Fecal Microbiota Transplantation (FMT) for MDRO UTI: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Fecal Microbiota Transplantation (FMT) for MDRO UTI (NCT03367910), a na phase 1, phase 2 study. The primary outcome is Number of Patients With Adverse Events During and After FMT.

2. Clinical Question

The study’s broader stated purpose was to assess safety and the impact of FMT on the fecal and urine microbiome, urine metabolome, risk of recurrent urinary tract infection, and persistent MDRO colonization. These aims cover several kinds of outcomes, from participant-level clinical events to biological measurements. The primary outcome named in the record concerns adverse events; recurrent UTI is listed as a secondary outcome.

Because the study has no control group, its registry record does not set up a direct comparison between FMT and another treatment or usual care. The question that can be addressed by the posted safety counts is descriptive: what adverse-event counts were recorded among the participant at risk? The record does not provide a controlled estimate of how FMT changes UTI recurrence or any microbiome measure.

3. Trial Design

This was an open-label phase 1-2 study with a single-group model. The registry lists allocation as not applicable and masking as none. Participants eligible for MDRO UTIs were to receive FMT, described as 150mL of RBX2660 by enema. The record lists Washington University School of Medicine as sponsor and the study status as completed.

The study began on 2018-02-08, and its primary completion date is listed as 2021-12-31. The recorded enrollment is 1. These design details matter for interpretation: there is no concurrent comparator, and the recorded participant count is too limited to support broad conclusions about variation in outcomes across a patient population.

The primary outcome was the number of participants with adverse events during and after FMT, with a timeframe of six months post-FMT. The record says that number, types, severity, and relation of adverse events to study procedures or product would be analyzed. A secondary outcome is the number of patients with recurrent UTI post-FMT. The registry lists 2 outcome measures and 0 analyses.

With no randomized comparison, the results cannot separate changes associated with the intervention from the natural course of illness, other care, or other influences. The registry record does not report a protocol-level explanation for the enrollment, a control strategy, or additional design details beyond those listed.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Number of Patients With Adverse Events During and After FMT, measured over Six months post-FMT.

The primary endpoint is the number of participants with adverse events during and after FMT. Its stated timeframe is six months post-FMT. The record also says that adverse events’ types, severity, and relation to study procedures or product would be analyzed. Thus, the endpoint is intended to characterize safety events, not to estimate a comparative treatment effect.

A participant count is different from an event count. The endpoint title concerns how many participants had an adverse event, even if a participant could experience more than one event. The registry record does not report a detailed rule for classifying events, how repeated events in one participant would be handled, or the criteria for judging an event’s relation to the intervention.

Safety outcomes are important in an early phase study because they describe unwanted events observed during a defined period of follow-up. However, the endpoint alone does not establish that an event was caused by FMT. The registry’s description explicitly includes assessment of relation, but the posted record does not give participant-level event narratives or a causal assessment. The endpoint is also not a substitute for the study’s other stated aims, including microbiome measures and UTI recurrence.

With an enrollment of 1, the reported participant counts are descriptive observations in a very small group. They do not estimate how often adverse events would occur in a broader population with comparable precision.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a single-group study, not a randomized comparison. This distinction determines which statistical questions are answerable. In a controlled trial, an analysis may compare outcome distributions between groups. In a single-group study, observations can describe what occurred among participants who received the intervention, but there is no internal untreated or alternative-treatment group to anchor a treatment contrast. General statistical principle: an observed outcome after treatment is not, by itself, an estimate of what would have happened without treatment.

What does a participant count represent?

The primary outcome is a count of participants with adverse events. It is a binary participant-level measure in the sense that each participant either is or is not counted as having an event under the study’s classification. The record’s outcome title does not mean that the count is a total of every adverse-event episode. It separately says that event number, types, severity, and relation would be analyzed, but the operational details for those classifications are not reported in the registry record.

For a binary outcome, uncertainty depends on how many participants are observed and how many meet the event definition. General statistical principle: a point estimate summarizes the observed proportion, while an interval estimate communicates uncertainty about the underlying event probability. With enrollment of 1, the posted counts offer very little information about variation across participants. No interval estimate or method for calculating one is reported in the registry record, and no new estimate can be inferred from the posted counts without performing a calculation.

Why is over-dispersion relevant?

Over-dispersion is a general concern when the observed variability in event counts is greater than a model expects. It can arise when participants differ in their underlying risk or when events cluster. For recurrent UTI, a count of events per participant could vary substantially, and treating all events as independent observations may understate uncertainty if events within the same participant are related. The listed secondary outcome is the number of patients with recurrent UTI post-FMT, rather than a detailed recurrent-event rate. The registry record does not report a recurrent-event model, an over-dispersion assessment, or the analysis used for this outcome.

