Comparison of mental health resources used by patients with bipolar disorder treated with risperidone, olanzapine, or quetiapine

Abstract

Objective: The atypical antipsychotics, risperidone, olanzapine, and quetiapine, have been approved by the U.S. Food and Drug Administration for treatment of mania associated with bipolar disorder. Information on the relative mental health resource use of these therapies is helpful to pharmacy managers since differences in efficacy and safety may translate into differences in mental health care utilization. We compared charges for other mental health services associated with risperidone, olanzapine, and quetiapine treatment of patients with bipolar disorder to assess whether there were significant differences between these therapies. A secondary analysis involved dose-equivalent adjustment of the average allowed charge of the 3 atypical antipsychotics.

Methods: This was a retrospective study based on administrative data for 46 U.S. commercial health plans represented in a commercial database covering the period January 1998 through April 2002. The 6,625 patients included in the study had at least 2 contiguous pharmacy claims for a study antipsychotic, had received no other antipsychotics concurrently, and had not switched from an alternative antipsychotic in the preceding 90 days. Provider-submitted (billed) charges were selected in preference to paid amounts as being more accurate indicators of relative differences in the use of mental health resources. Mental health care charges were measured per patient per month (PPPM) and included charges for the study antipsychotics and charges for the other mental health care services (inpatient, physician and other ambulatory, and other psychotropic medications). Differences in other mental health care charges PPPM among the 3 therapies were assessed with multivariate regression, adjusting for differing patient characteristics. Differences in antipsychotic drug charges PPPM were assessed after adjustment to reflect an equivalent average daily dose.

Results: Regression estimates adjusted for patient differences did not show statistically significant differences in other mental health care charges PPPM among the 3 antipsychotic drug therapies. Other mental health charges associated with quetiapine were estimated to be 14 US dollars, or 3% lower than those associated with risperidone, but this difference was not statistically significant (P = 0.069). The PPPM charges for quetiapine versus olanzapine and olanzapine versus risperidone were also not different (P = 0.231 and P = 0.39, respectively). After adjusting for differences in average daily dose, risperidone and quetiapine had antipsychotic drug charges that were 84 US dollars and 76 US dollars PPPM lower than those of olanzapine (P < 0.01); the difference between the adjusted drug charges PPPM for risperidone and quetiapine was not significant.

Conclusion: Total charges for mental health services other than the study drug were not different for risperidone, olanzapine, and quetiapine in patients treated for bipolar disorder. However, based on prescription charges, olanzapine appears to be considerably more costly at an equivalent daily dose than either risperidone or quetiapine.