Elsevier

The Lancet

Volume 349, Issue 9064, 24 May 1997, Pages 1498-1504
The Lancet

Articles
Alternative projections of mortality and disability by cause 1990–2020: Global Burden of Disease Study

https://doi.org/10.1016/S0140-6736(96)07492-2Get rights and content

Summary

Background

Plausible projections of future mortality and disability are a useful aid in decisions on priorities for health research, capital investment, and training. Rates and patterns of ill health are determined by factors such as socioeconomic development, educational attainment, technological developments, and their dispersion among populations, as well as exposure to hazards such as tobacco. As part of the Global Burden of Disease Study (GBD), we developed three scenarios of future mortality and disability for different age-sex groups, causes, and regions.

Methods

We used the most important disease and injury trends since 1950 in nine cause-of-death clusters. Regression equations for mortality rates for each cluster by region were developed from gross domestic product per person (in international dollars), average number of years of education, time (in years, as a surrogate for technological change), and smoking intensity, which shows the cumulative effects based on data for 47 countries in 1950–90. Optimistic, pessimistic, and baseline projections of the independent variables were made. We related mortality from detailed causes to mortality from a cause cluster to project more detailed causes. Based on projected numbers of deaths by cause, years of life lived with disability (YLDs) were projected from different relation models of YLDs to years of life lost (YLLs). Population projections were prepared from World Bank projections of fertility and the projected mortality rates.

Findings

Life expectancy at birth for women was projected to increase in all three scenarios; in established market economies to about 90 years by 2020. Far smaller gains in male life expectancy were projected than in females; in formerly socialist economies of Europe, male life expectancy may not increase at all. Worldwide mortality from communicable maternal, perinatal, and nutritional disorders was expected to decline in the baseline scenario from 17·2 million deaths in 1990 to 10·3 million in 2020. We projected that non-communicable disease mortality will increase from 28·1 million deaths in 1990 to 49·7 million in 2020. Deaths from injury may increase from 5·1 million to 8·4 million. Leading causes of disability-adjusted life years (DALYs) predicted by the baseline model were (in descending order): ischaemic heart disease, unipolar major depression, road-traffic accidents, cerebrovascular disease, chronic obstructive pulmonary disease, lower respiratory infections, tuberculosis, war injuries, diarrhoeal diseases, and HIV. Tobacco-attributable mortality is projected to increase from 3·0 million deaths in 1990 to 8·4 million deaths in 2020.

Interpretation

Health trends in the next 25 years will be determined mainly by the ageing of the world's population, the decline in age-specific mortality rates from communicable, maternal, perinatal, and nutritional disorders, the spread of HIV, and the increase in tobacco-related mortality and disability. Projections, by their nature, are highly uncertain, but we found some robust results with implications for health policy.

Introduction

Future health scenarios that are likely, or probable, or merely possible can have an important role in shaping public-health policy. Studies on health projections1, 2, 3 provide an indication of the strong interest shown by scientific and public-health communities in the definition and quantification of scenarios of future health. There have, however, been few comprehensive efforts to project health scenarios for a population4 and none for the entire world or for major regions. In this paper, the last of four on the Global Burden of Disease Study (GBD) (see Lancet 1997; 349: 1269–76; 1347–52; and 1436–42) we describe how we created three scenarios of future mortality and disability by cause, which may have important public policy implications.

Our scenarios were based on future health status as a function of projected changes in key socioeconomic variables, which influence health states. Uncertainties in the projections arise from the validity of these relational models, assumptions about their invariance over time, and, of course, uncertainty about the future rates and distribution of factors that currently influence health and survival. Despite these uncertainties, several robust projections—due largely to demographic change and the future effects of current smoking patterns—emerge from our analysis. Further detail on the methods used to estimate causes of death, to develop epidemiological profiles of each disabling sequela, to assess the burden attributable to major risk factors, and to project the burden of premature mortality and disability has been published.5

Section snippets

Projection methods

We used 12 separate analytical or computational steps to construct a baseline scenario, and optimistic and pessimistic scenarios. Separate projection models for both sexes and seven age-groups—0–4, 5–14, 15–29, 30–44, 45–59, 60–69, and 70 years or older—were developed to produce parsimonious equations for nine cause-of-death clusters: all group 1 (communicable, maternal, perinatal, and nutritional disorders); malignant neoplasms, cardiovascular diseases, digestive diseases, chronic respiratory

Results

Life expectancy at birth (figure 1) for women in all three scenarios was projected to increase in all regions, with the largest gains expected in sub-Saharan Africa, India, and other Asia and islands. Life expectancy for women in established market economies may reach close to 90 years—this is especially plausible since Asian women in the USA already have a life expectancy at birth of over 86 years.25 The smallest gain for women is projected for formerly socialist economies of Europe.

Discussion

In all three scenarios, substantial changes were predicted in regional patterns of mortality and disability. Some major themes are worth emphasising. The distribution of deaths by age will shift from younger to older ages. A major decline in the mortality and disability from communicable, maternal, perinatal, and nutritional disorders was predicted in all three scenarios, although the declines in the optimistic and baseline scenarios were much greater than in the pessimistic scenario. Deaths

References (25)

  • A Acharya et al.

    An econometric model for forecasting age-and cause-specific mortality rates

    (1996)
  • SH Preston

    Mortality patterns in national populations

    (1976)
  • Cited by (5769)

    • A review on the application of chitosan-based polymers in liver tissue engineering

      2024, International Journal of Biological Macromolecules
    View all citing articles on Scopus
    View full text