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 Effects of Lubiprostone on Small Bowel and Colonic Bacteria: A Correlation Study With Segmental and Whole Gut Transit (NCT00844831), a na phase 4 study. The primary outcome is Presence of Small Intestinal Bacterial Overgrowth.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00844831 |
| Phase | Phase 4 |
| Condition | Constipation |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 25 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Louisville |
| Results posted | Yes |
2. Clinical Question
The study concerns people with constipation. Its background describes bloating and abdominal distension as symptoms that may occur in this population, and says that the relationship between those symptoms and intestinal bacteria is unclear. The study hypothesis was that constipation treatment might reduce bacterial colonization in the small bowel and colon, change the balance of stool microorganisms, and improve dyspepsia and constipation symptoms.
Population
Participants with constipation were enrolled. The registry record lists an enrollment of 25 and identifies the primary outcome population as ITT; it does not further describe participant characteristics or the handling of participants in that population.
Intervention
Participants received lubiprostone. The study description says bacteria were measured before and after treatment. Dose and dosing schedule are not reported in the registry record.
Comparator
There was no separate control group. The design is listed as single-group, and allocation is listed as not applicable. The before-treatment measurement is a within-participant reference, not a concurrent like-for-like control.
Primary question
The primary endpoint was presence of small intestinal bacterial overgrowth, assessed before and after treatment. The registry description frames the measure as the percent of patients with bacterial overgrowth. The registry record does not report the before-and-after values or a treatment-effect estimate.
3. Trial Design
This was a Phase 4 study sponsored by the University of Louisville. The registry lists the study as completed, with a single-group model, no masking, and allocation not applicable. The treatment group was described as receiving lubiprostone, with bacteria measured before and after treatment. Enrollment was 25. The listed condition was constipation.
The study dates in the registry record are a start in 2009-05 and primary completion in 2011-05. These dates describe the study record; they do not establish when individual participants began or completed treatment. The intervention is identified as a drug, but the dose, schedule, treatment duration beyond the primary endpoint timeframe, adherence procedures, and details of the bacterial measurement procedures are not reported in the registry record.
The primary outcome is presence of small intestinal bacterial overgrowth, with a stated timeframe of 28 days. The registry also lists small bowel and colon transit time by SmartPill® transit study and small intestinal bacterial overgrowth as secondary outcomes. It identifies three outcome measures and two analyses, but detailed methods and results for those measures are not reported in the registry record.
Because there was no separate control group, the design can describe changes between measurements taken before and after treatment, but it cannot directly compare those changes with what would have happened over the same period without treatment. The registry record does not report randomization, masking, or a protocol-based statistical plan. The study’s single-group structure is important when interpreting any before-and-after findings: such changes may be associated with treatment timing, but they do not by themselves distinguish treatment effects from other explanations.
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.
Before assignment: Study consisted of a 4-week run-in period to wash out prior therapy for constipation. Subjects may withdraw if they can not stay off their medications for constipation.
Overall Study
| Stage | Lubiprostone Open Label |
|---|---|
| STARTED | 25 |
| COMPLETED | 19 |
| NOT COMPLETED | 6 |
Reasons for not completing this period:
| Reason | Lubiprostone Open Label |
|---|---|
| Withdrawal by Subject | 4 |
| Adverse Event | 1 |
| Physician Decision | 1 |
Analysis population for the primary outcome, as defined in the registry: ITT
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.
| Characteristic | Unit | Lubiprostone Open Label |
|---|---|---|
| Participants analysed | 25 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 25 |
| Age, Categorical: >=65 years | Participants | 0 |
| Age, Continuous | years | 52 (SD 5) |
| Sex: Female, Male: Female | Participants | 22 |
| Sex: Female, Male: Male | Participants | 3 |
| Region of Enrollment: United States | participants | 25 |
6. Primary Endpoint
The registry lists the primary outcome as Presence of Small Intestinal Bacterial Overgrowth, measured over 28 days.
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the presence of small intestinal bacterial overgrowth, described as the percent of patients with bacterial overgrowth before and after treatment. Its unit is participants, and its listed timeframe is 28 days. The endpoint therefore concerns whether bacterial overgrowth is present, rather than a continuous measure of bacterial quantity. The registry record does not define the diagnostic threshold or measurement procedure used to determine presence.
As a general statistical matter, a binary endpoint can be presented as counts and proportions in each measurement condition. For a before-and-after study, these summaries describe the observed status at each time point. If the same participants contribute both measurements, their paired status is also relevant: the number changing from presence to absence and the number changing from absence to presence may matter to an analysis. The registry record does not report those paired counts, the endpoint results, or the analysis method.
