Incidence and costs of polypharmacy: data from a randomized, double-blind, placebo-controlled study of risperidone and quetiapine in patients with schizophrenia or schizoaffective disorder.

OBJECTIVE: The use of adjunctive psychotropics and the costs of polypharmacy in patients randomized to receive risperidone or quetiapine were compared in a placebo-controlled double-blind study conducted in India, Romania, and the United States.

METHODS: The efficacy and safety of risperidone, quetiapine, and placebo were compared in a 14-day monotherapy phase in patients experiencing an acute exacerbation of symptoms of schizophrenia or schizoaffective disorder. This was followed by a 28-day, additive-therapy phase during which addition of antipsychotics or other psychotropic medications was permitted. Risperidone was received by 153 patients in the monotherapy phase and 133 in the additive therapy phase, quetiapine by 156 and 122, respectively, and placebo by 73 and 53. Rates of polypharmacy were examined using the Cochran-Mantel-Haenszel, Kaplan-Meier, and Cox regression methods. Costs of polypharmacy were analyzed by non-parametric Wilcoxon 2-sample tests.

RESULTS: Primary study results have been reported elsewhere (Potkin et al., Schizophr Res 2006;85:254-65). Mean (+/-SD) doses at the additive-therapy baseline were 4.7 +/- 0.9 mg/day of risperidone and 579.0 +/- 128.9 mg/day of quetiapine. Additional psychotropics were received by 36% of the risperidone group, 58% of the quetiapine group (p < 0.01), and by 58% of the placebo group. Antipsychotics accounted for > 95% of the added psychotropics, the most common being olanzapine and haloperidol. The relative risk (quetiapine vs. risperidone) for antipsychotic polypharmacy was 1.90 (p = 0.001; 95% CI 1.29, 2.80). The mean projected cost of additional antipsychotics per randomized patient during the additive-therapy phase was $57.03 in the risperidone group and $101.64 in the quetiapine group (p < 0.01).

CONCLUSIONS: The results confirm earlier reports of higher rates of polypharmacy with quetiapine than with risperidone. The findings also reveal substantial between-treatment differences in costs associated with polypharmacy. Limitations of the study include that the study was of short duration and that a high proportion of patients were recruited from countries other than the United States.