Substance use in persons with schizophrenia: Incidence, baseline correlates, and effects on outcome
One unintended consequence of shifting care for patients with schizophrenia away from institutional settings to the community has been exposing them to a much greater risk of using substances of abuse. Estimates of substance use/abuse in schizophrenia range from a low of 10% up to 70%, depending on variations in diagnostic assessment methods, use of collateral informants, and laboratory assessment techniques. Because self-report of illicit behaviors is frequently unreliable, inclusion of laboratory assessments and collateral informants tends to increase rates of detections of substance use. Substance abuse is a significant risk factor for a variety of poor outcomes in schizophrenia, including treatment non-adherence, relapse, rehospitalization, violence, victimization, HIV and hepatitis, and criminal justice involvement. On the whole, rates of substance use and their sequelae are underestimated. In fact, some surveys and treatment outcome studies continue to rely solely on self-report measures of illicit drug use, despite problems with reliability and validity. In a recent study comparing methods of detection of illicit substances in schizophrenia, use of urine drug testing combined with radioimmunoassay of hair specimens (RIAH) increased rates of detection of illicit drug use from 16% based solely on self-report to 38%. This is because urine drug testing generally detects substance use in the past 24 hours, while RIAH can detect 90 days or more of use, depending on the length of hair sampled.The importance of substance use is underappreciated in schizophrenia research.
