Combining health and social protection measures to reach the ultra ...

Decision-makingInequities in health status:findings from the 2001 GlobalBurden of Disease studyArticle by Alan Lopez (pictured) and Colin MathersThe 1990 Global Burden of Disease (GBD) studydeveloped a comprehensive framework for integrating,validating, analyzing, and disseminating fragmentedinformation on the health of populations so that it is trulyuseful for health policy and planning 7 . Features of thisframework included the incorporation of data on nonfatalhealth outcomes into summary measures of populationhealth (described in the next subsection), the development ofmethods and approaches to estimate missing data and toassess the reliability of data, and the use of a common metricto summarize the disease burden both from diagnosticcategories of the international classification of diseases (ICD)and the major risk factors that cause those health outcomes.The basic philosophy guiding the burden of diseaseapproach is that almost all sources of health data are likely tohave information content provided that they are carefullyscreened for plausibility and completeness and that internallyconsistent estimates of the global descriptive epidemiology ofmajor conditions are possible with appropriate tools,investigator commitment, and expert opinion. Thisphilosophy remains central to the GBD 2001 study, whichhas expanded the framework of the original GBD study to:✜ quantify the burden of premature mortality and disabilityby age, sex, and region for 135 major causes or groupsof causes;✜ develop internally consistent estimates of incidence,prevalence, duration, and case fatality rates for morethan 500 sequelae resulting from the foregoing causes;✜ analyze the contribution to this burden of majorphysiological, behavioural, and social risk factors by age,sex, and region.Estimating mortality: methods and dataComplete death registration data cover only one third of theworld’s population. Some information on another third isavailable through the national sample registration systemsand urban death registration systems of India and China. Forthe remaining one third of the world’s population, includingmost countries in sub-Saharan Africa, only partial informationis available from epidemiological studies, disease registers,and surveillance systems.To estimate the number of deaths by cause we drew on thefollowing four broad sources of data:✜ Death registration systems. Complete or incompletedeath registration systems provide information aboutcauses of death for almost all high-income countriesand for many countries in Europe (Eastern) and CentralAsia and in Latin America and the Caribbean. Somevital registration information is also available in allother regions.✜ Sample death registration systems. In China and India,sample registration systems for rural areas supplementurban death registration systems. Information systemsnow provide information on causes of death for severalother large countries for which information was notavailable at the time of the original GBD study.✜ Epidemiological assessments. Epidemiologists haveestimated deaths for specific causes, such as HIV/AIDS,malaria, and tuberculosis (TB), for most countries in theregions most affected. These estimates usually combineinformation from surveys on the incidence or prevalenceof the disease with data on case fatality rates.✜ Cause of death models. The cause of death models usedin the original GBD study 7 were substantially revised andenhanced for estimating deaths by broad cause group inregions with limited information on mortality. TheCodMod software developed for this study and describedlater drew on a data set of 1613 country-years ofobservation of cause of death distributions from 58countries between 1950 and 2001.For the GBD 2001 study, age- and sex-specific death rateswere calculated from the death and population data providedby countries, with adjustments made for completeness of theregistration data where needed, and then total deaths by ageand sex were calculated for each country by applying theserates to the United Nations Population Division estimates ofde facto populations for 2001.Four methods were used to construct life tables for eachcountry depending on the type of data available 2 :✜ Countries with death registration data for 2001. Suchdata were used directly to construct life tables for 56countries after adjusting for incomplete registration ifnecessary.✜ Countries with a time series of death registration data.Where the latest year of death registration data availableGlobal Forum Update on Research for Health Volume 4 ✜ 163