The prevalence of non-fatal overdose among people who inject drugs: A multi-stage systematic review and meta-analysis

Background: People who inject drugs (PWID) are at an elevated risk of fatal overdose in the first year after experiencing a non-fatal event. Such non-fatal events may also result in overdose-related sequelae, ranging from physical injury to paralysis. Given variation in drug markets and treatment availability across countries and regions, we may see similar variations in non-fatal overdose prevalence. Monitoring non-fatal overdose prevalence among PWID is essential for informing treatment intervention efforts, and thus our review aims to estimate the global, regional, and national prevalence of non-fatal overdose, and determine characteristics associated with experiencing such an event. Methods: We conducted a systematic review and meta-analyses to estimate country, regional, and global estimates of recent and lifetime non-fatal overdose prevalence among PWID. Using meta-regression analyses we also determined associations between sample characteristics and non-fatal overdose prevalence. Results: An estimated 3.2 (1.8-5.2) million PWID have experienced at least one overdose in the previous year. Among PWID, 20.5% (15.0-26.1%) and 41.5% (34.6-48.4%) had experienced a non-fatal event in the previous 12 months and lifetime respectively. Frequent injecting was strongly associated with PWID reporting recent and lifetime non-fatal overdose. Estimates of recent non-fatal overdose were particularly high in Asia and North America. Conclusion: Around one in five PWID are at an elevated risk of fatally overdosing every year, however there is substantial geographical variation. In countries with higher rates of non-fatal overdose there is need to introduce or mainstream overdose prevention strategies such as opioid agonist treatment and naloxone administration training programs.