Study of GORE® BIO-A® Fistula Plug for Use in Anal Fistula Repair: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study of GORE® BIO-A® Fistula Plug for Use in Anal Fistula Repair (NCT01290666), a registered phase not stated study. The primary outcome is Fistula Closure.

2. Clinical Question

In plain terms, the study was intended to describe whether fistula closure was recorded at the specified follow-up after plug placement. Its observational design can describe outcomes among patients receiving the device, but without a control group it cannot isolate the effect of the device from other influences. Those influences could include patient characteristics, care received alongside the procedure, follow-up, or how outcomes were assessed; the registry record does not provide details to evaluate them. The record identifies duration of drainage post procedure as a secondary outcome, but does not give its result. It also does not report the primary outcome analysis population or the method used to determine closure. Consequently, the central question can be identified, but its answer cannot be recovered from the registry record.

3. Trial Design

The registry describes a multicenter, prospective, observational study of the GORE® BIO-A® Fistula Plug for use in anal fistula repair. It lists enrollment of 93 and the condition as anal fistula. The study began in 2011-03, primary completion was recorded in 2014-05, and its status is TERMINATED. The reason for termination is not reported in the registry record.

All patients in the study received the plug. No separate control intervention is described, and allocation is not stated. The record therefore does not describe a randomized comparison. The recorded intervention group is not a like-for-like control comparison: outcomes in that group cannot be contrasted with outcomes under another assigned treatment using this record.

The primary outcome is fistula closure, measured as a number of participants, with a timeframe of 12 months post procedure. Duration of drainage post procedure is listed as a secondary outcome. The registry lists 2 outcome measures, but does not provide an analysis for either in the posted record. It lists 0 analyses. The primary outcome description does not specify how closure was defined or assessed, and the population field is blank.

The registry record does not report participant eligibility criteria, baseline characteristics, the number who completed follow-up, or how missing follow-up outcomes were handled. It also does not report the statistical analysis plan, sample-size justification, or interim analyses. These absences limit assessment of how the study was conducted and how representative the recorded outcomes might have been. In particular, because no outcome analysis is posted, the study design can be described, but the primary clinical outcome cannot be estimated from the 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.

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 Fistula Closure, measured over 12 months post procedure.

The primary endpoint is fistula closure, recorded as a number of participants, at 12 months post procedure. It is a binary outcome at the participant level: a participant either meets the study's closure criterion or does not. The registry record does not state the operational definition of closure, the examination or assessment used, or whether confirmation was required. Those details are important for understanding exactly what the endpoint represents and whether assessments were applied consistently.

In general, a closure endpoint offers a direct way to summarize the outcome of a repair procedure. Counting participants who meet a prespecified definition can make the result understandable, while the follow-up time gives the outcome a time context. The endpoint is useful only to the extent that its definition, timing, and assessment are clear. The registry names the timeframe but leaves the description and population fields blank.

No closure count, proportion, confidence interval, or statistical analysis is reported in the registry record. As a result, it is not possible to describe the observed closure frequency or its precision. The record also cannot establish how many participants contributed evaluable endpoint data or how any unavailable assessments were treated. The endpoint's stated purpose is identifiable, but its observed result and the strength of evidence around it are not available.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does an observational design mean?

The registry calls this study prospective and observational. In general, a prospective study defines what will be observed and follows participants forward in time. An observational study records care or outcomes without describing randomized assignment to different interventions. Here, the registry says all patients received the GORE® BIO-A® Fistula Plug, and allocation is not stated. No control treatment is listed. Thus, the record does not offer a randomized treatment contrast or a like-for-like comparison between groups.

General statistical interpretation: a treated-group outcome can describe what was observed among the people studied, if the outcome data and analysis are reported. It does not, by itself, estimate the outcome that would have occurred under a different treatment. Differences in patient characteristics, clinical care, and outcome assessment can complicate comparisons when treatment assignment is not randomized. The record does not provide details to assess those factors.

What would a binary endpoint analysis describe?

The primary endpoint is a number of participants with fistula closure at 12 months post procedure. This is a binary participant-level outcome: each assessed participant is classified according to whether the closure criterion is met. In general, an analysis might report the number meeting the criterion and the number assessed, along with an estimate and a confidence interval. A confidence interval communicates the uncertainty around an estimate under the assumptions of the analysis; it is not a guarantee that the true value lies within its bounds.

The posted registry record gives no closure count, denominator for the outcome analysis, estimate, or confidence interval. The endpoint description does not set out the closure definition, and the population field is blank. These omissions prevent reconstruction or appraisal of an endpoint analysis. The registry enrollment of 93 is not a substitute for an outcome denominator: the record does not say how many participants reached the specified follow-up or contributed data.

