Efficacy and Mechanism of Fecal Microbiota Transplantation of the Bai Ethnicity in the Treatment of UC: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Efficacy and Mechanism of Fecal Microbiota Transplantation of the Bai Ethnicity in the Treatment of UC (NCT06591013), a randomized na study. The primary outcome is a Composite of Steroid-free Clinical Remission Together With Endoscopic Remission or Response.

2. Clinical Question

3. Trial Design

The registry describes a randomized, double-masked, parallel-group study. Random allocation means that assignment to the donor groups was intended to be determined by chance. In general, random allocation can help balance participant characteristics between groups, although the record does not report how the random sequence was generated, whether allocation was concealed, or whether balance was assessed.

The two groups received fecal microbiota transplantation by colonoscope, with the bacterial solution originating from Bai or Han donors. The trial therefore compares donor-group strategies rather than transplantation with no transplantation. The record does not specify which participants, clinicians, outcome assessors, or other staff were masked, or how masking was maintained.

Enrollment is recorded as 102, and the study status is completed. The listed primary endpoint results involve 30 participants in the Bai group and 31 in the Han group. The safety records use different group counts: 41 and 48 participants at risk, respectively. The registry does not explain these differences in the recorded group sizes or identify the analysis populations behind them.

The registry lists no phase beyond NA. The study start is recorded as 2024-10-14, and primary completion as 2025-10-20. The trial is sponsored by First Affiliated Hospital of Kunming Medical University. Further protocol details, including eligibility criteria, study sites, recruitment procedures, and the original sample-size rationale, are not reported in the registry record.

Secondary outcomes concern steroid-free clinical and endoscopic results, changes in microbial measures, microbiota recovery and composition, the origins of microbiota in recipients, and bacterial strains in cases described as highly effective. Results for these outcomes are not included in the posted results summarized by the registry record.

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 a Composite of Steroid-free Clinical Remission Together With Endoscopic Remission or Response, measured over 12 weeks after fecal microbiota transplantation.

The primary endpoint is a count of participants meeting a composite outcome 12 weeks after fecal microbiota transplantation. Its registry title combines steroid-free clinical remission with endoscopic remission or response. The description defines the clinical component as a total Mayo score of ≤2 points, with no individual sub-score >1 point. It also requires at least a 1 point reduction from baseline in the endoscopy sub-score, identified as MES.

A composite combines more than one measure into a single endpoint. In general, this can represent different dimensions of a condition in one outcome, but interpretation depends on the exact definition and on whether each component is measured consistently. Here, the posted definition requires both the stated clinical score criteria and improvement in the endoscopy sub-score; the registry title additionally frames the endpoint in terms of steroid-free status. The record does not describe how steroid-free status was assessed or provide further adjudication rules.

Endoscopic assessment adds information about the bowel lining that is distinct from a symptom-based clinical score. Combining clinical and endoscopic criteria can therefore capture more than symptoms alone. The outcome is binary at the participant level: a participant either meets the composite criteria or does not. The posted result is a participant count in each group, rather than a continuous change in score.

7. Results Posted in the Registry

• the Han Nationality-UC: 51.6% (16/31) versus 80.0% (24/30) on control; risk difference -28.4 percentage points (95% CI -51.1 to -5.7), risk ratio 0.65 (0.44–0.95); unadjusted two-proportion z-test p = 0.020.

8. Statistical Interpretation

9. Statistical Methods Explained

The outcome is binary because each participant is counted as either meeting or not meeting the composite criteria. The registry describes the primary measure as a count of participants with an event. For a binary outcome, group counts can be expressed as proportions, and comparisons can be reported as differences, ratios, or odds ratios. These are different scales for describing the same underlying outcome and do not answer exactly the same interpretive question.

What does the risk difference describe?

The risk difference compares the proportions meeting the endpoint in the two groups by subtraction. The posted estimate is defined for Han relative to Bai and is negative. In general, the sign indicates direction according to the stated group order: a negative estimate means the measured proportion is lower in the first group of the comparison than in the reference group. The observed counts are 16 of 31 for Han and 24 of 30 for Bai. The registry reports the estimate and interval; no further adjustment is described.

How should the p-value be read?

The record gives an unadjusted p-value of 0.02. In general, a p-value measures the compatibility of the observed data with a specified null hypothesis under the assumptions of a statistical test. A smaller p-value indicates that data like these would be less expected under that null model, but it does not quantify the size or importance of a group difference. The exact test, its assumptions, and whether any prespecified analysis plan differs from the posted calculation are not reported in the registry record.

