Cost-effectiveness analysis of fidaxomicin versus vancomycin in <i>Clostridium difficile</i> infection

Fidaxomicin was non-inferior to vancomycin with respect to clinical cure rates in the treatment of Clostridium difficile infections (CDIs) in two Phase III trials, but was associated with significantly fewer recurrences than vancomycin. This economic analysis investigated the cost-effectiveness of fidaxomicin compared with vancomycin in patients with severe CDI and in patients with their first CDI recurrence. A 1 year time horizon Markov model with seven health states was developed from the perspective of Scottish public healthcare providers. Model inputs for effectiveness, resource use, direct costs and utilities were obtained from published sources and a Scottish expert panel. The main model outcome was the incremental cost-effectiveness ratio (ICER), expressed as cost per quality-adjusted life year (QALY), for fidaxomicin versus vancomycin; ICERs were interpreted using willingness-to-pay thresholds of A 20aEuroS000 pound/QALY and A 30aEuroS000 pound/QALY. One-way and probabilistic sensitivity analyses were performed. Total costs were similar with fidaxomicin and vancomycin in patients with severe CDI (A 14aEuroS515 pound and A 14aEuroS344 pound, respectively) and in patients with a first recurrence (A 16aEuroS535 pound and A 16aEuroS926 pound, respectively). Improvements in clinical outcomes with fidaxomicin resulted in small QALY gains versus vancomycin (severe CDI, +0.010; patients with first recurrence, +0.019). Fidaxomicin was cost-effective in severe CDI (ICER A 16aEuroS529 pound/QALY) and dominant (i.e. more effective and less costly) in patients with a first recurrence. The probability that fidaxomicin was cost-effective at a willingness-to-pay threshold of A 30aEuroS000 pound/QALY was 60% for severe CDI and 68% in a first recurrence. Fidaxomicin is cost-effective in patients with severe CDI and in patients with a first CDI recurrence versus vancomycin