Disability-adjusted life years:: an instrument for defining public health priorities?

Background: The objective of this paper is the study of a health indicator allowing surveillance and evaluation of the overall health of the Paris population, and providing information to help prioritize possible choices among preventive and curative actions. Moreover, comparison between results obtained for Paris with a global health indicator, "Disability-adjusted life years" (DALYs) and available bibliographical data will enable clarifying some points about summary measures of health. Methods: The method used is that of the Global Burden of Disease. It allows a ranking of diseases using an indicator called DALYs. This indicator integrates mortality and morbidity components by summing expected years of life lost due to premature mortality and calculated years of healthy life lost. DALYs were calculated using local mortality data and published regional disabilities tables from the World Health Organisation (WHO). Results: There were a total of 242 061 DALYs for Paris for the year 1999. The six leading specific causes are: alcoholic psychosis and dependence (accounting for 6.5% of the total), lung cancers (5.7%), ischaemic hearth disease (4.8%), depression (4.4%), dementias (4.2%), and arthritis (3.9%). Men contributed the majority of DALYs for the first three. For four of the six leading causes, the majority of DALYs came from years lived with disability, rather than mortality. Only for lung cancer and ischaemic hearth disease was the majority of DALYs from years of life lost by mortality. Conclusion: The results for Paris are used to illustrate how DALYs can illuminate debates about public health priorities. Such data can inform the population about health condition and provide decision makers with global health indicators. The next step will be to estimate the DALYs from local morbidity data when available, and compare these results to those based on the World Health Organisation tables, which are not sensitive to local results other than those due to mortality. Future steps include further evaluation and development of this method for surveillance, assessment and evaluation of public health actions. However, some of the results obtained with this indicator underline the limits of this kind of analysis.