Efficacy and Safety of Mebeverine + Simethicone in Patients With Functional Bowel Disorders: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Efficacy and Safety of Mebeverine + Simethicone in Patients With Functional Bowel Disorders (NCT05175131), a randomized phase 3 study. The primary outcome is Change From Baseline of Sum of NRS-11 Abdominal Pain and Bloating/Flatulence Intensity Scores After 4 Weeks of Treatment..

2. Clinical Question

3. Trial Design

NCT05175131 is a Phase 3, randomized, parallel-group, open-label comparative study. The official title describes it as multicenter. The registry lists Abbott as sponsor and the trial status as completed. A total of 465 participants were allocated to three treatment groups: mebeverine plus simethicone, mebeverine, or simethicone. The efficacy results include 154 participants in the combination group, 155 in the mebeverine group, and 154 in the simethicone group. The registry states that 463 participants formed the Full Analysis Sample after 2 participants with only baseline efficacy assessments were excluded.

The study objective was to evaluate efficacy and safety of the fixed-dose combination against each component given alone in people with functional bowel disorders and abdominal pain and excess gas formation. The primary endpoint was assessed after 4 weeks. It measured change from baseline in the sum of NRS-11 abdominal pain and bloating/flatulence intensity scores. The record also lists outcomes for pain intensity, bloating/flatulence intensity, days per week when drotaverine was taken, and quality of life using the IBSQOL questionnaire.

Open-label means participants and study personnel were not masked to treatment assignment. The registry lists masking as none. Random allocation can support fairer group comparisons by balancing factors at the time of assignment, but it does not remove possible effects of knowing the assigned treatment on participant reports or study conduct. The registry record does not report details of the randomization sequence, allocation concealment, or procedures used to standardize care across groups.

The record states that the combination and mebeverine were taken by mouth three times a day; simethicone was 80 mg, described as 2 capsules of 40 mg, by mouth three times a day. The combination’s component doses are not reported in the registry record. The trial’s original sample-size justification and its prespecified assumptions are not reported in 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

Analysis population for the primary outcome, as defined in the registry: 465 subjects were allocated to treatment. 2 subjects had only a baseline assessment of the efficacy parameters and were excluded from the full analysis sample. Therefore, 463 subjects were included in the Full Analysis Sample (FAS)

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 Change From Baseline of Sum of NRS-11 Abdominal Pain and Bloating/Flatulence Intensity Scores After 4 Weeks of Treatment., measured over 4 weeks.

The primary endpoint was the change from baseline in the sum of abdominal pain and bloating/flatulence intensity scores after 4 weeks of treatment. Participants rated these symptoms using the NRS-11, a numerical rating scale presented as a horizontal line marked from 0 to 10. Zero represented no pain or bloating, while 10 represented the most severe pain or bloating the participant could imagine. The baseline score was the average daily assessment over the 7 days before randomization. The week 4 score was the average from the last 7 days of the corresponding week.

A change score describes how the measured symptom score differed from baseline, rather than the score at a single assessment. Negative mean changes in the posted results indicate that the measured scores were lower at follow-up than at baseline. Because the endpoint combines abdominal pain and bloating/flatulence, it reflects both symptom dimensions in one outcome; the separate components are also listed as secondary outcomes.

Using a defined rating scale and averaging daily assessments gives a structured way to compare reported symptom intensity over time. Combining the two symptoms can represent the trial’s stated focus on pain and excess gas-related complaints. It also means the primary outcome should be interpreted as a joint score: it does not, by itself, show how much each symptom contributed to the overall change. The registry record does not report a clinically important difference threshold for this measure, so the clinical importance of a given score contrast cannot be established from the posted results alone.

