Concomitant Calcium Channel Blocker and Antipsychotic Therapy in Patients with Schizophrenia: Efficacy Analysis of the CATIE-Sz Phase 1 Data

Background This study evaluated the influence of concomitant calcium channel blocker (CCB) and antipsychotic (AP) therapy on efficacy measures in patients with schizophrenia. Methods Data from the Clinical Antipsychotic Trials of Intervention Effectiveness in Schizophrenia study were used to evaluate the effect of concomitant CCB therapy on the Clinical Global Impression-Severity (CGI-S) score, Positive and Negative Syndrome Scale (PANSS) score, and time to all-cause discontinuation of AP treatment. Concomitant treatment participants (CCB plus AP) were matched with controls (AP alone) by propensity scores using a 3:1 greedy match algorithm, then analyzed using a mixed linear effects model adjusted for fixed covariates. Results The least squares mean change in CGI-S scores revealed a significant time-by-treatment interaction term, with greater improvements for the concomitant treatment group (P = .03). Total PANSS score showed no significant difference between groups at various time periods (1,3,6,9,12, 15, and 18 months) and time to all-cause discontinuation was also similar (hazard ratio 0.94, P = .73). Conclusions Improvements in CGI-S scores over time suggest that concomitant CCB plus AP treatment may reduce severity of illness more than AP treatment alone. However, PANSS score and time to all-cause discontinuation of AP treatment did not demonstrate improved outcomes.