios for the poor and the rich.

Types of AssessmentThe impact of altering future disease trends wasassessed in two ways:

• Effect on the global poor alone. The central questionis how much the poor would benefit from a fasterdecline in communicable diseases, relative to a com-parably faster reduction in noncommunicable ail-ments. As noted earlier, this is the question that mat-ters if one’s interest is improving the health of thepoor, as distinct from reducing poor-rich differences.

• Effect on poor-rich differences. Here, the focus is onhow much a given reduction in one particular typeof disease—whether communicable or noncommu-nicable—would benefit the poor relative to the richand thus increase or decrease the global poor-richhealth gap. This is the matter of greatest concern forthose who look primarily at poor-rich health dis-parities, rather than at the health of the poor alone,as a major source of health inequity.

Findings

Change in Disease Burden under the Baseline ScenarioAccording to the baseline scenario, a worldwide demo-graphic-epidemiological advance between 1990 and2020 would benefit the global poor as well as otherpopulation groups. Communicable diseases woulddecline substantially in importance among the poorand, in relative terms, the significance of noncommu-nicable ailments would increase. As a result, noncom-municable diseases would in 2020 cause almost asmuch death and disability among the world’s poor ascommunicable illnesses. Communicable diseaseswould nonetheless remain the more important of thetwo for the poor, and even in 2020, communicable dis-eases would continue to be far more important for thepoor than for the world as a whole or for the rich.

Specifically, should the baseline scenario prove cor-rect:

Among the global poor, the percentage of deathsattributable to communicable disease would declinefrom 59 percent in 1990 to 44 percent in 2020. Duringthe same period, the percentage of deaths caused bynoncommunicable diseases would rise from 32 percentto 42 percent. DALY loss from communicable diseaseswould fall from 64 percent to 43 percent; DALY lossfrom noncommunicable diseases would increase from23 percent to 40 percent. By the end of the projectionperiod, communicable diseases would therefore con-tinue to be responsible for slightly more disease anddisability than noncommunicable ailments, althoughthe gap would largely have closed.

Since the importance of communicable diseaseswould also be declining in other population groups,communicable conditions would continue to be much


more important for the poor than for the better-off—despite the reduction in the importance of communi-cable diseases among the poor just described. As indi-cated, in 2020 communicable diseases would cause 44percent of deaths and 43 percent of DALY loss amongthe global poor, compared to about 15 percent ofdeaths and 20 percent of DALY loss in the world as awhole, and 7 percent of deaths and 8 percent of DALYloss among the global rich.

For the same reason, noncommunicable ailmentswould remain much less important for the poor thanfor other population groups, despite their rise inimportance among the poor. Among the poor, non-communicable diseases would cause 42 percent ofdeaths and 40 percent of DALY loss in 2020. But in theworld as a whole, such diseases would be responsiblefor 73 percent of deaths and 60 percent of DALY loss;among the global rich, they would cause 82 percent ofdeaths and 81 percent of DALY loss.

Injuries would account for an increased proportionof total deaths for all the population groups covered.The percentage of total deaths attributable to injurywould increase from 9 to 14 percent among the poor,from 10 to 12 percent in the world as a whole, and from7 to 10 percent among the rich. DALY losses wouldincrease from 13 to 17 percent for the poor and from15 to 20 percent for the population as a whole, butwould decline from 13 to 11 percent for the rich.

Changed Life Expectancy under the Baseline andAlternative ScenariosIntroduction. On the surface, the evidence of the base-line scenario just presented might appear to argue fora shift in priorities toward treatment of noncommuni-cable diseases—for the global poor as well as for theworld’s population as a whole. For, according to thisscenario, the relative importance of noncommunicablediseases is rising among the poor as well as amongother segments of the population, and communicablediseases are continuing their decline.

