BACKGROUND: While opioid agonist therapy (OAT) reduces the risk of HCV acquisition among people who inject drugs (PWID), protective effects may be attenuated in females compared to males. This study assessed sex disparities in HCV incidence among PWID exposed to OAT and factors independently associated with decreased protective efficacy. METHODS: Inc3 pools biological and behavioural data from prospective observational studies examining incident HIV and HCV. Independent predictors were identified using Cox regression models with random effects after accounting for the clustering effect of study sites. Unadjusted and adjusted hazard ratios (aHR) and 95% Confidence Intervals are presented in sex-specific analyses. RESULTS: Among 701 participants exposed to OAT observed over 3,003 visits and 1,427 person-years observation (PYO), HCV incidence was 16.5 PYO (95%CI 13.1-20.7) in females and 7.6 PYO (95%CI 6.0-9.5) in males (F:M aHR 1.80, 95%CI 1.37-2.22, p<0.001). Factors associated with HCV acquisition among females exposed to OAT included non-white race (aHR 1.79, 95%CI 1.25-2.56, p=0.001), recent unstable housing (aHR 4.00, 95%CI 3.62-4.41, p<0.001), recent daily or more frequent injection (aHR 1.45, 95%CI 1.01-2.08, p=0.042) and recent receptive syringe sharing (aHR 1.43, 95%CI 1.33-1.53, p<0.001). CONCLUSIONS: Female PWID exposed to OAT are twice as likely as their male counterparts to acquire HCV. While there is a need for better understanding of sex differences in immune function and opioid pharmacokinetic and pharmacodynamic parameters, structural and behavioural interventions that target women, including affordable housing and safe injection self-efficacy, are required to bolster the efficacy of OAT in preventing HCV transmission.
Link to publisher’s web site