Unadjusted means that the reported value is not presented as corrected for multiple comparisons. Because the record lists several secondary outcomes, testing many outcomes can increase the chance of finding at least one apparently unusual result by chance. The number and nature of analyses actually conducted, any hierarchy of endpoints, and any multiplicity strategy are not reported. The primary result should therefore be distinguished from exploratory interpretation of a wider set of outcomes.

What does randomization contribute?

In general, random assignment aims to make treatment groups comparable at the start of a study, on average, including for factors that may not have been measured. It does not ensure exact balance in a particular trial, nor does it address missing data or departures from the assigned intervention. The registry labels allocation as randomized but does not report the sequence-generation method, allocation concealment, baseline group characteristics, or a comparison of those characteristics. These details are needed to judge how well the intended design was carried out.

The registry also labels the study double-masked. Masking can reduce the influence of knowledge about assignment on participant reporting, care, or outcome assessment, depending on who is masked. The record does not identify the masked parties or describe how masking was maintained. Since the primary outcome includes clinical and endoscopic components, information about outcome assessment procedures would help readers evaluate the potential for measurement differences between groups.

What is not established about the analysis?

The number of posted analyses is recorded as zero, while a primary comparison and its summary statistics are present. The record does not explain this distinction. It also does not state whether the analysis followed intention-to-treat, per-protocol, or another population definition. There is no reported method for handling missing endpoint data, no covariate-adjustment specification, and no description of model diagnostics. These omissions do not change the posted counts, but they limit reproducibility and prevent a full appraisal of the statistical analysis.

In general, an analysis plan records in advance how outcomes, populations, missing observations, and statistical tests will be handled. The original protocol and its statistical analysis plan are not reported in the registry record. The registry does not report the study's original sample-size justification, interim analyses, or stopping rules. Those details cannot be inferred from the finished enrollment or from the planning illustration associated with the observed effect.

The sample-size illustration uses a normal approximation and equal allocation, with a two-sided significance level of 0.05. It explores planning targets based on fractions of the observed effect. These are retrospective planning illustrations, not evidence of the trial's original design assumptions. They do not describe the conduct of the registered trial or replace a prespecified analysis plan.

In general, careful interpretation of a randomized comparison joins the design, endpoint, analysis population, missingness, and precision. For this record, the primary endpoint definition and arm counts are available, and a risk difference, interval, and unadjusted p-value are posted. Several details needed to understand how those results were produced are not reported in the registry record. This is a limitation in the public statistical description, not proof that the procedures were absent.

10. Confidence Intervals and Precision

The risk-difference confidence interval extends from -0.511 to -0.057. Both endpoints are negative, so the reported interval does not include zero. The interval expresses uncertainty around the estimated difference: in general, it represents a range of values compatible with the data under the interval's statistical assumptions. The registry record does not state the confidence level or the method used to construct the interval.

The interval is relatively broad in relation to the estimate, indicating that the underlying difference is not pinned down to a narrow value by these outcome counts. Its negative range is consistent with a lower observed endpoint proportion in the Han group than in the Bai group, but the interval also shows that the size of that contrast remains uncertain. A confidence interval is not a guarantee that the true value lies within its limits, and it does not account for sources of bias or missing information that are not represented by the calculation.

The primary endpoint counts come from 30 Bai-group participants and 31 Han-group participants. With group counts of this size, each participant's outcome contributes appreciably to the observed proportion. The record does not provide a confidence interval for each group's proportion, or details of the statistical method used for the difference interval. The available interval therefore supports interpretation of the reported contrast, but not a full reconstruction of its precision calculation.

The reported unadjusted p-value is 0.02. It is not a substitute for the interval: the p-value addresses compatibility with a null model, while the interval communicates a range of estimates supported under a method and confidence level. Neither alone establishes clinical relevance, causal mechanism, or generalizability. The fact that the interval lies on one side of zero does not resolve the registry's unreported analysis-population and missing-data details.

11. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm, not total events. The registry's planning illustration assumes a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It uses the observed effect as its reference and considers planning for 100%, 75%, or 50% of that observed effect. The original design assumptions for the trial are not reported in the registry record.

The 80% power column gives the number of participants per arm that the illustration estimates would be needed to detect the selected effect under those planning assumptions, with an 80% chance of rejecting the null hypothesis if that effect and the assumptions were correct. The 90% power column gives the corresponding per-arm planning number for a 90% chance under the same assumptions. The entries are illustrations, not enrollment targets that can be attributed to the trial's original protocol.

