<qa>  What is the HCV database set up at North Manchester Hospital?There is a HCV database set up at North Manchester Hospital of all patients started on treatment since 2004. The investigator will access this and create a separate database of those patients with injecting drug use at any time as their risk factor for acquisition of HCV. The investigator will then identify those who were injecting drugs in the 6 months prior to treatment including those who continued to inject during treatment. These will be the active drug using group. The investigator will then identify the group of patients that stopped injecting drugs at least 6 months prior to commencing treatment. These will be the past drug using group. 