Dose-ranging Efficacy of Polydextrose Supplement on Colonic Transit Time and Symptoms in Adults With Functional Constipation: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Dose-ranging Efficacy of Polydextrose Supplement on Colonic Transit Time and Symptoms in Adults With Functional Constipation (NCT02314936), a randomized phase 2 study. The primary outcome is Change in Colonic Transit Time From Baseline to Day 15.

2. Clinical Question

The registry also lists gastrointestinal symptoms and bowel-function outcomes, including constipation symptoms, constipation-related quality of life, adequate relief, stool frequency, stool consistency, straining, and the sensation of complete bowel emptying. The primary question is specifically about colonic transit time, measured in hours, rather than a direct measure of symptom relief. The posted primary results are group means and standard deviations for change, alongside recalculated unadjusted comparisons with placebo. These results describe the observed differences in this trial; they do not establish what would occur in other populations or over periods longer than the trial’s 2-week supplementation period.

3. Trial Design

This was a Phase 2 randomized, quadruple-masked, parallel-group trial sponsored by KGK Science Inc. The registry record reports an enrollment of 192 and a completed status. The listed study dates are 2015-04 for the start and 2016-04 for primary completion. Four groups were assigned: three polydextrose doses and a placebo group. Each intervention was a daily sachet mixed with water and taken with breakfast for 2 weeks. The placebo contained maltodextrin.

Random allocation is intended, in general, to make groups comparable at the start of a trial with respect to measured and unmeasured characteristics. A parallel design means each participant is assigned to one group, rather than receiving each intervention in sequence. Masking is intended, in general, to reduce the influence of knowledge about treatment assignment on participant experience, care, assessment, and analysis. The registry identifies the masking level as quadruple but does not identify which specific roles were masked.

The primary outcome was change in colonic transit time from baseline to Day 15, assessed using abdominal x-ray. The record describes taking 24 radiopaque markers on 6 consecutive days immediately preceding the x-ray dates, amounting to 144 markers in total. The outcome summary uses per-protocol participants who met the study-product compliance requirement and consumed all radio opaque pellets. The record says 17 participants did not meet the per-protocol compliance requirement and 2 did not complete the study.

The original sample-size justification, planned primary analysis, allocation ratio details, randomization procedure, concealment method, and planned interim analyses are not reported in the registry record. The registry identifies several secondary outcomes, but does not report the analysis methods used for them. Those omissions limit the ability to assess how closely the posted summaries follow the original statistical plan.

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: The number of participants analysed is the number of participants who met the per protocol population requirement. 17 participants did not meet the per protocol compliance (must have consumed ≥80% of assigned study product and 100% of radio opaque pellets) and 2 participants did not complete the study (did not complete end-of-study visit).

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 in Colonic Transit Time From Baseline to Day 15, measured over Baseline and Day 15.

The primary endpoint is change in colonic transit time from baseline to Day 15, measured in hours. Colonic transit time describes how long material takes to move through the colon. In this trial, the measure was assessed with abdominal x-ray after participants took radiopaque markers on 6 consecutive days immediately before the x-ray dates. The record specifies 24 markers per day and 144 markers in total.

In general, a physiological measure such as transit time can provide information about bowel movement through the colon that is distinct from how a participant describes symptoms. The endpoint therefore addresses a measurable aspect of bowel function. It does not, by itself, represent every aspect of constipation experience, such as discomfort, straining, perceived relief, or quality of life; the registry lists separate secondary outcomes for several of these experiences.

The posted group values are mean changes from baseline, with standard deviations describing variation among participants. The placebo group mean change was 2.6 hours. The corresponding mean changes were -1.7 hours for the 12 g group, 4.0 hours for the 8 g group, and 2.5 hours for the 4 g group. The recalculated mean differences against placebo are estimates of the contrast between these group means. The registry record does not report a threshold for a change that would be considered clinically important, so the size of a difference cannot be classified as meaningful to participants on the basis of this record alone.

