Use of treatment services in a comparative effectiveness study of bipolar disorder.

OBJECTIVE Bipolar disorder is a severe, chronic mental illness with a high incidence of medical and psychological comorbidities that make treatment and prevention of future episodes challenging. This study investigated the use of services among outpatients with bipolar disorder to further understanding of how to maximize and optimize personalization and accessibility of services for this difficult-to-treat population. METHODS The Lithium Treatment-Moderate Dose Use Study (LiTMUS) was a six-month multisite, comparative effectiveness trial that randomly assigned 283 individuals to receive lithium plus optimized care-defined as personalized, guideline-informed care-or optimized care without lithium. Relationships between treatment service utilization, captured by the Cornell Service Index, and demographic and illness characteristics were examined with generalized linear marginal models. RESULTS Analyses with complete data (week 12, N=246; week 24, N=236) showed that increased service utilization was related to more severe bipolar disorder symptoms, physical side effects, and psychiatric and general medical comorbidities. Middle-aged individuals and those living in the United States longer tended to use more services than younger individuals or recent immigrants, respectively. CONCLUSIONS These data suggest that not all individuals with bipolar disorder seek treatment services at the same rate. Instead, specific clinical or demographic features may affect the degree to which one seeks treatment, conveying clinical and public health implications and highlighting the need for specific approaches to correct such discrepancies. Future research is needed to elucidate potential moderators of service utilization in bipolar disorder to ensure that those most in need of additional services utilize them.