"Before medically advised" hospital discharge and the risk of subsequent drug overdose: A case-crossover analysis

Patient-initiated or "before medically advised" (BMA) hospital discharge is more common among people who use drugs. Transitions of care can be destabilizing and might increase the risk of subsequent illicit drug overdose. This study sought to evaluate whether BMA discharge is associated with an increased risk of subsequent drug overdose (primary objective) and whether physician-advised discharge is associated with an increased risk of subsequent drug overdose (secondary objective). We performed a case-crossover analysis of population-based linked administrative health data for individuals experiencing an overdose between 2016 and 2019 in British Columbia, Canada. Using conditional logistic regression, we compared the likelihood of hospital discharge in the 28 days before overdose (the "pre-overdose interval") to the likelihood of hospital discharge in two self-matched 28-day control intervals ending 26 and 52 weeks before overdose. Over the 3.5-year study interval, 235 of 27,584 (0.9%) pre-overdose intervals and 189 of 55,168 (0.3%) control intervals included a BMA discharge, suggesting that BMA discharge was associated with a twofold increase in the risk of subsequent drug overdose (adjusted odds ratio [aOR], 2.08; 95% confidence interval [95% CI], 1.68-2.58; p