Fidaxomicin versus vancomycin for infection with Clostridium difficile in Europe, Canada, and the USA: a double-blind, non-inferiority, randomised controlled trial

Background Infection with Clostridium difficile is the primary infective cause of antibiotic-associated diarrhoea. We aimed to compare efficacy and safety of fidaxomicin and vancomycin to treat patients with C difficile infection in Europe, Canada, and the USA. Methods In this multicentre, double-blind, randomised, non-inferiority trial, we enrolled patients from 45 sites in Europe and 41 sites in the USA and Canada between April 19,2007, and Dec 11,2009. Eligible patients were aged 16 years or older with acute, toxin-positive C difficile infection. Patients were randomly allocated (1:1) to receive oral fidaxomicin (200 mg every 12 h) or oral vancomycin (125 mg every 6 h) for 10 days. The primary endpoint was clinical cure, defined as resolution of diarrhoea and no further need for treatment. An interactive voice-response system and computer-generated randomisation schedule gave a randomisation number and medication kit number for each patient. Participants and investigators were masked to treatment allocation. Non-inferiority was prespecified with a margin of 10%. Modified intention-to-treat and per-protocol populations were analysed. This study is registered with ClinicalTrials.gov, number NCT00468728. Findings Of 535 patients enrolled, 270 were assigned fidaxomicin and 265 vancomycin. After 26 patients were excluded, 509 were included in the modified intention-to-treat (mITT) population. 198 (91.7%) of 216 patients in the per-protocol population given fidaxomicin achieved clinical cure, compared with 213 (90.6%) of 235 given vancomycin, meeting the criterion for non-inferiority (one-sided 97.5% Cl -4.3%). Non-inferiority was also shown for clinical cure in the mITT population, with 221 (87.7%) of 252 patients given fidaxomicin and 223 (86-8%) of 257 given vancomycin cured (one-sided 97.5% Cl -4.9%). In most subgroup analyses of the primary endpoint in the mITT population, outcomes in the two treatment groups did not differ significantly; although patients receiving concomitant antibiotics for other infections had a higher cure rate with fidaxomicin (46 [90.2%] of 51) than with vancomycin (33 [73.3%] of 45; p=0.031). Occurrence of treatment-emergent adverse events did not differ between groups. 20 (7.6%) of 264 patients given at least one dose of fidaxomicin and 17 (6.5%) of 260 given vancomycin died. Interpretation Fidaxomicin could be an alternative treatment for infection with C difficile, with similar efficacy and safety to vancomycin. Funding Optimer Pharmaceuticals.