Miromatrix Biological Mesh for Hiatal Hernia Repair: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Miromatrix Biological Mesh for Hiatal Hernia Repair (NCT02436681), a na na study. The primary outcome is Number of Subjects With a Hernia Recurrence Requiring Reoperation.

2. Clinical Question

This is a focused question about a clinically consequential form of recurrence: recurrence that leads to another operative procedure. It is narrower than asking whether any anatomical recurrence occurred. The record says recurrence was assessed using a barium upper gastrointestinal series or, in some cases, other imaging to characterize the anatomy of the esophagus. It does not report how many participants had imaging, how imaging results were adjudicated, or whether recurrence that did not lead to reoperation was counted in another outcome.

Because there is no control group, the study can describe outcomes among participants treated with MIROMESH, if those outcomes are reported. It cannot, by itself, separate outcomes associated with the device from outcomes that might also occur with other approaches to hernia repair. The primary event count is absent from the registry record, so even a descriptive estimate of recurrence requiring reoperation is unavailable in the record.

3. Trial Design

The registry identifies NCT02436681 as a prospective post-market clinical evaluation of MIROMESH for hiatal hernia repair. It lists the study as completed, with an enrollment of 50. The recorded study dates are 2015-08 for the start and 2018-07 for primary completion. The study is classified as a single-group model; allocation is listed as NA, and masking is listed as NONE. The phase is also listed as NA.

MIROMESH is the only intervention and is classified as a device. The arm description says it was used in the surgical repair of hiatal hernias. The registry summary describes MIROMESH as a noncrosslinked, acellular mesh derived from highly vascularized porcine liver, and states that it received FDA 510(k) clearance for soft-tissue reinforcement on March 31, 2014. Those statements describe the device and its regulatory context, not a comparative clinical result.

A prospective design means the study was planned to observe outcomes after enrollment rather than relying only on a retrospective review, as indicated by the registry title and description. The record does not give further detail about visit schedules, follow-up procedures, eligibility criteria, surgical technique, or the conduct of the study beyond the outcome definition. Such details are not reported in the registry record.

With one group and no masking, the reported design does not support a blinded, randomized comparison. The results, if available, would describe the experience recorded for the MIROMESH group. They would not establish how outcomes compare with another mesh, another surgical approach, or no mesh. The registry record does not report a comparator arm, so there is no concurrent reference group against which to interpret the primary outcome.

The listed enrollment is not the same as a reported denominator for the primary endpoint. The outcome entry separately notes participants lost to follow-up, participants who withdrew consent, and deaths, but does not clarify which participants were included in the endpoint analysis or how missing outcome information was handled. That distinction matters when interpreting any event count or rate.

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: 3 found to be ineligible (inclusion/exclusion) at surgery 2 Withdrew consent prior to surgery 2 Mesh not implanted per surgeon discretion 2 Canceled procedure

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Lost to follow up 10 Withdrew Consent 2 Death 2

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 Subjects With a Hernia Recurrence Requiring Reoperation, measured over 2 years.

The primary endpoint is the number of participants with a hernia recurrence requiring reoperation, within the stated timeframe of 2 years. The record defines failure of the index hernia operation as recurrence that requires another operative procedure to correct it. It says recurrence was assessed with a barium upper gastrointestinal series or, in some cases, other imaging used to characterize the anatomy of the esophagus.

This endpoint focuses on recurrence that prompted further surgery, rather than every recurrence identified by imaging. It is therefore an outcome with a specific clinical consequence, but it does not capture the full range of anatomical findings or symptoms that might occur after repair. The registry record does not explain the criteria for deciding whether a recurrence required reoperation, whether the decision was standardized, or how a recurrence was confirmed across participants.

Counting participants with the event is a binary-outcome approach: each participant is classified as having or not having the defined event, assuming the outcome status is known. The record presents the primary measure as a participant count, not as a time-to-event estimate. It does not report the number of primary events or the analyzed denominator. Without both, the frequency of the defined outcome cannot be calculated from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a participant count represent?

The primary outcome is expressed as a count of participants meeting a binary definition: recurrence requiring reoperation within the stated timeframe. In general, a binary outcome records whether each participant meets a definition, rather than measuring how often or how severely a condition occurs. The count alone is not a rate. Interpreting frequency requires a clearly defined denominator: the participants whose outcome status was included in the analysis.

Here, the record gives enrollment of 50 but does not identify the primary endpoint denominator or report its event count. The number enrolled cannot automatically be treated as the number with known two-year outcome status. The outcome entry lists participants lost to follow-up, those who withdrew consent, and deaths, but does not state how these cases were handled in the endpoint analysis. No percentage should be inferred from these registry entries.

Why does endpoint definition matter?

Statistical interpretation depends on what qualifies as an event. This endpoint is not simply any anatomical recurrence: it requires recurrence that leads to another operative procedure. The record describes imaging methods used to assess recurrence, but does not specify the criteria used to determine that reoperation was required or how the decision was made. Different definitions can lead to different event counts, so the precise definition is central to interpreting a result.

The endpoint is presented as a participant count over a two-year timeframe, rather than as a time-to-event measure. In general, time-to-event methods use both whether an event occurred and the time until it occurred, while accounting for participants whose follow-up ends before an event is observed. The registry record does not report a time-to-event analysis for the primary endpoint, and such an analysis should not be presumed.

What can a single-group study estimate?

In general, a single-group study can describe the outcomes observed among participants receiving the intervention. It does not create a concurrent counterfactual showing what would have happened to comparable participants under another treatment. Without random allocation and a comparator group, an observed outcome cannot be attributed to the device alone. Differences between this group and a separate study population could arise from differences in patient characteristics, clinical procedures, follow-up, or outcome definitions.

