Comparison of the Efficacy of a Biological Implant to Reinforce Overlapping Sphincter Repair Versus Overlapping Sphincter Repair Alone: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Comparison of the Efficacy of a Biological Implant to Reinforce Overlapping Sphincter Repair Versus Overlapping Sphincter Repair Alone (NCT01044589), a randomized na study. The primary outcome is Number of Participants Reporting a Decrease in Incontinence Episodes Per Week.

2. Clinical Question

The question concerns whether adding a biological graft to the repair is associated with a different reported pattern of improvement than repair alone. The posted outcome counts are 2 participants in each arm, with 3 participants in each arm represented in those outcome results. Those counts describe the registry’s reported endpoint; they do not establish that the two treatments have equivalent effects. The registry record lists no statistical analysis comparing the arms, and the small outcome groups leave substantial uncertainty about how representative these counts are of a broader population.

3. Trial Design

The registry describes a randomized, single-masked, parallel-group trial. Participants were assigned to either overlapping sphincter repair alone or overlapping sphincter repair reinforced with the Biodesign Tissue Repair Graft. In a parallel-group design, participants receive one assigned study intervention rather than crossing between interventions. Random allocation is intended, in general, to reduce systematic differences between groups at assignment. The registry record does not report details of the randomization procedure, concealment of allocation, or which people were masked.

The stated enrollment was 13. The record gives a study start of 2010-05, primary completion of 2014-12, and status of terminated. The reason for termination and the timing or circumstances of that decision are not reported in the registry record. The posted primary outcome results include 3 participants in each arm, while the safety results use different denominators. The record does not explain the relationship between those denominators and enrollment, or why they differ by outcome.

The study’s stated aim was to compare the efficacy of graft-reinforced repair with standard overlapping repair in controlling incontinence episodes among people with fecal incontinence and an anal sphincter defect. The primary outcome is described as the number of participants reporting a decrease in incontinence episodes per week at 12 months. The registry lists fecal incontinence and anal incontinence as conditions. Phase is recorded as NA. The sponsor is Massarat Zutshi.

These design details describe the registry entry, but do not establish how the trial was conducted in practice beyond what the record states. Protocol details, eligibility criteria, recruitment flow, and the reason for termination are not reported in the registry record. No statistical analysis of the two arms is posted.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

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 Number of Participants Reporting a Decrease in Incontinence Episodes Per Week, measured over 12 months.

The primary endpoint counts participants who reported a decrease in incontinence episodes per week at the 12-month timeframe. It is a binary participant-level outcome summarized as a count: a participant either meets the stated decrease criterion or does not. The endpoint does not show how many episodes each participant experienced, the size of any decrease, or whether the decrease was sustained. A decrease is the direction described by the outcome; the registry record does not define a threshold for how large a decrease had to be.

A participant-count endpoint can offer a direct summary of how many people meet a defined response criterion. In general, this can be easier to interpret than a group average when the question is how many participants report improvement. Its meaning depends on how the response is defined, how outcomes are collected, and which participants are included. The registry record does not describe the questionnaire, measurement method, handling of baseline frequency, or analysis population.

The posted results list 2 participants reporting a decrease in each arm, with 3 participants represented in each arm. These are counts, not a comparison adjusted for other factors. The registry record does not provide an estimate of the difference between arms or its uncertainty. A count of participants reporting a decrease also does not, by itself, indicate the magnitude or clinical importance of the change.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary outcome as a binary participant-level endpoint: whether a participant reported a decrease in incontinence episodes per week at 12 months. The reported values are counts of participants meeting that outcome in each arm. This is distinct from analyzing the number of episodes as a continuous measure. The registry record does not provide individual participant data, episode counts, or a definition of the minimum decrease required to qualify as reporting a decrease.

What does a two-arm comparison estimate?