7. Results Posted in the Registry

• Mebeverine: mean -6.48 versus -7.23 on control; difference 0.75 (95% CI -0.02 to 1.52), standardized effect d = 0.22; z-test p = 0.056.
• Simethicone: mean -5.86 versus -7.23 on control; difference 1.37 (95% CI 0.57 to 2.17), standardized effect d = 0.38; z-test p = <0.001.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Change From Baseline of NRS-11 Pain Intensity After 4 Weeks of Treatment

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Mebeverine: mean -3.19 versus -3.59 on control; difference 0.40 (95% CI 0.00 to 0.80), standardized effect d = 0.22; z-test p = 0.049.
  • Simethicone: mean -2.75 versus -3.59 on control; difference 0.84 (95% CI 0.43 to 1.25), standardized effect d = 0.46; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Mebeverine than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Simethicone than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Change From Baseline of NRS-11 Bloating/Flatulence Intensity After 4 Weeks of Treatment

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Mebeverine: mean -3.29 versus -3.65 on control; difference 0.36 (95% CI -0.06 to 0.78), standardized effect d = 0.19; z-test p = 0.090.
  • Simethicone: mean -3.11 versus -3.65 on control; difference 0.54 (95% CI 0.11 to 0.97), standardized effect d = 0.28; z-test p = 0.014.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Mebeverine and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Simethicone than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Change in Number of Days Per Week During Study Treatment Period When Drotaverine Was Taken.

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Mebeverine: mean -1.10 versus -1.00 on control; difference -0.10 (95% CI -0.62 to 0.42), standardized effect d = -0.04; z-test p = 0.704.
  • Simethicone: mean -0.60 versus -1.00 on control; difference 0.40 (95% CI -0.12 to 0.92), standardized effect d = 0.17; z-test p = 0.129.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Mebeverine and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Simethicone and the control. The interval gives the range of effects that remain compatible with the data.

The registry lists secondary outcomes covering pain intensity, bloating/flatulence intensity, use of drotaverine, and quality of life measured with the IBSQOL questionnaire. The posted numeric secondary results include group-level changes for pain, bloating/flatulence, and days per week when drotaverine was taken. The IBSQOL result is not reported in the registry record. Across the posted symptom outcomes, mean scores moved downward from baseline in all three groups; the size and pattern of the between-group contrasts are not uniform across outcomes. The rescue-medication outcome does not show the same clear pattern of separation as the symptom-score outcomes.

These secondary outcomes add context to the primary combined symptom measure by separating pain and bloating/flatulence, and by including an outcome related to additional medication use. They are related questions but are not interchangeable with the primary endpoint. In particular, separate symptom measures can show whether the pattern in the combined endpoint is shared across its components, while the combined outcome alone cannot resolve that question. The registry’s absence of a posted IBSQOL result means the listed quality-of-life outcome cannot be evaluated from the available record.

Unadjusted secondary comparisons carry less weight than a prespecified primary analysis because several outcomes and pairwise comparisons create multiple opportunities to observe apparently notable results by chance. The registry record does not report whether multiplicity was addressed or identify a hierarchy for interpreting secondary outcomes. As a result, secondary findings are best treated as supportive or exploratory rather than as independent confirmation of the primary result. This caution does not imply that the outcomes are unimportant; it reflects the uncertainty created when several comparisons are interpreted without a reported adjustment strategy.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Change From Baseline of NRS-11 Pain Intensity After 4 Weeks of Treatment
• Change From Baseline of NRS-11 Bloating/Flatulence Intensity After 4 Weeks of Treatment
• Change in Number of Days Per Week During Study Treatment Period When Drotaverine Was Taken.
• Change in Quality of Life Evaluation Using IBSQOL Questionnaire Versus Baseline.

9. Statistical Interpretation

10. Statistical Methods Explained

What does a mean change represent?

The primary outcome is continuous: it is a numerical score, and the registry reports group means and standard deviations. A mean change is the average of participants’ follow-up scores minus their baseline scores, as represented in the posted outcome summaries. It describes the average direction and size of change within a group. It is not the same quantity as the difference between two groups. A comparison between groups asks whether their average changes differ, and that contrast is the relevant quantity for interpreting the randomized comparison.

