Secular Trend in Incidence and Mortality of Bipolar Disorder

Abstract

Introduction The world-wide interest in bipolar disorder is illustrated by an exponential increase in annual publications on the disorder registered in Pubmed since 1990. This inspired an overview on the clinical development. Objectives To assess bipolar disorder in a coherent timeframe to identify changing patterns in incidence and mortality. Aims To investigate secular trends in incidence of bipolar disorder in psychiatric care, examine the time lapse from first affective diagnosis to diagnosis of bipolar disorder and determine mortality and causes of death. Methods First-ever diagnoses of bipolar disorder (ICD-10 code F31) between 1995 and 2012 were identified in the nationwide Danish Psychiatric Central Research Register. Prior affective disorders were found as well. Causes of death were obtained from The Danish Register of Causes of Death.Age- and gender standardized incidence rates and standardized mortality ratio were calculated. Preliminary Results A total of 15,334 incident cases of bipolar disorder were identified. The incidence rate increased from 18.5/100,000 person-years (PY) in 1995 to 28.4/100,000 PY in 2012. The age group with the highest incidence decreased from 60-79 years to 20-39 years. The mean time from first affective diagnosis to diagnosis of bipolar disorder was 7.9 years (SD=9.1). The standardized mortality ratio was 1.7 (95%-CI=1.2-2.1). Causes of death were mainly natural, but 9% died from suicide. Conclusion The incidence of bipolar disorder increased significantly over a timeframe of 17 years mortality was higher compared to the general population. Treatment to lower mortality needs focus on both natural and unnatural causes.