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.

KEY POINTS

How much shorter is the life expectancy of people with mental illness compared to the general population and how many life years are lost due to natural and unnatural causes of death? The life expectancy of people with mental health diagnoses was 3.83 years shorter for men and 2.19 years shorter for women. Most excess life years lost were attributable to natural causes (3.42 among men and 1.94 among women). However, bipolar and substance use disorders were associated with considerable premature mortality from unnatural causes. Our findings support the implementation of interventions for improving the physical health of people with mental illness and targeted suicide prevention and substance use treatment programmes.