Efficacy and Safety of Bisacodyl and Lactulose as a Preparation for Colonoscopy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Efficacy and Safety of Bisacodyl and Lactulose as a Preparation for Colonoscopy (NCT02123017), a non-randomized phase 2 study. The primary outcome is Efficacy of Bisacodyl and Lactulose as a Preparation for Colonoscopy..

2. Clinical Question

The study also listed safety and tolerability outcomes, including adverse-event incidence, adverse-event severity, and patient preference. These outcomes broaden the stated objectives beyond colon cleanliness. However, the registry record does not provide analysis results for the primary cleanliness outcome or the listed secondary outcomes. It therefore describes what investigators intended to assess, not an estimate of the efficacy of any regimen or a supported ranking of the doses.

3. Trial Design

The registry identifies this as a phase 2 study with non-randomized allocation, single masking, and a single-group model. The official title describes it as observer-blinded and dose-finding. The record lists three crystalline-lactulose regimens, each paired with 15 mg of bisacodyl. It does not explain how participants were assigned to those regimens, so the allocation process should not be inferred from the dose descriptions.

The three listed regimens were 90 grams, 135 grams, and 180 grams of crystalline lactulose. Their arm descriptions specify 30 grams, 45 grams, or 60 grams of lactulose per dose, respectively, given over three doses. The record does not list a placebo or other control regimen. It explicitly notes that the arms are not a like-for-like control comparison. Differences between groups, if calculated elsewhere, would therefore need cautious interpretation rather than treatment as randomized causal contrasts.

Enrollment is recorded as 32. The registry gives a start date of 2014-04, a primary completion date of 2014-08, and a completed status. The primary endpoint was assessed 10-14 hours post last consumption. The record does not report the protocol’s planned sample size, the rationale for the enrollment target, or whether the listed enrollment represents all participants who were assessed for each outcome.

The study description emphasizes dose-finding, safety, efficacy, and patient preference. That description indicates the intended scope, but does not establish what dose differences were tested statistically or how any findings were interpreted. The statistical analysis plan, any planned interim analyses, and the method used to handle the non-randomized dose allocation are not reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

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.

Population: All patients adhered to the one set of study-level eligibility criteria.

6. Primary Endpoint

The registry lists the primary outcome as Efficacy of Bisacodyl and Lactulose as a Preparation for Colonoscopy., measured over 10-14 hours post last consumption.

The primary endpoint is the physician’s assessment of colon cleanliness using the Boston Bowel Preparation Scale (BBPS). The registry describes a score from 0 to 9: 0 represents a colon with no cleaning, and 9 is the maximum score, representing a fully cleansed colon. The planned assessment time was 10-14 hours post last consumption.

In general, a clinical endpoint should reflect an outcome relevant to the study’s purpose and should be measured consistently. A bowel-cleansing score is relevant to colonoscopy preparation because it records the physician’s assessment of cleanliness at the time specified for evaluation. A continuous summary such as a mean can describe the average score in a group, while a standard deviation describes how spread out individual scores are around that average. Neither summary alone shows every participant’s score or the shape of the score distribution.

The record identifies the primary measure as a mean with standard deviation, but does not report group means, standard deviations, confidence intervals, or a dose comparison. The endpoint definition therefore tells readers what was intended to be measured, not how clean the colons were in the observed study or how precisely that outcome was estimated. It also does not establish a threshold for adequate preparation; such a threshold is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation depends on both the outcome being measured and the design that produced the observations. In this study, the primary outcome is a physician-assessed BBPS score, summarized in the registry as a mean and standard deviation. The allocation is described as non-randomized, and the record classifies the model as single-group while listing three dose regimens. These design labels should be reported as they appear; the registry does not explain the assignment process or reconcile the model classification with the listed regimens.

What does a mean describe?

In general, the mean is an average that summarizes the observed values in a group. It can provide a compact description of the central level of an outcome, but it does not show how observations are distributed. Different sets of participant scores can have the same mean while differing in their spread or in the presence of unusually low or high values. For a bounded score such as the BBPS, the possible range also matters when considering what a mean can represent.

The standard deviation describes the spread of individual observations around the mean. A smaller standard deviation indicates scores are more tightly clustered around the group mean; a larger one indicates greater dispersion. It is not the same as the uncertainty in the estimated mean. A confidence interval for a mean, if reported, would instead express uncertainty about the estimate under the assumptions of the analysis. The registry identifies standard deviation as the dispersion measure but does not report either the means or standard deviations for the primary endpoint.

What would a confidence interval add?

In general, a confidence interval gives a range of values compatible with the data and the statistical method used, reflecting sampling uncertainty. It helps readers distinguish a relatively precise estimate from one that is uncertain. A confidence interval does not correct bias in the design, remove confounding, or guarantee that the range contains the true value. No confidence interval for the primary endpoint is reported in the registry record, so its precision cannot be assessed from the posted results.