In this trial, negative change values indicate lower scores at week 4 than at baseline. The primary score combines pain and bloating/flatulence intensity, each measured on the NRS-11. The recorded baseline and week 4 scores each rely on averages of daily assessments across a 7-day period, which can smooth some day-to-day fluctuation. That feature does not remove measurement error, differences in reporting, or possible effects of knowing the assigned treatment.

Why report standard deviations?

A standard deviation describes how spread out participant outcomes are around a group mean. It is not the uncertainty around the mean itself and should not be read as a confidence interval. Greater variation among participants generally makes a group average less precise for a fixed sample size. The posted standard deviations are around 3.42, 3.48, and 3.72 for the primary change outcome in the combination, mebeverine, and simethicone groups, respectively. These describe dispersion in the observed group scores; they do not describe a treatment effect.

General explanation: a confidence interval for a mean or contrast combines an estimate with information about its sampling uncertainty. It gives a range of values compatible with the analysis and its assumptions; it is not a range expected to contain every participant’s outcome. A p-value addresses how compatible the data are with a specified null hypothesis under the analysis assumptions. It does not measure the probability that the null hypothesis is true, or the probability that a treatment effect is clinically important.

What is the difference between the re-calculation and ANCOVA?

The simple unadjusted re-calculations use the posted group means and standard deviations to estimate mean differences and their uncertainty, without adjustment for baseline values or other covariates. They are useful as transparent checks based on summary statistics, but they do not reproduce the sponsor’s analysis. The posted re-calculated comparisons use the combination group as the reference and compare it separately with each monotherapy group.

The sponsor reports ANCOVA, or analysis of covariance, for both primary comparisons. General explanation: ANCOVA compares outcomes between groups while statistically accounting for one or more measured covariates. In clinical trials, baseline outcome values are often among the covariates, but the specific covariates in this trial are not reported in the registry record. Adjustment can change an estimate and its precision relative to a simple unadjusted comparison. The sponsor’s mean differences, intervals, and p-values therefore should not be expected to match calculations made solely from group-level changes and standard deviations. Given the discrepancy in this case, the sponsor’s own analysis takes precedence.

Why does the open-label design matter for a rating scale?

Randomization helps make treatment groups comparable in expectation at assignment, but open-label conduct means the treatment assignment was known. General explanation: expectations and awareness can influence how participants report subjective symptoms, as well as how staff communicate with participants or assess outcomes. This does not establish that such influence occurred in this trial; it identifies a possible source of bias to consider when interpreting participant-rated outcomes. The registry record does not report masking or blinded outcome assessment, and it lists masking as none.

Why can over-dispersion matter?

General explanation: over-dispersion occurs when a measure varies more than a statistical model assumes. If a model understates the true variability, uncertainty intervals may be too narrow and tests may appear more conclusive than warranted. The primary endpoint is continuous and reported with standard deviations; the registry record does not describe an over-dispersion assessment or identify a model for which over-dispersion was evaluated. This concept is not a reported finding about this trial. It illustrates why the assumptions and diagnostics for a statistical model matter, particularly when the distribution or variability of an outcome does not fit the model well.

How should the p-values be read?

The sponsor’s ANCOVA p-values are 0.004 for combination versus mebeverine and < 0.001 for combination versus simethicone. The simple unadjusted re-calculations yield p = 0.056 and p < 0.001, respectively. These p-values arise from different analyses and should not be substituted for one another. A p-value is not an effect size: the estimated mean difference and its confidence interval convey information about magnitude and precision. Statistical evidence also does not establish clinical importance, especially when the registry record does not identify a clinically important difference threshold.

The registry lists 5 outcome measures and 2 reported primary analyses. It also lists several secondary outcomes. The registry record does not report whether the sponsor adjusted for multiple comparisons, how missing outcome data were handled, or a detailed statistical analysis plan. Those omissions limit a reader’s ability to evaluate the family of tests, the assumptions behind the reported results, and whether the posted analyses follow the planned approach.

