Estimated disability weights for the severity of health outcomes: a systematic review and meta-analysis.

BACKGROUND: The disability weight quantifies the severity of health states from diseases and injuries. It is a fundamental index to estimate the disability-adjusted life year in the Global Burden of Disease studies. Disability weight estimates have been shown to vary across different national populations, suggesting the influence of cultural differences. However, survey data of disability weights in the Global Burden of Disease study is still limited worldwide. OBJECTIVES: To more accurately reflect the true health conditions of global populations, this study aims to systematically summarize the disability weight values from international authoritative surveys, and explore the influential factors of disability weight estimates. METHODS: Based on the Global Burden of Disease study, surveys used paired comparison questions wherein respondents considered two hypothetical individuals with different health states and specified which person was healthier. This study comprehensively searched multiple databases, including PubMed, Web of Science, Science Direct, and Google Scholar. We identified disability weight studies that utilized the paired comparison method and were conducted in national populations, published in international peer-reviewed journals. A meta-regression analysis was conducted to estimate the overall summary effect of disability weight values for 235 unique health states. These health states were estimated for all non-fatal consequences of disease and injury, including infectious diseases, cancer, cardiovascular diseases, diabetes, chronic respiratory diseases, neurological disorders, mental, behavior, and substance use disorders, hearing and vision loss, musculoskeletal diseases, injuries and others. Heterogeneity was assessed using the I2 statistics. Univariate meta-regression analysis was conducted to explore the impact of age, sex, education, population composition, and survey regions, respectively, on the summarized effect of each health state. RESULTS: The total analysis sample consisted of 610,818 respondents from the Global Burden of Disease 2013 disability weight surveys, the Japanese disability weight survey, and the Chinese disability weight survey. The summarized disability weights of health states ranged from mild anaemia (summarized disability weight = 0.008, 95% uncertainty interval 0.001-0.016, I2 = 0.95) to heroin and other opioid dependence (moderate to severe) (summarized disability weight = 0.737, 0.651-0.823, I2 = 0.823). Pearson correlation analysis showed that high correlation was observed between the set of overall summary disability weights of 235 health states from this meta-analysis and those from all included disability weight studies (all Pearson's r > 0.9, P < 0.001). Univariate meta-regression analysis indicated that age, sex, education level, panel composition of survey populations, and the survey regions were associated with the summarized disability weights of some health states. CONCLUSIONS: The overall summary of disability weights obtained from this meta-analysis is reliable. This study indicates that respondents' sociodemographic characteristics may impact a population's preference for health states, which should be considered in future disability weight assessments.