Hepatitis C virus incidence trend and its risk factors among people who inject drugs in Hai Phong, Vietnam.

Background: HCV incidence among people who inject drugs (PWID) remains unacceptably high. Using the data from the DRIVE study, we aimed to describe HCV incidence trends and investigate its associated risk factors among PWID in Hai Phong, Vietnam.

Methods: Active PWID were recruited through 3 annual respondent-driven sampling (RDS) surveys; part of them were included in the study cohorts. HCV seroincidence was calculated for PWID participating in multiple surveys (recaptures) or in cohorts. A nested case-control design was used for risk factor analysis. Controls were matched to HCV seroconversion cases on age, sex, cohort participation and HCV seroconversion visit. Risk factors were measured over the period preceding the HCV seroconversion visits.

Results: There were 83 HCV seroconversions during 844 person-years in 540 included participants. The overall HCV incidence was 9.8/100 person-years (95% CI 7.9-12.2). HCV incidence decreased over follow-up time and was particularly high among PWID living with HIV (PLWH), i.e., 37.2/100 person-years (95% CI 26.4-52.3). HIV infection (OR = 10.0, 95% CI 6.8-16.2) and active heroin injection (OR: 3.2, 95% CI 2.3-4.8) were associated with a higher risk of HCV seroconversion for cohort participants. Among RDS recaptures, living with a sexual partner and currently using methadone had opposite effects on HCV incidence, OR = 2.9, 95% CI 2.2-4.3 and OR = 0.4, 95% CI 0.3-0.5, respectively.

Conclusion: HCV incidence among PWID in Hai Phong was still 5 times higher than the WHO target for elimination. Along with strengthened HCV prevention programs, affordable HCV treatment should be made available for PWID to reach the elimination goal.