Modelling the Hepatitis C Virus Epidemic in Australia. Hepatitis C Virus Projections Working Group

Introduction: In Australia, to the end of 1997, more than 110,000 people have been diagnosed with hepatitis C virus (HCV) antibodies and reported to State/Territory surveillance systems. The available data indicate that the overwhelming majority (around 80%) of people with HCV antibodies were infected through injecting drug use.

Methods: Models of the HCV epidemic in Australia were developed based on estimates of the pattern of injecting drug use in Australia. Estimates of HCV infections due to injecting drug use thus obtained were then adjusted to allow for HCV infections resulting from other transmission routes. Projections of cirrhosis and hepatocellular carcinoma (HCC) resulting from HCV were obtained by combining modelled HCV incidence with estimates of the progression rates to these outcomes.

Results: Based on the models, it was estimated that there were 196,000 (lower and upper limits of 149,000 and 234,000) people in Australia living with HCV antibodies at the end of 1997, with HCV incidence in 1997 estimated to be 11,000 (8500-13,500). It was estimated that 8500 (4000-13,000) people were living with HCV-related cirrhosis in 1997 and that there were 80 (40-125) incident cases of HCV-related HCC.

Discussion: 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 HCC will more than double in Australia by 2010.