Comparative effectiveness of atypical antipsychotics in schizophrenia: what have real-world trials taught us?

Real-world, effectiveness studies add an important new dimension to the evaluation of the benefits of individual antipsychotics. Efficacy studies have already shown the unique effectiveness of clozapine, and suggested improved outcomes for olanzapine compared with some atypical antipsychotics and a reduced tendency to produce acute and chronic movement disorders for atypical compared with typical drugs. Recent effectiveness studies largely confirm these prior observations. The CATIE (Clinical Antipsychotic Trials of Intervention Effectiveness), CUtLASS (Cost Utility of the Latest Antipsychotic Drugs in Schizophrenia Study) and SOHO (Schizophrenia Outpatient Health Outcomes) programmes confirmed the superiority of clozapine over other antipsychotics; CATIE and SOHO also confirmed olanzapine as probably the second most effective antipsychotic. Effectiveness studies have confirmed the high incidence of adverse metabolic effects with clozapine, olanzapine and (with less certainty) quetiapine but the ZODIAC (Ziprasidone Observational Study of Cardiac Outcomes) study found no excess cardiovascular events or deaths for olanzapine compared with ziprasidone. Prior observations on reduced frequency of movement disorders for second-generation versus first-generation antipsychotics were also largely (but not uniformly) supported. Overall, recent real-world studies have done much to confirm prior observations from efficacy-based randomized, controlled trials.