How does allocation affect interpretation?

Random allocation is a design method intended to make treatment groups comparable, on average, with respect to both measured and unmeasured characteristics. Here, allocation is classified as non-randomized, and the record warns that the arms are not a like-for-like control comparison. General statistical reasoning therefore calls for caution with any comparison across dose groups. Differences in observed outcomes could reflect differences in who entered each group, alongside any effect of the regimen. The registry does not report an adjustment strategy, so readers cannot determine whether or how potential group differences were addressed.

A single-group model can be used to describe outcomes within a group, but the registry’s three listed dose regimens make the precise analytic structure unclear. No additional design or analysis details should be inferred from those labels. In particular, the record does not describe a prespecified contrast, a trend test, or a statistical model comparing doses. It reports zero analyses, and the primary outcome results are not reported.

Why do event counts need context?

Adverse-event counts describe how many participants in the recorded risk group had an event, according to the registry’s reporting categories. Counts alone do not describe the event types, how severe they were, when they occurred, or whether investigators considered them related to treatment. They also do not provide an adjusted comparison between regimens. In general, event rates can be compared only with careful attention to the denominator, the event definition, and the way participants were followed. The registry reports counts at risk and counts affected, but the detailed event information needed for a fuller interpretation is not reported.

What is the role of planning calculations?

In general, sample-size planning calculations illustrate the number of participants that might be needed under chosen assumptions. Such calculations are not observed results and do not show the power achieved by a completed study. The registry’s planning assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the target effect expressed as a stated fraction of the observed effect. These are planning assumptions, not a description of the study’s non-randomized allocation. The registry does not report the trial’s own sample-size justification, and no actual planning sample-size values are available in this record.

More broadly, statistical significance and clinical importance are different ideas. A p-value, if reported, would address how compatible the data are with a statistical model under a specified null hypothesis; it would not measure the size or importance of an effect. An effect estimate and its uncertainty are needed to assess magnitude and precision. Because neither the primary estimates nor inferential results are reported, those questions cannot be answered from this registry record.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("90 Grams of Crystalline Lactulose", "135 Grams of Crystalline Lactulose", "180 Grams of Crystalline Lactulose")
n   <- c(7, 12, 12)
m   <- c(5.7, 7.4, 7.8)
sp  <- c(2.8, 0.9, 0.8)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  90 Grams of Crystalline Lactulose  7  5.700  2.800  3.110  8.290
CARM  135 Grams of Crystalline Lactulose  12  7.400  0.900  6.828  7.972
CARM  180 Grams of Crystalline Lactulose  12  7.800  0.800  7.292  8.308

11. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures and identifies safety, tolerability, and preference among the secondary outcomes. It does not report an analysis plan specifying which comparisons were primary for each outcome, whether multiple dose comparisons were planned, or how multiplicity was to be handled. When several outcomes or contrasts are examined, the chance of finding an apparently notable result can increase. In general, a prespecified analysis plan helps readers understand which findings were confirmatory and how multiple testing was considered. Such details are not reported in the registry record.

The record lists zero analyses and does not report analysis populations, exclusions, or the number of participants contributing data to the primary endpoint. Enrollment is recorded as 32, but the registry does not establish from the information listed whether all enrolled participants were assessed or included in each outcome analysis. The primary outcome entry does not describe how missing scores would be handled, and the record does not state whether any primary endpoint data were missing. Absence of a missing-data report should not be taken to mean that no data were missing.

In general, an analysis population defines which participants contribute to an estimate. Different choices can affect the interpretation of results, especially if participants are excluded after enrollment or if outcome data are unavailable. Missing-data methods also rely on assumptions about why information is missing. Since neither the analysis population nor missing-data methods are reported, readers cannot evaluate those choices for this study.

The registry also does not report the statistical plan, interim analyses, or a sample-size justification. These items are relevant to understanding how analyses were selected and whether estimates were planned with a particular precision in mind. No conclusions about those procedures can be drawn from the listed outcomes and design labels alone.

12. 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 serious adverse events for the three listed regimens as 0 among 8 at risk in the 90 Grams of Crystalline Lactulose group, 0 among 12 at risk in the 135 Grams group, and 0 among 12 at risk in the 180 Grams group. These are the recorded serious-event counts. They do not establish that serious events could not occur, nor do they quantify the uncertainty around the underlying risk.

For other adverse events, the record lists 2 among 8 at risk in the 90-gram group, 4 among 12 at risk in the 135-gram group, and 6 among 12 at risk in the 180-gram group. These counts should be read descriptively. The groups were not randomized, and the record cautions against treating them as like-for-like controls. The counts do not by themselves support a causal comparison across regimens.

