Substance Use
Spatial Epidemiology of Nonfatal Overdose in a Community-Based Cohort of Marginalized Women in Vancouver, British Columbia (2014-2022) Shira Goldenberg* Shira Goldenberg Esteban Valencia Ofer Amram Kate Shannon Charlie Zhou Kathleen Deering
Given limited data regarding the spatial epidemiology of overdose among women amid the current overdose crisis, we evaluated the spatial epidemiology of nonfatal overdose in a cohort of marginalized women, including (a) potential changes in spatial clustering over time, and (b) the association between residential proximity to spatial overdose clusters and recent nonfatal overdose over 8-years. Baseline and follow-up questionnaire data were from a merged community-based cohort of marginalized women who use drugs in Vancouver, Canada (09/2014-08/2022). Kernel density estimation and hotspot analysis were used to describe the spatial distribution and clustering of overdose; bivariate and multivariable logistic regression with generalized estimating equations (GEE) modeled the association between residential proximity to spatial overdose clusters (assessed as living in or within 250, 500, or 750m of an overdose cluster) and recent (last 6 months) nonfatal overdose. Over the 8-year study, among 650 participants (3497 observations) the period-prevalence of recent nonfatal overdose was 36.0%. Annual prevalence of nonfatal overdose increased over the study, from 6.7% in 2014-15 to 14.3% in 2021-2022. 44.5% (n=289) of participants resided within an overdose cluster at least once during the study. Most overdoses occurred in Vancouver’s downtown and downtown eastside/Strathcona neighborhoods (78.7%). The highest-density clusters were in the downtown eastside/Strathcona, where clusters became larger and more dispersed from 2016-onwards. Multivariable GEE analysis indicated that residential proximity to overdose clusters was associated with higher odds of recent nonfatal overdose. Marginalized women face a high and rising burden of nonfatal overdose, which is influenced by the spatial ‘risk environments’ in which they reside. Scale-up of geographically tailored overdose prevention services, harm reduction, and safe housing for marginalized women are critically needed.
