Age- and time-dependent prevalence and incidence of hepatitis C virus infection in drug users in France, 2004-2011: model-based estimation from two national cross-sectional serosurveys

Abstract

Hepatitis C virus (HCV) infection is a public health issue worldwide. Injecting drug use remains the major mode of transmission in developed countries. Monitoring the HCV transmission dynamic over time is crucial, especially to assess the effect of harm reduction measures in drug users (DU). Our objective was to estimate the prevalence and incidence of HCV infection in DU in France using data from a repeated cross-sectional survey conducted in 2004 and 2011. Age- and time-dependent HCV prevalence was estimated through logistic regression models adjusted for HIV serostatus or injecting practices. HCV incidence was estimated from a mathematical model linking prevalence and incidence. HCV prevalence decreased from 58·2% [95% confidence interval (CI) 49·7-66·8] in 2004 to 43·2% (95% CI 38·8-47·7) in 2011. HCV incidence decreased from 7·9/100 person-years (95% CI 6·4-9·4) in 2004 to 4·4/100 person-years (95% CI 3·3-5·9) in 2011. HCV prevalence and incidence were significantly associated with age, calendar time, HIV serostatus and injecting practices. In 2011, the highest estimated incidence was in active injecting DU (11·2/100 person-years). Given the forthcoming objective of generalizing access to new direct antiviral agents for HCV infection, our results contribute to decision-making and policy development regarding treatment scale-up and disease prevention in the DU population.

Keywords: Drug users; hepatitis C virus; incidence; mixture model; prevalence.

Conflict of interest statement

None

Figures

Fig. 1.

Two-state compartmental model for HCV transmission. β is the proportion of new drug users; γ is the seroreversion (defined as the absence of HCV antibodies in a person previously known to be HCV positive) rate; μ1 is the all-cause mortality rate in those without HCV infection; μ2 (= μ1 + μHCV, μHCV is the HCV-related mortality rate) is the all-cause mortality rate in those with HCV infection and λ is the incidence rate.

Fig. 2.

Left panel: Curves represent the age-dependent HCV prevalence estimates from the logistic models in drug users in 2004 (grey) and 2011 (black). Circles represent the estimated prevalence by age. Their size is proportional to the number of persons in 2004 (solid grey circles) and 2011 (open circles). Middle panel: Curves represent the age-dependent HCV incidence estimates in drug users in 2004 (grey) and 2011 (black) with their confidence intervals (dashed curves). Right panel: Age-dependent HCV incidence estimates in drug users over 2000–2020. Curves were obtained from the model in 2004 (grey curves), 2011 (black curves) and the other years (dotted curves).

Fig. 3.

Left panels: Curves represent the age-dependent HCV prevalence estimates from the logistic models in 2004 (grey) and 2011 (black) in those not reporting injecting drug use (top panels) and those reporting injecting drug use (bottom panels). Circles represent the estimated prevalence by age. Their size is proportional to the number of individuals in 2004 (solid grey circles) and 2011 (open circles). Middle panels: Curves represent the age-dependent HCV incidence estimates in 2004 (grey) and 2011 (black) with their confidence intervals (dashed curves) in those not reporting injecting drug use (top panels) and those reporting injecting drug use (bottom panels). Right panels: Age-dependent HCV incidence estimates over 2000–2020 in those not reporting injecting drug use (top panels) and those reporting injecting drug use (bottom panels). Curves were obtained from the model in 2004 (grey curves), 2011 (black curves) and the other years (dotted curves).

Fig. 4.

Left panel: Curves represent the age-dependent HCV prevalence estimates from the logistic models in those reporting active injecting drug use in 2004 (grey) and 2011 (black). Circles represent the estimated prevalence by age. Their size is proportional to the number of individuals in 2004 (solid grey circles) and 2011 (open circles). Middle panel: Curves represent the age-dependent HCV incidence estimates in active injecting drug users in 2004 (grey) and 2011 (black) with their confidence intervals (dashed curves). Right panel: Age-dependent HCV incidence estimates in active injecting drug users over 2000–2020. Curves were obtained from the model in 2004 (grey curves), 2011 (black curves) and the other years (dotted curves).

Fig. 5.

Left panels: Curves represent the age-dependent HCV prevalence estimates from the logistic models in 2004 (grey) and 2011 (black) in HIV-negative drug users (top panels) and HIV-positive drug users (bottom panels). Circles represent the estimated prevalence by age. Their size is proportional to the number of individuals in 2004 (solid grey circles) and 2011 (open circles). Middle panels: Curves represent the age-dependent HCV incidence estimates in 2004 (grey) and 2011 (black) with their confidence intervals (dashed curves) in HIV-negative drug users (top panels) and HIV-positive drug users (bottom panels). Right panels: Age-dependent HCV incidence estimates over 2000–2020 in HIV-negative drug users (top panels) and HIV-positive drug users (bottom panels). Curves were obtained from the model in 2004 (grey curves), 2011 (black curves) and the other years (dotted curves).