Outpatient Foley Catheter Compared to Usual Inpatient Care for Labor Induction: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Outpatient Foley Catheter Compared to Usual Inpatient Care for Labor Induction (NCT02546193), a non-randomized na study. The primary outcome is Pre-delivery Hospitalization Time.

2. Clinical Question

3. Trial Design

The record describes a parallel-group clinical trial comparing outpatient Foley catheter cervical ripening with inpatient usual care. Its title refers to a randomized controlled trial, and the arm descriptions refer to participants who were randomized or who chose a group under a modified prospective design. However, the registry classifies the allocation as non-randomized and explicitly cautions that the arms are not a like-for-like control comparison. That classification matters: the record does not support interpreting the groups as if assignment was fully randomized.

The trial was sponsored by Mayo Clinic. The listed enrollment is 39, the status is terminated, and the phase is recorded as NA. The record gives a start date of 2015-09 and a primary completion date of 2017-06-08. It does not report why the trial was terminated, how many participants were assigned to each group, or how many completed follow-up.

The outpatient arm description combines randomized and prospective enrollment pathways. The inpatient arm description likewise refers to randomized and prospective pathways, while noting that no participants in the modified prospective study design were accrued due to screen failure. These descriptions sit alongside the non-randomized allocation classification, leaving the precise conduct and composition of the comparison unclear. The registry record does not provide enough detail to resolve that discrepancy.

The record lists Foley catheter and misoprostol as interventions. It also lists secondary outcomes including maternal satisfaction, induction methods, pain-relief medication, delivery timing, delivery mode, blood loss, and intrapartum and postpartum complications. Those listed outcomes are not themselves results: outcome values and corresponding statistical analyses 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.

Before assignment: Women were excluded from the study prior to randomization (the day before their scheduled induction of labor) due to spontaneous onset of labor or other maternal/fetal concern necessitating delivery prior to scheduled induction date.

Overall Study

Reasons for not completing this period:

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Pre-delivery Hospitalization Time, measured over Delivery, approximately 16 to 30 hours after admission.

The primary endpoint, pre-delivery hospitalization time, measures the time from hospital admission until delivery of the infant and placenta. It is recorded in minutes, with the stated timeframe of delivery, approximately 16 to 30 hours after admission. For the outpatient group, the endpoint includes both time at the Family Birth Center during evening Foley placement and inpatient time the next day during the remainder of induction until delivery.

As a general statistical point, a continuous time measure can describe the amount of time spent in hospital more finely than a simple category such as whether a person was admitted before delivery. The endpoint is relevant to the study question because the care approaches differ in whether cervical ripening begins at home or in hospital. Its interpretation depends on consistent definitions of when measurement starts and ends, and on comparable recording of both components for the outpatient group.

The registry specifies the mean as the summary measure and standard deviation as the dispersion measure. The mean describes the group’s average time, while the standard deviation describes variability among individual observations. Neither group mean nor standard deviation, nor a comparison between groups, is reported in the registry record. Therefore, the endpoint definition can be described, but the observed duration and the precision of any group difference cannot be assessed from the reported results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes the primary endpoint as continuous, summarized by a mean with standard deviation. It reports no outcome analyses. Accordingly, the statistical methods below explain the concepts relevant to this endpoint in general; they do not describe an analysis that the registry record confirms was performed.

What does a mean represent?

As a general statistical point, the mean is the arithmetic average of observed values. For hospitalization time, each participant’s recorded duration contributes to the group mean. The mean is easy to interpret in the endpoint’s stated unit of minutes, but it can be influenced by unusually long or short durations. A mean should therefore be read alongside a measure of variability and, where appropriate, a view of the distribution of individual observations.

The standard deviation describes how dispersed observations are around the mean. A larger standard deviation indicates more variability among recorded times, while a smaller one indicates values are more closely grouped around the mean. The standard deviation is not the same as the uncertainty in the estimated mean. As a general statistical point, the standard error and confidence interval quantify uncertainty in an estimate; the standard deviation describes variation in the observed data. The registry record does not report the mean, standard deviation, standard error, or confidence interval for the primary endpoint.

How would a group comparison be interpreted?

As a general statistical point, a comparison of group means would describe the difference in average hospitalization time between the care approaches. The estimate would need to be interpreted in the context of its uncertainty and the design that generated the data. A confidence interval would indicate the precision of the estimated difference, and a p-value, if reported, would assess compatibility with a specified null hypothesis under the analysis assumptions. Neither a p-value nor an interval establishes that a difference is important in practice.

No such comparison is reported in the registry record. There is no posted effect estimate or inferential statistic for the primary endpoint. It is not possible to reconstruct an unadjusted comparison from the registry information because group means, standard deviations, and analysis counts are not reported. No recalculated estimate is therefore available.

Why does allocation matter?

