The impact of harm reduction interventions on injection-related bacterial infections among people who inject drugs: A systematic review

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Abstract

BACKGROUND AND AIMS: Injection-related bacterial infections represent a major but under-recognised health issue among people who inject drugs (PWID). Harm reduction interventions (HRIs) like needle and syringe programmes (NSP) and opioid agonist treatment (OAT) could mitigate their burden. This review aimed to identify and synthesise evidence on the effectiveness of HRIs in preventing bacterial infections among PWID. METHODS: Systematic review with meta-analysis of studies with more than 40 participants from Medline, Embase, Cochrane Library and Web of Science, published between 1990 and 2023 in English or French. We included interventional and observational studies that reported a quantitative effect measure for an HRI conducted in community, harm reduction, healthcare and outreach settings, targeting bacterial infections among PWID, defined as individuals who had injected drugs at least once within the previous year. Twelve studies met the inclusion criteria, for a total of n = 11 611 participants. The primary outcome was the impact of HRI on the prevalence or incidence of bacterial infections, measured as a risk difference, relative risk, number needed to treat, relative risk reduction, odds ratio, incidence rate ratio, hazard ratio or preventable fraction among the unexposed. Risk of bias was assessed using the Newcastle-Ottawa Scale for observational studies and the Cochrane RoB 2 tool for randomised trials. Meta-analysis was performed when at least 3 comparable estimates were available. RESULTS: Overall, the available evidence was sparse and heterogeneous, with substantial variability in study design, intervention definitions and outcome measurement across the 12 included studies. Sterile injecting equipment provision was found protective in 2/6 studies (n = 1938), 1/6 (n = 5209) found increased risk and 3/6 (n = 1323) reported no statistically significant association. OAT was protective in 2 studies (n = 2934) when comparing current PWID or those who had never used OAT to past PWID. Only 1 study (n = 1876) evaluated a combination of these interventions, showing a statistically significant reduction in skin and soft tissue infections. Among hygiene interventions, 1 of 2 studies (n = 59) reported a statistically significant protective effect, and the same for drug consumption rooms (n = 665). Overall, 8/10 studies assessed were judged to be at high risk of bias. A random-effect meta-analysis of crude odds-ratios (ORs) associated with NSPs yielded a pooled OR of 1.25 (95% confidence interval = 1.07-1.47). CONCLUSIONS: Evidence on the effectiveness of harm reduction interventions in preventing bacterial infections among people who inject drugs is limited and inconsistent, as most studies are observational, focus on skin and soft tissue infections and present substantial methodological limitations.

Abstract as published, via PubMed.