Efficacy and Acceptability of Low-Residue Diet Package (Enimaclin®) as Diet Control Before Colonoscopy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Efficacy and Acceptability of Low-Residue Diet Package (Enimaclin®) as Diet Control Before Colonoscopy (NCT01665157), a randomized na study. The primary outcome is Overall Cleansing Level at Colonoscopy by Ottawa Bowel Preparation Scale.

2. Clinical Question

The central statistical question is about the observed scores and their uncertainty, not a claim that any protocol is clinically preferable. The primary comparison concerns the overall cleansing score, while the acceptability outcomes address participants’ reported experience. Because the study includes three treatment arms, it supports an overall comparison across the protocols and pairwise comparisons against the self-controlled diet arm. Those contrasts do not isolate every component of the preparation: the 1.5L arm differs from the comparator in both diet package and PEG-ELS volume. The registry record does not report more detailed eligibility criteria, participant characteristics, or the exact procedures used to collect acceptability ratings.

3. Trial Design

The registry record describes a randomized, single-blinded, parallel-group comparative study, with 180 participants enrolled. It lists three arms, each with 60 participants in the posted primary outcome results. The arms were a low-residue diet package with normal amount 2L PEG-ELS, a self-controlled diet with normal amount 2L PEG-ELS, and a low-residue diet package with low-volume 1.5L PEG-ELS. The record marks the study completed and gives a start date of 2011-11 and primary completion date of 2012-06.

The randomized, parallel design assigns participants to distinct preparation protocols rather than having every participant receive each protocol. Random allocation can help balance participant characteristics across groups, although the registry record does not report how the random sequence was generated, whether allocation was concealed, or how balance was assessed. Single-blinded is the masking designation; who was blinded and how masking was maintained are not reported in the registry record.

The primary outcome was overall cleansing level by the Ottawa Bowel Preparation Scale, assessed at 1 day. Three secondary outcomes were posted: willingness to choose the same protocol, satisfaction, and convenience, also at 1 day. The registry lists 7 outcome measures and 7 analyses, but the fuller descriptions of the other measures and analyses are not reported in the registry record.

The study record lists Enimaclin® as a dietary supplement and lists PEG-ELS interventions. The record does not report the trial’s original sample-size justification, detailed protocol, participant flow, or analysis-population definitions. These omissions limit how fully the design and implementation can be assessed from the registry results alone.

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 Overall Cleansing Level at Colonoscopy by Ottawa Bowel Preparation Scale, measured over 1 day.

The primary endpoint is the overall cleansing level at colonoscopy measured with the Ottawa Bowel Preparation Scale. The scale scores three colon segments—right, mid, and rectosigmoid—and also scores the amount of fluid in the whole colon. Segment scores range from 0 to 4, with 0 best and 4 worst; fluid quantity is scored from 0 for small to 2 for large. The total is the sum of the segment scores and fluid score, ranging from 0, the cleanest colon, to 14, the dirtiest.

This endpoint captures bowel cleanliness as a continuous measure rather than reducing the result to a clean/not-clean category. The posted arm summaries therefore report means and standard deviations. Lower mean scores represent cleaner preparation on the defined scale, while the standard deviation describes how spread out scores are within an arm. The registry notes that segment scores would be analyzed separately as continuous variables, but those results are not reported in the registry record.

A cleansing score is relevant to a preparation study because it records the degree of cleanliness observed at colonoscopy. It should be interpreted as a measure on the stated scale, not as a direct measure of every aspect of colonoscopy quality or participant experience. Satisfaction, willingness to repeat the protocol, and convenience are separate secondary outcomes and address different questions. The record does not report additional details on endpoint assessment procedures or whether the person scoring the colonoscopy was masked to assigned protocol.