Random allocation is intended, as a general design principle, to make treatment groups comparable on average with respect to measured and unmeasured characteristics. That principle does not apply automatically when allocation is classified as non-randomized. If participants choose a group, or if assignment depends on other factors, differences in participant circumstances may be related to both group membership and hospitalization time. Such differences can complicate causal interpretation.

In this record, arm descriptions refer to both randomized and participant-choice pathways, while the registry classification is non-randomized. The registry also states that the arms are not a like-for-like control comparison. The record does not provide enough information to determine which participants followed each pathway or how those pathways were handled in analysis. It does not report adjustment variables, a model, or a prespecified analysis strategy. These methods should not be inferred from the trial title or the arm labels.

What do planning assumptions tell readers?

The record describes sample-size planning illustrations based on the observed effect, using a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. Such calculations are planning illustrations, not observed power and not trial results. In general, they estimate how many participants per arm might be needed under stated assumptions about the effect to detect and the variability of the outcome. They do not show that a study had a particular probability of finding a result after it was completed.

The record does not report a primary-outcome effect estimate or standard deviation from which to assess the assumptions behind an illustration. It also does not report an original design-based sample-size justification. The sample-size assumptions described for planning should therefore not be treated as evidence about the actual conduct or adequacy of enrollment in this trial.

Why might variability matter?

As a general statistical point, clinical time outcomes can vary substantially between participants. A small number of unusually long durations can pull a mean upward, while differences in the spread of times between groups affect the uncertainty of a comparison. If a statistical model assumes that variability is similar across groups or that outcomes follow a particular distribution, departures from those assumptions can affect estimates and standard errors. The registry record does not report diagnostic checks, distributional summaries, or an alternative analysis for such circumstances.

The endpoint also combines time spent at the Family Birth Center during Foley placement with later inpatient time for the outpatient group. Clear and consistent measurement is important when a measure is assembled from multiple periods. The record defines those components but does not report participant-level data, missing-time handling, or whether the endpoint was recorded consistently across all groups. These omissions limit assessment of measurement quality and analytic robustness.

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("Outpatient Foley Catheter", "Inpatient Usual Care")
n   <- c(4, 4)
m   <- c(1197, 1398)
sp  <- c(267, 264)
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  Outpatient Foley Catheter  4  1197.000  267.000  772.143  1621.857
CARM  Inpatient Usual Care  4  1398.000  264.000  977.917  1818.083

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 15 outcome measures, including the primary hospitalization-time endpoint and secondary measures of satisfaction, induction method, pain-relief medication, delivery timing, delivery mode, blood loss, and complications. When a study examines multiple outcomes, the chance of at least one apparently notable finding can increase if each is tested separately without accounting for multiplicity. As a general statistical point, a prespecified hierarchy or adjustment approach can help clarify how multiple tests are interpreted. The registry record does not report a multiplicity strategy, a hierarchy among outcomes, or a statistical analysis plan.

The record reports zero analyses and does not provide outcome results. It does not describe missing-data amounts, reasons for missingness, or methods for handling missing observations. Missingness matters because the analysis can be affected if people without recorded outcomes differ systematically from those with recorded outcomes. No imputation method, complete-case approach, or sensitivity analysis is reported in the registry record.

The analysis populations are also not reported. The record does not specify whether analyses were intended to include all enrolled participants, participants assigned to a group, participants who received the assigned approach, or another subset. The arm descriptions include randomized and participant-choice pathways, but the allocation classification is non-randomized. Without definitions of analysis populations and group-specific counts, readers cannot determine which participants would contribute to each endpoint or how deviations from the intended approach would be handled.

These are reporting gaps, not evidence that a particular method was or was not used in practice. The registry record does not report whether interim analyses were conducted, whether outcomes were revised, or whether missingness affected the results. Those details should not be inferred.

12. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry safety summaries list 4 participants at risk in the outpatient Foley catheter group and 4 at risk in the inpatient usual-care group. In each group, the serious adverse event count is 0, the other adverse event count is 0, and deaths are recorded as 0. These are the safety figures recorded for the groups, not a complete account of all possible harms or clinical outcomes.

As a general statistical point, an event count should be read together with its denominator and the way events were defined and collected. Zero recorded events does not establish that an event could never occur, nor does it show that the approaches have identical safety profiles. With limited information about the safety population, follow-up, and event definitions, readers cannot assess how representative these summaries are or how precisely they characterize event risk.

The listed overall enrollment is 39, whereas the safety summaries identify 4 participants at risk in each group. The registry record does not explain how those safety denominators relate to overall enrollment, the endpoint analysis population, or follow-up completeness. These figures should not be expanded into broader conclusions about safety or used to infer the experience of participants not included in the listed safety denominators.

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

This record establishes that a trial was registered to compare outpatient Foley catheter cervical ripening with inpatient usual care, with pre-delivery hospitalization time designated as the primary endpoint. It also gives an operational definition of that endpoint, identifies the listed interventions, and records an enrollment of 39. The registry status is terminated, and the primary completion date is 2017-06-08.