In general, a comparison of two binary outcomes can estimate how often the event occurs in each group and summarize the difference or another contrast between groups. The choice of effect measure and statistical method should fit the outcome, design, and analysis plan. Here, no two-arm estimate is posted: the registry states that values are missing or not estimable for a comparison of this binary endpoint, and the analysis count is zero. It would therefore be inappropriate to present an unposted inferential result as if it were part of the registry’s analysis.

The raw counts are still informative descriptively. They show that 2 participants in each arm reported a decrease, among 3 participants in each arm represented in the primary outcome results. However, the counts alone do not quantify uncertainty around a treatment contrast. General statistical explanation: a confidence interval communicates the precision of an estimate under a specified method and assumptions. A wide interval indicates that the data are compatible with a broad range of effects; a narrow interval indicates greater precision. The registry record does not report a confidence interval for this comparison, so its precision cannot be assessed from a posted interval.

Why does the small endpoint count matter?

With few participants, an individual outcome can have a large influence on the group summary. This makes estimates unstable and limits the information available for distinguishing a real difference from chance variation. Small groups also constrain the usefulness of statistical approximations that rely on larger samples. The registry record does not state what method, if any, was planned for analyzing the binary outcome. No sample-size justification or formal power calculation for the trial is reported in the registry record.

The study record includes a general description of planning illustrations based on fractions of the observed effect, equal allocation, a two-sided significance level of 0.05, and a normal approximation. Such calculations, when displayed, are planning illustrations rather than observed power or evidence about what the trial established. They do not show the trial’s original design assumptions. The registry record does not report the protocol’s sample-size justification, and the illustrations should not be interpreted as a retrospective measure of the trial’s ability to detect an effect.

What can randomization and masking contribute?

General statistical explanation: random allocation aims to make treatment groups comparable, on average, with respect to measured and unmeasured characteristics at the time of assignment. In a small trial, randomization does not ensure that the groups will be balanced on every characteristic. Masking can reduce some forms of bias in care, measurement, or reporting, depending on who is masked and how the outcome is obtained. The registry describes the trial as randomized and single-masked, but does not report the randomization method, allocation concealment, or the identity of the masked party. These design labels alone do not establish that all potential sources of bias were controlled.

How should the posted counts be read?

The primary endpoint figures are participant counts, not percentages, rates per person-time, or a model-based treatment effect. No new contrast should be inferred from them as though it were an adjusted analysis. In particular, the result does not state whether a decrease was judged relative to a baseline measurement using a prespecified rule. The registry record does not report adjustment for baseline values or other covariates, the handling of repeated measurements, or whether the analysis followed the randomized assignment regardless of adherence.

Safety outcomes are reported separately, with at-risk denominators that differ from the endpoint denominators. General statistical explanation: adverse-event counts and efficacy outcomes can have different observation windows, eligibility for analysis, and definitions. A difference in denominators should prompt attention to the reporting and participant flow, not an assumption about why participants were included in one result and not another. The reason for these denominator differences is not reported in the registry record.

There are no posted statistical analyses for the primary outcome, no reported estimate of uncertainty, and no analysis population description. The registry record also does not report interim analyses or a multiplicity strategy. Without these details, the outcome counts can be described, but the strength and precision of a formal comparative conclusion cannot be assessed from the registry results.

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.

R code and output

arm    <- c("Overlapping Sphincter Repair", "Biodesign Tissue Repair Graft")
n      <- c(3, 3)
events <- c(2, 2)
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  Overlapping Sphincter Repair  3  2  66.7  9.4  99.2  20.8  93.9  19.4  93.2
ARM  Biodesign Tissue Repair Graft  3  2  66.7  9.4  99.2  20.8  93.9  19.4  93.2

11. Multiplicity, Missing Data and Analysis Populations

The registry lists one secondary outcome: the number of participants reporting a decrease in incontinence episodes per week. It also reports two outcome measures in total. The relationship between the primary and secondary outcome listings, including whether they represent distinct analyses or reporting entries, is not explained in the registry record. A prespecified hierarchy of outcomes, an adjustment for multiple testing, or another multiplicity strategy is not reported in the registry record. No multiple-comparison claims should therefore be inferred from the posted results.