7. Results Posted in the Registry

• Low-residue Diet Package and 2L PEG: mean 2.58 versus 3.22 on control; difference -0.64 (95% CI -1.59 to 0.31), standardized effect d = -0.24; z-test p = 0.187.
• Low-residue Diet Package Plus 1.5L PEG: mean 2.97 versus 3.22 on control; difference -0.25 (95% CI -1.30 to 0.80), standardized effect d = -0.09; z-test p = 0.641.

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.

Willingness to Choose the Same Protocol After Different Low Residual Diet and PEG-ELS Protocol

• Endpoint type: Binary: the percentage of participants with the event (counts rebuilt from the posted percentages and group sizes).
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Low-residue Diet Package and 2L PEG: 93.3% (56/60) versus 90.0% (54/60) on control; risk difference 3.3 percentage points (95% CI -6.5 to 13.2), risk ratio 1.04 (0.93–1.16); unadjusted two-proportion z-test p = 0.509.
  • Low-residue Diet Package and 1.5L PEG: 95.0% (57/60) versus 90.0% (54/60) on control; risk difference 5.0 percentage points (95% CI -4.4 to 14.4), risk ratio 1.06 (0.95–1.17); unadjusted two-proportion z-test p = 0.298.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Low-residue Diet Package and 2L PEG 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 Low-residue Diet Package and 1.5L PEG and the control. The interval gives the range of effects that remain compatible with the data.

Satisfaction of Different Low Residual Diet and Bowel Preparation Protocol

• Endpoint type: Binary: the percentage of participants with the event (counts rebuilt from the posted percentages and group sizes).
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Low-residue Diet Package and 2L PEG: 73.3% (44/60) versus 36.7% (22/60) on control; risk difference 36.7 percentage points (95% CI 20.1 to 53.2), risk ratio 2.00 (1.39–2.88); unadjusted two-proportion z-test p = <0.001.
  • Low-residue Diet Package and 1.5 L PEG-ELS: 76.7% (46/60) versus 36.7% (22/60) on control; risk difference 40.0 percentage points (95% CI 23.8 to 56.2), risk ratio 2.09 (1.46–3.00); unadjusted two-proportion z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the proportion with the event is statistically higher for Low-residue Diet Package and 2L PEG 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 proportion with the event is statistically higher for Low-residue Diet Package and 1.5 L PEG-ELS than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Convenience of Different Low Residual Diet and Bowel Preparation Protocol

• Endpoint type: Binary: the percentage of participants with the event (counts rebuilt from the posted percentages and group sizes).
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Low-residue Diet Package and 2L PEG: 88.3% (53/60) versus 76.7% (46/60) on control; risk difference 11.7 percentage points (95% CI -1.8 to 25.1), risk ratio 1.15 (0.97–1.36); unadjusted two-proportion z-test p = 0.093.
  • Low-residue Diet Package and 1.5L PEG: 93.3% (56/60) versus 76.7% (46/60) on control; risk difference 16.7 percentage points (95% CI 4.2 to 29.1), risk ratio 1.22 (1.04–1.42); unadjusted two-proportion z-test p = 0.011.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Low-residue Diet Package and 2L PEG 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 proportion with the event is statistically higher for Low-residue Diet Package and 1.5L PEG than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The secondary outcomes broaden the interpretation beyond bowel cleanliness. Willingness to choose the same protocol was reported at a high level across the three arms. Satisfaction was higher in the two package arms than in the self-controlled diet arm, and convenience was also numerically higher in the package arms. The overall pattern suggests that participants’ reported experience may not track the primary cleansing score in the same way: the primary overall test was not statistically notable, while some acceptability analyses had smaller p-values.

These outcomes are not interchangeable. Willingness, satisfaction, and convenience measure participant-reported preferences or experience, whereas the Ottawa score measures bowel cleanliness observed at colonoscopy. A difference in acceptability does not itself establish a difference in cleansing, and the primary result does not determine how participants felt about the preparation.

