Risk Factors for Natural Cause Mortality in Bipolar Disorder

Bipolar disorder is associated with premature mortality, but risk factors for natural cause mortality in this population have not been identified.

This was a prospective, cohort study of persons with bipolar disorder enrolled June 1, 2001-December 31, 2022, at a psychiatric system in Maryland, USA. Participants were evaluated with an in-person assessment of their cognitive functioning, medical illnesses, and other clinical domains. Natural cause mortality through 2022 was determined with data from the National Death Index. Cox proportional hazards models were employed to determine factors contributing to natural cause mortality.

The 553 persons in the study population had a mean age of 35.7 (SD13.0) years; 409 (74.0%) were White; 104 (18.8%) Black; 167 (30.2%) were male sex. The mean follow-up duration was 12.7 years (range 1.9-21.5). A total of 39 (7.1%) individuals died of natural causes such as cancer and cardiac disorders. The most significant predictor of natural cause mortality was a history of recent homelessness (HR 6.02, 95% CI 2.56, 14.19, p < 0.001). Additional baseline factors independently associated with mortality included a diagnosis of type 2 diabetes (HR 3.67, 95% CI 1.67, 8.04, p = 0.001), tobacco smoking (HR 2.99, 95% CI 1.57, 6.52, p = 0.001), and lower cognitive functioning (HR 0.97, 95% CI 0.95, 0.99, p = 0.018).

In this prospective study of persons with bipolar disorder, a history of recent homelessness was a strong risk factor for natural cause mortality. Efforts should be directed at preventing homelessness, improving cognitive functioning, promoting smoking cessation, and managing diabetes.