For adverse events, the primary endpoint is expressed as participants affected. If there were multiple events for an individual, participant-level counting would avoid treating each event as an independent participant, but it would not convey the full event burden. The record states that event number and characteristics would be analyzed, but does not post those details or specify a statistical model.

What can confidence intervals and tests tell a reader?

General statistical principle: a confidence interval describes the precision of an estimate under the assumptions of the method used. Wider intervals reflect greater uncertainty, while narrower intervals indicate more precision. A p-value, when used, assesses how compatible data are with a specified null model; it does not measure clinical importance or prove causation. Neither type of inferential result is reported for the posted outcomes. Their absence means that readers should not treat the adverse-event counts as a formal comparison or as a precise estimate of event risk.

There are no listed analyses in the registry record. The statistical methods for outcome analysis, handling of repeated events, adjustment for baseline characteristics, or construction of uncertainty intervals are not reported in the registry record. It is therefore not possible to determine whether a particular model or test was used.

How should the planning illustration be understood?

The record describes a sample-size planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The target effect is described as a stated fraction of the observed effect. General statistical principle: a sample-size calculation uses assumptions about the effect to be detected, variability, significance threshold, and desired power to illustrate the amount of information a proposed design might require. It is a planning device, not evidence about the actual treatment effect.

Here, those planning assumptions do not match the registered single-group design: equal allocation between two arms is not the design described for this study. The illustration is not an observed power calculation and cannot be read as proof that the study was adequately powered. No trial-specific sample-size justification or detailed design rationale is reported in the registry record. The registry record also does not report the observed-effect value used in the illustration or a set of analysis results from which to evaluate its assumptions.

These distinctions are especially important when outcomes are sparse. A small descriptive count can look definite, but it contains little information about the range of outcomes that might occur in a larger population. Statistical methods can quantify uncertainty when the data and analysis plan permit it; they cannot compensate for an absent comparator or create information that was not collected or posted.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("FMT for MDRO UTI")
n      <- c(1)
events <- c(1)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  FMT for MDRO UTI  1  1  100.0  2.5  100.0  20.7  100.0  15.8  98.7

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 2 outcome measures: the primary measure of participants with adverse events and the secondary measure of patients with recurrent UTI post-FMT. The study purpose also names fecal and urine microbiome, urine metabolome, and persistent MDRO colonization as areas of interest. The posted registry record does not give outcome analysis results for these aims.

When a study evaluates multiple outcomes, the chance of at least one apparently notable finding can increase if many statistical tests are performed. General statistical principle: multiplicity procedures can control the error rate across a defined family of tests, but the relevant family and procedure need to be specified. The registry record does not report whether multiplicity was considered, whether any adjustment was planned, or how primary and secondary outcomes would be prioritized in formal analyses.

Missing-data handling is also not reported in the registry record. The record does not describe the amount or pattern of missing outcome data, rules for excluding participants, imputation methods, or sensitivity analyses. With enrollment of 1, even an unreported or unavailable observation could materially affect the description, but no missingness details are posted.

Analysis populations are not reported in the registry record. It does not specify whether results would use all enrolled participants, participants who received FMT, or another defined population. The listed enrollment is 1, and the safety counts show 1 at risk in each listed category, but the record does not provide a fuller accounting of participant flow or outcome availability.

The registry lists 0 analyses. As a result, there is no reported multiplicity strategy, missing-data procedure, or analysis-population definition to evaluate against the observed outcomes. These are reporting gaps, not evidence that a particular method was or was not used outside the registry record.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent non-serious adverse event terms

The registry safety summary lists 1 participant at risk for serious adverse events and 0 affected. For other adverse events, it lists 1 participant at risk and 1 affected. Deaths are listed as 0. These are participant counts in the FMT for MDRO UTI group, not comparative rates against a control group.

The record does not provide serious adverse-event terms; the list of top serious terms is empty. Nor does the summary describe the other event’s type, timing, severity, or relationship to FMT. The primary outcome description says that types, severity, and relation to study procedures or product would be analyzed, but those details are not posted. It is therefore not possible to characterize the nature or likely cause of the event from this summary.

General statistical principle: a zero observed count does not mean the underlying risk is zero. It means that no event was recorded in the observed group during the specified observation period. Here, the group includes 1 participant at risk, so the count has limited ability to characterize uncommon events or variation across people. The other-event count similarly documents an observation without establishing causation.

These figures should be read as a limited descriptive safety record. They do not establish comparative safety, quantify a population-level risk, or resolve whether an event was related to the intervention.