This endpoint is relevant to the stated study question because the hypothesis concerns bacterial overgrowth. However, a change in this endpoint alone would not establish a change in gut transit, stool microorganism balance, or symptoms. Those are related questions, and the registry lists transit and bacterial outcomes separately. Without the reported endpoint values and methods, the direction and precision of any observed change cannot be assessed.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The key interpretive fact is that the registry record identifies the primary outcome but does not report its result. There are no posted before-and-after counts or percentages for small intestinal bacterial overgrowth, and no reported estimate of the change. The registry record also does not report a confidence interval or a p-value for this endpoint. Consequently, the magnitude, direction, and statistical precision of the primary finding cannot be described from the posted results.
The design helps define what a result could mean. This was a single-group, open-label study in which participants received lubiprostone and were assessed before and after treatment. A before-and-after comparison can show whether the recorded outcome differed over time among participants measured, but without a concurrent control group it cannot separate a treatment-associated change from other possible causes of change. The registry record does not report procedures that would establish that changes were caused by treatment.
For a binary outcome, counts and proportions would describe how many participants had the condition at each assessment. Paired information would further clarify whether the same participants changed status in one direction or the other. A difference between overall proportions alone does not reveal how many individual participants changed in each direction. The registry record does not provide these quantities, so none can be inferred.
Precision is also not assessable. A confidence interval, when reported, describes the range of effect values compatible with the data under the analysis assumptions; narrower intervals generally indicate more precise estimates. No interval is reported for the primary outcome. The enrollment of 25 indicates the study’s listed size, but enrollment alone does not reveal the precision of an endpoint estimate, particularly without event counts and an analysis method.
The record lists secondary outcomes concerning transit time and small intestinal bacterial overgrowth, but does not report their results in the registry record for this analysis. It also does not report a statistical plan specifying how outcomes were analyzed or how multiple outcomes were handled. The outcome list and the count of analyses are not substitutes for numerical findings.
Overall, the posted registry information establishes the study question, design, and endpoint, but not the observed primary result. The data presented in the record therefore cannot support a numerical account of the change in bacterial overgrowth or its precision. The absence of a reported result should not be interpreted as evidence that no change occurred; it means the registry record does not report whether, or by how much, the measure changed.
9. Statistical Methods Explained
Statistical interpretation begins with the endpoint type and the study design. The primary endpoint is binary: bacterial overgrowth is recorded as present or not present. The outcome is described in participant terms, with the registry framing it as the percent of patients with bacterial overgrowth before and after treatment. Because the study is single-group and measures participants before and after treatment, the observations are potentially paired rather than independent. The registry record does not describe the exact analysis used.
What does a binary outcome show?
As a general explanation, a binary outcome classifies each observation into one of two states. A count reports how many participants fall into a state, while a proportion relates that count to the number assessed. These summaries answer different descriptive questions from a continuous measure such as transit time. The registry record identifies the primary endpoint as presence of overgrowth but does not provide either the counts or the proportions at the assessments.
When the same participants are assessed twice, the pairing matters. Overall proportions at each assessment do not disclose each participant’s trajectory. Participants may remain in the same state, change from presence to absence, or change from absence to presence. A paired analysis uses the pattern of within-participant changes. The registry record does not give the transition counts, so it is not possible to identify the balance of changes or evaluate a paired test from the posted results.
Why does the single-group design matter?
As a general explanation, a before-and-after comparison describes change over time within the observed group. A separate concurrent control group can help distinguish change associated with the intervention from changes that might occur over time for other reasons. This study has no separate control group, so any before-and-after difference would not by itself establish that lubiprostone caused it. The open-label designation also means the record does not describe masking; masking procedures are not reported as part of this design.
The study has a stated timeframe of 28 days for the primary endpoint. A timeframe defines when an outcome is intended to be assessed, but it does not alone specify the visit schedule, the timing of measurements relative to treatment, or how missing assessments are handled. Those details are not reported in the registry record.
How should uncertainty be understood?
As a general explanation, an effect estimate describes the observed contrast, while a confidence interval expresses uncertainty about that estimate under the chosen model and assumptions. A p-value, if used, addresses compatibility of the observed data with a specified null hypothesis; it does not measure the size or clinical importance of an effect. Neither a primary estimate, its confidence interval, nor a p-value is reported in the registry record. Therefore, statistical significance and precision cannot be evaluated.
Sample size and precision are related but not interchangeable. The record lists enrollment of 25, but that number alone does not show how informative the primary endpoint was. For a binary outcome, the amount of information also depends on how many participants have the outcome and on how the paired observations are distributed. Those outcome details are not reported. No protocol-based sample-size justification is reported in the registry record.
What do planning calculations represent?
