Modelling hepatitis C virus incidence, prevalence and long-term sequelae in Australia, 2001

To plan an appropriate public health response to the hepatitis C virus (HCV) epidemic requires that estimates of HCV incidence and prevalence, and projections of the long-term sequelae of infection, are as accurate as possible. In this paper, mathematical models are used to synthesize data on the epidemiology and natural history of HCV in Australia to estimate HCV incidence and prevalence in Australia to end 2001, and project future trends in the long-term sequelae of HCV infection.

Mathematical models of the HCV epidemic in Australia were developed based on estimates of the pattern of injecting drug use. Estimates of HCV infections due to injecting drug use were then adjusted to allow for HCV infections resulting from other transmission routes. Projections of the long-term sequelae of HCV infection were obtained by combining modelled HCV incidence with estimates of the progression rates to these outcomes.

It was estimated that there were 210 000 (lower and upper limits of 157 000 and 252 000) people in Australia living with HCV antibodies at the end of 2001, with HCV incidence in 2001 estimated to be 16 000 (11 000-19 000). It was estimated that 6500 (5000-8000) people were living with HCV-related cirrhosis in 2001, that 175 (130-210) people developed HCV-associated liver failure, and that there were 50 (40-60) incident cases of HCV-related hepatocellular carcinoma (HCC). It was estimated that in 2001 22 500 quality adjusted life years were lost to chronic HCV infection, the majority (77%) in people with early (stage 0/1) liver disease.

Model-based estimates were broadly consistent with other sources of information on the HCV epidemic in Australia. These models suggest that the prevalence of HCV-related cirrhosis and the incidence of HCV-related liver failure and HCC will more than triple in Australia by 2020.