Meta-regression of hepatitis C virus (HCV) infection in relation to time since onset of illicit drug injection

The authors examined the relationship between time since onset of illicit drug injection (time at risk) and hepatitis C virus infection rates in a meta-regression. Median time since onset of injection in 72 prevalence studies was 6.89 years and median prevalence was 64.1%. The model showed statistically significant linear and quadratic effects of time at risk on HCV prevalence rates, and significantly higher prevalence in developing and transitional countries and in earlier samples (1985-1995). In non-developing/transitional countries post-1995, mean fitted prevalence was 36.2% (95% confidence interval 35.6, 36.8%) at one year of injection, 40.6% (39.3, 41.8%) at two years, and 52.5% (50.2, 54.8%) at five years. In developing/transitional countries post-1995, mean fitted HCV prevalence was 53.7% at one year of injection. In ten incidence studies, median time at risk was 3.9 years, and median HCV incidence was 26.4/100 PY. Mean fitted incidence was 39.6/100PY (33.3, 45.9) at one year of drug injection, 36.3/100PY (24.7, 47.9) at 2 years and 27.8 (5.6, 50.0) at five years. The authors concluded that the expansion of “harm reduction” programs in non-developing transitional countries has made a small but detectable impact on HCV infection in new and young injectors, but that further gains will require a much more substantial investment of resources.