Incident Substance Use Disorder Following Anxiety Disorder in Privately Insured Youth

Purpose: Anxiety disorders in childhood might be associated with an increased risk of substance use disorders. Incident substance use–related diagnoses were quantified in the 2 years after youth were newly diagnosed with an anxiety disorder and in a similar cohort of youth without diagnosed anxiety. Methods: Privately insured youth (10–17 years) were identified in a commercial claims database who were newly diagnosed with an anxiety disorder (2005–2014), treatment naïve, and without baseline substance-related disorder diagnoses. The comparison cohort included age, sex, region, and date matched youth with equivalent baseline exclusions. We used Kaplan–Meier estimator to calculate 2-year cumulative incidence of substance use disorder diagnosis following a new office-based anxiety disorder diagnosis (or match date for comparison cohort). Results: In 131,271 youth with a new anxiety disorder diagnosis (male = 41%, median age = 14 years), 1.5% (95% confidence interval = 1.5–1.6) had an incident substance use disorder diagnosis 1 year after their anxiety diagnosis, 2.9% (95% confidence interval = 2.8–3.0) by 2 years. Over the same period, .5% and 1.1% of the comparison cohort had incident substance use disorder diagnoses (n = 1,321,701). In the anxiety cohort, 2-year incidence was higher in youth aged 14–17 years (4.6%) versus 10–13 years (.7%). Incidence of substance use diagnosis varied by anxiety disorder (e.g., 2-year incidence: 4.3% for post-traumatic stress disorder, 3.0% for generalized anxiety disorder). Conclusion: Approximately 3% of youth newly diagnosed with anxiety received an incident substance use disorder diagnosis within 2 years, almost threefold the incidence in youth without an anxiety diagnosis, emphasizing the need for increased awareness and prevention of substance-related disorders in pediatric anxiety.