However, the projected baseline trend is notably lessrelevant for policy formulation than what economistscall a “marginal” approach—that is, an approach basedon an assessment of the potential impact that policy-induced changes in the projected baseline trend makeon the future situation. Application of this approach

means investigating the impact on people at differenteconomic levels of accelerated progress against differ-ent types of illness.

In other words, suppose that the world’s leaderswere to intervene and bring about a faster rate ofdecline in a particular disease group than is currentlyprojected. How much of the resulting incrementalreduction in death and disability would accrue to thepoor? How much to the rich? Addressing questionslike this is the best way to measure the impact of alter-native strategies to disease reduction, and thus to pro-vide the guidance that policymakers need.

Table 3 provides answers to some of these questions.The table shows, for the global poor and for the glob-al rich, the life expectancy at birth that prevailed in1990 and that would prevail in 2020 under the base-line scenario and under the two alternative scenariosthat are under consideration.

1990-2020 Life Expectancy Increase under theBaseline Scenario. The life expectancy figures for thebaseline scenario presented in Table 3 are constructedfrom the sum of cause-specific mortality data present-ed in the previous chapter, and are consistent withthese data. The table shows that in 1990, the globalpoor had a life expectancy of about 54 years, more than20 years less than that of the global rich. Under thebaseline scenario, the life expectancy of the poor wouldincrease by almost 9 years between 1990 and 2020,compared with 5 years for the rich. The result wouldbe a noticeable diminution in the poor-rich gap.

The table also shows, however, that either of the twoalternative scenarios (i.e., faster reductions in commu-nicable or in noncommunicable diseases) would pro-duce a larger life expectancy gain for each populationgroup than would the baseline scenario. These gainswould range from 10.0 to 12.7 years for the globalpoor, compared with the 8.6 years of the baseline. Forthe global rich, the gain would be 5.7 to 10.6 years,rather than the 5.3-year increase that the baselinewould produce.

Both poor and rich, in other words, would gain toat least some degree from an acceleration in progressagainst disease, whether those diseases are communi-cable or noncommunicable. However, the amount ofbenefit that the poor and rich would gain differs sig-


nificantly under the two alternative scenarios. It is thesize of these differences that is of particular interestfrom a poverty or equity perspective, and is thus thefocus of what follows.

Impact of Accelerated Improvement on the Healthof the Poor. If the objective is to improve the health ofthe poor to the maximum possible extent, as distinctfrom reducing the poor-rich gap, the comparison ofgreatest interest is between communicable and non-communicable diseases and their effect on the pooralone. Looking at Table 3, this means comparing theincrease in life expectancy among the poor producedby alternative scenario I (an accelerated decline incommunicable illnesses) with that resulting from alter-native scenario II (a comparably faster reduction indeath and disability from noncommunicable diseases).

This comparison is illustrated in the left-hand panelof Figure 6, which represents graphically the data con-tained in Table 3. This figure shows that an accelera-

tion in the rate of decline of death and disability fromcommunicable diseases would result in a 1990–2020life expectancy gain among the global poor that is 4.1years greater than under the baseline projection.35 Acomparably accelerated decline in noncommunicablediseases among the global poor over the same periodwould result in a year 2020 life expectancy gain 1.4years greater than under the baseline projection.

Such calculations indicate that an acceleration inoverall progress against communicable diseases wouldbring about a significantly larger gain for the global poorthan would an acceleration of comparable magnitudeachieved against noncommunicable conditions. Theadditional 4.1 years of life expectancy that fasterprogress against communicable ailments would gener-ate (compared to the baseline scenario) is almost threetimes as great as the 1.4-year increase that fasterdeclines in noncommunicable diseases would produce.

