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 Bladder Drainage During Labor: A Randomized Controlled Study of Obstetric Foley Therapy (NCT00959920), a randomized na study. The primary outcome is Time to Delivery (by Any Route).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00959920 |
| Phase | NA |
| Condition | Labor |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 139 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Loyola University |
| Results posted | Yes |
2. Clinical Question
Population
Women in labor who required bladder emptying. The registry record describes the condition as labor and reports enrollment of 139. It does not provide further eligibility criteria or participant characteristics in the trial description.
Intervention
Indwelling Foley catheterization when bladder emptying was necessary, with the catheter remaining in place until delivery.
Comparator
Intermittent straight catheterization performed as needed during labor.
Primary question
How did time from IV placement to delivery of the infant compare between the two bladder-drainage approaches? The registry identifies time to delivery by any route as the primary outcome and states that the study aimed to compare the techniques.
The clinical question is about the timing of delivery following IV placement, not a broader comparison of all maternal or infant outcomes. The primary outcome was specified as a median, with inter-quartile range as its dispersion measure. The reported arm values are 10.43 hours for indwelling Foley catheterization and 11.23 hours for intermittent straight catheterization. The sponsor analysis reports a median difference of .8 and p = .42. The registry record does not state the direction convention for that difference or provide a confidence interval for the comparison.
A secondary outcome was the difference in cost between the interventions. The registry record does not report a result for that outcome. The study description says its results were intended to inform decisions about catheterization during labor; the posted primary outcome addresses only the time interval defined in the record.
3. Trial Design
This was a randomized, parallel-group trial with no masking reported. The registry lists Loyola University as the sponsor and the study status as completed. The record gives a study start of 2009-07 and primary completion of 2009-12. The enrollment was 139.
Participants were assigned to indwelling Foley catheterization or intermittent straight catheterization. In the indwelling arm, the catheter was to remain in place until delivery after insertion when bladder emptying was necessary. In the intermittent arm, straight catheterization was to be performed as needed during labor. The record does not describe the randomization sequence, allocation concealment, or procedures used to implement assignment; those details are not reported in the registry record.
The primary outcome was time to delivery by any route, defined as the interval from IV placement to delivery of the infant. Its stated summary measure was the median, with inter-quartile range. The timeframe is listed as 1 day. The secondary outcome was the difference in cost between the interventions. One analysis is posted in the registry record.
The sample-size statement says that the a priori plan required 138 women, with 69 per group, for 80% power to detect a clinically relevant 30 minute difference in time to delivery using a .05 alpha error. The record does not give further information about how that clinically relevant difference was selected, or about any other design assumptions. The enrollment and outcome arm counts are reported separately; the record does not explain any difference between those counts.
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: Every patient was assigned to a group immediately following enrollment.
Overall Study
| Stage | Indwelling Foley Catheter | Intermittent Straight Catheterization |
|---|---|---|
| STARTED | 72 | 67 |
| COMPLETED | 72 | 66 |
| NOT COMPLETED | 0 | 1 |
Analysis population for the primary outcome, as defined in the registry: Our a priori sample size required 138 women (69 per group) for 80% power to detect the clinically relevant 30 minute difference in the time to delivery interval with a .05 alpha error.
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 | Indwelling Foley Catheter | Intermittent Straight Catheterization | Total |
|---|---|---|---|---|
| Participants analysed | 72 | 67 | 139 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 72 | 67 | 139 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 |
| Age, Continuous | years | 27.6 (SD 6) | 28.7 (SD 6) | 28.14 (SD 6.13) |
| Sex: Female, Male: Female | Participants | 72 | 67 | 139 |
| Sex: Female, Male: Male | Participants | 0 | 0 | 0 |
| Region of Enrollment: United States | participants | 72 | 67 | 139 |
6. Primary Endpoint
The registry lists the primary outcome as Time to Delivery (by Any Route), measured over 1 day.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Inter-Quartile Range |
| Unit | Hours |
| Endpoint classification | not reduced to a single comparison |
Time to delivery measures the interval between IV placement and delivery of the infant, as defined in the registry record. The endpoint is reported in hours and is designated as time to delivery by any route. The record lists a timeframe of 1 day. It does not provide a more detailed account of how the timing was recorded or how events outside that timeframe were handled.
