Risk factors for non-fatal overdose

From Alcohol, Other Drugs, and Health: Current Evidence:

an overdose more than 6 months before study entry (odds ratio [OR], 28.6)

younger age (e.g., OR, 7.2 for subjects 18–24 versus those 45 and older)

cocaine use in the last 6 months (OR, 2.1)

serious withdrawal symptoms in the last 2 months (OR, 2.7)

alcohol use in the last 6 months (OR, 1.9)