The prevalence and geographic distribution of complex co-occurring disorders: a population study

A subset of people with co-occurring substance use and mental disorders require coordinated support from health, social welfare and justice agencies to achieve diversion from homelessness, criminal recidivism and further health and social harms. Integrated models of care are typically concentrated in large urban centres. The present study aimed to empirically measure the prevalence and distribution of complex co-occurring disorders (CCD) in a large geographic region that includes urban as well as rural and remote settings.

Linked data were examined in a population of roughly 3.7 million adults. Inclusion criteria for the CCD subpopulation were: physician diagnosed substance use and mental disorders; psychiatric hospitalisation; shelter assistance; and criminal convictions. Prevalence per 100 000 was calculated in 91 small areas representing urban, rural and remote settings.

2202 individuals met our inclusion criteria for CCD. Participants had high rates of hospitalisation (8.2 admissions), criminal convictions (8.6 sentences) and social assistance payments (over $36 000 CDN) in the past 5 years. There was wide variability in the geographic distribution of people with CCD, with high prevalence rates in rural and remote settings.

People with CCD are not restricted to areas with large populations or to urban settings. The highest per capita rates of CCD were observed in relatively remote locations, where mental health and substance use services are typically in limited supply. Empirically supported interventions must be adapted to meet the needs of people living outside of urban settings with high rates of CCD.