Comparison of Clenpiq vs Golytely Bowel Preparation: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Comparison of Clenpiq vs Golytely Bowel Preparation (NCT03198221), a randomized phase 4 study. The primary outcome is Percentage of Participants With Satisfactory Bowel Cleansing.

2. Clinical Question

3. Trial Design

The registry describes a prospective, randomized, parallel-group, phase 4 study of bowel preparation before inpatient colonoscopy. Masking is listed as none. The sponsor is The Cleveland Clinic. The study started on 2018-07-11, had a primary completion date of 2019-03-26, and is listed as terminated. A reason for termination is not reported in the registry record.

The study compared Golytely, a polyethylene glycol-based preparation, with Clenpiq, a sodium picosulfate, magnesium oxide, and citric acid preparation. The summary describes the Golytely preparation as 4 liters and Clenpiq as low volume. It also says either preparation could be given as a full dose the evening before colonoscopy or as a split dose across the evening before and the day of the procedure. The registry lists four groups. Group A and Group B are described as Golytely groups, while Group C and Group D are described as Clenpiq groups. The group descriptions are truncated, so the specific dosing schedule and distinctions between the two groups for each preparation are not fully reported in the registry record.

The posted primary outcome is satisfactory bowel cleansing, assessed over 1 day. The secondary outcome listed is the proportion of participants requiring a repeat colonoscopy. The record reports an enrollment of 14, but does not explain whether enrollment was stopped early, whether the target enrollment changed, or why the study was terminated. A sample-size justification, recruitment plan, allocation procedure details, and planned statistical analysis are not reported in the registry record. These omissions limit the ability to assess the design beyond the broad randomized, parallel-group description.

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 Percentage of Participants With Satisfactory Bowel Cleansing, measured over 1 day.

The primary endpoint is the number of participants with satisfactory bowel cleansing, assessed using the Boston Bowel Preparation Scale (BBPS). The BBPS scores the right, transverse, and left colon segments separately. Each segment receives a score from 0 to 3, based on how much of the mucosa can be seen and the presence of residual stool, staining, or opaque liquid. A total BBPS score of 6 or greater, together with a score of 2 or greater in every segment, defines satisfactory preparation. A total score below 6 or a score below 2 in any segment defines unsatisfactory cleansing.

This endpoint is used to describe the visibility of the colon during colonoscopy. Segment-level scoring makes the definition sensitive to inadequate cleansing in any part of the colon, rather than relying only on an overall impression. The registry’s primary outcome title uses the word “percentage,” but the posted results are counts: Group A has 2 satisfactory results among 3 participants; Group B, 2 among 2; Group C, 4 among 7; and Group D, 2 among 2. No percentages, uncertainty intervals, or group comparison estimates are reported in the registry record. These counts describe the posted endpoint results but do not, by themselves, quantify a reliable difference between preparations.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What kind of outcome is being counted?

The primary endpoint is binary at the participant level: each participant either meets the stated BBPS definition of satisfactory cleansing or does not. A binary outcome records the presence or absence of an event or condition. Here, the event is satisfactory cleansing. The posted results report counts of participants meeting that definition and the number in each group, rather than a model-based estimate of the probability of satisfactory cleansing.

Counts are useful for showing what happened among the participants whose results were posted. They are not, on their own, a full account of uncertainty. A treatment comparison generally needs a clearly defined contrast and an estimate of how different the groups are, together with an indication of precision. The registry does not report those comparative quantities for this endpoint.

Why does the group structure matter?

The record lists four groups: two associated with Golytely and two associated with Clenpiq. Its summary says that each preparation could be administered as a full dose or split dose, but the available group descriptions do not fully identify the regimen assigned to every group. A statistical comparison depends on which groups are intended to be contrasted. Combining groups or selecting one group from each preparation without a documented analysis plan would require assumptions not reported in the registry record.

Randomization can support a fair comparison when the allocation, analysis population, and planned contrasts are clearly specified and the analysis follows that plan. The registry identifies the study as randomized, but does not report the allocation procedure, the planned contrasts, or an analysis population definition. The randomized label alone does not supply those missing details.

What would a confidence interval contribute?

In general, a confidence interval expresses the range of effect sizes compatible with the data and the statistical method, under its assumptions. It helps readers distinguish a precise estimate from one that is uncertain. The registry does not report a confidence interval for the primary comparison, and no such interval can be inferred from the posted summary without choosing a comparison and method. That absence means the precision of a treatment contrast is not quantified in the record.

Why can small groups be difficult to interpret?

