METHODS A decision analytic model (combined decision tree and Markov) was developed in Microsoft Excel® to investigate the impact of case finding and treatment on progression of HCV disease in a hypothetical cohort of former IDUs. This was compared to a cohort in whom spontaneous presentation for testing may occur. Case finding was explored in a “general case” and three specific settings: family practice, prisons and drug services. Diagnosis is based on ELISA and PCR testing and treatment is with pegylated interferon and ribavirin.

Best available data are used to inform the model, based on systematic searches of available literature, contact with researchers in the field and clinical expert opinion. Progression of HCV disease is modelled as transitions between discrete health states: mild, moderate, or severe hepatitis; cirrhosis; decompensated cirrhosis; transplant and death.

Model uncertainty was explored using extensive one-way sensitivity analyses, threshold analyses, and probabilistic sensitivity analysis. A range of scenarios were explored using stochastic analyses. Value of information analysis was carried out to determine the value of further research.

RESULTS Little information is available on acceptance of testing and diagnosis and rates of spontaneous presentation are difficult to estimate. Despite limited data, case finding is likely to be considered cost effective. Cost utility was estimated at around £16,000 per QALY. At willingness to pay of £30,000 per QALY, case finding is around 70% likely to be cost effective. Cost effectiveness is more favourable if case finding is targetted at people with more advanced hepatitis – in people whose infection was acquired 20 years previously, case finding yields benefits at less than £15,000 per QALY. Results are reasonably insensitive to changes in most parameters although discounting has important effects given the long duration of infection.

CONCLUSIONS Case finding for hepatitis C among former drug users is cost effective. Further empirical research into setting up, targetting and delivering case finding programmes is justified.