13. What the Result Does, and Does Not, Mean

The registry record documents an open-label, single-group phase 1-2 study of FMT using RBX2660 for recurrent UTIs due to MDROs. It reports enrollment of 1 and safety counts that include 0 participants affected by serious adverse events, 1 affected by other adverse events, and 0 deaths. Those counts describe the record for this study; they are not estimates from a large or controlled comparison.

The data do not establish whether FMT changes the risk of recurrent UTI, persistent MDRO colonization, or microbiome and metabolome measures. Although those topics appear in the study purpose and recurrent UTI is listed as a secondary outcome, no corresponding analysis is reported in the registry record. The record also does not report a formal analysis of the primary safety outcome.

The absence of a comparator means that changes observed after treatment cannot be separated from other influences. Even a clearly recorded event after FMT does not, by timing alone, establish that FMT caused it. Similarly, no serious adverse events in the posted summary does not establish that serious events are impossible or that the intervention is safe for a broader population.

The findings do not support a conclusion that treatment works or does not work. Nor do they provide a precise estimate of benefit or harm. They show only a narrow descriptive record, with very limited participant information and no posted inferential analysis. Statistical precision and causal interpretation require more than a count from a single group.

14. Why This Trial Matters Statistically

This study is statistically notable because it combines a broad set of biological and clinical aims with a very small recorded enrollment. The registry describes interest in safety, fecal and urine microbiome, urine metabolome, recurrent UTI, and persistent MDRO colonization, while the posted record reports enrollment of 1 and lists 0 analyses. That gap between the breadth of the questions and the limited posted analysis is central to interpreting the evidence.

The single-group design also makes the distinction between description and comparison especially important. Safety counts can document what was recorded among participants who received FMT, but without a comparator they cannot estimate how outcomes differ under another strategy. This distinction applies even if an event is temporally associated with the intervention.

The record illustrates why outcome definitions and analysis details matter. A participant-level adverse-event count is not the same as a count of event episodes, and an event’s severity or relation to treatment cannot be inferred from the count alone. The registry states that such characteristics would be analyzed but does not post them.

Finally, the planning illustration uses assumptions for equal allocation between two arms, whereas the registered design is single-group. This is a reminder that sample-size illustrations depend on the design and assumptions they encode. They are not evidence of observed power or a substitute for results. Clear reporting of the analysis population, missing data, methods, and uncertainty would be needed to support stronger statistical interpretation.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The most direct limitation is the recorded enrollment of 1. With so little participant information, the safety counts are descriptive and cannot characterize the range of outcomes across a broader group. No control group is described, so the study cannot provide a direct estimate of how outcomes differ from an alternative treatment or from no FMT.

The registry record lists 0 analyses. It does not post an analysis of recurrent UTI, adverse events, or the broader biological outcomes named in the study purpose. It also does not report confidence intervals, p-values, or other uncertainty estimates. The safety summary lacks event terms and detail about timing, severity, and relationship to study procedures or product, despite the outcome description naming those features as intended areas of analysis.

Methods that would clarify interpretation are not reported in the registry record, including missing-data handling, analysis populations, outcome classification rules, and multiplicity procedures. The record does not provide participant flow or enough information to assess outcome completeness. The secondary outcome is stated as the number of patients with recurrent UTI post-FMT, but operational definitions and analysis details are not reported.

The planning illustration is described using equal allocation between two arms and a normal approximation, but the registered trial is single-group. Such planning assumptions do not describe the trial design and are not observed power. A sample-size rationale specific to the registered design is not reported in the registry record. Taken together, these limitations prevent a precise or causal interpretation of the posted counts.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Fecal Microbiota Transplantation (FMT) for MDRO UTI — NCT03367910.
• Registry record last updated 2022-03-18; status last verified 2022-03.
• Results first posted 2022-02-28.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

NCT03367910 is a completed, open-label phase 1-2 single-group study sponsored by Washington University School of Medicine. It evaluated fecal microbiota transplantation using RBX2660, described as 150mL delivered by enema, for recurrent urinary tract infections due to multidrug resistant organisms. The registry lists enrollment of 1, a start date of 2018-02-08, and a primary completion date of 2021-12-31.

The primary outcome is the number of participants with adverse events during and after FMT, with a six months post-FMT timeframe. The secondary outcome is the number of patients with recurrent UTI post-FMT. The safety summary lists 0 serious adverse events, 1 participant with another adverse event, and 0 deaths among the participant at risk. The registry lists 2 outcome measures and 0 analyses. No comparator, formal outcome analysis, or inferential estimate is reported in the registry record.