METHODS: Collation and review of existing estimates of IDU prevalence and HIV prevalence from published and unpublished documents for the period 1998-2003. The strength of evidence for the information was assessed based on the source and type of study.
RESULTS: Estimates of IDU prevalence were available for 130 countries. The number of IDU worldwide was estimated as approximately 13.2 million. Over ten million (78%) live in developing and transitional countries (Eastern Europe and Central Asia, 3.1 million; South and South-east Asia, 3.3 million; East-Asia and Pacific, 2.3 million). Estimates of HIV prevalence were available for 78 countries. HIV prevalence among IDU of over 20% was reported for at least one site in 25 countries and territories: Belarus, Estonia, Kazakhstan, Russia, Ukraine, Italy, Netherlands, Portugal, Serbia and Montenegro, Spain, Libya, India, Indonesia, Malaysia, Myanmar, Nepal, Thailand, Viet Nam, China, Argentina, Brazil, Uruguay, Puerto Rico, USA and Canada.
CONCLUSIONS: These findings update previous assessments of the number of countries with IDU and HIV-infected IDU, and the previous quantitative global estimates of the prevalence of IDU. However, gaps remain in the information and the strength of the evidence often was weak.
DESIGN: Systematic review and meta-analysis.
SETTING: Primary care setting.
PARTICIPANTS: Of 1568 studies screened, 14 studies with 7035 PWID were included.
MEASURES: PubMed, Embase, Web of Sciences, CENTRAL and Cochrane review databases were searched without language restriction from their inception to 27 January 2016. All published study designs with control groups that reported the effectiveness of pharmacy-based NSP on outcomes of interest were included. Outcomes of interest are risk behaviour (RB), HIV/hepatitis C virus (HCV) prevalence and economic outcomes. The estimates of pooled effects of these outcomes were calculated as pooled odds ratio (OR) with 95% confidence interval (CI) using a random-effects model. Heterogeneity was assessed by I2 and χ2 tests.
FINDINGS: Most studies (nine of 14, 64.3%) were rated as having a serious risk of bias, while 28.6 and 7.1% were rated as having a moderate risk and low risk of bias, respectively. For sharing-syringe behaviour, pharmacy-based NSPs were significantly better than no NSPs for both main (OR = 0.50, 95% CI = 0.34-0.73; I2 = 59.6%) and sensitivity analyses, excluding studies with a serious risk of bias (OR = 0.52, 95% CI = 0.32-0.84; I2 = 41.4%). For safe syringe disposal and HIV/HCV prevalence, the evidence for pharmacy-based NSPs compared with other NSP or no NSP was unclear, as few of the studies reported this and most of them had a serious risk of bias. Compared with the total life-time cost of US$55 640 for treating a person with HIV infection, the HIV prevalence among PWID has to be at least 0.8% (for pharmacy-based NSPs) or 2.1% (for other NSPs) to result in cost-savings.
CONCLUSIONS: Pharmacy-based needle/syringe exchange programmes appear to be effective for reducing risk behaviours among people who inject drugs, although their effect on HIV/HCV prevalence and economic outcomes is unclear.