The registry reports an overall chi-squared p-value below 0.01 for satisfaction and below 0.01 for convenience. The posted pairwise calculations include unadjusted comparisons, some of which have p-values below conventional thresholds and some of which do not. The willingness comparisons have no such pattern of small p-values. These distinctions should be retained rather than treating the secondary outcomes as a single composite finding.

Unadjusted secondary results carry less weight as confirmatory evidence because multiple outcomes and comparisons create more opportunities for chance findings. The registry record does not report a hierarchy of secondary hypotheses or multiplicity adjustment. These results can help describe the observed participant responses and motivate further study, but should not be treated as conclusive evidence about every protocol component.

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

• Willingness to Choose the Same Protocol After Different Low Residual Diet and PEG-ELS Protocol
• Satisfaction of Different Low Residual Diet and Bowel Preparation Protocol
• Convenience of Different Low Residual Diet and Bowel Preparation Protocol

9. Statistical Interpretation

10. Statistical Methods Explained

The primary endpoint is continuous: each participant has an Ottawa scale score, and the registry reports the mean and standard deviation for each arm. A mean describes the central value of scores in a group. A standard deviation describes how much individual scores vary around that mean. It is not itself a measure of uncertainty in the estimated mean; confidence intervals serve that separate purpose.

What does the overall ANOVA test address?

The registry reports an ANOVA analysis across all three arms, with p = 0.435. In general, analysis of variance tests whether the group means are consistent with a common mean or whether the data provide evidence that at least one group mean differs. An overall test does not identify which specific pair of arms differs. Nor does a non-small p-value prove that all group means are the same. The registry record does not report the details of the ANOVA model, assumptions checks, or any covariate adjustment.

What do the pairwise recalculations add?

The recalculated comparisons estimate unadjusted mean differences between each package arm and the self-controlled diet arm. A mean difference is the first group mean minus the comparator mean in the direction used for the posted results. Negative estimates indicate lower mean scores in the package arm. Since lower Ottawa scores represent cleaner preparation, the negative estimates point toward lower average scores in those arms. The confidence intervals for both comparisons include zero, and the corresponding unadjusted p-values are 0.187 and 0.641. These are simple, unadjusted comparisons based on the posted summary statistics, not the sponsor’s reported overall analysis.

In general, an unadjusted p-value evaluates a particular contrast without accounting for other comparisons that may also have been examined. If multiple contrasts or outcomes are tested, the chance of observing at least one apparently notable result can increase. The registry record does not report a multiplicity adjustment for the recalculated pairwise comparisons. Consequently, they should be read as descriptive comparisons rather than as a set of confirmatory tests.

How should the binary outcomes be read?

Willingness, satisfaction, and convenience are reported as percentages of participants. For those outcomes, the posted recalculations express pairwise differences as risk differences: the proportion reporting the outcome in one arm minus the proportion in the comparator arm. In general, a confidence interval around a risk difference describes a range of values compatible with the data and method; an interval containing zero does not rule out no difference. The reported percentages are rounded, so they should not be used to reconstruct participant-level data or to infer details not recorded.

The sponsor-reported secondary analyses use chi-squared tests for satisfaction and convenience, with p-values below 0.01. Those are overall tests across groups, not the same as each pairwise recalculation. The sponsor also reports an overall ANOVA for the primary outcome. The posted pairwise p-values are not substitutes for those reported analyses because they address different contrasts and are unadjusted.

Why can over-dispersion matter?

In general, over-dispersion occurs when observed variability exceeds what a statistical model assumes. When that happens, standard errors and resulting confidence intervals or p-values can be too optimistic if the model does not account for the extra variability. The primary outcome is reported with standard deviations, but the registry does not describe a model-based variance assessment or an over-dispersion check. No claim about over-dispersion in this trial can be made from the registry record.

More broadly, statistical interpretation depends on how participants were randomized, how outcomes were assessed, how missing observations were handled, and which analysis population was used. The registry record does not report these details. The posted calculations therefore characterize the reported summaries and stated sponsor analyses, but cannot resolve every design or analysis question.

