Adjusted risk ratios and 95% CIs for lifetime illicit drug use associated with number of potentially traumatic experiences before age 11 among adolescents in the National Comorbidity Survey–Adolescent Supplement (N=9,956). Note: For each model, the reference group is adolescents exposed to no potentially traumatic events (PTEs) prior to age 11. All models adjusted for age, sex, race/ethnicity, parent income, and parent substance use problems.