What can be inferred from the analysis listing?

The registry lists 0 analyses. This is distinct from a result showing no effect or no events; it indicates that no analysis is listed in the record. No primary-outcome test, effect estimate, p-value, or uncertainty interval is reported. The record also does not state the statistical analysis plan, whether any interim analyses were conducted, or how the primary endpoint would be analyzed.

General statistical context: a p-value, when reported, measures how compatible data are with a specified statistical model and null hypothesis. It does not measure the size or clinical importance of an effect. A confidence interval adds information about precision and plausible values under the model. Neither measure can be interpreted when the relevant result and analysis are absent.

How should planning illustrations be understood?

Any sample-size planning illustration associated with this record is a hypothetical planning calculation, not an observed result and not the study's own sample-size justification. The stated assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a stated fraction of the observed effect. The record does not report a randomized two-arm comparison, and all patients received the plug. Those assumptions therefore should not be mistaken for the actual design or for evidence that the study had a particular level of power.

General statistical context: power is a design-stage probability of detecting an effect under specified assumptions. It is not a measure of whether a completed study's result is reliable, and a planning calculation is not observed power. Sample-size illustrations depend on the assumed effect and analysis model; they do not replace a reported outcome estimate with its uncertainty. The record does not provide a trial-specific sample-size justification or an observed closure effect for interpreting such a calculation.

What does the registry tell readers about safety analyses?

The adverse-event record gives numbers at risk and numbers affected for serious and other adverse events in the GORE® BIO-A® Fistula Plug group. These are descriptive counts, not a comparative safety analysis, because no control group is described. The record does not list serious adverse-event terms, and the death count is not reported in the registry record. It does not explain event definitions, collection procedures, or whether affected counts refer to participants or events. In general, safety counts need their definitions and observation period to be interpreted fully.

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("GORE® BIO-A® Fistula Plug")
n      <- c(55)
events <- c(35)
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  GORE® BIO-A® Fistula Plug  55  35  63.6  49.6  76.2  50.4  75.1  50.4  75.1

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 2 outcome measures: fistula closure as the primary outcome and duration of drainage post procedure as a secondary outcome. It does not report analyses for these outcomes. The record does not describe a statistical plan for handling multiple outcomes, specify any testing hierarchy, or say whether adjustments for multiple comparisons were planned. Therefore, the approach to multiplicity is not reported in the registry record.

In general, evaluating multiple outcomes can increase the chance of finding an apparently notable result by chance when each is tested separately. A prespecified hierarchy or adjustment can address that issue, but no such method is described. Since no outcome analyses or p-values are posted, there is also no multiplicity-adjusted or unadjusted result to interpret.

The registry does not report the number with available follow-up at 12 months, the number with missing endpoint data, or the reasons for any missing data. It does not describe imputation, censoring, or other missing-data methods. The population field for the primary outcome is blank, so the analysis population cannot be identified from the record. It is not possible to tell whether an analysis would have included all enrolled patients, only those with follow-up, or another defined group.

These gaps matter because missing outcomes can affect both the estimated event frequency and its precision. General statistical context: the consequences depend on how much data are missing and on the relationship between missingness and outcomes. Without follow-up completeness and a stated handling method, that uncertainty cannot be assessed. The registry's enrollment of 93 does not establish the denominator for the primary endpoint.

12. 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 0% reporting threshold.

Most frequent non-serious adverse event terms

For the GORE® BIO-A® Fistula Plug group, the registry lists 93 at risk for serious adverse events and 0 affected. For other adverse events, it lists 93 at risk and 45 affected. These are the recorded counts; no percentages or comparative estimates are reported in the registry record.

The serious-event count of 0 means the registry reports no affected participants in that category for this group. It does not establish that serious events are impossible, nor does it measure comparative risk without a control group. The record does not list serious adverse-event terms. The death count is not reported in the registry record.

The other-adverse-event entry reports 45 affected, but the registry does not explain the event definitions, the nature of those events, or whether the affected count represents people with at least one event or events themselves. It also does not describe the observation period or how events were collected. These details are needed for a complete interpretation. Because the study has no described comparator, the counts are descriptive and do not show whether the device changed adverse-event risk relative to another approach.

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

The record tells readers what the study set out to observe: fistula closure at 12 months post procedure among patients receiving the GORE® BIO-A® Fistula Plug. It also describes the study as multicenter, prospective, and observational, lists enrollment of 93, and identifies duration of drainage post procedure as a secondary outcome. The safety record supplies counts for serious and other adverse events in the device group.