11. Confidence Intervals and Precision

Precision concerns how narrowly an effect is estimated, not whether the estimate is important. A confidence interval gives a range of values compatible with the observed data and the interval method. Narrower intervals generally indicate more precise estimates; wider intervals indicate greater uncertainty. The interval should be considered alongside the estimate and the scale’s meaning.

For the primary pairwise comparisons, the posted recalculated mean differences were -0.64 for the package with 2L PEG and -0.25 for the package with 1.5L PEG, each compared with the self-controlled diet and 2L PEG arm. Both intervals include zero. Thus the data do not precisely distinguish these estimates from no difference under the posted unadjusted calculations. The intervals also permit effects in either direction, so the point estimates alone should not be treated as definitive.

The primary arm standard deviations were 2.15, 3.08, and 2.79. These values show that individual scores varied within each group; the differences between group means are small in relation to the observed within-arm spread. The sponsor-reported overall p-value, 0.435, is consistent with the absence of strong evidence for an overall difference, but a p-value is not a measure of precision or the probability that a hypothesis is true.

For secondary outcomes, some confidence intervals for risk differences exclude zero while others include it. This variation reflects differences in observed percentages and uncertainty, and should be read with the multiplicity context in mind. The registry record does not report confidence intervals for the sponsor’s overall ANOVA result. Precision also depends on the underlying analysis and assumptions; the record does not provide enough detail to evaluate all such choices.

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 sample-size display gives planning illustrations based on the observed effect, not the trial’s own original design assumptions. For these continuous and binary outcomes, the reported figures are participants per arm, not total events. The listed planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation; the effect to detect is the stated fraction of the observed effect. The original trial’s sample-size justification and assumptions are not reported in the registry record.

The 80% power column describes a planning target under which a study designed to detect the specified effect would have an 80% chance of detecting it under the stated assumptions, if that effect and assumptions were correct. The 90% power column uses a higher chance-of-detection target. These are design calculations, not guarantees about the results of a future study. They depend on the assumed effect, variability or event frequency, and analysis method.

Rows for planning at 75% or 50% of the observed effect illustrate the effect of targeting a smaller difference. Smaller effects are harder to distinguish from ordinary variation and generally require more participants. For example, for the primary comparison with the 2L package, planning for the full observed effect gives 271 participants per arm for 80% power, while planning for 50% of that effect gives 1,082 participants per arm for 80% power. The estimates can be read alongside the curve as illustrations of how the target effect and planned sample size relate. This is not observed power.

These calculations do not validate the trial’s enrollment or establish what the original investigators planned. They are based on observed effects, which may be unstable, and should be treated as planning scenarios rather than forecasts of a particular study’s results.

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 = -0.640; pooled standard deviation σ = 2.656.
2. n = 2 × (1.96 + 0.842)² × 2.656² / -0.640² = 270.4, rounded up to 271 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 <- -0.64                      # observed difference in means
sigma <- 2.65602146075667                     # 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(1665157)
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 = 271 (80% power), 362 (90% power)
 75% of observed effect: n per arm = 481 (80% power), 644 (90% power)
 50% of observed effect: n per arm = 1,082 (80% power), 1,448 (90% power)
power.t.test: 271.3 
Simulated power at n = 271 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. Analyses Reported by the Sponsor

The sponsor-reported primary analysis is an overall ANOVA across the three groups, with p = 0.435. The posted recalculations instead compare each package arm separately with the self-controlled diet and 2L PEG arm, using unadjusted mean differences and confidence intervals. The two approaches address related but different hypotheses: one tests for an overall difference across all groups, while the others estimate particular pairwise contrasts.

The recalculated mean differences were -0.64 for the 2L package arm and -0.25 for the 1.5L package arm. Their unadjusted p-values were 0.187 and 0.641, respectively. Both pairwise confidence intervals include zero. These results do not conflict with the sponsor’s overall ANOVA result; they describe separate comparisons and use different summaries of the data.

