Disability burden due to stroke in Western Australia: new insights from linked data sources

Abstract

Background: The disability-adjusted life year index is used extensively to compare disease burden among diseases and locations, but difficulties remain in accurately estimating the nonfatal stroke burden in years lived with disability. Aims: To improve stroke-related years lived with disability estimates in Western Australia for 2000, by improving the accuracy of component inputs: nonfatal (28-day survivor) incidence, disease duration and disability (severity) weights. Methods: Nonfatal stroke incidence and the mortality difference between prevalent cases and the general population were estimated from linked hospital and mortality data using the Western Australian Data Linkage System. dismod software used these inputs to model disease duration. Disability weights were estimated from population-based stroke survey data, using indirect health valuation methods and adjusting for prestroke disability. Years lived with disability were calculated from the three components. Results: The annual age-standardised nonfatal incidence (n=1985) was higher in males (121/100 000) than females (96/100 000). The duration varied between 35·8 (females 15–24 years) and 3·4 years (males 85+ years). The mean pre-stroke-adjusted disability weight was higher at 4-months (0·38) than at 12-months (0·31). The age-standardised rate of nonfatal burden in males (302/100 000; 95% CI 290–314) was significantly higher than that in females (250/100 000; 95% CI 240–260). The nonfatal proportion of stroke burden (males 45%; females 37%) was higher than estimated in previous studies. Conclusion: This study illustrates that previous reports most likely underestimated disability burden as a contributor to the total stroke burden in Australia. Methodological refinements will contribute to burden of disease studies elsewhere.