As a general explanation, sample-size planning calculations are hypothetical illustrations, not trial outcomes. The stated planning assumptions describe two-sided significance level 0.05, equal allocation between two arms, a normal approximation, and a target effect defined as a fraction of an observed effect. Those assumptions do not describe the actual single-group design, which has no two-arm allocation. Any such calculation is therefore a planning illustration rather than an observed trial result or evidence of observed power. The registry record does not report the trial’s own sample-size justification or design assumptions.
Over-dispersion is a general concern when observed variation exceeds what a simple statistical model assumes. If it is present, standard errors and confidence intervals from an overly restrictive model may be too small, making results appear more precise than warranted. The registry record does not report whether over-dispersion was assessed or whether any model that could be affected by it was used. It would not be appropriate to infer an adjustment or a particular model.
Finally, a statistical method cannot be selected confidently from the endpoint label alone. The analysis would depend on the assessment structure, data completeness, and the prespecified estimand and model. The record does not report those analysis details. The proper conclusion is therefore descriptive: the registry identifies a binary before-and-after endpoint but does not provide results or enough methodological detail to reconstruct an inferential analysis.
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.
| Arm | Participants | Events | Observed % | Clopper-Pearson 95% CI | Wilson 95% CI | Bayesian 95% credible interval |
|---|---|---|---|---|---|---|
| Before Open Label Lubiprostone | 19 | 8 | 42.1% | 20.3% to 66.5% | 23.1% to 63.7% | 23.1% to 63.9% |
| After Open Label Treatment | 19 | 9 | 47.4% | 24.4% to 71.1% | 27.3% to 68.3% | 27.2% to 68.5% |
R code and output
arm <- c("Before Open Label Lubiprostone", "After Open Label Treatment")
n <- c(19, 19)
events <- c(8, 9)
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 Before Open Label Lubiprostone 19 8 42.1 20.3 66.5 23.1 63.7 23.1 63.9
ARM After Open Label Treatment 19 9 47.4 24.4 71.1 27.3 68.3 27.2 68.511. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary endpoint and secondary outcomes concerning small bowel and colon transit time by SmartPill® transit study and small intestinal bacterial overgrowth. It also identifies three outcome measures and two analyses. The registry record does not report a statistical plan describing the relationship between those outcomes and analyses, the order in which they were tested, or any adjustment for multiple comparisons.
As a general statistical explanation, when several outcomes or hypotheses are examined, the chance of at least one apparently notable result can increase if each is interpreted without regard to the others. A prespecified hierarchy or multiplicity adjustment can help define how evidence is assessed across multiple tests. Without the analysis plan and results, it is not possible to determine whether multiplicity was addressed or whether it affects interpretation of any finding.
The primary population is listed as ITT. That label identifies the intended population designation in the record, but the registry does not explain who was included in the analysis, how participants with missing assessments were treated, or whether any departures from the intended population occurred. The record does not report the number with complete measurements at each time point, reasons for missingness, imputation methods, or sensitivity analyses.
As a general matter, missing outcome data can affect both the estimated proportion and the uncertainty around it. The consequences depend on how much information is missing and why it is missing. With paired outcomes, missing either assessment can also prevent a participant from contributing to a within-person comparison. Since the relevant details and primary results are not reported in the registry record, the direction or extent of any missing-data impact cannot be evaluated.
12. 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 |
|---|---|---|---|
| Lubiprostone Open Label | 1 | 25 | 4.0% |
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 |
|---|---|
| Lubiprostone Open Label | 0 of 25 |
Most frequent serious adverse event terms
| Event term | Organ system | Lubiprostone Open Label |
|---|---|---|
| Transient ischemic attack | Nervous system disorders | 1 of 25 |
Serious events with the highest arm-level rate: transient ischemic attack (4.0%).
The registry safety figures list 25 participants at risk for serious adverse events in the Lubiprostone Open Label group and 1 affected participant. The corresponding figures for other adverse events are 25 at risk and 0 affected. The record also lists transient ischemic attack as a top serious term at 4.0%. It does not explain the relationship between that term listing and the participant-level serious-event count, so the term should not be treated as a separately verified participant count.
These figures are descriptive. The registry record does not provide event narratives, timing, severity grading details, attribution to treatment, or a comparison group. Without a control group, these counts cannot establish whether an event occurred more often because of treatment. Deaths are not reported in the record’s safety information; a missing death value should not be read as a reported zero.
Safety counts also do not establish the overall safety profile of an intervention. They describe the events recorded for this study and depend on how events were collected and coded, details not reported in the registry record. The figures should therefore be read as limited registry summaries rather than as a comparative estimate of risk.
