Substance use disorders among youth with chronic physical illness

•Interrelationships among physical, mental, and substance use disorders are complex.•Odds of substance use disorder is dependent on specific physical-mental comorbidity.•Integration of mental health and addiction services in medical care is warranted. This study estimated prevalence of substance use disorder in youth with chronic physical illness; quantified magnitudes of association between different chronic physical illnesses with substance use disorder; and, tested whether mental disorder moderates these associations. Data come from 6,377 individuals aged 15–30 years in the Canadian Community Health Survey—Mental Health. Alcohol, cannabis, or other drug use disorder measured using the WHO Composite International Diagnostic Interview 3.0. Individuals with chronic physical illness were more likely to have other drug use disorder compared to healthy controls (2.4% vs. 1.3%; p