OBJECTIVES : Treatment of Clostridium difficile infection (CDI) has undergone significant change in recent years with the introduction of fidaxomicin and bezlotoxumab. This study evaluated the cost-effectiveness of fidaxomicin and bezlotoxumab for initial and recurrent CDI compared to standard therapy with oral vancomycin.

METHODS : A Markov model with 8 health states was built based on transition probabilities, costs, and health utilities derived from literature to evaluate the cost-effectiveness of fidaxomicin and bezlotoxumab vs. standard oral vancomycin over a lifetime horizon from the United States societal perspective.

RESULTS : Standard therapy with oral vancomycin had the lowest cost of $37,310 and was associated with a gain of 11.31 quality-adjusted life years (QALYs). Bezlotoxumab plus vancomycin led to a similar QALY gain compared to vancomycin at an incremental cost of $517,501 per QALY. At a willingness-to-pay (WTP) threshold of $150,000 per QALY, adding bezlotoxumab to standard therapy was more cost-effective than vancomycin alone just 34% of the time, yielding an incremental net monetary benefit (INMB) of -$1,697 (80% uncertainty interval [UI], -$5,072 - $2,670). Fidaxomicin had a relatively higher QALY gain of 11.60 than vancomycin at an incremental cost of $741 per QALY, and was always cost-effective relative to vancomycin at a WTP threshold of $150,000 per QALY, producing INMB of $43,489 (80% UI, $40,754 - $48,625). One-way sensitivity analysis suggested that the probabilities of sustained cure from the initial episode were the most sensitive inputs, and results were overall not particularly sensitive to any drug costs.

CONCLUSIONS : Based on a WTP threshold of $150,000, fidaxomicin was estimated to be the most cost-effective therapy for treating an episode of CDI and preventing further recurrence. The addition of bezlotoxumab to vancomycin was estimated to be not cost-effective for initial and recurrent CDI compared to either fidaxomicin or vancomycin alone.