Theme: Epidemiology & Public Health Research Year: 2017
Background: Needle Syringe Programmes (NSP) and Opioid Substitution Therapy (OST) are the primary interventions to reduce Hepatitis C (HCV) transmission among people who inject drugs (PWID); but evidence is weak.
Methods: We searched multiple databases (Medline, PsycInfo, Embase, CINAHL, NHSEED, HTA, CLIB, Cochrane and Web of Science) up to 16 November 2015. Authors of studies were contacted and asked to provide unpublished data. We included studies that that measured exposure to NSP and/or OST against no intervention or a reduced exposure and reported HCV incidence as an outcome, and used new methods for classifying risk of bias.
Main results: We identified 28 studies (21 published, 7 unpublished) from North America (13), UK (5), Europe (4), Australia (5), and China (1) comprising 1821 HCV incident infections and 8798.7 person years of follow-up. HCV incidence ranged between 0.09 and 42 cases per 100 person years across the studies. Only two studies were judged to be moderate overall risk of bias, 17 at serious risk and 7 were at critical risk; for two unpublished datasets there was insufficient information to assess bias. As none of the intervention effects were generated from RCT evidence quality typically is categorised as low. We found evidence that current OST reduces risk of HCV acquisition by 50% (risk ratio 0.50 95% CI 0.40-0.63, I2 =0%, p=0.859, 12 studies across all regions, 7391 participants). The intervention effect was maintained in sensitivity analyses that excluded unpublished datasets or papers judged to be at critical risk of bias. We found evidence of differential impact by proportion of female participants in the sample, but not region of study, main drug used, history of homelessness or imprisonment.
Overall, we found weak evidence that high NSP coverage reduces risk of HCV acquisition, (Risk Ratio=0.77 95% 0.38-1.54) with high heterogeneity (I2=78.8%, p<0.001) based on 7 studies from North America and Europe only, 6271 participants. After stratification by region, high NSP coverage in Europe was associated with a 56% reduction in HCV acquisition risk (RR=0.44 95% CI=0.24-0.80) with less heterogeneity (I2 =12.3%, p=0.337). We found moderate quality evidence of the impact of combined high coverage of NSP and OST, from 4 studies, 4305 participants, resulting in a 71% reduction in the risk of HCV acquisition (Risk Ratio=0.29 95% CI=0.13-0.65). Conclusion: OST is associated with a reduction in the risk of HCV acquisition, which is strengthened in studies that assess the combination of OST and NSP. There was greater heterogeneity between studies and weaker evidence for the impact of NSP on HCV acquisition.Download abstract Download presentation Watch video