Reference: JAMA Netw Open. 2026 Feb 2;9(2):e2560495
Practice Point: The addition of a 2-week taper to a 2-week pulse of oral vancomycin might reduce recurrence in adults with first episode or first recurrence of Clostridioides (Clostridium) difficile infection (CDI).
EBM Pearl: Bayesian analyses in randomized trials answer the key clinically important question: What is the probability that one treatment is more effective than another? In trials with slow recruitment or limited sample size, a Bayesian approach can make more efficient use of accumulating data and support earlier, more clinically meaningful comparisons.
CDI is an unfortunate and potentially dangerous complication of antibiotic use. CDI most frequently arises due to disruption of the gut microbiome and remains one of the leading causes of hospital-acquired diarrhea. Nearly any antibiotic can be implicated, and risk varies by class, with highest risk associated with clindamycin, fluoroquinolones, cephalosporins, and carbapenems. As of 2021, guidelines recommend oral fidaxomicin for 10 days as first-line therapy over oral vancomycin, with data supporting higher cure rates and lower recurrence compared with vancomycin. As a result, vancomycin is generally saved for situations in which fidaxomicin is unavailable. Although a generic formulation of fidaxomicin became available in the United States in 2024, cost and formulary coverage continue to limit the use of fidaxomicin. Given this reality, vancomycin remains an important treatment option, and more than 66% of clinicians still use vancomycin for the initial treatment of CDI. This raises the question: What is the optimal way to prescribe it?
The TAPER-V trial sought to address this by evaluating an extended vancomycin regimen. In this randomized study, adults with a first episode or first recurrence of CDI were assigned to either a 4-week pulse-and-taper regimen or a standard 2-week pulse regimen. Notably, most participants (93%) were experiencing their first episode of CDI. All patients initially received vancomycin 125 mg orally 4 times daily for 2 weeks and achieved clinical cure on day 10. They were then randomized to either an additional 2-week taper (125 mg twice daily for 7 days followed by 125 mg once daily for 7 days) or similar placebo. The primary outcome was CDI recurrence at 56 days. The trial was terminated early due to limited recruitment (recall that fidaxomicin is first-line) and lower-than-expected event rates, both of which resulted in a change to the statistical plan.
So, let’s chat about stats. Because recruitment lagged, investigators switched to a Bayesian approach, framing the question the way clinicians actually think: What is the probability that an extended vancomycin taper works better than standard therapy? Instead of relying on p values and arbitrary significance cutoffs, credibility intervals and posterior probabilities were reported instead, which directly quantify the likelihood of benefit. In other words, rather than asking “Is there a statistically significant difference?”, the trial answered the more clinically relevant question: How likely is it that this extended treatment is better? In a small, slow-to-enroll study, the Bayesian approach extracts more usable insight from limited data and allows for earlier, more meaningful comparisons.
At 38 days, recurrence rates were lower in the extended taper group (6.7% vs. 15.4%), with a 99% posterior probability of superiority. However, this benefit was attenuated by 56 days (14.8% vs. 17.7%), during which the posterior probability of superiority of the extended taper decreased to 74%.
This trial suggests that an extended vancomycin taper may reduce early CDI recurrence, but the benefit may not be sustained at 56 days and remains uncertain given early termination and limited sample size. The trial does not establish superiority of an extended vancomycin taper over the standard regimen, nor does it address how an extended taper compares with first-line fidaxomicin. In the absence of definitive evidence, an extended vancomycin taper is a reasonable alternative when fidaxomicin is unavailable or not feasible, but it should be viewed as a practical alternative rather than a proven improvement.
For more information, see the topic Clostridioides (Clostridium) difficile Infection in Adults in DynaMed.
DynaMed EBM Focus Editorial Team
This EBM Focus was written by McKenzie Ferguson, PharmD, BCPS, Senior Clinical Writer at DynaMed. Edited by Katharine DeGeorge, MD, MS, Executive Editor at DynaMed and Associate Professor of Family Medicine at the University of Virginia; Alan Ehrlich, MD, FAAFP, Executive Editor at DynaMed and Associate Professor in Family Medicine at the University of Massachusetts Medical School; Rich Lamkin, MPH, MPAS, PA-C, Senior Clinical Writer at DynaMed; Claire Symanski, PhD, Medical Editor and Team Lead for ENT at DynaMed; Michael Butler, PhD, Medical Writer at DynaMed; Matthew Lavoie, BA, Senior Medical Copyeditor at DynaMed; Hannah Ekeh, MA, Senior Associate Editor II at DynaMed; and Jennifer Wallace, BA, Senior Associate Editor at DynaMed.