7. Results Posted in the Registry

• Litesse Powder Containing 12 g Polydextrose: mean -1.70 versus 2.60 on control; difference -4.30 (95% CI -14.74 to 6.14), standardized effect d = -0.17; z-test p = 0.419.
• Litesse Powder Containing 8 g Polydextrose: mean 4.00 versus 2.60 on control; difference 1.40 (95% CI -9.10 to 11.90), standardized effect d = 0.06; z-test p = 0.794.
• Litesse Powder Containing 4 g Polydextrose: mean 2.50 versus 2.60 on control; difference -0.10 (95% CI -10.66 to 10.46), standardized effect d = -0.00; z-test p = 0.985.

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 in Stool Frequency From Baseline to Day 15

• 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:
  • Litesse Powder Containing 12 g Polydextrose: mean 1.20 versus -0.90 on control; difference 2.10 (95% CI 0.62 to 3.58), standardized effect d = 0.60; z-test p = 0.005.
  • Litesse Powder Containing 8 g Polydextrose: mean -0.20 versus -0.90 on control; difference 0.70 (95% CI -0.79 to 2.19), standardized effect d = 0.20; z-test p = 0.358.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Litesse Powder Containing 12 g Polydextrose than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Litesse Powder Containing 8 g Polydextrose and the control. The interval gives the range of effects that remain compatible with the data.

Change in Stool Consistency From Baseline to Day 15

• 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:
  • Litesse Powder Containing 12 g Polydextrose: mean 0.33 versus 0.13 on control; difference 0.20 (95% CI -0.20 to 0.60), standardized effect d = 0.21; z-test p = 0.331.
  • Litesse Powder Containing 8 g Polydextrose: mean -0.11 versus 0.13 on control; difference -0.24 (95% CI -0.64 to 0.16), standardized effect d = -0.26; z-test p = 0.239.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Litesse Powder Containing 12 g Polydextrose 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 Litesse Powder Containing 8 g Polydextrose and the control. The interval gives the range of effects that remain compatible with the data.

Change in the Degree of Straining During Defecation From Baseline to Day 15

• 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:
  • Litesse Powder Containing 12 g Polydextrose: mean -0.07 versus -0.09 on control; difference 0.02 (95% CI -0.26 to 0.30), standardized effect d = 0.03; z-test p = 0.887.
  • Litesse Powder Containing 8 g Polydextrose: mean -0.26 versus -0.09 on control; difference -0.17 (95% CI -0.46 to 0.12), standardized effect d = -0.24; z-test p = 0.259.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Litesse Powder Containing 12 g Polydextrose 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 Litesse Powder Containing 8 g Polydextrose and the control. The interval gives the range of effects that remain compatible with the data.

The registry lists a range of secondary measures covering symptoms, quality of life, bowel function, perceived relief, stool frequency and consistency, straining, and complete bowel emptying. Across the posted summaries, the results do not form a consistent pattern of differences across every outcome or dose. Some recalculated comparisons suggest a difference from placebo, while others are close to zero or have intervals that include zero. These summaries are exploratory context rather than a replacement for the primary outcome.

The primary endpoint concerns colonic transit time, a physiological measure, while the secondary outcomes address aspects of daily bowel function and participants’ experience. In general, these measures can complement one another because a change in a physiological measure need not correspond to a change in reported symptoms, and the reverse is also possible. The results available in the registry record do not establish a consistent relationship between the primary measure and the symptom-related outcomes.

Several secondary outcomes and dose comparisons create multiple opportunities to observe apparently notable estimates by chance. General statistical explanation: when many hypotheses are tested, the chance of at least one apparently unusual result increases unless the analysis accounts for multiplicity or treats the findings as exploratory. The registry record does not report a multiplicity adjustment or a hierarchy of secondary hypotheses. It also does not report the sponsor’s analyses for the listed secondary outcomes. Accordingly, unadjusted secondary findings carry less weight than a prespecified, fully reported primary analysis and should not be treated as confirmatory evidence in isolation.

