DALYS - THE AGE-WEIGHTS ON BALANCE

In studies for the 1993 World development report: investing in health Murray et al. developed the disability-adjusted life year (DALY). This article examines one particular aspect of the DALY methodology: the w eighting of life years by age. For the quantitative implementation of this notion Murray proposed a general equation to weight life years by age, which specifies that the years lived between the ages of 9 and 5 4 years have a weight greater than unity, and for the years outside th is range less than unity. The age-weighted life years are used to calc ulate the ''expected years of life lost'' (EYLL). Comparison of age-we ighted and unweighted age-specific life expectancies shows that the ag e range which becomes more important due to weighting is not 9-54 year s, but 0-27 years. This happens because the EYLL is an age-weighting s ystem in itself, emphasizing the young. The result of piling one age-w eighting system on top of the other gives an even stronger emphasis on the young than the EYLL generates by itself. Although this is unlikel y to upset the results from the Global Burden of Disease study, we do not think it is desirable. And it is certainly different from what we were led to expect.