Economic Evaluation of Fidaxomicin for the Treatment of Clostridium Difficile Infection (C. difficile-associated diarrhoea) in Ireland

Background: Clostridium difficile is associated with 20–30% of cases of antibiotic-associated diarrhoea. The incidence of C. difficile infection (CDI) is higher in Ireland than in other countries in Europe, and it is associated with considerable morbidity. Previously recommended standard therapeutic options were vancomycin and metronidazole, but the macrocyclic antibiotic fidaxomicin has recently been recommended for use in adults with CDI in Ireland. Objectives: To perform a cost-utility analysis of fidaxomicin compared to oral metronidazole (used to treat initial non-severe disease and first non-severe recurrence) and oral vancomycin (used to treat severe disease and any non-severe recurrence beyond the first) for the treatment of CDI. Methods: A Markov model was used to determine the cost-utility of fidaxomicin in the treatment of all adult CDI patients (base case), patients with severe CDI and patients with initial CDI recurrences, respectively. Patients enter the model in the CDI health state and are treated either with fidaxomicin or current standard of care (oral metronidazole for non-severe CDI; vancomycin for severe CDI) for 10 days. The time horizon was 1 year. Deterministic and probabilistic sensitivity analyses were performed. Health state utilities were derived from the literature. The perspective was that of the Irish Health Service Executive (HSE). Results: In the base case, fidaxomicin was dominant to current standard-of-care therapy, with cost savings of €2,904 and incremental quality-adjusted life year (QALY) gain of 0.031. The main drivers of costeffectiveness were recurrence rates and cost of hospitalization. Fidaxomicin was also dominant for all patient subgroups. The probability of fidaxomicin being cost-effective in all patients with CDI at a willingness to pay threshold of €45,000 per QALY gained was 82%. Conclusion: Fidaxomicin was dominant to the current standard-of-care therapy for CDI. Based on this analysis, fidaxomicin has received reimbursement for CDI treatment under the High Tech Drug Scheme in Ireland.