The registry lists 45 outcome measures and reports 11 secondary outcomes as posted. The additional secondary summaries should be read as descriptions of the posted outcomes, not as a complete account of all planned comparisons. The record does not explain why some outcomes have analyses listed while others do not, or whether the set of posted results reflects a prespecified reporting plan. That uncertainty reinforces a cautious, broad reading: the secondary information helps characterize outcome patterns but does not resolve the uncertainty in the primary comparison.

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

• Change in Participant Assessment of Constipation Symptoms (PAC-SYM) From Baseline to Day 15
• Change in Participant Assessment of Constipation Quality of Life (PAC-QoL) From Baseline to Day 15
• Change in Bowel Function Index From Baseline to Day 15
• Change in Adequate Relief of Constipation Symptoms From Baseline to Day 15
• Change in Stool Frequency From Baseline to Day 15
• Change in Stool Consistency From Baseline to Day 15
• Change in the Degree of Straining During Defecation From Baseline to Day 15
• Change in the Sensation of Complete Bowel Emptying From Baseline to Day 15

9. Statistical Interpretation

10. Statistical Methods Explained

What does a mean change represent?

Each reported group value is the mean change in colonic transit time from baseline to Day 15. A mean is the arithmetic average of the participant-level changes. The mean difference against placebo compares the intervention group’s mean change with the placebo group’s mean change. In general, the sign of a difference depends on the order of subtraction. Here, the comparison estimates are expressed as the polydextrose group relative to placebo. A negative estimate therefore indicates a lower mean change in that group than in placebo; it does not, without a prespecified clinical interpretation, establish whether that direction is beneficial.

What does the standard deviation describe?

The standard deviation describes how dispersed individual values are around a group mean. It is not the uncertainty of the group mean itself, and it is not a range containing all participants. General statistical explanation: when individual outcomes vary widely, the mean difference can be difficult to estimate precisely unless the study has enough participants or the analysis otherwise improves precision. The primary outcome standard deviations range from 23.4 to 25.9 hours across the reported groups, while the recalculated mean differences are much smaller in magnitude than those spreads. The registry record does not report adjusted analyses that might account for baseline values or other predictors.

How should a mean difference and its interval be read?

A mean difference is a point estimate: the single value that summarizes the observed contrast under the calculation used. An interval expresses uncertainty about the contrast. In general, an interval that includes zero is compatible with both a negative difference and a positive difference, as well as no difference. The primary comparison intervals all include zero. Their width indicates that the estimates do not precisely determine the direction or magnitude of the population contrast. The registry record does not state the confidence level for these recalculated intervals, so the interval bounds are best read as the posted statistical intervals rather than assigned an unreported confidence level.

What does an unadjusted p-value tell a reader?

The reported comparison p-values are recalculated and unadjusted. General explanation: a p-value measures how unusual data at least as incompatible with a specified null model would be if that model and the test assumptions were true. It does not measure the probability that the null hypothesis is true, the size of an effect, or its clinical importance. An unadjusted p-value does not account for the fact that multiple outcomes or comparisons may have been examined. Since the registry does not report the sponsor’s analysis or full multiplicity plan, these values are descriptive inferential calculations rather than a complete account of the trial’s planned statistical testing.

Why does randomization matter?

General explanation: random assignment helps balance prognostic factors between groups on average, including factors that may not have been measured. It does not guarantee identical groups, particularly in a trial with limited group sizes. The registry identifies the study as randomized but does not report its sequence-generation or allocation-concealment methods. Those methods are important to evaluate whether assignment could have been predicted or influenced before enrollment.

What does masking contribute?

General explanation: masking can reduce bias when expectations influence reporting, clinical decisions, or outcome assessment. The registry identifies quadruple masking, but does not specify the roles included in that label or describe whether masking was assessed. The primary outcome involved an x-ray assessment, while many secondary outcomes involved participant-reported symptoms or bowel function. The record does not provide additional detail on outcome assessment procedures for these measures.

What is a per-protocol population?

A per-protocol analysis includes participants who meet stated requirements for adherence or completion. Here, the registry describes the primary outcome analysis as including participants who met the per-protocol population requirement, including consumption of at least 80% of assigned study product and 100% of radio opaque pellets. General explanation: a per-protocol estimate can describe outcomes among participants who followed specified trial requirements, but it may not preserve all the protections of the original random assignment if participants are excluded after randomization. The registry does not report an intention-to-treat analysis for the primary outcome.

