Dual Diagnosis Patients in Clinical Trials of Antipsychotics

Abstract

ABSTRACT Objectives: Substance abuse and schizophrenia comorbidity are common, and substance abuse may negatively affect schizophrenia treatment effectiveness. This research was conducted to determine whether lifetime history of substance abuse diagnosis or concurrent substance use is associated with poor prognosis in schizophrenia as measured by the treatment outcome in controlled clinical trials of atypical antipsychotics. Methods: A post hoc analysis of four randomized, double-blind, 24-to 28-week studies of schizophrenia treatment was performed to examine effect of historical substance abuse diagnosis on treatment outcome. Patients with a diagnosis of substance dependence within 1 or 3 months (specific to study) were excluded from the trials. Positive and Negative Syndrome Scale (PANSS) scores were compared between patients who had and did not have a history of substance abuse. PANSS scores were also compared between patients who reported different degrees of concurrent substance use for two of the trials. Results: Patients with lifetime history of substance abuse had earlier onset of illness and tended to have lower PANSS scores at baseline compared with other patients. Male patients with lifetime history of substance abuse had less improvement in PANSS scores than those without a history. Patients who reported alcohol use during the trials also tended to have less improvement in PANSS scores and a higher rate of dropout than patients without reported alcohol use. Conclusions: These results suggest that patients with a lifetime history of substance abuse disorders may have earlier disease onset and may respond poorly to treatment compared with other patients with schizophrenia.