This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Cystic Fibrosis and Gut Dysmotility: The Effect of Polyethylene Glycol (PEG) on Intestinal Transit (NCT04210427), a na phase 4 study. The primary outcome is Change is Being Assessed: Total Intestinal Transit Time at Baseline and Two Weeks Following Initiation of Therapy.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04210427 |
| Phase | Phase 4 |
| Condition | Cystic Fibrosis Gastrointestinal Disease |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 3 |
| Arms in the primary outcome | n/a |
| Lead sponsor | St. Louis University |
| Results posted | Yes |
2. Clinical Question
Population
Adults with cystic fibrosis and gastrointestinal symptoms are the primary endpoint population. The study summary describes recruiting adults with constipation; the primary endpoint description refers more broadly to adults with cystic fibrosis and gastrointestinal symptoms.
Intervention
Participants were to take polyethylene glycol (PEG), also identified as Miralax, at 17 grams once daily. Intestinal transit was assessed using a SmartPill motility system, with a baseline assessment and another assessment after two weeks of therapy.
Comparator
The planned comparison is each participant’s transit assessment at baseline versus the assessment following therapy. The registry describes a single-group study, not a randomized comparison with a separate control group. Baseline therefore serves as a within-participant reference, not as a concurrent untreated control.
Primary question
The primary question is whether total intestinal transit time changes between baseline and two weeks after PEG therapy begins. Transit time is measured in hours, from SmartPill ingestion to expulsion. Numerical results for this endpoint are not reported in the registry record, so the direction and magnitude of any observed change cannot be described.
The study addresses a measurement question in a defined clinical context: whether intestinal transit, recorded by the device, differs between the two planned assessment occasions during PEG therapy. The registry record describes an intervention and assessment schedule, but does not report the numerical baseline or follow-up measurements, the mean change, its standard deviation, or an inferential analysis. Consequently, the clinical question can be stated from the protocol description, but the posted record does not establish how transit changed in participants who enrolled.
3. Trial Design
The registry identifies this as a completed, Phase 4, single-group study with no masking and no randomized allocation. The intervention is polyethylene glycol 3350, accompanied by use of the SmartPill Motility System and a PillCam Patency Capsule. The intervention description says participants would have motility assessed at baseline, take PEG once daily, and repeat the survey and SmartPill assessment after two weeks of therapy.
The registry summary describes a plan to recruit 15 adults with cystic fibrosis and constipation. The recorded enrollment is 3. The record gives a start date of 2019-12-12 and a primary completion date of 2023-06-06, and lists the study status as completed. These details describe the registration record; they do not show why enrollment differed from the recruitment plan or whether the protocol changed. Such explanations are not reported in the registry record.
Because the study has one group, the intended endpoint comparison is within participants: baseline transit versus transit following the treatment period. This design can describe change over time in those assessed, but it does not include a separate group to estimate what would have happened over the same period without PEG. Changes could therefore reflect treatment, time, measurement circumstances, or other influences; the record does not provide information that separates these possibilities.
The registry record lists two outcome measures and zero analyses. It does not report a statistical analysis plan, a sample-size justification, details of interim analyses, or results for the primary endpoint. The completed status should not be read as evidence that a particular outcome was observed or that the study met its recruitment plan. The posted information supports a description of the registered design and enrollment, but not a quantitative estimate of the treatment-associated change.
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
| Stage | Intervention With Polyethylene Glycol & SmartPill |
|---|---|
| STARTED | 3 |
| COMPLETED | 3 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: Adult patients with Cystic Fibrosis with gastrointestinal symptoms.
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: Patients with GI symptoms and Cystic Fibrosis.
| Characteristic | Unit | Intervention With Polyethylene Glycol & SmartPill |
|---|---|---|
| Participants analysed | 3 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 3 |
| Age, Categorical: >=65 years | Participants | 0 |
| Sex: Female, Male: Female | Participants | 1 |
| Sex: Female, Male: Male | Participants | 2 |
| Race and Ethnicity Not Collected | Participants | — |
| Region of Enrollment: United States | Participants | 3 |
6. Primary Endpoint
The registry lists the primary outcome as Change is Being Assessed: Total Intestinal Transit Time at Baseline and Two Weeks Following Initiation of Therapy, measured over Change is being assessed: total intestinal transit time (measured in hours) at baseline and two weeks following initiation of therapy with PEG.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | hours |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is total intestinal transit time, measured in hours. The registry defines it as the time from ingestion of the SmartPill to its expulsion. The planned assessment is at baseline and again two weeks after initiation of PEG therapy; the endpoint title describes change between those occasions. The registry specifies a mean as the summary measure and standard deviation as the measure of dispersion.
