A Study to Evaluate the Safety, Tolerability and Effectiveness of the Renew Insert in Treating Accidental Bowel Leakage: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study to Evaluate the Safety, Tolerability and Effectiveness of the Renew Insert in Treating Accidental Bowel Leakage (NCT01475474), a na na study. The primary outcome is Co-primary Effectiveness Endpoint: A Relative Percentage Change in Episodes of Accidental Bowel Leakage (ABL) Determined by Comparing Treatment Results to Pre-treatment Results From the Baseline Period as Measured by Daily Diary Recordings..

2. Clinical Question

3. Trial Design

This was a prospective, multi-center, non-randomized, single-group study of the Renew Insert. The registry lists masking as none, so the study was not masked. It was marked completed, with study start in 2009-12 and primary completion in 2011-11. Enrollment was 97. The registry lists the study phase as NA and classifies the intervention as a device.

Because the study had a single group rather than randomized arms, its main effectiveness comparison was between diary-recorded baseline and treatment periods. Baseline covered Weeks 1-4, and the treatment period covered Weeks 5-16. This design can describe within-participant change over time, but it cannot separate a device-related change from other explanations as reliably as a concurrent randomized comparison might. The registry record does not report a control group or a randomized allocation process.

The primary effectiveness population was the Modified Intent-To-Treat cohort. It included subjects who completed at least one week of Insert use during the 12 week Treatment Period. Safety results were reported for an Intent-to-treat cohort. These are distinct analysis-population descriptions; the registry does not report further details about how participants entered or were excluded from either population.

The record describes two outcome measures and two analyses, but the additional outcome and analysis details are not reported in the registry information. It also does not report the protocol’s sample-size justification or a detailed statistical analysis plan. The enrollment figure therefore should not be interpreted as evidence of a particular power target or as proof that the study could detect a specified effect.

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: Renew Medical conducted a multi-center, prospective, open label, single-arm, non-randomized pivotal study designed to establish the safety, effectiveness, and tolerability of the Renew Insert in subjects with moderate-to severe bowel incontinence (defined as having a Wexner score greater than 12).

Baseline Period - 4 Weeks

Reasons for not completing this period:

Treatment Period - 12 Weeks

Return to Baseline Period - 4 Weeks

Analysis population for the primary outcome, as defined in the registry: Primary cohort for the effectiveness analyses was the Modified Intent-To-Treat cohort which included all subjects who completed at least one week of Insert use during the 12 week Treatment 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 Co-primary Effectiveness Endpoint: A Relative Percentage Change in Episodes of Accidental Bowel Leakage (ABL) Determined by Comparing Treatment Results to Pre-treatment Results From the Baseline Period as Measured by Daily Diary Recordings., measured over Reduction in accidental bowel leakage from Baseline (Weeks 1-4) through Treatment period (Weeks 5-16)..

The described co-primary effectiveness endpoint measures relative percentage change in accidental bowel leakage episodes, comparing the baseline period with the treatment period. Diary recordings were used, with baseline defined as Weeks 1-4 and treatment as Weeks 5-16. The registry specifies the calculation as 100 multiplied by the difference between baseline and treatment-period ABL, divided by baseline ABL. The endpoint is summarized by the median and inter-quartile range.

A relative change expresses the difference in relation to the baseline level, rather than only as a raw difference in episodes. That can make changes easier to interpret across participants whose starting levels differ. It also means that interpretation depends on the baseline value: a relative measure is not interchangeable with an absolute change in episode counts. The record does not provide the underlying diary summaries or the numerical endpoint result.

The median describes the middle of the observed distribution and is less affected by extreme values than the mean. The inter-quartile range describes the spread of the central portion of that distribution. Together, these summaries can be useful for an outcome whose participant-level changes vary or are skewed. They do not, by themselves, show the precision of the estimated group result; a confidence interval or other uncertainty estimate would be needed for that. Such an estimate is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical approach described for effectiveness centers on a within-participant comparison of diary-recorded accidental bowel leakage during a baseline period and a later treatment period. Baseline covered Weeks 1-4; treatment covered Weeks 5-16. The endpoint is a relative percentage change and is summarized by the median and inter-quartile range. The registry record does not report a more detailed model or inferential procedure for this endpoint.

What does a relative change measure?

In general, a relative change places a difference in relation to a reference value. The registry’s stated calculation takes baseline ABL minus treatment-period ABL, divides by baseline ABL, and multiplies by 100. Under this direction of subtraction, a positive reduction corresponds to treatment-period ABL being lower than baseline ABL, while a negative reduction corresponds to treatment-period ABL being higher. This explains the meaning of the formula; it does not describe a reported study result. The record does not provide the numerical endpoint estimate.

