Validation of the co-occurring disorder quadrant model

The co-occurring disorders quadrant model has been used as a framework for characterizing the heterogeneity in persons with low- and high-severity substance use and psychiatric disorders. This study investigated the validity and stability of the quadrant model in 155 adults who presented to one county hospital with psychiatric, substance use, or medical complaints. Quadrant placement was defined using data that is routinely gathered in clinical care or available in administrative data sets (i.e., substance dependence diagnosis, Global Assessment of Functioning scores). Fifty-four percent (n = 84) of study participants were categorized into quadrant IV (high-severity psychiatric/substance use), followed by quadrant I (low-severity psychiatric/substance use) (n = 32, 21%), quadrant II (high-severity psychiatric & low-severity substance use) (n = 25, 16%), and quadrant III (low-severity psychiatric & high-severity substance use) (n = 14, 9%). Quadrant placement was correlated with psychiatric and/or substance use diagnoses, psychiatric symptom severity, drug/alcohol toxicology and psychiatric and substance use health utilization, supporting the concurrent validity of the model. Initial quadrant placement was correlated with validity measures administered at three-month follow-up supporting predictive validity of the model. Initial and follow-up quadrant placement was significantly correlated suggesting stability of the quadrant model. Data support the validity of the quadrant model for application in clinical and administrative purposes.