Cost-effectiveness of early responders versus early nonresponders to atypical antipsychotic therapy

BACKGROUND To compare the cost-effectiveness of treating early responders versus early nonresponders to an atypical antipsychotic (risperidone) and the cost-effectiveness of treating early nonresponders maintained on risperidone versus those switched to olanzapine. METHODS This post hoc analysis used data from a randomized, double-blind, 12-week schizophrenia study (Study Code: HGMN, n = 628). Participants were initially assigned to risperidone therapy. Early response was defined as a ≥ 20% improvement on the Positive and Negative Syndrome Scale (PANSS) total score from baseline to two weeks. Early responders continued on risperidone, whereas early nonresponders were randomized in a double-blind manner to continue on risperidone or switch to olanzapine for 10 additional weeks. Early responders and early nonresponders maintained on risperidone were compared for health-state utilities (benefits) and total cost over the 12-week study; early nonresponders maintained on risperidone or switched to olanzapine were compared from randomization (10-week period). Utilities were derived from the PANSS and adverse events. Mixed models were used to assess group differences in utilities. Treatment costs were calculated based on health states. Incremental cost-effectiveness ratios were then utilized to compare treatment groups. RESULTS Early responders to risperidone had significantly greater total utility and lower total treatment costs than early nonresponders to risperidone. Compared with early nonresponders who continued on risperidone, those who were switched to olanzapine had significantly higher total utility scores at endpoint and numerically lower total treatment costs, reflecting significantly lower nonmedication treatment costs, even though medication costs were significantly higher compared with generic risperidone. CONCLUSION Treatment of early responders was more cost-effective than treatment of early nonresponders to atypical antipsychotic therapy. Switching early nonresponders to olanzapine resulted in improved treatment effectiveness, met the criteria for some dominance, and appeared modestly more cost-effective than maintaining treatment with generic risperidone.