Non-fatal overdose as a risk factor for subsequent fatal overdose among people who inject drugs. (1st May 2016)

• Record Type: Journal Article
• Authors: Caudarella, Alexander; Dong, Huiru; Milloy, M.J.; Kerr, Thomas; Wood, Evan; Hayashi, Kanna
• Is Part Of: Drug and alcohol dependence. Volume 162(2016)
• Page Start: 51
• Page End: 55
• Publication Date: 2016-05-01
• Subjects: Mortality -- Injection drug use -- Vancouver -- Non-fatal overdose; Drug abuse -- Periodicals; Alcoholism -- Periodicals; 616.86
• DOI: 10.1016/j.drugalcdep.2016.02.024
• Languages: English
• ISSNs: 0376-8716

Abstract

Highlights: We assessed risk factors for overdose death among two prospective cohorts of persons who inject drugs (PWID). Recent non-fatal overdose was independently associated with subsequent overdose mortality. A dose-dependent relationship was found between fatal overdose and number of previous overdoses. Abstract: Objectives: To examine the relationship between non-fatal overdose and risk of subsequent fatal overdose. Methods: We assessed risk factors for overdose death among two prospective cohorts of persons who inject drugs (PWID) in Vancouver, Canada. Extended Cox regression was used to examine if reports of non-fatal overdose were associated with the time to fatal overdose while adjusting for other behavioral, social and structural confounders. Results: Between May, 1996 and December, 2011, 2317 individuals were followed for a median of 60.8 months. In total, 134 fatal overdose deaths were identified for an incidence density of 8.94 (95% confidence interval [CI]: 7.55–10.59) deaths per 1000 person-years. During the study period there were 1795 reports of non-fatal overdose. In a multivariate model, recent non-fatal overdose was independently associated with the time to overdose mortality (adjusted hazard ratio [AHR] = 1.95; 95% CI: 1.17–3.27). As well, there was a dose response effect of increasing cumulative reports of non-fatal overdose on subsequent fatal overdose. Conclusion: Reports of recent non-fatal overdose were independently associated with subsequent overdose mortality in a dose-response relationship. These findings suggest that individuals reporting recent non-fatal overdose should be engaged with intensive overdose prevention interventions.