11. Confidence Intervals and Precision

Precision is conveyed by the range of values compatible with an estimate under the analysis used. A narrower confidence interval indicates less sampling uncertainty than a wider interval, though it does not address every source of uncertainty, such as outcome measurement or bias. A confidence interval is not a guarantee that the true effect lies inside it, nor does it describe the range of likely individual outcomes.

For the sponsor’s ANCOVA comparison of the combination with mebeverine, the reported mean difference is 1.1 and the 95% confidence interval is 0.3 to 1.8. For the comparison with simethicone, the reported mean difference is 1.6 and the 95% confidence interval is 0.9 to 2.4. Both reported intervals are above zero. These are the sponsor’s adjusted estimates and should be distinguished from the simple unadjusted re-calculations.

The unadjusted re-calculated mean difference for combination versus mebeverine is 0.75, with a confidence interval from -0.019 to 1.519. This interval includes zero. For combination versus simethicone, the recalculated mean difference is 1.37, with a confidence interval from 0.572 to 2.168. The discrepancy between these re-calculations and the sponsor’s ANCOVA results matters: they use different approaches, and the sponsor’s own analysis takes precedence for the trial’s reported inference.

General explanation: intervals describe uncertainty conditional on the analysis and its assumptions. They do not account automatically for open-label reporting effects, multiplicity, missing-data decisions, or other design limitations. The registry record does not report the sponsor model’s covariates or the confidence-interval method in detail. Precision should therefore be considered alongside both the statistical method and the limits of what the record documents.

12. 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 illustrations express sample sizes as participants per arm for 80% power and participants per arm for 90% power. They do not report total events; total-event presentation applies to time-to-event outcomes, and the outcomes in this trial are not time-to-event measures. The illustrations use a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is set to a stated fraction of the observed effect: 100%, 75%, or 50%. These are planning assumptions for the illustrations, not the trial’s original design assumptions. The trial’s original sample-size justification and design assumptions are not reported in the registry record.

Power is the probability that a study design will detect an effect of a specified size under the assumptions used, if that effect is present. In plain terms, the 80% column shows the participants per arm estimated for an 80% chance of detecting the chosen effect under those assumptions; the 90% column uses a higher target chance. Neither column describes the probability that the trial’s result is correct. The planning values are not observed power.

The rows that plan for 75% or 50% of the observed effect ask what sample size would be needed if the effect of interest were smaller than the observed estimate. Smaller effects are harder to distinguish from random variation, so they generally require more participants for the same power target. The resulting figures are illustrations based on the observed effect and the stated calculation assumptions; they are not evidence that the trial was designed around those sample sizes or that the observed effects will recur.

13. 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, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 0.750; pooled standard deviation σ = 3.450.
2. n = 2 × (1.96 + 0.842)² × 3.450² / 0.750² = 332.2, rounded up to 333 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
delta <- 0.75                      # observed difference in means
sigma <- 3.45022814710868                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^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 (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(5175131)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 333 (80% power), 445 (90% power)
 75% of observed effect: n per arm = 591 (80% power), 791 (90% power)
 50% of observed effect: n per arm = 1,329 (80% power), 1,779 (90% power)
power.t.test: 333.2 
Simulated power at n = 333 per arm: 0.802 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-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.

14. Analyses Reported by the Sponsor

The registry reports sponsor ANCOVA analyses for the two primary comparisons. For the combination versus mebeverine, the sponsor reports a mean difference of 1.1, a 95% confidence interval of 0.3 to 1.8, and p = 0.004. For the combination versus simethicone, the sponsor reports a mean difference of 1.6, a 95% confidence interval of 0.9 to 2.4, and p < 0.001. Both analyses are labelled superiority analyses in the registry.

The simple re-calculations from the posted group summaries are unadjusted and differ from those results. They estimate a mean difference of 0.75 for the mebeverine comparison and 1.37 for the simethicone comparison. The re-calculated uncertainty and p-values also differ from the sponsor’s reported figures. This is a discrepancy between analytical approaches, not a basis for replacing the sponsor’s stated analysis with the re-calculation.

