Life-years lost associated with mental illness: a cohort study of beneficiaries of a South African medical insurance scheme

IMPORTANCE: People with mental illness have a reduced life expectancy, but the extent of the mortality gap and the contribution of natural and unnatural causes to excess mortality among people with mental illness in South Africa are unknown. OBJECTIVE: To quantify excess mortality due to natural and unnatural causes associated with mental illness. DESIGN, SETTING AND PARTICIPANTS: Cohort study using reimbursement claims and vital registration of beneficiaries of a South African medical insurance scheme, aged 15–84 years and covered by medical insurance at any point between January 1, 2011, and June 30, 2020. EXPOSURES: ICD-10 diagnoses of mental disorders including organic, substance use, psychotic, mood, anxiety, eating, personality, and developmental disorders. OUTCOMES: Mortality from natural, unnatural, unknown and all causes, as measured by the life-years lost (LYL) metric. RESULTS: We followed 1 070 183 beneficiaries (51.7% female, median age 36.1 years for a median duration of 3.0 years, of whom 282 926 (26.4%) received mental health diagnoses and 27 640 (2.6%) died. Life expectancy of people with mental health diagnoses was 3.83 years (95% CI 3.58–4.10) shorter for men and 2.19 years (1.97–2.41) shorter for women. Excess mortality varied by sex and diagnosis, ranging from 11.50 LYL (95% CI 9.79–13.07) among men with alcohol use disorder to 0.87 LYL (0.40–1.43) among women with generalised anxiety disorder. Most LYL were attributable to natural causes (3.42 among men and 1.94 among women). A considerable number of LYL were attributable to unnatural causes among men with bipolar (1.52) or substance use (2.45) disorder. CONCLUSIONS AND RELEVANCE: The burden of premature mortality among persons with mental disorders in South Africa is high. Our findings support implementing interventions for prevention, early detection, and treatment of physical comorbidities among people with mental disorders. Suicide prevention and substance use treatment programmes are needed to reduce excess mortality from unnatural causes, especially among men.