Evidence for the Effectiveness of Sterile Injecting Equipment Provision in Preventing Hepatitis C and Human Immunodeficiency Virus Transmission Among Injecting Drug Users: A Review of Reviews

The study authors aimed to review the evidence on the effectiveness of harm reduction interventions involving the provision of sterile injecting equipment to prevent hepatitis C virus (HCV) and HIV among injecting drug users. Among the interventions assessed: needle and syringe programs (NSP), alternative modes of provision (pharmacies, vending machines and outreach), and the provision of injecting equipment other than needles or syringes.

This review of reviews used systematic searches of the English language literature to March 2007 to identify systemic, narrative, or meta-analytical reviews of the interventions' impact on HCV transmission, HIV transmission or injecting risk behavior (IRB). "Critical appraisal criteria classified the reviews as either high quality ('core') or supplementary: a framework based on the quality of reviews, the reviewers' conclusions, and the designs/findings of the primary studies was used to derive evidence statements," the investigators reported.

The team identified three core and two supplementary reviews of injecting equipment interventions. According to the study's proposed framework, the investigators found (a) insufficient evidence supporting the conclusion that any of the interventions are effective in preventing HCV infection; (b) tentative evidence to support the effectiveness of NSP in preventing HIV transmission; (c) sufficient evidence to support the effectiveness of NSP (and tentative evidence of an additional impact of pharmacy NSP) in reducing self-reported IRB; and (d) scant to no evidence on vending machines, outreach, or providing other injecting equipment in relation to any of the outcomes.

"The evidence is weaker than given credit for in the literature," the authors concluded. "The lack of evidence for effectiveness of NSP vis-á-vis biological outcomes (HIV and HCV incidence/prevalence) reflects the limitations of studies that have been undertaken to investigate these associations. Particularly for HCV, low levels of IRB may be insufficient to reduce high levels of transmission. New studies are required to identify the intervention coverage necessary to achieve sustained changes in blood-borne virus transmission."

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