Interpreting and Applying the CATIE Results: With CATIE, context is key, when sorting out Phases 1, 1A, 1B, 2E, and 2T.

The NIMH-funded Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) for schizophrenia enrolled close to 1500 patients and is the largest randomized clinical trial to date that compares several of the second-generation antipsychotics on overall effectiveness. This article reviews the use of the evidence-based medicine tool "number needed to treat" to interpret what the CATIE results mean when choosing among the different antipsychotics available. Depending on the phase of CATIE, different antipsychotics had different rankings for overall effectiveness. CATIE can be viewed as a switch study, and depending on the circumstances or reason for the switch and the medication the patient was switched from, different outcomes were seen for the antipsychotics tested. Olanzapine had advantages in terms of all-cause discontinuation and efficacy, particularly in Phase 1. Quetiapine (and olanzapine) had advantages in terms of all-cause discontinuation in Phase 1B where patients had failed perphenazine. Clozapine was superior to risperidone and quetiapine for patients who discontinued a second-generation antipsychotic in Phase 1 (or 1B) because of poor efficacy. Risperidone had advantages in terms of overall tolerability in Phase 1, 2E, and 2T. Ziprasidone had the most benign metabolic profile, and in phase 2T was associated with a higher likelihood of weight loss for patients who gained greater than seven percent of their initial body weight in Phase 1. Treating clinicians need access to all of these medications in order to optimize treatment for the individual patient.