In general, estimates based on few observations can change noticeably when one participant’s outcome changes. This makes them less stable and often less precise than estimates based on more information. The posted group counts are 3, 2, 7, and 2 participants, respectively. These counts describe the groups, but do not establish a formal power calculation or allow observed power to be inferred. The registry does not report a design-stage sample-size justification.

For a binary outcome, methods may compare group proportions, model the event probability, or use methods suited to sparse counts. The choice depends on the planned contrast, sample size, and analysis assumptions. No method for the primary comparison is reported in the registry record. The reported values are counts, not a stated model output; they should not be read as adjusted estimates.

What does the sample-size illustration represent?

Any sample-size figures accompanying these results are planning illustrations based on the observed effect, not observed power and not the trial’s original design justification. The stated illustration assumptions are a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and detection of a stated fraction of the observed effect. In general, such an exercise asks how many participants per arm a future study might require under selected assumptions. It does not show that the current study had that level of power, and the assumed two-arm structure should not be mistaken for a documented analysis of all four groups.

Planning estimates based on an observed effect can be particularly uncertain when the original study has limited observations. The observed effect may not represent the effect that would recur in another study. A planning illustration is therefore conditional on its assumptions and should not be interpreted as proof that a future study will achieve a particular result.

Why is over-dispersion not central to these posted results?

Over-dispersion describes variation greater than a model expects, often arising when outcomes are more heterogeneous than the model allows. It matters for some count or rate models because underestimated variation can make uncertainty appear too small. The primary outcome is reported as a participant-level binary count, and no model or dispersion estimate is reported. It would be inappropriate to claim that over-dispersion was assessed or adjusted for. More generally, a suitable analysis should match the outcome type and the structure of the randomized groups.

Because the record contains no reported comparative analysis, the main statistical task for readers is to distinguish the posted group counts from an inferential result. The counts describe observed outcomes; they do not supply a treatment contrast, its precision, or evidence that any assumed model fits the data.

10. Exact Estimates for Each Arm

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

R code and output

arm    <- c("Group A", "Group B", "Group C", "Group D")
n      <- c(3, 2, 7, 2)
events <- c(2, 2, 4, 2)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Group A  3  2  66.7  9.4  99.2  20.8  93.9  19.4  93.2
ARM  Group B  2  2  100.0  15.8  100.0  34.2  100.0  29.2  99.2
ARM  Group C  7  4  57.1  18.4  90.1  25.0  84.2  24.5  84.3
ARM  Group D  2  2  100.0  15.8  100.0  34.2  100.0  29.2  99.2

11. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures: the primary BBPS-based satisfactory-cleansing outcome and the secondary outcome of repeat colonoscopy. It posts results for the primary outcome but no result for repeat colonoscopy. The registry record does not report how multiple outcomes or multiple comparisons were handled, whether a hierarchy of tests was planned, or whether any multiplicity adjustment was used.

Multiplicity is a general concern when several hypotheses are tested: the chance of a misleading positive result can increase if each is treated as a separate opportunity to find a difference. This record does not report inferential tests for the primary outcome, so there is no reported family of p-values to interpret or adjustment procedure to assess. The number and definition of planned comparisons are not reported in the registry record.

Missing-data procedures, reasons for missing outcome measurements, and the number of participants with unavailable BBPS results are not reported in the registry record. The posted group counts give the group sizes and satisfactory-result counts, but do not describe whether every randomized participant was included in the outcome analysis or how any missing observations were handled. The record also does not define an intention-to-treat, per-protocol, or other analysis population.

Interim analyses and stopping rules are not reported in the registry record. The study is listed as terminated, but the reason for termination and whether termination affected recruitment, follow-up, or the planned analyses are not reported. These gaps prevent assessment of whether outcome reporting and analysis followed a prespecified plan.

12. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The posted adverse-event figures list zero serious adverse events, zero other adverse events, and zero deaths in each group. The corresponding numbers at risk are 3 in Group A, 2 in Group B, 7 in Group C, and 2 in Group D. These are the registry’s reported counts; they should be read as observations recorded for the listed groups, not as proof that adverse events cannot occur.

Safety counts require context. With limited numbers of participants, the absence of a reported event does not establish that the risk is zero or that two preparations have the same safety profile. The record does not provide event definitions beyond the serious/other categories, detailed follow-up duration for safety, or a comparative safety analysis. The primary outcome timeframe is 1 day, but that does not establish the adverse-event observation period.

No serious adverse-event terms are listed. The figures therefore describe what the registry reports, while leaving uncertainty about event ascertainment and the ability to detect uncommon harms. They are not a basis for medical advice or a broad safety conclusion.

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

The registry documents a randomized comparison of Golytely and Clenpiq for inpatient colonoscopy preparation and posts counts for participants meeting a BBPS definition of satisfactory cleansing. Those counts are useful as a record of the observed group outcomes. They are not a reported estimate of the difference between the preparations, and the registry does not provide a confidence interval, p-value, or comparative model for the primary endpoint.