The sponsor’s model details, including its covariates and precise handling of analysis populations, are not reported in the registry record. Therefore, the ANCOVA cannot be independently reproduced from the posted summary statistics alone. Because a discrepancy is present, the sponsor’s own analysis takes precedence when describing the trial’s reported inferential results. The re-calculations remain useful as a separate, unadjusted check, but should not be presented as if they were the sponsor’s analysis.

15. Multiplicity, Missing Data and Analysis Populations

The trial includes a primary endpoint, multiple secondary outcomes, and two reported sponsor comparisons for the primary endpoint. Considering several outcomes and treatment contrasts raises the issue of multiplicity: the more statistical tests that are examined, the greater the chance that at least one result may appear compelling by chance alone. A prespecified approach can address this, for example by defining which tests are confirmatory and how error rates are controlled. The registry record does not report a multiplicity adjustment, a testing hierarchy, or a plan for interpreting the secondary outcomes alongside the primary endpoint.

The registry identifies the primary endpoint and reports sponsor analyses labelled superiority, but the detailed statistical analysis plan is not reported in the registry record. The record does not state whether the two primary pairwise comparisons were both intended as confirmatory tests under a shared error-control strategy. The sponsor’s reported p-values should therefore be read as the results of the posted analyses, without assuming an unreported adjustment or decision rule.

Missing-data handling is another important element of analysis. The record states that 465 participants were allocated and 463 were included in the Full Analysis Sample because 2 participants had only baseline efficacy assessments. It does not report the method used to handle other missing assessments, the extent of missing week 4 data, or whether sensitivity analyses were performed. Without those details, it is not possible to assess whether missing outcomes could have affected the group comparisons.

The Full Analysis Sample description gives a useful indication of who contributed to the reported efficacy results, but the exact analysis populations for each sponsor ANCOVA are not reported in the registry record. The record also does not describe deviations from assigned treatment, adherence, or how such information was incorporated into analyses. These details matter because the interpretation can differ depending on whether participants are analyzed according to random assignment, actual treatment received, or another defined population. No specific approach should be inferred where the registry does not state one.

16. 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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: covid-19 pneumonia (0.6%).

The registry reports serious adverse events in 0 of 155 participants at risk in the combination group, 1 of 155 in the mebeverine group, and 0 of 155 in the simethicone group. It reports 0 deaths in each group. The listed serious adverse event term is Covid-19 Pneumonia at 0.6%; the registry information does not assign that term to a particular group in the posted summary. These counts describe events recorded in this trial and should not be interpreted as establishing that serious events cannot occur.

Other adverse events affected 39 participants in the combination group, 36 in the mebeverine group, and 31 in the simethicone group, with 155 at risk in each group. The registry’s serious-event counts are small, so they provide limited precision for comparing uncommon harms. The record does not provide further detail in the listed summary about event timing, severity beyond seriousness, causality assessment, or exposure-adjusted rates. A lack of reported serious events in a group is not proof of no risk, and the counts alone do not establish comparative safety.

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

The posted primary outcome describes average changes in a combined abdominal pain and bloating/flatulence score over 4 weeks. Mean scores decreased from baseline in each randomized group. The sponsor’s ANCOVA results report positive mean differences for the combination compared separately with mebeverine and simethicone, with 95% confidence intervals above zero. These are statistical comparisons of group averages in this trial, not predictions for any one participant.

The record does not report a threshold for a clinically important difference on the combined score. A statistical difference therefore cannot be translated directly into a conclusion about whether participants would notice a meaningful improvement. Nor does the primary combined score show how much of the result is attributable to pain versus bloating/flatulence. The separate secondary outcomes provide additional symptom information, but the registry record does not report an IBSQOL result.

The simple unadjusted re-calculations differ from the sponsor’s ANCOVA analyses. The sponsor’s analysis takes precedence for the trial’s reported inference, while the difference between methods is a reason to keep the analytic distinction visible. Details of the ANCOVA model and of missing-data handling are not reported in the registry record, which limits independent assessment of those decisions.

