FMT Long-term Safety Outcomes of Fecal Microbiota Transplantation: Real-World Data over Eight Years from the Hong Kong FMT Registry (Sep 2023)

Fecal Microbiota Transplants

Michael Harrop

Active member
Jul 6, 2023


Background and aims:
Prospective long-term real-world safety data after fecal microbiota transplantation (FMT) remain limited. We reported long-term outcomes of FMT from a population-based FMT registry in Hong Kong.

We recruited patients undergoing FMT for recurrent Clostridioides difficile infection (CDI) and non-CDI indications from clinical trials, from June 2013 to April 2022 in Hong Kong. We captured data on demographics, FMT indications and procedures, clinical outcomes and short-to-long-term safety. New medical diagnoses were obtained from electronic medical records and independently adjudicated by clinicians. Long-term safety in patients with recurrent CDI was compared with a control group treated with antibiotics.

Overall, 123 subjects (median age 53 years; range 13-90; 52.0% male) underwent 510 FMTs and were prospectively followed up for a median of 30.3 months (range, 1-57.9). The most common indication for FMT was type 2 diabetes mellitus (DM). The most common short-term adverse events within one month of FMT included diarrhea and abdominal pain. At long-term follow-up beyond 12 months, 16 patients reported 21 new onset medical conditions confirmed by electronic medical records. All were adjudicated to be unlikely to be related to FMT. There was no new case of inflammatory bowel disease, irritable bowel syndrome, allergy, DM or psychiatric disorder. In a subgroup of patients with recurrent CDI, FMT was associated with a significantly higher cumulative survival probability compared with matched controls.

This prospective real-world data from Asia's first FMT registry demonstrated that FMT has an excellent long-term safety profile. The risk of developing new medical conditions beyond 12 months after FMT is low.

The part I bolded is really interesting. I don't recall this being tracked & reported in any other FMT safety analysis.

Unfortunately, the paper is behind a paywall so we can't analyze the likelihood of their conclusion that they were "unlikely to be related to FMT". But I'm extremely skeptical.

I think the lack of this type of long-term tracking & follow-up is making FMT seem more safe than it actually is. I think a ton of people are developing new problems and getting worse due to the widespread use of low-quality donors, but it's not being tracked & reported.
Format correct?
  1. Yes
Interesting -- with median age of 53 it does seem plausible that some of these new onset conditions were not directly related to the FMT -- however, I share your skepticism. That said, 16/123 is better than I would have expected...
That said, 16/123 is better than I would have expected
Yeah. I'm skeptical about that too though. On various microbiome and FMT communities I constantly see people displaying ignorance about the gut microbiome's impacts on the whole body and thus discounting microbiome/FMT's impacts and side effects. And thus regularly erroneously designating symptoms as "unrelated to FMT/the gut microbiome". And these are people who are spending a lot of time reading & participating in the topic. So it would be even more so for people just casually getting one from their doctor.

And that phenomenon absolutely extends into the "professional" sphere.

Patients making poor lifestyle choices would complicate things as well though. In a perfectly controlled environment, you could say "if your health decreased in any way, or you experienced any new symptoms after the FMT that can be counted as an adverse event caused by the FMT".

I largely control my own FMT experiments to that degree, but others certainly don't.