The median describes the middle of the observed time distribution, rather than its arithmetic average. It can be useful when a distribution is asymmetric or includes unusually long intervals, because extreme values do not pull the median in the same way they can affect a mean. The registry identifies the inter-quartile range as the intended measure of spread, but an inter-quartile range is not posted with the arm values. The record does include bounds with the arm summaries, but does not identify what those bounds represent.
Time to delivery is relevant to the stated comparison because the study asks whether the bladder-drainage approaches differ in the interval from IV placement to delivery. It does not, by itself, describe other aspects of labor, catheterization, maternal experience, infant outcomes, or cost. Those outcomes require their own definitions and results.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted primary outcome medians are 10.43 hours for indwelling Foley catheterization and 11.23 hours for intermittent straight catheterization. The corresponding posted bounds are 5.52 to 15.34 and 7.15 to 15.31. The registry record does not label the bounds, so they should not be interpreted as a particular kind of interval from this information alone. The record names inter-quartile range as the dispersion measure, but does not post that measure alongside the arm values.
The sponsor's reported analysis gives a median difference of .8, with a two-sided t-test and p = .42. No confidence interval for the difference is reported. The result therefore gives a point estimate and a p-value, but does not show the range of effect sizes that would be compatible with the analysis. The reported p-value is not a probability that the treatments are equivalent, nor does it establish that the true difference is exactly zero. A non-small p-value can reflect limited precision as well as a small underlying difference.
The method label also merits care. The endpoint is described using medians, and the reported comparison parameter is called a median difference, while the test is named as a t-test. A conventional t-test is generally associated with comparing means. The registry record does not explain the calculation underlying this combination of labels, or provide additional details that would resolve how the estimate and test were constructed. It is therefore best to report the sponsor's analysis as recorded rather than infer a different estimand or method.
The two arm medians are close in the sense that both are around the same range of hours, but no new contrast should be calculated from them. The reported median difference is .8; its direction convention is not stated. The absence of a confidence interval for the comparison limits assessment of precision. The arm-level bounds are not enough to recover a comparison interval, particularly because their meaning is not identified in the record.
The record's planning statement concerned detection of a clinically relevant 30 minute difference, with 80% power and a .05 alpha error, and specified 138 women. Enrollment is listed as 139. These are design details, not evidence that the completed study achieved a particular power or that its observed result rules out a clinically relevant difference. Power calculated from an observed effect is not a substitute for an uncertainty interval and should not be described as observed power.
Overall, the posted evidence is a pair of arm summaries and one sponsor-reported analysis. It does not establish equivalence or exclude meaningful differences. A careful reading keeps the point estimate, p-value, missing comparison interval, and incomplete description of the analysis method distinct.
9. Statistical Methods Explained
The registry record presents a median-based primary endpoint and reports one comparison using a two-sided t-test. Interpreting these results requires attention to what each statistic describes and to details that are not explained in the record.
What does a median describe?
General: The median is the midpoint of a distribution: half of the observations lie at or below it and half at or above it, subject to ties. Unlike a mean, it is not calculated by adding all values and dividing by the number of observations. This can make a median less sensitive to unusually large or small values. A median does not describe the full shape of a distribution, so it is usually read alongside a measure of spread and, where useful, a distribution display.
For this endpoint, the registry specifies the median and inter-quartile range. The posted arm values are 10.43 and 11.23 hours. The record does not include the stated inter-quartile ranges. Bounds are included with each arm summary, but their statistical meaning is not identified in the registry record. They should not be treated as a confidence interval, range, or another measure without that information.
What does a p-value convey?
