Comorbidities and Mortality in Bipolar Disorder

Abstract

Bipolar disorder is a severe, chronic mental illness with a reported worldwide prevalence of 1% to 5%.^1-8 It is among the leading causes of disability worldwide⁹ because of its substantial neuropsychiatric and social effects and medical comorbidities.^10,11 In the past 20 years, an increasing body of research has found that bipolar disorder is associated with premature mortality,¹² including an almost 2-fold risk of cardiovascular disease mortality¹³ and 15-fold suicide mortality¹⁴ compared with the general population. However, the effects of other comorbidities and the underlying pathways remain unclear. These issues have been understudied for bipolar disorder compared with other disorders, such as schizophrenia and unipolar depression.¹⁵ The few previous studies have also had important limitations, including an overreliance on inpatient data or community-based samples. The sole use of inpatient data may potentially result in bias and poor generalizability by including only more severe cases, whereas community-based samples are often further limited by insufficient sample sizes. No studies have examined physical comorbidities and mortality in persons with bipolar disorder using complete outpatient and inpatient data for a national population. Such information would advance our understanding of the underlying causes of premature mortality among bipolar disorder patients and help facilitate better strategies to improve the health of this vulnerable population. We conducted a national cohort study of 6.5 million Swedish adults to examine the association between (1) bipolar disorder and physical comorbidities, (2) bipolar disorder and all-cause or cause-specific mortality, and (3) commonly used medications in bipolar disorder and mortality.