The figures rise as the effect used for planning becomes smaller. In general, smaller differences are harder to distinguish from random variation, so detecting them with the same target power typically requires more participants. The rows based on fractions of the observed effect show how strongly a planning estimate can depend on the assumed effect size; the observed estimate may not be a stable forecast of what a future study would find.

This is not observed power. It is a planning illustration calculated from the observed effect, not a retrospective measure of whether the completed trial had adequate power. The registry does not report the original sample-size justification, and these values should not be read as evidence about the assumptions used when the trial was designed.

12. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.800; treatment proportion p₁ = 0.516; average p̄ = 0.658.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.6708 = 1.3148.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.6401 = 0.5387.
4. n = (1.3148 + 0.5387)² / (-0.2839)² = 42.6, rounded up to 43 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
p0 <- 0.8                          # control proportion
p1 <- 0.516129032258065                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(6591013)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 43 (80% power), 57 (90% power)
 75% of observed effect: n per arm = 73 (80% power), 97 (90% power)
 50% of observed effect: n per arm = 153 (80% power), 204 (90% power)
power.prop.test: 42.6 
Simulated power at n = 43 per arm: 0.813 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

13. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary composite endpoint and eight secondary outcomes. The secondary outcomes cover steroid-free clinical and endoscopic outcomes, microbial changes and recovery, recipient microbiota composition and origins, and dominant bacterial strains in cases described as highly effective. Results for these secondary outcomes are not reported in the posted results summarized by the record.

When researchers examine multiple outcomes or conduct repeated tests, the chance of at least one apparently notable result can increase. In general, multiplicity procedures can control or otherwise address that issue, but the appropriate approach depends on which outcomes and comparisons were planned and on the purpose of the analyses. The registry does not report a prespecified hierarchy, multiplicity adjustment, or the full set of analyses conducted. The primary comparison's p-value is explicitly unadjusted, so it should not be interpreted as a correction for other outcomes.

The number of analyses is listed as zero even though a primary comparison appears in the posted result information. The registry does not explain that discrepancy. It is therefore not possible to determine from the record whether the analysis listing is incomplete or whether the summary result was entered by a separate process.

Missing-data handling and analysis populations are not reported in the registry record. The primary result uses 30 and 31 participants in the two groups, while enrollment is recorded as 102 and the safety records list 41 and 48 at risk. The reasons for these differing counts are not reported. There is no description of missing primary outcomes, exclusions, withdrawals, or whether participants were analyzed according to randomized assignment.

These omissions matter because exclusions and missing outcomes can affect the composition of the analyzed groups. In general, a transparent analysis account identifies which participants contribute to each endpoint and how unavailable measurements are handled. Without that information, the posted comparison can be described as reported, but its relationship to all enrolled participants cannot be fully assessed. The registry record also does not report the original statistical analysis plan or protocol amendments.

14. 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.

The registry's serious-adverse-event records list 41 participants at risk in the Bai donor group and 48 in the Han donor group. Serious adverse events are reported for 0 participants in each group, and deaths are also reported as 0 in each group. The record lists no serious adverse-event terms.

Other adverse events are reported for 0 participants in each group, with the same at-risk counts of 41 and 48. The safety denominator is not the same as the participant count used for the primary endpoint. The registry does not explain why the group sizes differ, identify the safety observation period, or provide definitions and ascertainment details for adverse events.

These entries mean that the registry reports no events in the listed categories among the participants counted as at risk. They do not establish that no events occurred outside the recorded categories, that every participant was observed for the same duration, or that the intervention has no safety risks. In general, interpreting safety data requires the event definitions, follow-up duration, completeness of reporting, and the number of participants monitored. Those details are not reported in the registry record.

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

The primary result records the composite endpoint in 24 of 30 participants in the Bai donor group and 16 of 31 in the Han donor group at the stated 12-week timepoint. The registry reports a negative risk difference for Han relative to Bai, with an interval that remains below zero, and an unadjusted p-value of 0.02. This describes the observed contrast for this endpoint in the participants represented by those counts.

The finding does not by itself show that donor ethnicity caused the observed difference. The record describes randomization, but important details about allocation, masking, analysis populations, missing data, and outcome assessment are not reported. Nor does the primary result establish how the groups compare on the secondary outcomes concerning microbial composition, recovery, or bacterial strains; those results are not reported in the registry record.

The primary outcome combines clinical and endoscopic criteria and is recorded as steroid-free. It should not be generalized to outcomes beyond that specific definition and timeframe. The registry does not provide a longer-term result, a separate account for each component of the composite, or information about how the endpoint relates to participants' experience beyond the recorded measures.