What can be inferred from the available methods?

The outcome summaries and recalculated comparisons support a descriptive reading of the observed changes, but do not reveal the full planned analysis. The original sample-size justification, model specification, covariate adjustments, assumptions about missing outcomes, and interim-analysis plan are not reported in the registry record. No additional modeling assumptions should be inferred from the fact that means and standard deviations are posted. A fuller statistical assessment would require the protocol or analysis plan and the sponsor’s reported analyses.

11. Confidence Intervals and Precision

The primary comparison intervals are broad. For the 12 g group, the recalculated mean difference against placebo is -4.3 hours, with bounds of -14.74 and 6.136. For 8 g, the estimate is 1.4 hours, with bounds of -9.101 and 11.9. For 4 g, the estimate is -0.1 hours, with bounds of -10.66 and 10.46. Each interval crosses zero, so each is compatible with contrasts in either direction, including no difference.

In general, an interval conveys both the estimated direction and how much uncertainty remains around that estimate. A narrow interval can distinguish among a smaller range of plausible values, while a broad interval leaves more possibilities unresolved. The intervals for these primary comparisons leave considerable uncertainty about the size and direction of the difference. They should not be interpreted as proof that the groups are equivalent: showing equivalence requires a prespecified margin and an analysis designed for that purpose, and such a margin is not reported in the registry record.

The mean changes are accompanied by substantial standard deviations: 23.6 hours for 12 g, 23.4 hours for 8 g, 23.7 hours for 4 g, and 25.9 hours for placebo. In general, variation between individuals contributes to uncertainty in group comparisons. The analyzed group counts are 45, 43, 43, and 42, respectively. The record does not give individual-level data, baseline-to-follow-up correlations, or sponsor-reported adjusted estimates, so those sources of precision cannot be evaluated from the posted summaries.

The intervals and p-values are recalculated unadjusted comparisons rather than sponsor-reported analyses. The registry record does not state the confidence level for the intervals or describe a multiplicity adjustment. Readers should therefore distinguish the estimates’ numerical precision from the certainty of any clinical interpretation, which also depends on the outcome’s meaning and a clinically important difference that is not reported.

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 figures are participants per arm for the comparisons of each dose with placebo. They are not total sample sizes across all four groups and are not event counts: this is a continuous outcome. The calculations use a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. They explore detecting 100%, 75%, or 50% of the observed effect. The trial’s own original sample-size assumptions and justification are not reported in the registry record.

The 80% power column gives the modeled number of participants per arm for an 80% chance of detecting the specified effect under those planning assumptions, if the assumed effect and other calculation assumptions hold. The 90% column gives the corresponding per-arm number for a 90% chance. These are planning targets, not descriptions of the trial’s achieved power, and the displayed calculations are not observed power.

The pattern across effect assumptions follows a general principle: smaller effects are harder to distinguish from random variation, so they require more participants for the same target power. For instance, planning for 75% or 50% of the observed effect yields larger participant requirements than planning for the full observed effect. The effect estimates are taken from this trial’s observed differences, so these illustrations are sensitive to the uncertainty of those estimates. When an observed effect is very close to zero, the resulting planning figures can become extremely large. Such figures are not a recommendation or a claim about what a future study must enroll; they are conditional illustrations based on the stated assumptions.

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 = -4.300; pooled standard deviation σ = 24.736.
2. n = 2 × (1.96 + 0.842)² × 24.736² / -4.300² = 519.5, rounded up to 520 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 <- -4.3                      # observed difference in means
sigma <- 24.736125047245                     # 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(2314936)
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 = 520 (80% power), 696 (90% power)
 75% of observed effect: n per arm = 924 (80% power), 1,237 (90% power)
 50% of observed effect: n per arm = 2,078 (80% power), 2,782 (90% power)
power.t.test: 520.4 
Simulated power at n = 520 per arm: 0.798 (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. Multiplicity, Missing Data and Analysis Populations

Multiplicity arises when a trial evaluates many endpoints, doses, time points, or pairwise comparisons. General explanation: with multiple statistical tests, the chance of at least one apparently unusual result can increase even if none of the underlying effects is real. Methods such as a prespecified testing hierarchy or adjustment of significance levels can address this issue, but the registry record does not report whether either approach was planned or used. The record lists 45 outcome measures, several polydextrose doses, and multiple secondary outcomes. The recalculated comparison p-values are unadjusted, so they should not be interpreted as controlling the overall chance of false-positive findings across the full set of outcomes.

