The effect of medication adherence on health care utilization in bipolar disorder.

A retrospective analysis of electronic prescription and medical claims representing approximately 1.4 million managed care commercial health plan members with mental health benefits was conducted. The effect of patient adherence to traditional mood-stabilizer therapy (lithium, valproate, carbamazepine, lamotrigine, or oxcarbazepine) for bipolar disorder on mental health-related hospitalization was assessed among 1,399 patients (mean age, 42.9 yr; 66.3% female) studied. Reduced adherence to traditional mood-stabilizing therapy (< 80%) in patients with bipolar disorder was associated with significantly greater risk of mental health-related, emergency room visits (odds ratio, 1.98; 95% confidence interval, 1.38-2.84) and inpatient hospitalizations (odds ratio, 1.71; 95% confidence interval, 1.27-2.32), even after adjusting for age, gender, and comorbidity.