The results do not establish that one preparation is superior, that the preparations are equivalent, or that any apparent group pattern would recur in another sample. A lack of a reported inferential comparison is not evidence that there is no difference. Conversely, separate observed counts do not by themselves establish a meaningful treatment effect. The four groups and incomplete dosing descriptions also make it important not to assume which specific schedules were compared.

The study’s enrollment was 14 and its status is terminated. The reason for termination, planned enrollment, and analysis plan are not reported in the registry record. The posted results therefore offer limited information about the study’s intended statistical question and about the precision of any possible comparison. The secondary outcome, repeat colonoscopy, is listed without a posted result.

In general, a randomized trial can help distinguish treatment effects from differences in participant characteristics when its design and analysis are implemented and reported clearly. Here, the registry’s randomized designation is informative, but it does not replace missing details about allocation, analysis populations, or planned comparisons. The defensible interpretation is narrow: the record reports group-level satisfactory-cleansing counts and no adverse events in its listed categories, but it does not report a statistical comparison capable of supporting a treatment-effect conclusion.

14. Why This Trial Matters Statistically

This study illustrates why statistical interpretation depends on more than the direction of observed counts. The endpoint is clinically structured: satisfactory cleansing requires both an adequate total BBPS score and an adequate score in every colon segment. The registry defines that threshold clearly, making the event being counted interpretable. However, a clear outcome definition does not itself answer whether the randomized preparation groups differed.

The record also illustrates the importance of transparent group and regimen descriptions. Four groups are listed, with two associated with each preparation, while the summary says full-dose and split-dose schedules were possible. Because the available descriptions do not fully map each schedule to each group, readers cannot confidently isolate a preparation effect from any regimen distinction using the registry information alone.

Reporting counts without an estimate of uncertainty is another important statistical limitation. Counts show the observed outcomes, but do not communicate how uncertain an underlying contrast may be. This matters especially when group sizes are limited. A comparative estimate with an appropriate uncertainty interval, paired with a prespecified analysis, would provide a different and more informative basis for evaluating the primary question. Neither is reported in the registry record.

Finally, the study is listed as terminated, with an enrollment of 14, but the reason and the planned analysis are not reported. This means readers cannot assess whether the posted data represent the intended analysis or how termination affected the study. The record is a useful example of the distinction between a randomized design, descriptive outcome reporting, and a completed statistical comparison.

15. Limitations

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

The available record leaves several trial-specific uncertainties. Although the study is randomized and parallel-group, it does not describe the allocation method, concealment, or the procedures used to implement randomization. Masking is listed as none. The implications of that design for outcome assessment cannot be evaluated further because details about who scored BBPS and how scoring was conducted are not reported in the registry record.

The group descriptions are truncated, and the summary’s full-dose and split-dose options are not clearly mapped to all four groups. This limits interpretation of the individual group counts and makes the intended comparison structure unclear. The record does not report a protocol, a statistical analysis plan, a sample-size justification, or the planned primary contrast. Nor does it report why the study was terminated.

The primary outcome is posted as counts, without a treatment-effect estimate or measure of uncertainty. Missing-outcome counts, missing-data handling, and analysis-population definitions are not reported. The secondary outcome is listed but has no posted result. No interim analysis information or multiplicity procedure is reported in the registry record.

These limitations are specific to interpreting this registry record. They do not establish that procedures or analyses were absent; they indicate that the relevant details are not reported in the registry record. Accordingly, readers should distinguish what is documented—the randomized design, group labels, endpoint definition, and posted counts—from what remains unknown about implementation and analysis.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Comparison of Clenpiq vs Golytely Bowel Preparation — NCT03198221.
• Registry record last updated 2021-03-04; status last verified 2021-02.
• Results first posted 2021-03-04.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

NCT03198221 is a phase 4 randomized, unmasked, parallel-group study sponsored by The Cleveland Clinic. It compared Golytely and Clenpiq preparations for inpatient colonoscopy. The registry lists an enrollment of 14, a start date of 2018-07-11, a primary completion date of 2019-03-26, and a terminated status.

The primary outcome was satisfactory bowel cleansing using the BBPS, assessed over 1 day. The posted group counts are 2 of 3 in Group A, 2 of 2 in Group B, 4 of 7 in Group C, and 2 of 2 in Group D. No comparative analysis is reported. Repeat colonoscopy is listed as a secondary outcome without a posted result. The registry reports zero serious adverse events, zero other adverse events, and zero deaths in each group. The reason for termination and key analysis details are not reported in the registry record.