Simultaneous Comparison of Efficacy and Tolerability of Second-Generation Antipsychotics in Schizophrenia: Mixed-Treatment Comparison Analysis Based on Head-to-Head Trial Data

OBJECTIVE Second-generation antipsychotics have been repeatedly shown to be superior to placebo. However, the comparative efficacy among these drugs has not been systematically evaluated. In this study, we used Mixed Treatment Comparison (MTC) procedures to elucidate the comparative efficacy and tolerability of second-generation antipsychotics. METHODS Seven antipsychotics were selected based on the availability of the relevant data. Data were gathered from a series of review article published by the Cochrane Collaboration. Six outcome measures were analyzed: 1) percentage of no clinically important response as defined by the original authors, 2) PANSS total score change from baseline to endpoint, 3) percentage of akathisia, 4) percentage of antiparkinson medication use, 5) percentage of total body weight increase more than 7%, and 6) percentage of drop-out due to any reasons. RESULTS All the second-generation antipsychotics included in this study showed fairly similar efficacy but widely different tolerability. In terms of efficacy, amisulpride, clozapine and olanzapine were ranked higher than aripiprazole, quetiapine and ziprasidone. Clozapine and olanzapine were superior in terms of akathisia and extrapyramidal symptom risk, but, far more prone to induce clinically important weight gain. CONCLUSION Using MTC methodology, we could line up the second generation antipsychotics according to their hierarchical superiority in terms of efficacy and tolerability. Though the wide overlap among the confidence intervals and the inconsistency between the direct and indirect comparison results may limit the validity of these results, it may still allow the important insights into the relative merits of the available drugs.