The record does not flag a discrepancy between the posted sponsor analysis and the recalculations. The sponsor’s ANOVA should therefore be presented as the reported analysis, while the pairwise estimates are supplementary unadjusted calculations from the posted arm summaries. The record does not provide enough detail to assess differences in model specification, missing-data handling, or analysis population.

15. Multiplicity, Missing Data and Analysis Populations

The study reports a primary outcome, three posted secondary outcomes, and multiple arms. In general, testing several outcomes or contrasts increases the chance that at least one result will appear notable by chance, even when there is no underlying effect. Methods such as a prespecified testing hierarchy or adjustment of significance thresholds can address that issue. The registry record does not report whether a multiplicity plan was specified or applied. The unadjusted pairwise recalculations should therefore be interpreted cautiously, especially for secondary outcomes.

The sponsor reports an overall ANOVA for the primary outcome and overall chi-squared tests for satisfaction and convenience. The registry does not report whether those analyses were prespecified, whether additional comparisons were conducted, or how any family of tests was defined. The record also does not report an overall sponsor analysis for willingness to choose the same protocol. The presence or absence of an unadjusted p-value should not be taken to answer those missing analysis-plan questions.

Missing-data handling is not reported in the registry record. The posted primary and secondary arm summaries each show 60 participants, but those counts alone do not establish how missing measurements, withdrawals, or protocol deviations were handled. The analysis population—such as whether all randomized participants were analyzed in their assigned groups—is also not reported. No conclusions about attrition or the effects of missing data can be drawn from the record.

Other methodological details are absent as well, including the randomization procedure, allocation concealment, assessor masking, covariate adjustment, and any sensitivity analyses. Their absence does not show that these procedures were not used; it means the registry record does not report them. These uncertainties limit assessment of the robustness of the results and the extent to which the posted analyses reflect the original statistical plan.

16. 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 0% reporting threshold.

Most frequent non-serious adverse event terms

The registry reports zero serious adverse events in each of the three groups, with 60 participants at risk in each group. It reports no serious adverse event terms. These figures describe the serious events recorded in the registry results; they do not demonstrate that the protocols have no serious risks, particularly for uncommon outcomes or outcomes not captured in the posted record.

For other adverse events, the registry reports zero among 60 participants in the low-residue diet package group, one among 60 participants in the self-controlled diet group, and zero among 60 participants in the low-residue diet package plus 1.5L PEG-ELS group. The record does not provide a detailed description of that event or an assessment of its relationship to the preparation protocol. Death figures are not reported in the registry record.

These counts are small and should be interpreted descriptively rather than as a comparison capable of establishing safety differences. The record does not report the method or duration of adverse-event monitoring, or whether all events were actively solicited. Accordingly, the counts provide limited information about events recorded during the study and do not support broad conclusions about safety.

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

The posted primary data show mean Ottawa scores of 2.58, 3.22, and 2.97 across the three arms. Since lower scores indicate cleaner preparation, the two package arms had numerically lower means than the self-controlled diet arm. The sponsor-reported overall ANOVA p-value was 0.435, and the unadjusted pairwise recalculations had confidence intervals that include zero. The results do not provide clear statistical evidence of a difference in the primary outcome, but they also do not establish that the protocols are equivalent.

Equivalence requires a specific design and analysis that defines how small a difference must be to count as clinically or practically equivalent. The registry record does not report an equivalence or non-inferiority framework. A non-small p-value in a superiority-style comparison is not proof that the treatments have the same effect. It can reflect a small effect, uncertainty, or both.

The secondary results indicate differences in some reported aspects of acceptability, especially satisfaction, while willingness to repeat the protocol was high in all groups. Those findings concern distinct outcomes and are subject to the limitations of multiple unadjusted comparisons. The primary cleanliness result and participant-reported responses therefore need to be considered separately.

