Systematic Literature Review and Meta-Analysis to Estimate the Burden of Fatal and Non-Fatal Overdose Among Persons Who Inject Drugs.

Background. People who inject drugs (PWID) have elevated risk for infectious diseases, psychiatric disorders, non-fatal overdose, and most importantly fatal overdose. Due to stigma, cost, and generalizability limitations, the burden of fatal and non-fatal overdose within this population is difficult to measure. We conducted a systematic review and meta-analysis to estimate fatal and non-fatal overdose rates among PWID. Methods. A comprehensive search of PubMed was conducted to identify studies published between January 2010 and August 2020 that reported a rate or period prevalence estimate of overdose among PWID living in OECD countries. Titles and abstracts were independently screened by four researchers. Studies eligible for full text review were double screened and evaluated using inclusionary criteria before three researchers independently extracted study data related to overdose and PWID. Rates of non-fatal and fatal overdose rates were pooled using meta-analysis and assessed for heterogeneity. National non-fatal overdose rates were estimated for selected countries, and meta-regression was performed to examine geographical differences associated with non-fatal overdose. Results. Abstract screening and full text review of 2319 studies resulted in inclusion of 59 (2.5%) studies for meta-analysis. The mean non-fatal overdose rate was estimated as 30.22 per 100 PY (95% confidence interval [CI]: 22.2 – 41.1; 95% prediction interval [PI]: 4 – 230). The estimated mean fatal overdose rate was 1.17 per 100 PY (CI: 0.5 – 2.8; PI: 6 – 2129). Mean non-fatal overdose rates for Australia, Canada, and the United States were 12.27 per 100 PY, 28.98 per 100 PY, and 41.81 per 100 PY, respectively. Conclusion. Despite increased public health focus and surveillance on non-medical drug overdose, overdose attributable to injection is not well understood and requires improved monitoring. This systematic review and meta-analysis revealed that a substantial population of PWID experience non-fatal overdose which has been shown to increase their risk for subsequent fatal overdose. To combat this critical public health issue, increased access to harm reduction programs is needed for PWID