It does not establish how the approaches compared on hospitalization time. The registry record does not report group means, standard deviations, an estimated difference, confidence intervals, or p-values. It therefore cannot show whether the observed time was longer or shorter in either group, how large any difference was, or how precise an estimate might be. No conclusion about effectiveness or lack of effectiveness follows from the absence of posted results.

The design information also requires caution. Although the title and arm descriptions use randomized language, the registry classifies allocation as non-randomized and says the arms are not a like-for-like control comparison. This leaves uncertainty about group assignment and the relationship between randomized and participant-choice pathways. Any comparative interpretation would need to account for that design information rather than relying on the title alone.

The listed secondary outcomes indicate that the study planned to collect information on several aspects of induction and delivery, but listed outcomes are not evidence of observed findings. The safety summaries record no serious adverse events, other adverse events, or deaths in the stated at-risk groups; their denominators are limited, and the relationship to overall enrollment is not explained. Those figures should be read narrowly and do not demonstrate that risk is absent.

In short, the registry record describes a clinical question and an endpoint, but it does not report results that can answer the comparative question. Interpretation is constrained by absent outcome analyses, unclear analysis populations, and the non-randomized allocation classification.

14. Why This Trial Matters Statistically

This trial raises a practical statistical question about how to compare an outpatient cervical-ripening approach with inpatient usual care when the primary outcome is time spent in hospital. The endpoint definition recognizes that outpatient care includes time in the Family Birth Center for Foley placement as well as later inpatient time. That makes the measurement rule central to interpreting the comparison: the recorded duration is not simply an inpatient stay beginning at a single point for every group.

The record also illustrates why design labels need to be read alongside allocation details. A title can describe a randomized controlled trial, and arm labels can refer to randomization, while the registry classification says allocation was non-randomized and warns against treating the arms as a like-for-like comparison. For statistical interpretation, this distinction bears on whether group differences could be attributed to the care approach or might reflect differences associated with assignment or participant choice.

Another important issue is the difference between a registered outcome and a reported result. The record names a primary endpoint and multiple secondary outcomes, but does not report their analyses. A planned measure does not reveal the size, direction, or precision of an observed result. Likewise, sample-size planning illustrations are not evidence of observed power or findings.

The record’s termination status, modest overall enrollment as listed, and limited safety denominators make transparent reporting particularly important. Readers need group counts, analysis populations, outcome summaries, missing-data information, and a clear account of how the allocation pathways were handled to evaluate the evidence. Because those details are not reported in the registry record, the statistical significance of this trial lies in the questions it highlights about endpoint construction, design classification, and complete outcome reporting—not in a comparative result that the record does not contain.

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 main limitation for interpretation is the absence of posted outcome analyses. The registry record does not report the primary endpoint values, group-specific sample sizes for that endpoint, or an estimate of the difference between groups. It therefore offers no direct information about the magnitude or precision of the primary comparison.

The design description is difficult to reconcile. The trial title calls the study randomized, and arm descriptions refer to randomization as well as participant choice, but the allocation classification is non-randomized. The registry explicitly warns that the arms are not a like-for-like control comparison. Details that might clarify the assignment pathways, their relative contribution, and their analytic treatment are not reported in the registry record.

Although the overall enrollment is listed as 39, enrollment by arm, follow-up completion, and endpoint-specific analysis counts are not reported. The safety summaries list 4 participants at risk in each group, but the registry does not explain the relationship between those counts and overall enrollment. The record also does not report missing-data amounts, analysis populations, or methods for handling incomplete observations.

The trial is marked terminated, but the reason for termination and its implications for outcome collection are not reported in the registry record. The record does not provide a statistical analysis plan, a multiplicity strategy, an original sample-size justification, or information about interim analyses. The endpoint definition is stated, but the record does not report measurement completeness or checks of statistical assumptions. These limitations prevent a detailed assessment of how the study was conducted and analyzed.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Outpatient Foley Catheter Compared to Usual Inpatient Care for Labor Induction — NCT02546193.
• Registry record last updated 2019-06-20; status last verified 2019-05.
• Results first posted 2019-06-20.
• 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 parallel-group trial comparing outpatient Foley catheter cervical ripening with inpatient usual care. It lists Mayo Clinic as sponsor, pregnancy as the condition, enrollment of 39, status as terminated, and phase as NA. The recorded start is 2015-09, with primary completion on 2017-06-08.

The primary endpoint is pre-delivery hospitalization time in minutes, defined from admission until delivery of the infant and placenta. The registry classifies allocation as non-randomized, despite randomized language in the title and arm descriptions, and cautions that the arms are not a like-for-like control comparison. The record lists 15 outcome measures and reports zero analyses. It does not report primary or secondary outcome results, an analysis population, or missing-data methods.