Background
Renal impairment is not a consistently cited risk factor for recurrent Clostridioidesdifficile infection (rCDI). We examined the association between renal impairment and rCDI and the effect of bezlotoxumab, an anti-Toxin B monoclonal antibody, in reducing rCDI in participants with renal impairment.

Methods
We pooled data from two randomized, double-blind, placebo-controlled, multicenter, phase 3 clinical trials conducted in participants receiving bezlotoxumab or placebo infusion during oral antibacterial drug treatment for CDI. We assessed the association between renal impairment and rCDI in placebo-treated participants and evaluated the effect of bezlotoxumab vs placebo in reducing rCDI among participants with renal impairment, defined as estimated GFR<90 mL/min.

Results
The proportion of placebo-treated participants experiencing rCDI within 12 weeks was higher in those with renal impairment (n=919) vs those without renal impairment (n=612) (36.6% and 27.7%, respectively; difference [95% CI]: 8.9% [1.3, 16.3]). Renal impairment was significantly associated with a higher rate of recurrence in placebo-treated participants lacking commonly recognized risk factors for rCDI (renal impairment as only risk factor 28·8% vs normal renal function and no risk factors 12.5%; difference [95% CI]: 16.3 [3.4, 28.8]). Among all participants with renal impairment, the rate of rCDI was 19.5% among bezlotoxumab-treated vs 36.6% among placebo-treated participants (difference [95% CI]: -17.1% [-23.4, -10.6]).

Conclusions
This post hoc analysis adds to the literature suggesting an association of renal impairment as an independent risk factor for rCDI and provides preliminary evidence that patients with renal impairment that suffer with CDI may benefit from adjunctive treatment with bezlotoxumab.