Health care utilization and costs among patients treated for bipolar disorder in an insured population

Objective: The study examined health care utilization and costs among patients treated for bipolar-spectrum disorders in an insured population. Methods: Computerized data on prescriptions and on outpatient and inpatient diagnoses from a large health plan were used to identify patients treated for cyclothymia, bipolar disorder, or schizoaffective disorder. Three age- and sex-matched comparison groups consisting of general medical outpatients, patients treated for depression, and patients treated for diabetes were selected from health plan members. Utilization and cost of health services for the four groups over a six-month period were assessed using computerized accounting records. Results: Total mean +/- SD costs for patients in the bipolar disorder group ($3,416 +/- $6,862) were significantly higher than those in any of the comparison groups. Specialty mental health and substance abuse services accounted for 45 percent of total costs in the group with bipolar disorder (mean +/- SD = $1,566 +/- $3,243), compared with 10 percent in the group with depression. Among patients treated for bipolar disorder, 5 percent of patients accounted for approximately 40 percent of costs for specialty mental health and substance abuse services, 90 percent of inpatient costs for specialty mental health and substance abuse services, and 95 percent of out-of-pocket costs for inpatient care. In the bipolar disorder group, parity coverage of inpatient mental health and substance abuse services would increase overall health care costs by 6 percent. Conclusions: Health care costs for patients with bipolar disorder exceed those for patients treated for depression or diabetes, and specialty mental health and substance abuse treatment costs account for this difference. Costs to the insurer and costs borne by patients are accounted for by a small proportion of patients. Elimination of discriminatory mental health coverage would have a small effect on overall health cafe costs.