General: A p-value measures how unusual data at least as incompatible with a specified null hypothesis would be if that hypothesis and the test's assumptions held. It is not the probability that the null hypothesis is true. It is also not a measure of the size or practical importance of an effect. A p-value by itself does not show whether a result is sufficiently precise to exclude effects that matter clinically.
The posted analysis reports p = .42 and labels the test as two-sided. A two-sided test considers departures in either direction from its null value. The record does not specify the null hypothesis in detail, the test statistic, or the exact analysis procedure beyond the test label and reported parameter. As a result, interpretation should remain tied to the analysis as registered rather than fill in an unstated method.
Why does the method label matter?
General: A conventional t-test is commonly used to compare means. Its usual formulation relies on assumptions about the observations and the sampling distribution of the estimated mean difference. A median difference is a different summary parameter. There are statistical procedures designed for medians and other distributional features, but the registry does not name such a procedure or explain how the reported median difference was tested.
This difference in labels does not prove that the sponsor's calculation was invalid. It does mean that the posted description is not enough to reproduce or fully evaluate the analysis. The record does not report whether data were transformed, whether a robust or rank-based procedure was used, whether covariates were included, or whether assumptions were checked. These details are not reported in the registry record.
What would an interval add?
General: A confidence interval gives a range of estimates compatible with the data and a stated procedure under repeated sampling assumptions. Its width communicates precision; its limits can help readers judge whether both small and substantial effects remain compatible with the data. A confidence interval is not the probability that the true value lies within the particular calculated interval.
No confidence interval for the median difference is reported. The posted arm-level bounds cannot stand in for a comparison interval: they summarize each arm separately, and the registry does not identify their type or how the comparison was estimated. Without a comparison interval, the precision of the reported .8 estimate cannot be read directly from the record.
How does planning relate to the result?
General: A sample-size calculation is a planning exercise based on a target effect, a significance level, a desired power, and assumptions about the data and analysis. It does not guarantee that a completed study will detect the target effect. A study can produce an imprecise estimate even when its planned sample size is reached, and a non-significant p-value does not demonstrate equivalence.
The registry states an a priori requirement of 138 women, 69 per group, for 80% power to detect a clinically relevant 30 minute difference with a .05 alpha error. It does not report the calculation's other assumptions or explain how the target difference was chosen. The planned power is not observed power and should not be interpreted as a probability that this particular result is correct. Nor does the p-value establish whether the target difference has been ruled out.
In combination, the median summaries, p-value, and planning statement answer different questions. The arm medians describe the centers of the posted distributions; the p-value describes compatibility with a null hypothesis under an incompletely specified test; and the planning statement describes the intended sensitivity of the design under its assumptions. The record does not provide a comparison confidence interval or enough methodological detail to bridge those pieces into a more complete estimate of uncertainty.
10. Analyses Reported by the Sponsor
| Method | Estimate | 95% CI | P-value |
|---|---|---|---|
| t-test, 2 sided | Median Difference (Final Values) .8 | not reported | 0.420 |
The registry's sponsor analysis reports a median difference of .8 for the primary endpoint, using a two-sided t-test, with p = .42. It does not report a confidence interval for that comparison. The arm summaries report medians of 10.43 hours and 11.23 hours, but the direction convention for the reported difference is not stated.
The registry record does not report a separate recalculated comparison estimate. Consequently, there is no second comparison estimate in the record to set against the sponsor's result. The arm summaries can be described as posted, but a new difference should not be inferred or presented as though it were the sponsor's analysis. The record does not flag a discrepancy between analyses.
The sponsor result should therefore be read as the analysis recorded, with its limitations: the p-value is not an estimate of effect size, the comparison interval is absent, and the description pairs a median-difference parameter with a t-test without explaining the procedure. These gaps limit independent assessment of the calculation, but they do not justify replacing the reported result with an unreported analysis.