13. What the Result Does, and Does Not, Mean
The study addresses a specific biological and clinical question: whether bacterial overgrowth and related gut measures change during treatment with lubiprostone in participants with constipation. The registry record establishes that a before-and-after, single-group study was conducted and identifies presence of small intestinal bacterial overgrowth as the primary endpoint. It does not report the primary endpoint values, so the observed direction and size of any change are unknown from the posted results.
This absence of a reported result is not a finding of no effect. It also is not evidence of a beneficial or harmful effect. It means the registry record does not provide the numerical information needed to characterize the primary outcome. No conclusion about statistical significance or precision can be drawn without an estimate and its uncertainty.
Even if a before-and-after difference were reported, the design would limit causal interpretation. Without a concurrent control group, a change over time cannot be separated confidently from other influences. The registry record does not report additional procedures that address this limitation. The study’s open-label, single-group structure therefore supports a description of within-group measurements, not a like-for-like treatment comparison.
The stated hypothesis also spans several domains: bacterial colonization, stool microorganism balance, dyspepsia, constipation symptoms, and transit. The registry lists bacterial overgrowth and transit outcomes, but the information available for this analysis does not report results for those outcomes or establish results for the symptom and stool-balance questions. One endpoint should not be used as a substitute for another.
The appropriate reading is narrow: the study was designed to examine bacterial overgrowth before and after lubiprostone treatment, but the registry record does not report the primary outcome result. The design and safety counts can be described, but they do not fill the gap in the outcome data or establish a treatment effect.
14. Why This Trial Matters Statistically
This study is statistically instructive because its research question and design have to be considered together. A before-and-after bacterial measure may be useful for describing change within participants, but a single-group design does not provide a concurrent estimate of what would have happened without treatment. Recognizing that distinction prevents an observed temporal pattern, if reported, from being overinterpreted as a causal comparison.
The endpoint is binary, while the broader scientific question spans multiple biological and symptom domains. For a binary endpoint, participant counts and paired changes are central to interpretation. For transit time, the measurement scale and distribution would raise different analytic questions. Results from one outcome cannot stand in for another, and the outcome list alone does not reveal how any endpoint was analyzed.
The record also illustrates why completeness of results matters. It names a primary endpoint, timeframe, analysis population, and secondary outcomes, but does not report the primary before-and-after values or an effect estimate. Without those data, neither magnitude nor precision can be assessed. A listed enrollment does not replace outcome information, and it does not establish that a study was adequately powered for a particular effect.
Finally, the planning assumptions describe a hypothetical two-arm framework, whereas the registered study is single-group. Keeping planning illustrations separate from the implemented design is essential: a hypothetical allocation and effect target cannot be read as the trial’s actual comparison or as observed power. The distinction between design, planning, and results is particularly important when the registry record offers limited outcome reporting.
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 most consequential limitation for interpretation is that the registry record does not report the primary before-and-after outcome values. It also does not provide an effect estimate, confidence interval, or p-value for presence of small intestinal bacterial overgrowth. The magnitude, direction, and precision of the primary outcome are therefore unknown.
The single-group, open-label design has no concurrent control arm. Any before-and-after change would be vulnerable to influences other than the intervention, and the design does not provide a like-for-like control comparison. The registry record does not describe procedures that would resolve this limitation.
Important measurement details are not reported, including the diagnostic definition or threshold for bacterial overgrowth, the measurement procedures, dose and schedule of lubiprostone, and the timing of assessments beyond the 28-day primary timeframe. Participant characteristics beyond constipation and enrollment are not described in the record.
The record lists secondary outcomes but does not report their results in the available information. It also does not describe the statistical analysis plan, multiplicity handling, missing-data methods, or detailed membership and handling for the ITT population. These omissions limit assessment of analytic choices, completeness, and possible bias. The safety figures are likewise limited by absent event detail and the lack of a comparator.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: Effects of Lubiprostone on Small Bowel and Colonic Bacteria: A Correlation Study With Segmental and Whole Gut Transit — NCT00844831.
- Registry record last updated 2017-07-27; status last verified 2017-06.
- Results first posted 2017-07-27.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
19. Record Summary
NCT00844831 is a completed Phase 4, single-group study sponsored by the University of Louisville. It enrolled 25 participants with constipation and evaluated lubiprostone in an open-label before-and-after design. The registry lists presence of small intestinal bacterial overgrowth as the primary endpoint, with a timeframe of 28 days and an ITT population.
Small bowel and colon transit time by SmartPill® transit study and small intestinal bacterial overgrowth are listed as secondary outcomes. The registry record does not report the primary outcome values, an effect estimate, or its precision. Safety listings include 1 participant with a serious adverse event and 0 with other adverse events among 25 at risk; transient ischemic attack is listed as a top serious term at 4.0%. The absence of a concurrent control and of reported outcome results limits what can be concluded from the registry record.