Transit time is used as a quantitative measure of movement through the intestine. In general, measuring the same quantity before and after an intervention can describe whether the recorded value differs over the treatment period. A mean can summarize the central value across measured participants, while a standard deviation describes how much participant values vary around that mean. These are general statistical interpretations of the registered summaries, not findings from this study.
The record does not report the baseline mean, follow-up mean, mean change, standard deviation, or participant-level endpoint data. It also does not report an estimate of uncertainty around a change or a test of whether the change differs from zero. Thus, the endpoint’s definition and measurement schedule are available, but the numerical result is not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted information supports a limited interpretation. This is a single-group study in which the registered primary outcome is total intestinal transit time, measured at baseline and after two weeks of PEG therapy. The record states that 3 participants were enrolled. It does not provide the primary endpoint values or an analysis of change. Therefore, no direction, size, or precision of a transit-time change can be stated from the registry record.
The description of an intended baseline-to-follow-up assessment is not itself evidence that transit time improved, worsened, or stayed the same. To interpret the endpoint quantitatively, readers would need at least the observed baseline and follow-up summaries, or a reported summary of within-participant change, together with its variability and uncertainty. Those results are not reported in the registry record. The record also lists zero analyses, so it does not contain a reported inferential result for the endpoint.
The enrollment count is lower than the recruitment target described in the study summary. That difference matters when considering how much information the study could contribute, but the record does not report the reason for it or a sample-size justification. It would be inappropriate to infer a planned or achieved level of statistical power from the enrollment count alone. Any sample-size planning illustrations elsewhere should be read as planning scenarios, not as observed power or as evidence about an unreported treatment effect.
The single-group structure also limits causal interpretation. A before-and-after contrast can describe change among participants with paired measurements, but without a concurrent comparator it cannot isolate the effect of PEG from other changes over time or assessment conditions. This design feature does not invalidate a descriptive change estimate; it does mean that such an estimate, even if reported, would not by itself establish that PEG caused the change.
The registry does report safety counts for the intervention group: 3 participants were listed as at risk, with 0 serious adverse events, 0 other adverse events, and 0 deaths. These counts describe the record’s safety fields. They do not replace the missing efficacy results, and a zero count in a small enrolled group cannot establish that an event is impossible or that the intervention is free of risk. The registry does not list serious adverse event terms.
Overall, the record documents the intended clinical question, the assessment schedule, enrollment, and limited safety counts. It does not report the primary outcome result needed to estimate the observed change or its precision. Conclusions about the magnitude or clinical importance of a transit-time change are therefore not supported by the posted results.
9. Statistical Methods Explained
What does a mean describe?
General statistical explanation: a mean is an average that summarizes the values observed in a group. For a continuous measure such as transit time, it provides a compact description of the central value. The registry specifies that the primary endpoint will be summarized as a mean. It does not report the observed mean at either assessment, so the endpoint’s summary method is known but its result is not.
What does the standard deviation describe?
General statistical explanation: a standard deviation describes the spread of individual observations around their mean. A smaller standard deviation indicates that observed values are more clustered around the mean; a larger one indicates more variation. It is not the same as a confidence interval and does not, by itself, quantify uncertainty about the mean. The registry specifies standard deviation as the dispersion measure but does not report its value for the primary endpoint.
Why is a paired comparison relevant?
General statistical explanation: when the same participants are assessed before and after an intervention, the most direct change measure is calculated from each participant’s two values. The mean of these individual changes describes the average within-participant change. Pairing can account for the fact that measurements from the same person are related. A comparison of two group means without preserving the pairing may not represent the same quantity and may not use the available information as efficiently.
The registered schedule is consistent with a within-participant assessment: baseline measurement followed by measurement after two weeks of therapy. However, the record does not report paired observations, a mean change, the standard deviation of the changes, or the number of participants with complete paired measurements. It also does not state the statistical test or model used for analysis. A specific paired analysis should not be attributed to the investigators without a reported analysis.
What would a confidence interval add?
General statistical explanation: a confidence interval gives a range of values compatible with the data and the assumptions of the analysis, expressing uncertainty around an estimate. For a mean change, it would help readers distinguish a relatively precise estimate from one that remains uncertain. A confidence interval is not reported for the primary endpoint in the registry record. Without an estimate and its uncertainty, the size and precision of any observed change cannot be evaluated.
Why does the single-group design matter?