The reverse is true for the global rich. As shown inthe right-hand panel of Figure 6, alternative scenario I


Table 3. Impact of Alternative Global Disease-Reduction Scenarios on the Health of the Poor and Rich

(1) (2) (3) (4) (5) (6) (7)Global poor Global rich

1990–2020 1990–2020Gain in Life Gain in Life

1990 Life 2020 Life Expectancy 1990 Life 2020 Life ExpectancyScenario Expectancy Expectancy (col. 3 – col. 2) Expectancy Expectancy (col. 6 – col. 5)

Baseline Scenario: 53.6 years 62.2 years 8.6 years 75.3 years 80.6 years 5.3 years• Baseline Global Burden of

Disease Project projectionAlternative Scenario I 53.6 years 66.3 years 12.7 years 75.3 years 81.0 years 5.7 years(faster communicable diseasedecline):

• Doubled Pace in Decline in Death Rates fromCommunicable Diseases

• Baseline Pace of Declinein Death Rates fromOther Causes of Death

Alternative Scenario II 53.6 years 63.6 years 10.0 years 75.3 years 85.9 years 10.6 years(faster noncommunicabledisease decline):

• Doubled Pace in Declinein Death Rates fromNoncommunicableDiseases

• Baseline Pace of Declinein Death Rates fromOther Causes of Death

would lead only to an additional 0.4 years of lifeexpectancy among the rich in 2020. Scenario II, in con-trast, would produce 5.3 additional years of lifeexpectancy. In other words, while faster reductions incommunicable diseases are most important for theglobal poor, the global rich have more to gain fromaccelerated progress against noncommunicable condi-tions.

Impact of Accelerated Improvement on Poor-RichHealth Differences. Measuring the impact of the alter-native strategies on the poor-rich difference requires afurther type of comparison. In dealing with the pooralone, the relevant comparison was between the effectsof different strategies on the same population group. Togauge the impact on poor-rich differences, the relevantcomparison concerns the effects of the same strategyon different population groups—i.e., on the poor andon the rich.

This type of comparison is presented in Figure 7,which again draws on the data contained in Table 3.

The Figure 7 data show that: Doubling the rate of decline in communicable dis-

ease (alternative strategy I) would be much more ben-eficial for the poor than for the rich. For the poor, alter-native strategy I would lead to a year 2020 lifeexpectancy 4.1 years greater than the baseline year2020 life expectancy. The benefit of this strategy for therich would be only 0.4 years. The life expectancy gainfor the poor would be 3.7 years more than for therich—or greater by a factor of more than 10.

Conversely, the rich would gain more than the poorwould from a doubled rate of reduction of noncom-municable disease (alternative scenario II). Under thisscenario, the year 2020 life expectancy of the richwould be 5.3 years more than it would be under thebaseline scenario; for the poor, it would be only 1.4years more. The gain for the rich, in other words,would be 2.9 years more than it would be for the poor,or nearly four times as much.36

The impact of these different strategies on the lifeexpectancy difference between the global richest andpoorest 20 percent is shown in Figure 8. Again, thedata are drawn from Table 3.

Under the baseline scenario, the global rich wouldin 2020 have a life expectancy 18.4 years longer than


Figure 6 Additional 1990–2020 Life Expectancy GainProduced in a Given Population Group by DifferentDisease-Reduction Strategies

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Alternative Strategy I: Faster Communicable Disease Reduction

Alternative Strategy II: Faster Noncommunicable DiseaseReduction

Figure 7 Additional 1990–2020 Life Expectancy GainProduced by a Given Disease-Reduction Strategy inDifferent Population Groups

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Figure 8 Life Expectancy Difference Between Global Rich andGlobal Poor in 2020 Under Different Disease-ReductionScenarios

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would the poor (80.6 years versus 62.2 years). Underalternative strategy I, which projects an accelerateddecline in deaths from communicable diseases evenlyspread across all economic classes, this gap would bereduced by 3.7 years, to 14.7 years (81.0 years versus66.3 years). If declines in mortality from noncommu-nicable diseases in all economic levels were to be accel-erated instead (alternative scenario II), the gap wouldactually rise, by 3.9 years to 22.3 years (85.9 years ver-sus 63.6 years)

In brief, overall accelerated declines in communica-ble diseases would benefit the poor more than the richand would thus reduce the future poor-rich lifeexpectancy gap. Faster overall reductions in death fromnoncommunicable diseases would have the oppositeeffect.