The registry lists zero analyses for the primary outcome, and no between-arm analysis is posted. The analysis population is not reported in the registry record. It is also not reported whether analysis was based on randomized assignment, treatment received, or another population definition. These omissions matter because the interpretation of an estimate depends on which participants are included and how they are assigned to groups for analysis.

The posted outcome results include 3 participants per arm, while the stated enrollment is 13. Safety denominators are 6 in the control arm and 7 in the graft arm. The registry record does not report participant flow, the reasons for the differing denominators, how many participants had missing primary outcome data, or how missing values were handled. It does not report whether an imputation method or sensitivity analysis was used. No assumptions about why participants do not appear in a particular outcome denominator can be made from the counts alone.

General statistical explanation: missing outcomes can affect a comparison if the chance of being observed is related to participants’ characteristics or outcomes. Methods for handling missing data rely on assumptions, so both the method and its rationale are important to interpretation. Neither is reported in the registry record. The absence of these details does not establish that any particular bias occurred; it limits assessment of whether missingness could have influenced the posted results.

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 5% reporting threshold.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: myocardial infarction (14.3%).

The registry’s safety results list 0 serious adverse events among 6 participants at risk in the overlapping-repair-alone arm and 1 serious adverse event among 7 participants at risk in the graft arm. Deaths are listed as 0 in the control arm and 1 in the graft arm. These are the posted counts and denominators; they are not an adjusted comparison of risk between groups.

Myocardial infarction is listed among the top serious adverse event terms, with 14.3%. The registry record does not provide further context in the entry for that term, such as the event’s timing, relationship to treatment, or the method used to summarize it. The presence of a serious adverse event or death in an arm does not by itself establish that the study intervention caused it. Conversely, a zero count in an arm does not prove the absence of risk.

The safety denominators differ from the primary outcome denominators. The registry record does not explain the difference, give a complete participant flow for safety follow-up, or report a formal statistical safety analysis. The small numbers mean that these results are descriptive and provide limited information about how often such events might occur. They should be read as recorded events in this trial, not as a reliable estimate of comparative safety.

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

The result directly shows that 2 participants in each arm were reported as having a decrease in weekly incontinence episodes at 12 months, among 3 participants represented in each arm’s primary outcome result. This is a description of the posted counts. It does not quantify the amount of decrease, indicate how often participants experienced episodes after treatment, or establish how durable any change was.

The matching counts do not establish that the treatments have the same effect. A small set of observations can fail to reveal a difference even when effects differ, and the registry reports no inferential comparison or measure of uncertainty. Equivalence or noninferiority requires a prespecified framework and an analysis suited to that question; neither is reported in the registry record. In the same way, the counts do not establish that the graft improves outcomes compared with repair alone.

The trial is recorded as terminated and had enrollment of 13, but the reason for termination is not reported in the registry record. The primary outcome results include fewer participants than the enrollment figure, and the explanation for this is also not reported. This prevents a clear assessment of participant follow-up and missing outcome data from the registry entry alone. It also cautions against treating the endpoint counts as a complete account of all enrolled participants.

The safety results record one serious adverse event and one death in the graft arm, and none in the control arm. These observations are not enough to establish a causal connection to treatment or to compare safety reliably. The denominators are small and differ from those for the primary endpoint. No formal safety analysis or treatment-attribution details are reported.

In general, a trial’s results are most useful when the endpoint definition, analysis population, participant flow, statistical comparison, and uncertainty are all clear. The registry record provides limited descriptive outcome information but does not report those elements in sufficient detail for a precise comparative conclusion. The appropriate reading is therefore narrow: the listed participant counts and safety events are the record’s observations, while broader claims about efficacy, equivalence, or causation are not established by them.

