The burden of disease among the global poor.

BACKGROUND: Global and regional estimates show that non-communicable diseases in old age are rising in importance relative to other causes of ill health as populations age, and as progress continues against communicable diseases among infants and children. However, these estimates, which cover population groups at all income levels, do not accurately reflect conditions that prevail among the poor. We estimated the burden of disease among the 20% of the global population living in countries with the lowest per capita incomes, compared with the 20% of the world's people living in the richest countries.

METHODS: Estimates for the global poorest and richest 20% were prepared for 1990 for deaths and disability-adjusted life years (DALYs), by a procedure used in a prominent recent study of the global disease burden. Projected mortality rates in the year 2020 were established for the world's poorest and richest 20% under various assumptions about the future rate of decline in communicable and non-communicable diseases.

FINDINGS: In 1990, communicable diseases caused 59% of death and disability among the world's poorest 20%. Among the world's richest 20%, on the other hand, non-communicable diseases caused 85% of death and disability. A raised baseline rate of communicable disease decline between 1990 and 2020 would increase life-expectancy among the world's poorest 20% around ten times as much as it would the richest 20% (4.1 vs 0.4 years). However, the poorest 20% would gain only around a quarter to a third as much as the richest 20% from a similar increase in non-communicable diseases (1.4 vs 5.3 years). As a result, a faster decline in communicable diseases would decease the poor-rich gap in 2020, but under an accelerated rate of overall decline in non-communicable diseases, the poor-rich gap would widen.

INTERPRETATION: Our estimates are crude, but despite their limitations, they give a more accurate picture of changes in attributable mortality among the world's poor than do the global averages in current use.