Global incidence of hepatitis C virus (HCV) and HIV infection among people who inject drugs: A systematic review and meta-analysis

Background: Data on the incidence of hepatitis C virus (HCV) and HIV infection among people who inject drugs (PWID) are key to informing prevention. We conducted a systematic review and meta-analysis to synthesize global data on primary HCV and HIV incidence among PWID.

Methods: We searched MEDLINE, Embase and PsycINFO for studies published between 01/01/2000 and 14/09/2020 that tested for HCV or HIV infection and estimated incidence among community-recruited PWID. We also contacted the authors of 35 studies to request updated or unpublished data. We used random-effects meta-analysis to pool HCV and HIV incidence rates and the relative risks of HCV and HIV acquisition among women who inject drugs compared to men who inject drugs and young PWID (defined as <20 - ≤35) compared to PWID who were not young.

Results: We retrieved 58 and 51 estimates for HCV and HIV incidence, derived from 25 and 24 countries, respectively. Globally, the pooled HCV incidence was 14.4 per 100 person-years (100py; 95% confidence interval (CI): 12.1-17.0, I2=96.2%) and the pooled HIV incidence was 1.6 per 100py (95%CI: 1.1-2.2, I2=98.2%). We found regional variation in both estimates, although data were sparse in the Eastern Mediterranean, South-East Asia and African regions. Relative to men, women had a higher risk of HCV and HIV acquisition [pooled relative risks: 1.20 (95%CI: 1.07-1.34; 32 estimates) and 1.30 (95%CI: 1.09-1.55; 25 estimates), respectively]. Relative to PWID who were not young, PWID who were had a higher risk of HCV and HIV [pooled relative risks: 1.32 (95%CI: 1.11-1.57; 24 estimates) and 1.42 (95%CI: 1.17-1.73; 21 estimates), respectively].

Conclusion: High HCV and HIV incidence, particularly among young PWID and women who inject drugs, emphasize the importance of targeted prevention strategies. The limited data available in some regions indicate a pressing need to monitor HCV and HIV incidence among PWID.