Using disability-adjusted life years to assess the burden of disease and injury in Rhode Island

Objectives

Disability-adjusted life years (DALYs) measure the burden of disease and injury in a population. We tested the feasibility of calculating DALYs to assess the burden of disease and injury in Rhode Island (RI).

Methods

We computed DALYs for the 2008 RI population using methods developed by the World Health Organization, Harvard University, and the World Bank. DALYs are a composite measure that sum years of life lost (YLLs) due to premature mortality with years lived with disability (YLDs). We calculated crude mortality, YLLs, YLDs, and DALYs for 90 major health conditions for RI and stratified them by gender and age. Calculations for YLLs and YLDs were based on five-year averages. We compared our results with U.S. and Los Angeles County, California, estimates.

Results

A DALYs ranking produces a different picture of RI''s disease and injury burden than does mortality-based ranking. Of 90 major health conditions assessed for RI, six of the top 10 causes for mortality and DALYs were the same, but were ranked differently: ischemic heart disease, cerebrovascular disease, Alzheimer dementia and other dementias, trachea/bronchus/lung cancer, chronic obstructive pulmonary disease, and diabetes mellitus. These six conditions accounted for 59% of deaths but only 35% of DALYs. Causes and rank orders for DALYs differed between males and females and among age groups.

Conclusions

Including nonfatal health conditions in an assessment of population health provides a different picture than traditional mortality-based assessments. This study demonstrates the feasibility and constraints of using DALYs to assess the burden of disease and injury at the state level.Mortality data have been used traditionally to identify a population''s most important health problems.¹ However, falling death rates often mean people are living longer but with years of illness and disability. Mortality measures provide incomplete information about overall population health, necessitating the development of alternate summary measures.^1,2 The World Health Organization (WHO), Harvard University, and the World Bank introduced disability-adjusted life years (DALYs) in the Global Burden of Disease (GBD) study.^3,4 DALYs reflect the years of life lost (YLLs) to premature death and the years spent in unhealthy states, combining the impacts of mortality and disability.DALYs are a “health gap” measure that represents the gap between the current health status of a population and one in which everyone lives into old age free of disease and injury.^5,6 It includes the impact of usually nonfatal conditions, such as alcohol use, mental disorders, arthritis, and injuries, and provides a different picture of population health than traditional mortality-based assessments.Several studies have implemented DALYs and published disease and injury burden reports for countries and subnational entities, ^1–3,5,7 including for the United States² and for Los Angeles (LA) County, California.³ In this study, we applied DALYs to the Rhode Island (RI) population using the GBD study methods.⁴ We estimated DALYs for major health conditions, compared DALYs results with traditional mortality measures, and assessed the benefits and limitations of estimating DALYs at the state level. To our knowledge, RI is the first U.S. state to attempt the use of DALYs to evaluate the burden of disease and injury at the state level.