Using Claims Data to Examine Hospital Readmission Risk in Patients With Schizophrenia and Comorbid Marijuana Use Disorders

Objective:Few epidemiologic studies have examined marijuana use disorder and repeated hospitalizations related to schizophrenia. To address this gap, this study examines time to readmission by indicators for recent marijuana use disorder in the presence of alcohol use disorder (AUD) and other drug use disorder.Method:Our sample consisted of 4,349 patients with a primary diagnosis of schizophrenia spectrum disorder (SSD) in 2005 in individually linked California Health Care Cost and Utilization Project (CA HCUP) data. Readmissions were assessed from 2005 to 2011. Predictors for readmission were examined using a stratified, recurrent-event, Cox proportional hazards model. Sensitivity analyses were conducted on patients readmitted in 2010 or 2011.Results:We found that having marijuana use disorder or AUD alone within 90 days of initial hospitalization was associated with longer times until first readmission. A lower risk of readmission for those with recent marijuana use disorder persisted through the fifth ...