The results apply to the studied protocols and the participants represented in this trial. They do not isolate the effect of the diet package from PEG-ELS volume in the low-volume arm, and the registry does not provide enough participant or protocol detail to assess broader applicability. The findings describe observed trial data and their uncertainty; they do not establish that a treatment works or does not work, or provide medical advice.

18. Why This Trial Matters Statistically

This study illustrates why a trial’s statistical question should be kept distinct from its numerical pattern. The package arms had lower average Ottawa scores than the comparator, but the reported overall analysis and pairwise uncertainty do not establish a clear primary-outcome difference. Readers can see the direction of the point estimates without mistaking direction for certainty.

It also illustrates the value of separating an overall test from pairwise comparisons. The sponsor’s ANOVA addresses whether the three-arm means differ overall; the recalculated contrasts estimate particular differences against one comparator. Neither answers every possible question about the three protocols, and the pairwise comparisons are unadjusted.

The range of outcomes is another statistical lesson. Cleanliness, satisfaction, convenience, and willingness are related to the preparation experience but measure different things. Findings for one outcome cannot be substituted for results on another. Multiple endpoints also raise the importance of prespecification and multiplicity planning, details not reported in the registry record.

Finally, the sample-size illustrations show how assumptions about the effect to detect influence planning. Smaller target effects require more participants under the stated assumptions. Because the planning calculations use observed effects and are not the original design justification, they should not be mistaken for evidence about the adequacy of the trial’s enrollment. Together, these features make the study useful for understanding interpretation, uncertainty, and the limits of registry-level reporting.

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 registry record leaves several trial-specific questions unanswered. It does not report participant eligibility details or baseline characteristics, limiting assessment of who the findings represent. Although the study is described as single-blinded, it does not identify who was blinded or report how blinding was maintained. Random-sequence generation and allocation concealment are also not reported.

The comparison involving 1.5L PEG-ELS changes the bowel-preparation volume as well as using the low-residue diet package. It therefore cannot isolate the package’s contribution from the volume difference. The registry does not describe further protocol details that would help assess implementation or adherence.

For analysis, the original sample-size justification, missing-data handling, analysis population, covariate adjustment, and sensitivity analyses are not reported. The registry lists 7 outcome measures and 7 analyses, but the posted descriptions do not fully explain how all outcomes were analyzed. Multiplicity procedures are not reported, which matters when interpreting the several outcomes and unadjusted contrasts.

The posted sample-size illustrations use observed effects and stated planning assumptions rather than the trial’s original design rationale. They cannot establish whether the trial was adequately planned for its intended question. Finally, adverse-event details are limited: the one other event is not described, deaths are not reported, and the record does not specify event-monitoring procedures. These limitations concern what can be evaluated from the registry record and do not establish that unreported procedures or information were absent from the study.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Efficacy and Acceptability of Low-Residue Diet Package (Enimaclin®) as Diet Control Before Colonoscopy — NCT01665157.
• Registry record last updated 2014-04-02; status last verified 2014-02.
• Results first posted 2014-02-06.
• 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

This completed randomized, single-blinded, parallel-group study enrolled 180 participants in three colonoscopy preparation arms: low-residue diet package with 2L PEG-ELS, self-controlled diet with 2L PEG-ELS, and low-residue diet package with 1.5L PEG-ELS. The primary outcome was the Ottawa Bowel Preparation Scale, for which lower scores represent cleaner preparation.

The posted primary means were 2.58, 3.22, and 2.97, respectively. The sponsor-reported overall ANOVA had p = 0.435. Recalculated pairwise comparisons were unadjusted, with confidence intervals including zero. Acceptability outcomes showed a different pattern, particularly for satisfaction, but multiple-testing procedures are not reported.

The registry records zero serious adverse events in each arm and one other adverse event in the self-controlled diet arm. Several design and analysis details, including the original sample-size justification, missing-data handling, and analysis populations, are not reported in the registry record.