Comparison of long-acting and oral antipsychotic treatment effects in patients with schizophrenia, comorbid substance abuse, and a history of recent incarceration: An exploratory analysis of the PRIDE study

INTRODUCTION Comorbid substance abuse is known to blunt response to treatment for underlying psychiatric disorders, but it has not been investigated in schizophrenia when comparing the effects of long-acting injectable antipsychotics with those of oral antipsychotics. METHODS This exploratory analysis compared once-monthly paliperidone palmitate (PP1M) with daily oral antipsychotics on time to treatment failure in patients with schizophrenia and a history of incarceration. Subjects were stratified into substance abuse (reported substance or alcohol misuse in the past 30days on the baseline Addiction Severity Index-Lite Version and/or met criteria for a current MINI diagnosis of a substance abuse disorder) and nonabuse cohorts. RESULTS In the substance abuse cohort, treatment failure was observed in 56.2% (73/130) and 64.2% (86/134) of subjects in the PP1M and oral antipsychotic groups, respectively. For the nonabuse cohort, treatment failure was observed in 36.5% (35/96) and 53.6% (45/84) of subjects in the PP1M and oral antipsychotic groups, respectively. Median (95% confidence interval [CI]) time to first treatment failure was 291 (179-428) days and 186 (94-296) days in the PP1M and oral antipsychotic groups, respectively. Median (95% CI) time to first treatment failure was >450 and 284 (147 to >450) days in the respective treatment groups. CONCLUSION Greater treatment effects were evident with PP1M compared with oral antipsychotics in both cohorts. The observed beneficial effect of PP1M was attenuated in the substance-abuse cohort, further reinforcing both the need for and value of continued research to optimize patient care in these complex patient populations.