The open-label design is also relevant because the main outcomes rely on participant ratings. Randomization supports comparisons between assigned groups, but it cannot ensure that awareness of treatment assignment had no effect on reported symptoms. The trial’s results apply to the population and follow-up represented in the record; they do not establish what would occur in other settings, over a longer period, or for every person with a functional bowel disorder. No individual treatment decision follows from these group-level statistics alone.

18. Why This Trial Matters Statistically

This trial illustrates several important statistical distinctions in clinical research. First, a within-group change is not the same as a randomized between-group comparison. The mean symptom scores changed in all three arms, but a comparison of assigned groups is needed to describe how their average changes differ. That distinction helps avoid attributing every change from baseline to the assigned treatment.

Second, the record contains both sponsor ANCOVA results and simple unadjusted re-calculations based on group summaries. Their estimates and inferential results are not identical. This shows why results depend on the analysis method, and why adjusted sponsor analyses should not be conflated with summary-statistic re-calculations. In this case, the sponsor’s own analysis takes precedence for the reported inference, while the re-calculation makes the discrepancy visible.

Third, precision and clinical meaning are separate questions. Confidence intervals describe statistical uncertainty under an analysis, while a clinically important difference requires a meaningful interpretation of the outcome scale. The registry record does not report such a threshold. Finally, the open-label design, multiple listed outcomes, and missing details about multiplicity and missing-data handling all shape how confidently the estimates can be interpreted. These are not reasons to disregard the findings; they identify the information needed to judge how robustly the reported comparisons answer the clinical question.

19. 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 open-label design is a trial-specific limitation for outcomes based on participant ratings. Participants and study personnel were not masked to treatment assignment, so expectations or reporting behavior could potentially affect symptom ratings. The registry record does not report whether outcome assessment was otherwise blinded or whether steps were taken to reduce such influences.

The primary endpoint combines pain and bloating/flatulence into one score. This directly reflects the trial’s combined symptom question but does not reveal the contribution of each component. Separate secondary outcomes are listed, yet the registry does not report numeric IBSQOL results. The record also gives no clinically important difference threshold, which limits interpretation of the practical importance of the score contrasts.

The registry reports sponsor ANCOVA analyses, but the covariates and model details are not reported in the registry record. The ANCOVA estimates differ from simple unadjusted re-calculations based on posted summary statistics. The sponsor’s own analysis takes precedence, but the lack of model detail prevents independent reproduction from the posted summaries. The registry record also does not report a multiplicity strategy, detailed missing-data methods, or sensitivity analyses. These omissions make it harder to assess the robustness of the reported inference across analytic choices.

The primary outcome was assessed after 4 weeks. Longer-term outcomes are not reported in the registry record. The record describes 2 participants with only baseline efficacy assessments as excluded from the Full Analysis Sample, but does not describe other missing outcome data or adherence. Finally, the listed serious adverse event counts are sparse, limiting the precision of any safety comparison. These limitations qualify interpretation of this trial; they do not by themselves determine the direction or validity of its results.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Efficacy and Safety of Mebeverine + Simethicone in Patients With Functional Bowel Disorders — NCT05175131.
• Registry record last updated 2025-09-16; status last verified 2025-09.
• Results first posted 2024-01-03.
• 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.

23. Record Summary

NCT05175131 is a completed, Phase 3, randomized, parallel-group, open-label study comparing mebeverine plus simethicone with mebeverine and simethicone alone in functional bowel disorders with abdominal pain and excess gas formation. The registry reports allocation of 465 participants and a Full Analysis Sample of 463 for efficacy after excluding 2 participants with only baseline assessments.

The primary outcome was change from baseline in the sum of NRS-11 abdominal pain and bloating/flatulence intensity scores after 4 weeks. The sponsor reported ANCOVA superiority analyses for the combination versus each monotherapy. Simple unadjusted re-calculations differ, so the sponsor’s own analysis takes precedence for the reported inference. The registry record does not report the original sample-size justification, detailed model covariates, multiplicity adjustment, or full missing-data methods.