Relative and absolute changes answer different questions. An absolute change describes the difference in the original measurement scale, while a relative change describes that difference compared with the baseline level. Relative measures can aid comparison across participants with different baseline levels, but they can be sensitive to the size and stability of the baseline value. The registry does not report participant-level baseline values, treatment values, or episode-count summaries, so neither an absolute change nor a recalculated relative estimate can be derived from the available record.

Why report a median and inter-quartile range?

In general, the median is the middle value when observations are ordered. It can give a representative description when a distribution is skewed or contains unusually large or small observations. The inter-quartile range describes the span from the lower to the upper quartile and indicates how dispersed the central observations are. It is a measure of variation across observations, not a confidence interval for the median and not a direct measure of uncertainty about a treatment effect. The registry record names these summaries but does not provide their numerical values.

For an episode-count outcome, participants may have different counts and different changes between periods. General statistical practice considers whether the distribution is skewed and whether variability is greater than a chosen model would expect. Over-dispersion is a general concern when count data vary more than a model assumes; if present, it can make standard errors and inferential conclusions unreliable unless the analysis accounts for it. This is general context only. The registry record does not report a count-data model, an over-dispersion assessment, or the assumptions used in an inferential analysis.

What can a confidence interval add?

In general, a confidence interval gives a range of values compatible with an estimate under the method’s assumptions. It helps readers assess precision: a narrower interval indicates greater precision than a wider interval, all else equal. A confidence interval would complement a median and inter-quartile range because the latter describes the distribution of observations rather than uncertainty about the estimated endpoint. No confidence interval for the primary effectiveness endpoint is reported in the registry record. No p-value or other test result for that endpoint is reported either, so statistical significance cannot be assessed from the record.

How does the design affect the analysis?

With a single group, the baseline period is the reference rather than a concurrent control. A within-participant comparison can account for the fact that each person has their own starting measurement, but the comparison remains vulnerable to time-related changes and other influences. A randomized concurrent comparison is generally used to better distinguish an intervention’s effect from changes that could have occurred without it. This is a general design principle, not a claim about an unreported analysis. The registry identifies the study as non-randomized and single-group.

The registry’s Modified Intent-To-Treat definition required at least one week of Insert use during the 12 week Treatment Period. The details of the statistical analysis beyond the endpoint formula and summary measure are not reported in the registry record. In particular, no adjustment procedure, model specification, confidence-interval method, or sensitivity analysis is described. The available information therefore supports explanation of the endpoint and its summaries, but not reconstruction of the inferential analysis.

10. Multiplicity, Missing Data and Analysis Populations

The registry describes a co-primary effectiveness endpoint and lists two outcome measures and two analyses. Multiple endpoints or analyses can raise a multiplicity issue: in general, conducting several statistical tests can increase the chance that at least one result appears notable by chance. Possible approaches include prespecifying a primary comparison, adjusting inference, or treating results as exploratory. The registry record does not report how multiplicity was addressed, and the additional outcome and analysis details are not reported in the information. No significance tests for the described endpoint are reported.

The primary effectiveness population was the Modified Intent-To-Treat cohort, defined by completing at least one week of Insert use during the 12 week Treatment Period. The safety results use an Intent-to-treat cohort. These definitions should not be treated as interchangeable. The registry record does not report the number contributing to the effectiveness endpoint, the amount of missing diary data, or whether participants with incomplete records were included in any particular calculation.

Missing-data handling can affect an estimate when available observations differ systematically from missing ones. General approaches include analyzing available data under stated assumptions, imputing missing values, or examining how conclusions change under alternative assumptions. The registry record does not report which approach, if any, was used, why records may have been missing, or whether sensitivity analyses were conducted. It also does not report interim analyses or a detailed statistical analysis plan. Those omissions limit assessment of how robust the endpoint summary would be to incomplete follow-up or analytic choices.

11. Safety Results

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

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent non-serious adverse event terms

Safety results are reported for the Intent-to-treat cohort. For serious adverse events, the registry lists 91 at risk and 0 affected. For other adverse events, it lists 91 at risk and 91 affected. These are the registry’s reported counts; they do not supply details about the nature, timing, duration, or severity of the non-serious events. The record lists no top serious adverse event terms.

The serious adverse event figure means that the registry reports no participants affected in that category among those listed as at risk. It does not establish that every possible safety event was absent, and it should not be read as proof of safety. The other adverse event figure indicates that all 91 participants listed as at risk were recorded as affected in that category; the record does not give event-level descriptions or distinguish causes. It also does not report a safety follow-up timeframe or the criteria used to classify events in the information. Death information is not reported in the registry record. These figures describe what was recorded, not whether an event was caused by the device.

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

The registry record describes a prospective evaluation of the Renew Insert using daily diary recordings and a pre-treatment baseline comparison. It specifies a relative percentage change in accidental bowel leakage episodes as a co-primary effectiveness endpoint, with the median and inter-quartile range as summaries. These details make clear what the endpoint was intended to measure and how its distribution was to be described.