The groups are small in the posted primary outcome comparison, and the confidence interval indicates uncertainty about the size of the contrast. The reported result is not a guarantee of the same difference in another group of participants or in another clinical setting. Generalizability also depends on eligibility criteria, disease characteristics, transplant procedures, donor selection, and follow-up, several of which are not reported.

Accordingly, the result can be read as a registry-posted comparison between two donor groups on a specified composite outcome. It is not a complete account of the study's methods or of every outcome that may have been collected. No conclusion about treatment advice, mechanism, or unreported outcomes follows from the primary comparison alone.

16. Why This Trial Matters Statistically

This trial is statistically notable because it compares two active donor-source groups rather than transplantation against no transplantation. The primary contrast therefore concerns differences between bacterial solutions from Bai and Han donors, as described in the registry, within the same stated procedure. Interpretation depends on the groups being comparable and on the donor-source distinction being sufficiently well defined; details of donor selection and solution preparation are not reported.

The primary endpoint brings clinical and endoscopic criteria together, making its definition central to interpretation. The registry gives a Mayo score threshold, a limit for individual sub-scores, and an endoscopy-sub-score reduction from baseline. It also names steroid-free status. Because the registry does not further specify assessment rules for steroid use or each composite component, readers have limited information for reconstructing exactly how endpoint status was assigned.

The reported risk difference and its interval convey both the direction of the observed contrast and the uncertainty around its size. The interval lies below zero, but its width cautions against treating the point estimate as a precise forecast. The unadjusted p-value adds a test-based summary, while not addressing multiplicity or the missing details of the analysis plan.

The record also highlights the difference between enrollment and outcome-specific denominators. The enrollment figure is 102, while the primary result and safety records use different group counts. Without an explanation of those counts and missing-data handling, readers cannot trace participant flow from enrollment to analysis. This is an important statistical transparency issue, not evidence about why participants are absent from a particular denominator.

Finally, the study's listed secondary outcomes focus substantially on microbiota. Their results are not included in the posted material described by the registry record, so the primary endpoint cannot answer the mechanistic questions named in the study titles. The record is useful for identifying the planned comparison and reported primary result, while leaving key design, analysis, and secondary-result details unresolved.

17. 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.

Several limitations are specific to the information recorded for this trial. The primary outcome counts involve 30 Bai-group participants and 31 Han-group participants, while the total enrollment is 102. Safety counts are 41 and 48. The registry does not explain the different denominators, describe participant flow, or state whether outcomes were unavailable for some participants. That limits assessment of how representative the posted endpoint counts are of those enrolled.

The condition is listed as inflammatory bowel diseases, while the arm descriptions refer to ulcerative colitis. The record does not report detailed eligibility criteria or the characteristics of the enrolled population, so the precise participant group represented by the results is not fully described. It also does not describe disease severity, prior therapies, concurrent treatment, or other factors that could inform interpretation of the clinical outcome.

The comparison is identified by donor nationality, but donor selection, the number of donors, bacterial preparation, and the characteristics of the transplanted material are not reported. The record therefore does not establish which donor or material features distinguish the groups beyond the descriptions given. These gaps are especially relevant to interpreting the study's mechanistic aims.

The registry does not report which parties were masked, how the sequence was generated, how allocation was concealed, or how the composite endpoint was assessed. It also does not report the analysis population, missing-data procedures, a statistical analysis plan, or the original sample-size rationale. No secondary outcome results are posted, despite the registry listing eight secondary outcomes. These limits prevent a fuller appraisal of bias, precision across outcomes, and the intended analysis.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: Efficacy and Mechanism of Fecal Microbiota Transplantation of the Bai Ethnicity in the Treatment of UC — NCT06591013.
• Registry record last updated 2026-06-30; status last verified 2026-06.
• Results first posted 2026-06-30.
• 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.

21. Record Summary

The registry record identifies NCT06591013 as a completed, randomized, double-masked, parallel-group study sponsored by First Affiliated Hospital of Kunming Medical University. It records enrollment of 102 and compares fecal microbiota transplantation using bacterial solution from Bai donors with solution from Han donors, delivered by colonoscope.

The primary endpoint is a steroid-free clinical and endoscopic composite assessed 12 weeks after transplantation. The registry reports 24 of 30 participants meeting the endpoint in the Bai group and 16 of 31 in the Han group. The reported risk difference for Han relative to Bai is negative, its interval lies below zero, and the unadjusted p-value is 0.02.

The registry lists eight secondary outcomes but does not include their results in the posted information. Safety records report zero serious adverse events, other adverse events, and deaths in each group, with differing at-risk counts. Further details about participant flow, missing data, analysis populations, masking, and the original design assumptions are not reported in the registry record.