Long-term remission in schizophrenia and schizoaffective disorder: results from the risperidone long-acting injectable versus quetiapine relapse prevention trial (ConstaTRE)

Objective: The objective of this study was to report the long-term remission results from the ConstaTRE relapse prevention trial, in which clinically stable adults with schizophrenia or schizoaffective disorder treated with oral risperidone, olanzapine, or oral conventional antipsychotics were randomized to risperidone long-acting injectable (RLAI) or oral quetiapine, dosed according to package-insert recommendations. Methods: In the ConstaTRE trial, efficacy and tolerability were recorded for up to 24 months. This post hoc analysis presents remission data, defined, according to the Schizophrenia Working Group criteria, as achieving and maintaining eight core symptoms of schizophrenia that are mild or less over 6 months. Additional secondary outcome measures are also presented. Results: A total of 710 patients were randomized to RLAI (n = 355) or quetiapine (n = 355). Mean mode ± standard deviation (SD) drug doses were RLAI 33 ± 10 mg every 2 weeks and quetiapine 413 ± 159 mg daily. Full remission was achieved by 51.1% of patients with RLAI and 39.3% with quetiapine (p = 0.003). Mean ± SD of full remission durations were not significantly different with RLAI (540 ± 181 days) and quetiapine (508 ± 188 days). Overall tolerability was similar between treatment groups. Conclusions: Among stable patients with schizophrenia or schizoaffective disorder, remission was more likely after switching to RLAI than quetiapine.