11. Multiplicity, Missing Data and Analysis Populations
The registry lists one primary outcome, time to delivery, and one secondary outcome, the difference in cost between the interventions. It reports one analysis. The record does not explain whether the outcomes were assessed using a prespecified hierarchy, whether any adjustment for multiple testing was planned, or how the secondary outcome would affect interpretation of the primary result. Those details are not reported in the registry record.
General: When several outcomes or analyses are examined, the chance of finding at least one apparently unusual result can increase, depending on the testing strategy and the dependence among outcomes. Multiplicity procedures can control that issue, but not every trial uses an adjustment, and the appropriate approach depends on the questions and analysis plan. The existence of a secondary outcome alone does not show that a particular adjustment was required or omitted. Here, the registry does not provide enough detail to determine the prespecified strategy.
The record does not describe missing primary outcome data, exclusions after randomization, or the population included in the reported comparison. It lists outcome arm counts of 72 and 66, while the enrollment is 139. The record does not explain the relationship between enrollment and these outcome counts. It also does not say whether participants were analyzed according to their assigned groups, whether any observations were excluded, or how missing measurements were handled. These points are not reported in the registry record.
Analysis populations matter because estimates can depend on which participants contribute data and how assignment is respected. Missing-data methods matter because the observed participants may differ from those with unavailable outcomes. Without a description of participant flow, analysis set, and handling of missing outcome values, the extent or direction of any such influence cannot be assessed from the registry entry.
The posted p-value should be read as the single reported analysis, not as proof that all planned outcomes or analytic choices have been fully documented. The record does not report an analysis plan detailed enough to evaluate multiplicity or missing-data procedures.
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 |
|---|---|---|---|
| Indwelling Foley Catheter | 0 | 72 | 0.0% |
| Intermittent Straight Catheterization | 0 | 67 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Indwelling Foley Catheter | 0 of 72 |
| Intermittent Straight Catheterization | 0 of 67 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Indwelling Foley Catheter | 0 of 72 |
| Intermittent Straight Catheterization | 0 of 67 |
For serious adverse events, the registry reports zero events among 72 participants at risk in the indwelling Foley catheter group and zero among 67 participants at risk in the intermittent straight catheterization group. The record also reports zero deaths in each group and lists no serious adverse event terms. Other adverse events are reported as zero among 72 and 67 participants at risk, respectively.
These figures describe what was recorded in the registry; they do not establish that no adverse events could occur. The record does not provide event definitions, the safety observation period, the collection procedures, or further detail about ascertainment. The at-risk counts also differ from the primary outcome arm counts, and the registry does not explain that difference.
General: A zero event count means that no events in that category were recorded for the stated group and record. It does not mean that the underlying risk is known to be zero, particularly when the number of participants and observation period are limited or incompletely described. These safety figures should be interpreted as reported counts, not as a comprehensive comparison of safety between the interventions.
13. What the Result Does, and Does Not, Mean
The results describe a randomized comparison of two bladder-drainage approaches during labor, using time from IV placement to delivery as the primary endpoint. The arm medians are 10.43 hours for indwelling Foley catheterization and 11.23 hours for intermittent straight catheterization. The sponsor reports a median difference of .8 and p = .42. No confidence interval for the comparison is reported.
These data do not establish that the approaches are equivalent. A p-value of .42 does not show that the true difference is zero, and the absence of a statistically unusual result under the stated test does not rule out effects of potential importance. Without a confidence interval, the precision of the comparison is especially difficult to judge. The posted arm bounds do not resolve that uncertainty because their meaning is not given.
The results also do not show that either approach is better overall. The primary endpoint is one defined time interval, and the record lists cost as a secondary outcome without reporting its result. Other clinical outcomes are not characterized in the posted primary comparison. The serious adverse event counts are zero in both groups, but these counts do not establish the absence of risk or provide a complete assessment of safety.
