Incidence and predictors of drug overdoses among a cohort of >10,000 patients treated for substance use disorder

Abstract

Background: Drug overdoses remain a significant public health burden throughout the world. This study assessed the incidence and predictors of non-fatal and fatal drug overdoses among patients with an opioid use, treated for drug use disorders (DUD) at public treatment centers in Denmark.

Methods: A consecutive cohort of patients (n = 11,199) were tracked from date of first registered enrollment between the year 2000 and 2010 to first registered drug overdose, death or December 31st 2010, whichever occurred first. Competing-risks regression models were fitted to estimate the sub hazard ratios (SHRs) of non-fatal and fatal drug overdoses and confounding risk factors.

Results: A total of 3186 (28%) patients experienced a non-fatal drug overdose during follow-up, and 572 (6%) died from an overdose. Use of benzodiazepines (SHR: 1.15 95% CI 1.03, 1.28) was significantly associated with non-fatal overdose. Intravenous drug use and previous hospitalization for a non-fatal overdose increased the risk of later non-fatal (SHR: 1.57 95% CI 1.42, 1.73) and fatal overdoses (SHR: 1.43 95% CI 1.12, 1.82).

Conclusions: Patients who use opioids remain at risk of overdoses for a long time after discharge from drug treatment. Besides relevant monitoring and psychosocial support in opioid maintenance treatment, there is a need for informing and educating opioid users in risk factors and preventive measures in settings where they are often difficult to access for traditional treatment services.

Keywords: Longitudinal; Methadone; Opioid; Overdose; Risk; Substance use disorders.