Higher incidence of HCV in females compared to males who inject drugs: A systematic review and meta-analysis

Abstract

Women who inject drugs have been shown to have higher incidence of HIV and risk behaviours than men, but there are conflicting reports about hepatitis C virus (HCV) incidence. We systematically reviewed the literature to examine the female-to-male (F:M) HCV incidence in female and male persons who inject drugs (PWID), and also to explore the heterogeneity (i.e. methodological diversity) in these differences. We searched PubMed and EMBASE for studies published between 1989 and March 2015 for research that reported incidence of HCV infection by sex or HCV incidence F:M rate ratio. A total of 28 studies, which enrolled 9325 PWID, were included. The overall pooled HCV incidence rate (per 100 person-years observation) was 20.36 (95% CI: 13.86, 29.90) and 15.20 (95% CI: 10.52, 21.97) in females and males, respectively. F:M ratio was 1.36:1 (95% CI: 1.13, 1.64) with substantial heterogeneity (I-squared=71.6%). The F:M ratio varied by geographic location from 4.0 (95% CI: 1.80, 8.89) in China to 1.17 (95% CI: 0.95, 1.43) in the U.S. In studies which recruited participants from community settings, the F:M ratio was 1.24 (95% CI: 1.03, 1.48), which was lower than that reported in the clinical settings (1.72, 95% CI: 0.86, 3.45). The number of studies included provided sufficient statistical power to detect sex differences in this analysis. Our findings raise questions and concerns regarding sex differences with respect to the risk of HCV. Both behavioural and biological studies are needed to investigate causes and potential mechanisms as well as sex-specific prevention approaches to HCV infection.

Keywords: females; hepatitis C; incidence; meta-analysis; sex differences; systematic review.

Figure 1

Flow Chart of Selection Process of Reviewed Studies

Figure 2

Forest plot of the studies and pooled estimates of incident HCV per 100 person-years observation in female and male PWID (ES: Effect Size which is the HCV incidence).

Figure 3

Forest plot of the studies and pooled estimates of female to male rate ratios of HCV infection in people who inject drugs by geographic area. Within each continent, studies are sorted by recruitment date midpoint. F-M IRR ranges between 0 and +infinity; 1 would be the F-M equality and amount less than 1 is favors males.

Figure 4

Publication bias in studies of people who inject drugs: the female to male incidence rate ratio funnel plot is symmetric, indicating that there is no publication bias (Egger’s test P = 0.736).