Medical Comorbidity Among Youth Diagnosed With Bipolar Disorder in the United States

Objective: This study examines the number and type of medical comorbidities among youth diagnosed with bipolar disorder.

Method: This is a retrospective data analysis using the 2000-2001 Thomson Medstat MarketScan medical claims and administrative files. The population included a national sample of youth (ages 6-18 years) from privately insured families within the United States. Number of chronic medical conditions and type of medical comorbidity were analyzed in ICD-10-diagnosed youth with bipolar disorder (N = 832) and other types of psychiatric disorders (N = 21,493) using The Johns Hopkins Adjusted Clinical Groups Case Mix System, Version 8.0.

Results: Thirty-six percent of youth with bipolar disorder had 2 or more chronic health conditions versus 8% of youth with other psychiatric diagnoses. The following categories of medical conditions were significantly more prevalent in youth diagnosed with bipolar disorder: cardiology, gastrointestinal/hepatic, neurologic, musculoskeletal, female reproductive, and respiratory. Toxic effects and adverse events were also higher in youth with bipolar disorder, compared to youth with other psychiatric disorders.

Conclusions: Youth with bipolar disorder experience higher rates of several medical illnesses compared to youth with other psychiatric diagnoses. Several factors may explain this phenomenon, including worse medication side effects, unhealthy lifestyle behaviors, poorer access to health care services, socioeconomic status, and biologic
susceptibility. Moreover, a diagnosis of bipolar
disorder may reflect more frequent health care
utilization and therefore more opportunities for
additional medical diagnoses. Further understanding regarding reasons for these relatively high rates of comorbidity among youth diagnosed with bipolar disorder may be helpful in improving overall health and quality of life during the early stages/onset of this disorder.

Submitted: October 25, 2008; accepted March 10, 2009.

Online ahead of print: September 8, 2009.

Corresponding author: Sara E. Evans-Lacko, PhD, Health Services Research Department, Institute of Psychiatry, King’s College London, De Crespigny Park, London SE5 8AF, United Kingdom ([email protected]).