14. Why This Trial Matters Statistically

This trial raises a useful statistical question: what can be learned from a randomized comparison when the posted endpoint groups are very small and no between-arm analysis is available? The randomized design is relevant because random allocation is generally intended to support a fair comparison. But design intent does not remove the need for adequate outcome information, transparent participant flow, and an analysis that estimates the comparison with its uncertainty.

The endpoint is a count of participants reporting a decrease, which is intuitive as a responder-style summary. Yet its interpretation depends on a clear response definition. The registry describes a decrease in weekly episodes but does not report a threshold, measurement instrument, or analysis population. Those omissions make it difficult to know exactly how the response was classified and who contributed to the result.

The difference between the enrollment figure, endpoint denominators, and safety denominators illustrates why participant accounting matters. Such differences may arise for different reasons, but the registry does not state the reason. Without that explanation, readers cannot assess the extent of missing outcome information or determine how the analysis relates to randomized assignment.

The record also illustrates the distinction between a descriptive result and a statistical conclusion. Equal posted counts describe the observed participants; they do not demonstrate equivalence or rule out a meaningful difference. An estimate with an uncertainty interval and a clear analysis plan would be needed to interpret the comparative evidence more fully. Because no such analysis is posted, the result is informative mainly as a limited account of what was recorded, rather than as a precise answer to the comparative question.

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 primary outcome results include 3 participants in each arm, despite stated enrollment of 13. The registry record does not explain why the endpoint denominators are smaller than enrollment or report a participant flow. This limits assessment of follow-up and the possibility that missing outcomes affected the descriptive results.

The endpoint itself is not fully operationalized in the record. It describes participants reporting a decrease in weekly incontinence episodes, but does not state the measurement instrument, the threshold for a decrease, or how the report was collected. The analysis population and missing-data procedures are not reported in the registry record, nor are adjustment methods, a prespecified statistical plan, or any formal comparison between arms.

The trial is marked terminated, but the reason for termination is not reported in the registry record. The record does not report a sample-size justification or interim analyses. Although the design is identified as randomized and single-masked, the method of randomization, concealment of allocation, and identity of the masked party are not stated.

Safety denominators differ from the primary endpoint denominators, and the reason is not reported. Safety event counts are small, with no formal comparative analysis or details sufficient to attribute events to treatment. The registry lists myocardial infarction with 14.3% among top serious adverse event terms, but provides no additional context in the entry for interpreting that value.

Taken together, these limitations mean that the registry supports a description of the posted counts, but not a precise estimate of comparative effect or a broad conclusion about safety. They do not establish that bias or harm occurred; they identify details needed to judge the strength and scope of the available evidence.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Comparison of the Efficacy of a Biological Implant to Reinforce Overlapping Sphincter Repair Versus Overlapping Sphincter Repair Alone — NCT01044589.
• Registry record last updated 2017-08-01; status last verified 2017-07.
• Results first posted 2017-08-01.
• 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

NCT01044589 is a randomized, single-masked, parallel-group study comparing overlapping sphincter repair alone with repair reinforced by the Biodesign Tissue Repair Graft. The listed conditions are fecal incontinence and anal incontinence. The stated enrollment is 13, the study status is terminated, and the primary completion date is 2014-12.

The primary outcome is the number of participants reporting a decrease in incontinence episodes per week at 12 months. The posted counts are 2 of 3 in each arm. The registry lists zero analyses and indicates that values are missing or not estimable for a two-arm comparison of this binary endpoint. The reason for termination, participant flow, analysis population, missing-data approach, and formal statistical plan are not reported in the registry record.

Safety results list 0 serious adverse events among 6 at risk in the control arm and 1 among 7 at risk in the graft arm; deaths are listed as 0 and 1, respectively. These small descriptive counts do not establish comparative efficacy, equivalence, or causation.