General statistical explanation: a within-participant before-and-after comparison can describe how measurements changed over time among participants with both assessments. It does not automatically identify the cause of a change. Without a separate concurrent comparison group, treatment effects cannot be separated from other influences that might change measurements over time. The registry lists allocation as not applicable and the model as single group; it does not describe a randomized control comparison.
This limitation concerns interpretation, not the arithmetic of a change score. A numerical paired change could still be useful as a description of the assessed participants. But the result would need to be described as change over the study period rather than as a causal effect attributable solely to PEG.
What can be concluded from a test result?
General statistical explanation: a statistical test evaluates data against a specified null hypothesis under assumptions about the measurements and analysis. A p-value, if reported, would not measure the size or clinical importance of a change. It would also not replace an estimate and its confidence interval. No p-value, test statistic, or primary endpoint analysis is reported in the registry record; therefore, no inferential conclusion should be attributed to the study.
The registry’s sample-size assumptions describe planning illustrations based on an observed effect and specify a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Those assumptions do not match the registered single-group design as a like-for-like control comparison, and the record does not supply a primary outcome result from which an observed effect can be read. Such illustrations are not observed power and should not be treated as evidence that the study had a particular probability of detecting an effect. The registry does not report the investigators’ own sample-size justification.
How should variability and data quality be considered?
General statistical explanation: variability among participants and measurement error both affect the precision of a mean change. Repeated measurement with a device may produce values that differ because of true participant variation or measurement conditions. A sound analysis also requires clarity about which measurements were available, how incomplete observations were handled, and whether the endpoint definition was applied consistently. The registry describes the device-based endpoint but does not report measurement-quality procedures or participant-level data.
The small recorded enrollment means that each observed participant’s data would have substantial influence on an overall summary. This is a general caution about interpreting estimates from a very limited enrolled group, not a calculation of power or a claim about the unreported endpoint values. The record does not provide enough outcome information to quantify that influence or estimate the uncertainty of a change.
In short, the registered endpoint and its planned summaries are understandable, but the registry record does not report the numerical data or analysis needed to apply these methods to the trial. The statistical concepts explain what the planned summaries would mean; they do not supply missing results.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists two outcome measures and zero analyses. It identifies total intestinal transit time as the primary outcome, but does not report the numerical results for that endpoint. The other outcome measure is not described in the available registry entries, so its definition and analysis are not reported in the registry record.
Multiplicity refers generally to the increased chance of a misleading finding when several outcomes, comparisons, time points, or analyses are examined. A prespecified primary outcome can help clarify which question is central, but the record does not report a multiplicity adjustment or a detailed analysis plan. It is not possible to determine how other outcomes were handled, whether additional analyses were conducted, or whether any adjustment was considered.
The registry does not report how missing measurements were handled, whether all enrolled participants completed both assessments, or which analysis population was used. It also does not report participant-level data or the number with paired endpoint measurements. These details matter because a before-and-after mean change depends on having measurements from the same participants at both occasions. Excluding incomplete pairs or using another method can affect the estimate and its uncertainty.
The record does not state whether analyses were intended to follow an intention-to-treat, per-protocol, or other population definition. Such an analysis population is not reported in the registry record. No assumptions about missingness or imputation methods should be inferred from the endpoint description alone.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Intervention With Polyethylene Glycol & SmartPill | 0 | 3 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Intervention With Polyethylene Glycol & SmartPill | 0 of 3 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Intervention With Polyethylene Glycol & SmartPill | 0 of 3 |
The registry lists one intervention group, titled “Intervention With Polyethylene Glycol & SmartPill.” In that group, 3 participants were listed as at risk for serious adverse events and 0 were recorded as affected. The same group lists 3 participants at risk for other adverse events and 0 affected, with 0 deaths. No serious adverse event terms are listed.
These are counts in the registry’s safety fields. They should be read as a description of what the record reports, not as proof that no adverse events could occur. The record does not provide additional detail on the duration or completeness of safety observation, the definitions used for other adverse events, or the relationship of any event to the intervention. Those details are not reported in the registry record.
The safety counts concern the enrolled group and do not provide a comparison with an untreated or alternative-treatment group. They also do not inform the unreported primary transit-time result. With 3 participants listed at risk, the zero counts are limited observations, not a precise estimate of safety in a broader population.
12. What the Result Does, and Does Not, Mean
The registry record establishes that the study was registered as a single-group assessment of PEG and intestinal transit in adults with cystic fibrosis and gastrointestinal symptoms. It describes a baseline SmartPill assessment, daily PEG therapy, and a repeat assessment after two weeks. It also records enrollment of 3 and a completed status.