The registry record does not report the original statistical analysis plan, a multiplicity strategy, the sponsor’s primary or secondary analysis methods, or interim analyses. It also does not state how missing outcome measurements were handled, whether any imputation was performed, or what assumptions would support such methods. These details matter because missingness can affect both the number of participants contributing to an outcome and the interpretation of group comparisons.

The primary outcome population is described as per protocol. The record says 17 participants did not meet the compliance requirement—consuming at least 80% of assigned product and 100% of radio opaque pellets—and 2 did not complete the study. The primary outcome group counts are 45, 43, 43, and 42. The registry does not provide a participant flow by group explaining all differences between enrollment, completion, and the analyzed population. Nor does it provide an intention-to-treat estimate alongside the per-protocol summary.

In general, restricting analysis to participants who adhered to treatment can be informative about outcomes among adherent participants, but exclusion after randomization may introduce bias if the excluded participants differ in prognosis or outcome. Without reasons for noncompliance, group-specific completion information, and sensitivity analyses for missing data, the direction and extent of any such influence cannot be determined. This is a limitation of interpretation, not evidence that the posted results are necessarily biased.

15. Safety Results

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

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent non-serious adverse event terms

The serious adverse event summaries report 0 affected participants in each group, with 48 participants at risk in each group: 12 g, 8 g, 4 g, and placebo. No serious adverse-event terms are listed in the registry record. The deaths field is not populated, so deaths are not reported in the registry record; a blank field should not be read as an explicit report of zero deaths.

These figures describe serious events recorded for the groups and period represented in the registry entry. They do not show that no other adverse events occurred. The record separately lists other adverse events affecting 11 participants in the 12 g group, 10 in the 8 g group, 1 in the 4 g group, and 11 in the placebo group. The registry does not provide event descriptions in the registry record for this summary, nor does it provide enough detail to assess severity, timing, or attribution.

In general, safety counts are most informative when considered with follow-up duration, event definitions, completeness of reporting, and the size of the exposed groups. This trial’s supplementation period was 2 weeks, and the serious-event counts are zero in the listed groups. Those observations are limited to the registry’s reported information and should not be generalized beyond it.

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

The posted primary data show that mean change in colonic transit time varied across the four groups. The recalculated unadjusted comparisons with placebo are -4.3 hours for 12 g, 1.4 hours for 8 g, and -0.1 hours for 4 g. The intervals for all three comparisons include zero and extend to values on both sides of zero. The estimates therefore leave substantial uncertainty about whether, and by how much, each dose differed from placebo in the population represented by the trial.

That uncertainty does not establish that the groups were equivalent, and the point estimates alone do not establish a meaningful difference. The record does not report a clinically important threshold for colonic transit time. It also does not report the sponsor’s inferential analyses or the original statistical plan, while the comparisons discussed are unadjusted recalculations from posted group summaries. These features limit the strength of claims that can be made from the estimates.

The endpoint is a measure of transit time, not a complete measure of functional constipation or a participant’s overall experience. The registry lists separate secondary outcomes for symptoms and bowel function, but multiple outcomes and the absence of a reported multiplicity plan mean those results should be interpreted cautiously. The primary comparison’s uncertainty is not resolved by selecting a secondary result in isolation.

The study tested four assigned groups over a 2-week supplementation period, and the primary results use a per-protocol population. The record notes participants who failed to meet the compliance requirement or did not complete the study, but does not report a full group-by-group flow or a parallel intention-to-treat estimate. The conclusions that can be drawn are therefore limited to the posted summaries and their uncertainty. They do not establish what would happen over longer periods, in other populations, or under different study conditions.