The numerical primary endpoint result is not reported in the registry record. Consequently, the record does not establish whether ABL was lower or higher during treatment, the size of any change, how variable individual changes were, or how precise an estimated change might be. It does not report the inferential results needed to assess statistical compatibility with no change. The record therefore cannot support a conclusion about the magnitude or statistical certainty of an effectiveness result.

Even if a pre-treatment and treatment-period difference were reported, the non-randomized, single-group design would not by itself establish that the Renew Insert caused it. A concurrent comparison can help account for changes over time that are unrelated to an intervention; this study’s described comparison is against baseline. This is a general limitation of the design, not evidence that a particular alternative explanation occurred.

The safety record reports 0 affected among 91 at risk for serious adverse events, and 91 affected among 91 at risk for other adverse events. These figures should be interpreted as registry-reported counts, not as proof that the device is safe or that the recorded non-serious events were caused by it. Overall, the available record identifies the study question, design, endpoint, analysis populations, and safety counts, but does not provide the numerical effectiveness result or enough detail to assess its precision and robustness.

13. Why This Trial Matters Statistically

This study illustrates an important distinction between measuring change and establishing its cause. Diary recordings before and during treatment can describe how reported accidental bowel leakage episodes changed over time. A single-group, non-randomized design, however, does not provide the same protection against alternative explanations as a randomized comparison with a concurrent control. That distinction matters whenever a within-person baseline is used as the reference.

The endpoint also highlights how the choice of summary affects interpretation. A relative percentage change expresses change in relation to baseline, while the median and inter-quartile range describe the center and spread of the observed changes. Those summaries are useful for understanding a distribution, but they do not replace an uncertainty interval or a clearly reported inferential analysis. The registry record’s endpoint definition is informative, while its missing numerical result prevents assessment of the observed magnitude and precision.

The stated analysis populations show why denominators and eligibility definitions matter. The effectiveness analysis used a Modified Intent-To-Treat cohort defined by treatment-period use, while safety was reported for an Intent-to-treat cohort. Readers need those definitions, along with missing-data and analysis details, to judge which observations contribute to each result and how broadly findings may apply.

Finally, the safety counts illustrate that serious and other adverse events should be read separately and in context. A zero serious-event count does not resolve questions about other harms, attribution, event descriptions, or completeness of follow-up. Clear reporting of endpoint results, uncertainty, missing-data methods, and event details is necessary for a balanced statistical interpretation.

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.

The main limitation for interpreting effectiveness is that the numerical result for the described co-primary endpoint is not reported in the registry record. Without an estimate and a measure of uncertainty, the direction, size, and precision of any change cannot be evaluated. The record identifies two outcome measures and two analyses, but details for the additional outcome and analysis are not reported in the available information.

The study was non-randomized and single-group, with no masking. Its baseline-to-treatment comparison cannot isolate change associated with the device from other changes over time. The record does not report a concurrent control group, or information that would allow readers to assess the influence of expectations, diary-reporting behavior, or other time-varying factors.

The primary effectiveness cohort was defined by completing at least one week of Insert use during the 12 week Treatment Period. The registry record does not report how many participants contributed to the primary endpoint, the completeness of daily diaries, reasons for missing observations, or methods for handling missing data. It also does not describe sensitivity analyses, a detailed model, or a multiplicity procedure. These gaps limit assessment of robustness and precision.

For safety, the record provides counts of participants at risk and affected but does not report event descriptions, timing, follow-up duration, attribution, or death information. The absence of listed serious-event terms and the reported serious-event count do not answer those broader safety questions. The record also does not report the sample-size justification, so enrollment cannot be taken as evidence that a particular effect size could be detected.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: A Study to Evaluate the Safety, Tolerability and Effectiveness of the Renew Insert in Treating Accidental Bowel Leakage — NCT01475474.
• Registry record last updated 2013-11-28; status last verified 2013-09.
• Results first posted 2013-11-28.
• 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.

18. Record Summary

The registry describes a completed, prospective, multi-center, non-randomized, single-group study of the Renew Insert for accidental bowel leakage due to bowel incontinence. Enrollment was 97. Study start was 2009-12 and primary completion was 2011-11. Masking was listed as none, and the intervention was classified as a device.

The described co-primary effectiveness endpoint compared diary-recorded ABL in baseline Weeks 1-4 with treatment Weeks 5-16. It was defined as relative percentage change and summarized by median and inter-quartile range. The primary effectiveness cohort included subjects who completed at least one week of Insert use during the 12 week Treatment Period. The numerical effectiveness result and its uncertainty are not reported in the registry record.

Safety results for the Intent-to-treat cohort list 0 affected among 91 at risk for serious adverse events and 91 affected among 91 at risk for other adverse events. Further event details and death information are not reported in the registry record.