What the record does not establish is the observed change in total intestinal transit time. Numerical baseline and follow-up values, a mean change, its standard deviation, a confidence interval, and a statistical test are not reported in the registry record. As a result, there is no basis in the posted results for saying whether transit time changed, in which direction it changed, how large any change was, or how precisely it was estimated.
Even if a before-and-after change were reported, the single-group design would support a description of change during the study period rather than a definitive causal attribution to PEG. A concurrent comparison group would help distinguish treatment-associated change from other influences over time; no such group is described in the registry record.
The record’s safety fields list 0 serious adverse events, 0 other adverse events, and 0 deaths among 3 participants at risk for each category. These counts should not be interpreted as proof of no risk, particularly because the registry does not provide further safety follow-up details.
Thus, the record is informative about the registered question, design, enrollment, and reported safety counts. It does not provide the outcome data required to judge the magnitude, direction, precision, or clinical importance of any transit-time change.
13. Why This Trial Matters Statistically
This trial is statistically notable because it poses a within-participant measurement question while the registry records a very limited enrollment and no primary endpoint analysis. The central issue is not merely whether an endpoint was named, but whether the posted information includes enough observations and analysis to estimate change and uncertainty. For total intestinal transit time, the record supplies the measurement definition and timing but not the numerical results.
The single-group design also makes the estimand important. A baseline-to-follow-up contrast can describe what happened to measured transit time among participants with assessments at both occasions. It cannot, on its own, identify how much of that change is attributable to PEG. Statistical interpretation must match the design and avoid treating a before-and-after difference as though it came from a randomized treatment comparison.
Enrollment is another key context for precision. With 3 recorded participants, an estimate would be highly dependent on the individual measurements. Yet no endpoint estimates or uncertainty measures are reported, so the extent of that dependence cannot be evaluated from the posted results. The recruitment target of 15 in the summary and the recorded enrollment of 3 are both relevant to understanding the record, while the reason for the difference is not reported.
Finally, this record illustrates why outcome availability and safety counts answer different questions. The safety fields document zero recorded events in the listed categories, but they do not supply evidence about the primary transit endpoint. Statistical interpretation depends on having the outcome measurements, a transparent analysis, and uncertainty estimates—not solely a completed status or a defined endpoint.
14. 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 limitations specific to this record constrain interpretation. The registry reports enrollment of 3, while its study summary describes a recruitment plan for 15 adults. The record does not explain the difference, report a sample-size justification, or state whether recruitment or protocol changes occurred. The limited enrollment would make any estimate vulnerable to the influence of individual observations, although the missing endpoint values prevent quantifying that concern.
The primary outcome is defined as total intestinal transit time in hours, measured by SmartPill ingestion to expulsion, with an assessment at baseline and after two weeks of PEG therapy. However, the registry does not report the observed values, paired changes, dispersion, or uncertainty. It is therefore impossible to assess the magnitude or precision of the endpoint from this record.
The study is single group, with no masking and no randomized allocation. A within-participant comparison lacks a concurrent control, limiting causal interpretation. The record does not report whether all enrolled participants completed both assessments or how missing measurements were handled. It also does not report the analysis population, statistical test, multiplicity approach, or a detailed statistical plan.
The study summary refers to adults with constipation, while the primary endpoint population is described as adults with cystic fibrosis and gastrointestinal symptoms. The record does not clarify whether these descriptions correspond to identical eligibility criteria. It also does not explain whether the listed safety counts reflect the full planned follow-up or provide further detail on adverse-event ascertainment.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Cystic Fibrosis and Gut Dysmotility: The Effect of Polyethylene Glycol (PEG) on Intestinal Transit — NCT04210427.
- Registry record last updated 2024-08-09; status last verified 2024-07.
- Results first posted 2024-08-09.
- 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.
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18. Record Summary
NCT04210427 is a completed, Phase 4, single-group study of polyethylene glycol 3350 and intestinal transit in adults with cystic fibrosis and gastrointestinal symptoms. The registry describes daily PEG at 17 grams and SmartPill assessments at baseline and after two weeks. Total intestinal transit time, measured in hours, is the primary endpoint.
The study summary describes a recruitment plan for 15 adults with constipation; the recorded enrollment is 3. The registry lists zero analyses and does not report numerical primary endpoint results or a statistical analysis plan. Safety fields list 0 serious adverse events, 0 other adverse events, and 0 deaths among 3 participants at risk for each category. The record supports description of the design and these counts, but not an estimate of transit-time change.