The trial's planning statement identifies a target of 138 women, 69 per group, and an intended ability to detect a clinically relevant 30 minute difference with 80% power and a .05 alpha error. That plan is not evidence that the completed comparison can exclude that difference. The registry does not provide a comparison interval or enough details about the analysis and missing data to support a stronger conclusion.
A defensible summary is therefore limited: the posted medians and sponsor analysis report the observed time-to-delivery summaries and a p-value, but leave substantial uncertainty about the precision and interpretation of the comparison. They do not justify conclusions about equivalence, broader clinical outcomes, or overall safety.
14. Why This Trial Matters Statistically
This trial illustrates why the endpoint definition, summary measure, and test description need to be read together. The primary outcome is a time interval, and the registry specifies a median with inter-quartile range. Yet the posted arm summaries do not include that stated spread measure, and the comparison is labeled as a t-test while its parameter is called a median difference. These details affect how readily readers can understand and evaluate the result.
The record also shows the difference between a design target and an observed result. The planning statement sets out a target effect, power, significance level, and planned group sizes. Those assumptions describe what the design was intended to detect; they do not convert a non-significant p-value into evidence of equivalence. Precision is best evaluated with an interval for the comparison, which is not reported.
Finally, a randomized design does not make every reporting gap disappear. The registry does not describe participant flow, missing outcome handling, or the analysis population. Those details help readers understand who contributed to the estimate and whether the analysis followed the intended assignment strategy. Without them, the reported comparison remains informative but difficult to assess fully.
The statistical lesson is not that a particular analysis must be preferred from the limited record. It is that clear reporting of the estimand, test, uncertainty interval, and analysis population is essential for translating a trial result into a precise account of what the data support.
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 registry entry leaves several trial-specific questions unresolved. It does not report the randomization sequence or allocation concealment, nor does it describe the procedures used to assign participants. Masking is listed as none. The record does not provide further eligibility criteria or participant characteristics, which limits assessment of who was represented in the trial.
The primary endpoint is defined as IV placement to delivery of the infant, with a timeframe of 1 day. The record does not explain how the timing was measured, whether timing was recorded consistently, or how any unavailable or unusual measurements were handled. Although the specified dispersion is inter-quartile range, that measure is not posted alongside the arm values. The registry includes bounds but does not identify their type.
The comparison is reported as a median difference tested with a two-sided t-test. The registry does not explain the estimation procedure, provide a confidence interval for the comparison, or report diagnostic information or other analytical details. It also does not describe the analysis population, participant flow, or missing-data handling. As a result, the estimate's precision and sensitivity to analysis choices cannot be assessed from the entry alone.
The secondary cost outcome is listed without a reported result. The registry does not report a multiplicity strategy or enough detail to determine how the primary and secondary outcomes were handled together. Safety reporting gives zero serious adverse events and deaths in both groups, but does not describe the observation period or ascertainment procedures. These limitations concern the completeness of the registry record and should not be mistaken for evidence that unreported procedures or data were absent.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: Bladder Drainage During Labor: A Randomized Controlled Study of Obstetric Foley Therapy — NCT00959920.
- Registry record last updated 2017-05-19; status last verified 2017-05.
- Results first posted 2012-05-23.
- 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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19. Record Summary
NCT00959920, the Study of Obstetric Foley Therapy (SOFT Trial), is listed as a completed randomized, parallel-group study sponsored by Loyola University, with no masking. It enrolled 139 participants and compared an indwelling Foley catheter, kept in place until delivery, with intermittent straight catheterization performed as needed during labor.
The primary endpoint was time to delivery by any route, defined as IV placement to delivery of the infant and summarized as a median. The posted arm values are 10.43 hours and 11.23 hours. The sponsor reports a median difference of .8 and p = .42 using a two-sided t-test. A comparison confidence interval is not reported. The secondary outcome was cost difference; its result is not reported in the registry record.
The record reports zero serious adverse events and deaths in both groups. Details about missing data, analysis populations, and several aspects of the statistical procedure are not reported in the registry record.