What the record does not provide is the primary endpoint result. There is no reported closure count, outcome denominator, estimate, confidence interval, or analysis. The secondary outcome is named but has no reported result. Accordingly, the record cannot establish the frequency or precision of closure, and it cannot show whether that outcome differs from what would occur under another treatment or without the device.

Even a reported outcome from a single treated group would describe observed experience rather than a controlled causal effect. General statistical context: to attribute a difference in outcomes to an intervention, a comparison must address what would have happened to comparable participants under an alternative. This record does not describe such a comparison. It also does not report enough information about eligibility, participant characteristics, follow-up completion, endpoint definition, or analysis populations to judge how the observed study group relates to other patients.

The serious and other adverse-event counts should likewise be read as descriptive entries, not comparative safety estimates. The registry does not provide serious-event terms, and the death count is not reported. The study's TERMINATED status is recorded, but its reason is not reported in the registry record. That status alone does not explain the missing efficacy analysis or imply a particular clinical outcome. Overall, the record supports a description of the research question and selected study details, but not a conclusion about effectiveness or comparative safety.

14. Why This Trial Matters Statistically

This study is statistically informative as an example of the distinction between a clearly stated outcome question and a reported outcome analysis. The registry identifies fistula closure at 12 months post procedure as primary, and specifies that the measure is a number of participants. Yet the record lists 0 analyses and does not report the closure count. Without an outcome estimate and its denominator, readers cannot assess either the observed result or its precision.

The observational design also shapes what a result could mean. All patients received the GORE® BIO-A® Fistula Plug, and the record does not describe a control group or random allocation. Even if a treated-group closure outcome were posted, it would not alone quantify a comparative treatment effect. This distinction is central when interpreting clinical outcome data: describing what happened in a group is different from estimating what the intervention caused.

The record also illustrates why endpoint details and follow-up information matter. The primary endpoint's timeframe is stated, but its definition and analysis population are not. Follow-up completeness and handling of missing outcome data are not reported. Those omissions limit assessment of whether the endpoint was consistently measured and how representative any result might be.

Finally, the safety entries show why counts need context. The registry records serious and other adverse-event counts, but does not report serious-event terms, the death count, or a comparator. Those data can be described but not used to estimate relative risk. The statistical importance of this record lies in clarifying the boundaries of what can be concluded: the study question and some design and safety information are available, while the primary outcome analysis is not.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The most consequential limitation for interpretation is that the registry record does not report a primary endpoint result or any analysis. Fistula closure is named as the outcome, but its count, analysis denominator, estimate, and uncertainty are absent. The secondary outcome, duration of drainage post procedure, is also listed without a result. The registry records 0 analyses.

The absence of a comparator limits causal interpretation. All patients received the GORE® BIO-A® Fistula Plug; allocation is not stated, and the record does not describe a like-for-like control comparison. The study is observational, so even a reported outcome would describe the treated group rather than establish a comparative effect.

Important endpoint and population details are not reported in the registry record. The closure definition is not described, and the primary outcome population field is blank. Eligibility criteria, baseline characteristics, follow-up completion, reasons for missing data, and missing-data methods are also not reported. The enrollment figure does not establish how many participants contributed to the 12-month endpoint.

Further limitations include the absence of a reported statistical analysis plan, sample-size justification, or interim-analysis information. The study is marked TERMINATED, but the reason for termination is not reported. The safety record gives counts but does not describe event definitions, collection procedures, serious-event terms, or the death count. Without these details, neither outcome interpretation nor safety assessment can be complete.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Study of GORE® BIO-A® Fistula Plug for Use in Anal Fistula Repair — NCT01290666.
• Registry record last updated 2017-01-13; status last verified 2016-11.
• Results first posted 2017-01-13.
• 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 describes a multicenter, prospective, observational study of the GORE® BIO-A® Fistula Plug for anal fistula repair. Enrollment is listed as 93; all patients in the study received the plug. The study began in 2011-03, primary completion was recorded in 2014-05, and status is TERMINATED.

Fistula closure, measured as a number of participants at 12 months post procedure, is the primary outcome. Duration of drainage post procedure is listed as a secondary outcome. The record lists 2 outcome measures and 0 analyses, and does not report either outcome result. It also does not report the reason for termination, the primary endpoint definition, or the outcome analysis population.

For the plug group, the adverse-event record lists 0 affected among 93 at risk for serious adverse events, and 45 affected among 93 at risk for other adverse events. Serious-event terms are not listed, and the death count is not reported in the registry record. The available information supports a description of the study design and recorded safety counts, but not an estimate of fistula closure or a comparative treatment effect.