Comorbidities and mortality in bipolar disorder: a Swedish national cohort study

Abstract

Importance: Bipolar disorder is associated with premature mortality, but the specific causes and underlying pathways are unclear.

Objective: To examine the physical health effects of bipolar disorder using outpatient and inpatient data for a national population.

Design, setting, and participants: National cohort study of 6,587,036 Swedish adults, including 6618 with bipolar disorder.

Main outcomes and measures: Physical comorbidities diagnosed in any outpatient or inpatient setting nationwide and mortality (January 1, 2003, through December 31, 2009).

Results: Women and men with bipolar disorder died 9.0 and 8.5 years earlier on average than the rest of the population, respectively. All-cause mortality was increased 2-fold among women (adjusted hazard ratio [aHR], 2.34; 95% CI, 2.16-2.53) and men (aHR, 2.03; 95% CI, 1.85-2.23) with bipolar disorder, compared with the rest of the population. Patients with bipolar disorder had increased mortality from cardiovascular disease, diabetes mellitus, chronic obstructive pulmonary disease (COPD), influenza or pneumonia, unintentional injuries, and suicide for both women and men and cancer for women only. Suicide risk was 10-fold among women (aHR, 10.37; 95% CI, 7.36-14.60) and 8-fold among men (aHR, 8.09; 95% CI, 5.98-10.95) with bipolar disorder, compared with the rest of the population. Substance use disorders contributed only modestly to these findings. The association between bipolar disorder and mortality from chronic diseases (ischemic heart disease, diabetes, COPD, or cancer) was weaker among persons with a prior diagnosis of these conditions (aHR, 1.40; 95% CI, 1.26-1.56) than among those without a prior diagnosis (aHR, 2.38; 95% CI, 1.95-2.90; P(interaction) = .01).

Conclusions and relevance: In this large national cohort study, patients with bipolar disorder died prematurely from multiple causes, including cardiovascular disease, diabetes, COPD, influenza or pneumonia, unintentional injuries, and suicide. However, chronic disease mortality among those with more timely medical diagnosis approached that of the general population, suggesting that better provision of primary medical care may effectively reduce premature mortality among persons with bipolar disorder.