17. Why This Trial Matters Statistically

This trial is statistically useful as an example of why a point estimate should not be read without its uncertainty. The primary mean differences are relatively small in relation to the observed spread of individual changes, and each comparison interval includes zero. Reading only the direction of a point estimate would give an incomplete account of what the data can support.

The four-group, dose-ranging design also creates an interpretive challenge. It allows several dose comparisons, while the registry lists many outcomes. Without a reported multiplicity plan, isolated findings across dose and outcome combinations carry a higher risk of being overinterpreted. A structured analysis plan would clarify which comparison was primary, how secondary questions were prioritized, and how the overall error from multiple testing was handled. Those details are not reported in the registry record.

The study also illustrates the difference between a planning calculation and evidence about the trial’s performance. The sample-size illustrations are conditional on observed effects and stated assumptions; they do not describe the trial’s original design justification or its observed power. The original justification is not reported. Because the observed primary contrasts are uncertain, planning values based on them should be treated as illustrations rather than definitive estimates of the sample size needed for a future investigation.

Finally, the per-protocol population and incomplete reporting of participant flow matter statistically as well as operationally. Randomization supports fair comparisons at assignment, while post-randomization exclusions can affect that balance. The registry does not report enough detail to assess this fully. These features make clear why analysis population, missing-data handling, prespecified hypotheses, and complete results reporting are essential to understanding clinical trial evidence.

18. 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 trial-specific limitations constrain interpretation. The primary comparison summaries are based on the per-protocol population, and the registry notes 17 participants who did not meet compliance requirements and 2 who did not complete the study. Group-specific reasons for noncompliance and completion are not reported in the registry record. An intention-to-treat analysis is not reported, so the posted results do not show how an analysis retaining all randomized participants would compare.

The trial’s original sample-size justification and analysis plan are not reported. There is no registry description of the planned model, adjustment for baseline values, handling of missing data, or multiplicity control. The primary analysis comparisons in this explanation are unadjusted recalculations from group summary statistics, not a substitute for the sponsor’s analysis. No discrepancy between these recalculations and a sponsor analysis is reported, but the registry entry does not include sponsor analyses for the comparisons discussed.

The registry includes many outcome measures, and the record does not describe a hierarchy for secondary outcomes or explain the status of each planned measure. This creates uncertainty about how to interpret isolated secondary findings. In addition, the clinical importance threshold for a change in colonic transit time is not reported, limiting assessment of the practical importance of the observed differences.

The intervention period lasted 2 weeks, and the primary endpoint was assessed at baseline and Day 15. The results therefore address a short-term measurement period and do not establish longer-term patterns. The reported outcome summaries also do not provide individual-level data, which would be needed to explore distributions, outliers, and alternative modeling choices. The registry record reports quadruple masking but does not define which roles were masked or describe masking procedures. These gaps do not invalidate the posted summaries, but they limit independent assessment of robustness and generalizability.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Dose-ranging Efficacy of Polydextrose Supplement on Colonic Transit Time and Symptoms in Adults With Functional Constipation — NCT02314936.
• Registry record last updated 2018-11-09; status last verified 2018-04.
• Results first posted 2018-11-09.
• 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.

22. Record Summary

NCT02314936 is a completed randomized, quadruple-masked, parallel-group Phase 2 trial sponsored by KGK Science Inc. The registry reports an enrollment of 192 and compares daily polydextrose powder at 12 g, 8 g, and 4 g with a maltodextrin placebo over 2 weeks in adults with functional constipation.

The primary outcome was change in colonic transit time from baseline to Day 15, assessed with abdominal x-ray. The posted summaries are per-protocol group means and standard deviations. Recalculated unadjusted comparisons with placebo have broad intervals that include zero for all three doses. The record does not report the original sample-size justification, full analysis plan, multiplicity handling, or missing-data methods. Secondary measures cover symptoms and bowel function, while serious adverse-event counts are zero in each listed group; deaths are not reported in the registry record.