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. 2016 May 1:162:51-5.
doi: 10.1016/j.drugalcdep.2016.02.024. Epub 2016 Feb 26.

Non-fatal overdose as a risk factor for subsequent fatal overdose among people who inject drugs

Alexander Caudarella  1 , Huiru Dong  1 , M J Milloy  2 , Thomas Kerr  2 , Evan Wood  3 , Kanna Hayashi  2
Affiliations

Non-fatal overdose as a risk factor for subsequent fatal overdose among people who inject drugs

Alexander Caudarella et al. Drug Alcohol Depend. .

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.

Keywords: Injection drug use; Mortality; Non-fatal overdose; Vancouver.

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Figures

Figure 1
Figure 1
Time to overdose mortality stratified by reporting non-fatal overdose in the last six months at baseline.
Figure 2
Figure 2
Dose-response effect of reporting non-fatal overdose on subsequent fatal overdose *Hazard ratios adjusted for age and HIV serostatus.
See this image and copyright information in PMC

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