Trends in health-related quality of life and health service use associated with body mass index and comorbid major depression in South Australia, 1998-2008

Purpose To investigate 10-year trends in health-related quality of life and health service use associated with body mass index (BMI) and comorbid major depression in South Australia. Methods Data were obtained from 9,059 people aged ≥15 years who participated in representative surveys of the South Australian population in 1998, 2004, and 2008. Major depression was determined using the mood module of the PRIME-MD. Health-related quality of life was assessed using the SF-36 and 15-item AQoL instruments. Results Mean health-related quality-of-life scores were 8-55% lower (worse), and health service use was 58-85% higher in all unhealthy BMI groups (underweight, overweight, and obesity) with major depression than in the healthy weight group independent of all covariates (sociodemographic and chronic medical conditions), consistently over the 10-year period. In contrast, only some unhealthy BMI groups without major depression had worse SF-36 physical component scores (overweight/obesity), AQoL scores (underweight/obesity), and health service use outcomes (overweight/obesity), and by only 2-6%. Conclusion Comorbid major depression explained most of the excess health-related quality of life and health service use in people with unhealthy BMI, consistently from 1998 to 2008. Interventions and policies that can mitigate the persistent excess population health and economic burden of major depression are needed.