Duration of drug therapy is a key measure of drug effectiveness in schizophrenia. The Clinical Antipsychotic Trials of Intervention Effectiveness (CATIE) trial found that only olanzapine achieved a longer time to all-cause-discontinuation (TTAD) than a standard therapy comparator. This study compares the TTAD achieved when using alternative antipsychotics to treat patients with schizophrenia in real-world practice settings.
A total of 219,504 episodes of antipsychotic therapy initiated in the years 2000 to 2002 were identified using data from the California Medicaid (Medi-Cal) program. To capture the full range of treatment scenarios facing clinicians, four episode types were included: restarting therapy using the drug used in the preceding episode; restarting therapy using a different medication (delayed switches); switching therapy without a break in therapy; and augmentation. TTAD and changes in therapy were analyzed using ordinary least squares and logistic regressions and Cox proportional hazards models.
Atypical antipsychotics consistently achieved longer TTAD and reduced switching rates relative to conventional antipsychotics. Differences in TTAD favoring atypical antipsychotics were 13 to 15 days in restart episodes; 28 to 36 days for delayed switching episodes; 41 to 52 days in switching episodes; and 59 to 63 days for augmentation (P 0.0001 for all estimates). Differences between the atypical antipsychotics were smaller than reported in other studies and may not be clinically significant.
This study confirms two results from the CATIE study: Patients with schizophrenia frequently do not achieve stable, long-term drug therapy regardless of the specific drug used, and olanzapine achieved longer TTAD than conventional drugs. However, this study also found that patients treated with risperidone and quetiapine also achieved longer TTAD than patients treated with conventional antipsychotics.