Effectiveness of sterile needle and syringe programmes

Abstract

This is the first comprehensive international review of the evidence for needle syringe programmes. The major, and now overwhelmingly strong, finding is that needle syringe programmes reduce HIV transmission effectively, safely and cost effectively. The size of the benefit is substantial. There is compelling evidence that needle syringe programmes reduce HIV incidence and HIV prevalence by reducing HIV risk behaviour. The Bradford Hill criteria, generally regarded as the most robust method of assessing public health interventions, were used for the evaluation framework. Conservatively, six of the nine Bradford Hill criteria were fulfilled (strength of association, replication of findings, temporal sequence, biological plausibility, coherence of evidence, and reasoning by analogy). Three of the Bradford Hill criteria were not fulfilled (specificity of association, biological gradient and experimental evidence). Five additional criteria were clearly fulfilled (cost-effectiveness, absence of negative consequences, feasibility of implementation, expansion and coverage, unanticipated benefits, and application to special populations). The findings in this review are consistent with seven published national reviews conducted by, or on behalf of, United States government agencies, which had previously found that needle syringe programmes were effective in reducing HIV infection among injecting drug users and did not increase illicit or injecting drug use. Countries affected or threatened by HIV infection among injecting drug users should carefully consider the convincing evidence now available for the effectiveness and safety of needle syringe programs with a view to establishing or expanding needle syringe programs to scale. Although some research questions still remain unanswered, and areas exist where improved research methodology is needed, the failure to implement needle syringe programmes in time and on a sufficient scale cannot be justified by a lack of available evidence.