FMT oral capsules vs. colonoscopy: is one more effective than the other?

In general, FMT is well-established to be more effective than vancomycin in treating recurrent and refractory C diff infections. A meta-analysis including 37 studies found a cure rate of 92% (PMID 28707337). 

However, FMT can be delivered in four different ways: oral capsules, colonoscopy, enema, or through the nose (nasojejunal or nasoduodenal tube). Is one method better than the rest?

It’s already known that retention enemas require multiple doses to start approaching an effectiveness level of 90%, and that nasal administration is particularly risky and unpleasant. This leaves colonoscopy and oral capsule delivery as the two primary options remaining.  

While there are still very few studies comparing these two methods side by side, here are 4 recent ones that give us some hints: 

A 2019 study looking at all FMTs administered in open-label studies and clinical trials between 1978 and 2017 found that colonoscopy and oral delivery had equivalent cure rates. 610 people were included in this analysis.  (PMID 30957161) 

In a 2016 randomized clinical trial with 116 patients, prevention of recurrent C. Diff infection after a single treatment was “achieved in 96.2% in both the capsule group (51/53) and the colonoscopy group (50/52). Rates of minor adverse events were 5.4% for the capsule group vs 12.5% for the colonoscopy group. A significantly greater proportion of participants receiving capsules rated their experience as "not at all unpleasant" (66% vs 44%).” (PMID 29183074) 

A 2021 meta-analysis found that patients receiving FMT via colonoscopy experienced more adverse effects than patients who received oral capsules (71.6% vs 35.3%, respectively). The comparison between colonoscopy and capsule showed that delivery of the FMT by capsule was statistically significantly more effective. (PMID 33864273)

And, most recently, a 2022 paper shows early evidence that FMT delivered by both capsule and colonoscopy result in durable long-term engraftment of microbial populations. (PMID 35372103 ) 

Not everyone can swallow capsules, and capsules are not currently covered by insurance, meaning FMT delivered by colonoscopy is the best choice for many people. However, research continues to show that lower rate of adverse effects and the equivalency in effectiveness between capsule and colonoscopy makes oral FMT capsules an accessible, non-invasive, and safe choice for many people seeking treatment for recurrent C. Diff infection. And that is fantastic news!