Interpretation

Explanation of Findings This conclusion is perhaps surprising in light of theearlier projection that, even among the poor, commu-nicable illness would decline and noncommunicablediseases would rise in relative importance between1990 and 2020. However, there is a ready explanationfor why the accelerated reduction of communicabledisease should be of continuing central importance forthe global poor; and, more generally, for why acceler-ated declines in the different disease groups have thedistributional consequences that they do:

• Communicable diseases. Even in 1990, communi-cable diseases were of little concern to the rich. Aswas shown in Figure 1, communicable diseases wereresponsible for only 10 percent or less of all deathand disability among the global rich. Even if suchdiseases were completely eliminated from the earth,the impact on this rich population group would beminimal. Not so, however, for the global poor.Among the poor, communicable diseases causedwell over half of all death and disability in 1990.Given the predominance of communicable diseasesin the overall burden of disease, the faster reductionof this group of diseases would inevitably signifi-cantly benefit the poor.

• Noncommunicable diseases. The converse is truefor noncommunicable diseases. In 1990, this groupof diseases played a significantly smaller role in thehealth of the global poor than in that of the rich,being responsible for only 25–35 percent of alldeath and disability among the former comparedwith 75–85 percent among the latter. The rich thusstand to gain a great deal more than the poor fromreduced noncommunicable disease.

The conclusions reported here concerning theimpacts on poor and rich of the faster reduction ofcommunicable and noncommunicable diseases aretherefore intuitively plausible, as well as statisticallystraightforward. The difference between these conclu-sions and the seemingly contrary findings of earlierreports is the result simply of the application of an ana-lytical perspective that is different from, and, as arguedearlier, more relevant for policy development than thatwhich went before.

Role of Cost-Effectiveness ConsiderationsHowever, there remain other, important ways in whicheven the calculations just presented are removed fromthe realities of the world in which policymakers work.One of these is the lack of explicit consideration of therelative cost-effectiveness of the different interventionsavailable to address each type of disease and each pop-ulation group. Cost information is obviously important:to tell a policymaker that an accelerated decline in dis-ease category A would benefit the poor twice as muchas the same decline in disease category B would be quitemisleading should it cost 10 times as much to producethat degree of acceleration in A as opposed to B.

The absence of information about intervention andcost-effectiveness in Table 3 and Figures 6, 7, and 8therefore means that the conclusions based on thesedata are directly applicable for policy formulation onlyif the interventions available to deal with communica-ble and noncommunicable diseases among the globalpoor and rich are equally cost-effective. How likely isthis to be the case?

The available information is too general and impre-cise to permit a confident response to this question. Itis also inadequate to justify the preparation of a quan-titative adjustment to the data in Figures 6, 7, and 8


that could account for any systematic differences in thecost-effectiveness of the interventions available toaddress specific disease or population groups.

Despite such limitations, however, the existinginformation is sufficient to indicate that in general:

• Currently available intervention options appearcapable of reducing death and disability from com-municable diseases at considerably less cost thanwould be incurred in reducing mortality and mor-bidity caused by noncommunicable conditions.

The evidence most directly relevant to this pointcomes from a prominent, careful investigation intothe cost-effectiveness of a wide range of interven-tions in developing countries.37 The data cover 54interventions, 30 of which can produce a unit ofDALY loss for $75 or less, and 24 of which cost morethan $75 per unit of DALY loss. Of the 30 less expen-sive interventions, 28, or 93 percent, are

Documents

The Burden of Disease among the Global Poor · 2016. 7. 17. · The Burden of Disease among the Global Poor. Current Situation, Future Trends, and Implications for Strategy. The World