The registry does not report the event terms or severity details in the safety information, and the death count is not reported in the registry record. Event timing, duration, and attribution to study treatment are also not reported. Therefore, the counts offer a limited description of reported safety outcomes rather than a complete assessment or comparative safety estimate.

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

The registry record describes a phase 2 dose-finding study of three bisacodyl-and-lactulose bowel-preparation regimens in adults preparing for colonoscopy. It states that the primary endpoint was physician-assessed colon cleanliness using the BBPS, with assessment 10-14 hours post last consumption. It also reports selected adverse-event counts and lists tolerability and preference as secondary outcome areas.

However, the primary endpoint’s observed scores and statistical results are not reported in the registry record. There is no reported mean, standard deviation, confidence interval, or analysis comparing the dose regimens. Consequently, the record does not establish what level of colon cleanliness was observed or whether scores differed across the listed doses. The stated purpose and endpoint should not be mistaken for findings.

The safety counts show the number of participants recorded with serious and other adverse events in each group, but they do not provide a full account of event types, severity, or attribution. The non-randomized allocation and the registry’s warning about the arms further limit comparative interpretation. Even if outcomes were available by group, an observed difference would not automatically demonstrate that dose caused it.

In general, a study result is most informative when its estimate, uncertainty, analysis population, and methods are reported together. Those elements are not available for the primary outcome in this record. The posted information therefore supports a description of study aims, regimen details, design labels, endpoint definition, and reported safety counts. It does not support a conclusion about efficacy, the superiority of one regimen, or comparative safety.

14. Why This Trial Matters Statistically

This study is statistically notable as a dose-finding evaluation with three listed regimens, but its registry record illustrates why design labels and outcome reporting need to be read together. The allocation is non-randomized, and the record cautions that the arms are not a like-for-like control comparison. This makes causal interpretation of any across-group contrast more difficult than in a randomized comparison.

The primary outcome is described clearly enough to identify its measurement scale, assessor, and timing. Yet the record does not report the outcome values or an analysis. This gap separates a well-specified endpoint from evidence about the endpoint. Readers cannot judge the observed mean, its variability, or the precision of an estimate without those results.

The record also combines an efficacy question with safety, tolerability, and preference objectives. Multiple outcomes can address different aspects of a preparation, but interpretation depends on reporting which analyses were performed and how they were planned. The registry lists four outcome measures and zero analyses, while details of multiplicity handling and the statistical plan are not reported.

More generally, the record demonstrates why event counts are not substitutes for comparative estimates, and why a planning illustration is not evidence of achieved power. A transparent account of group allocation, outcome availability, analysis populations, missing data, and uncertainty is important for a complete statistical assessment. Those details are not reported for this study’s primary endpoint. The result is a record that conveys the research question and study structure, but leaves the central efficacy estimate unavailable.

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.

A central limitation for interpreting this trial is that the registry record does not report the primary BBPS results or any analysis comparing the regimens. Without group estimates and uncertainty, the primary efficacy question cannot be assessed from the posted information. The record does not report a threshold for adequate preparation or a prespecified contrast among doses.

The design is classified as non-randomized, and the record explicitly warns that the groups are not a like-for-like control comparison. The assignment process and any adjustment for differences between groups are not reported. This limits the interpretation of any potential differences by dose, independent of the fact that primary outcome results are absent.

The record classifies the model as single-group while listing three dose regimens. It does not explain how those labels relate to the study’s actual analysis structure. It also does not provide the analysis population, the number assessed for the primary endpoint, missing-data handling, or the statistical analysis plan. These omissions prevent evaluation of how the planned endpoint might have been summarized or compared.

Safety reporting is limited to counts of participants at risk and affected. The event details and severity information are not included in the reported safety summary, and the death count is not reported in the registry record. Tolerability and preference are listed as outcomes without results. The registry also does not report the study’s sample-size justification, so the adequacy of enrollment for the intended analyses cannot be assessed.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Efficacy and Safety of Bisacodyl and Lactulose as a Preparation for Colonoscopy — NCT02123017.
• Registry record last updated 2016-02-24; status last verified 2016-01.
• Results first posted 2016-02-24.
• 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

The registry record describes a completed phase 2, non-randomized, single-masked study of bisacodyl combined with escalating crystalline-lactulose doses for colonoscopy preparation. It records enrollment of 32 and lists 90-gram, 135-gram, and 180-gram lactulose regimens, each paired with 15 mg of bisacodyl.

The primary endpoint was physician-assessed colon cleanliness using the BBPS, measured 10-14 hours post last consumption. Safety, tolerability, and preference were also listed as outcomes. Primary endpoint results and outcome analyses are not reported in the registry record. The safety information includes serious and other adverse-event counts by regimen; the death count is not reported.