The registry lists a single-group model, allocation as NA, and masking as NONE. These design features mean that the study is not a randomized masked comparison. They do not, on their own, determine whether an observed outcome is valid or invalid; they determine which comparative conclusions the design can support. In this case, the primary outcome count is not reported, further limiting even descriptive interpretation.

How should uncertainty be assessed?

In general, an estimate is more informative when accompanied by an interval expressing its uncertainty. A confidence interval reflects the range of parameter values compatible with the data and statistical assumptions. It does not guarantee that the true value lies within that range, and it is not a measure of clinical importance. The registry record does not report a primary estimate or confidence interval, so precision for recurrence requiring reoperation cannot be assessed.

A hypothesis test would address a specified statistical question, such as whether a contrast differs from a null value. The record does not report a primary test result or a comparator contrast. A p-value cannot substitute for an effect estimate or its precision, and no p-value for the primary endpoint is available in the registry record.

How do planning illustrations differ from trial results?

General sample-size illustrations estimate how many participants might be needed under stated assumptions to detect a specified effect with a chosen statistical approach. The planning assumptions described for the accompanying illustrations use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is expressed as a fraction of the observed effect. These are planning illustrations, not a description of the single-group design, and they do not establish that the trial was planned or conducted with two arms.

For non-time-to-event outcomes, the stated convention is participants per arm; time-to-event illustrations use a total event count. Those conventions concern hypothetical planning calculations, not observed participant outcomes in this study. The registry record does not report the trial’s own sample-size justification or design assumptions. A planning estimate must not be described as observed power: observed power is not a substitute for reporting the actual endpoint estimate and its uncertainty.

In general, over-dispersion matters when data vary more than the statistical model expects, potentially making standard errors too small if the extra variation is ignored. That issue is relevant to some count-data models; the primary outcome is described as a participant count with a binary event definition. The registry record does not report a model for this endpoint or a method addressing over-dispersion, so no such model or adjustment can be attributed to this study.

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("MIROMESH")
n      <- c(27)
events <- c(0)
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  MIROMESH  27  0  0.0  0.0  12.8  0.0  12.5  0.1  12.3

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists 8 outcome measures and 4 analyses. It does not state how many were prespecified as primary, how the outcomes were prioritized, or whether the analyses were planned before the data were examined. It also does not report a multiplicity adjustment or a strategy for controlling the chance of false-positive findings across multiple statistical tests. Without those details, the relationship between the listed outcomes and analyses cannot be evaluated. No claim about an adjusted or unadjusted primary comparison is supported by the record.

Missing outcome information is especially relevant because the primary endpoint is defined over a two-year timeframe. The primary outcome entry lists 10 participants lost to follow-up, 2 who withdrew consent, and 2 deaths. It does not describe when these events occurred in relation to follow-up, whether outcome status was known before follow-up ended, or whether the categories overlap. It also does not specify whether participants were excluded, treated as having no event, censored, or handled by another method. These handling details are not reported in the registry record.

The record does not describe an intention-to-treat population, a per-protocol population, or another defined analysis population for the primary endpoint. Enrollment and analysis denominators are not interchangeable: an analysis denominator should reflect the participants whose outcomes were included under the stated method. Since that method and denominator are absent, the extent and possible influence of missing data cannot be assessed.

The registry record also does not report imputation methods, sensitivity analyses for missing outcomes, or a plan for handling deaths in the endpoint analysis. These details matter because different assumptions about unknown outcomes can affect interpretation. No particular assumption should be assigned to this study in their absence.

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.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: acute respiratory distress (2.4%), nausea/vomiting (2.4%).

The MIROMESH safety entry lists 41 at risk for serious adverse events and 2 affected, alongside 41 at risk for other adverse events and 10 affected. The registry also lists 2 deaths. These are descriptive figures, not a comparison with an untreated or alternative-treatment group. The record does not establish whether the events or deaths were caused by MIROMESH or by the procedure.

The listed serious adverse-event terms include acute respiratory distress at 2.4% and nausea/vomiting at 2.4%. These percentages are reported as written in the registry. The record does not provide further detail about event timing, severity grades, recurrence, clinical course, or attribution. The terms and percentages should not be interpreted as proof of a causal safety signal, nor do they establish that other events did not occur.

Counts of participants affected and counts of events are not necessarily interchangeable: one participant can potentially experience more than one event. The registry entry does not explain whether its figures count people, event episodes, or both for each listed term. The safety data therefore provide a limited descriptive account. They should be read alongside the study’s single-group design and the absence of a concurrent comparator, rather than as comparative estimates of risk.

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

The record establishes that a prospective, single-group post-market evaluation of MIROMESH for hiatal hernia repair was completed, and it defines a primary endpoint focused on recurrence requiring reoperation within 2 years. It also reports enrollment and some adverse-event figures. These registry entries describe the study’s purpose, design, and selected registry entries.

The record does not report the primary endpoint event count, its analysis denominator, or an uncertainty interval. Consequently, it does not show how often recurrence requiring reoperation occurred among participants whose outcomes were assessed, and it does not permit a judgment about the precision of that outcome estimate. The primary result cannot be reconstructed from enrollment and follow-up-status entries.

Even a complete event count from a single-group study would not establish that MIROMESH caused a particular outcome or performed better or worse than another option. A comparator is needed to make a direct comparative estimate, and random allocation is a method for supporting a fair comparison by balancing measured and unmeasured factors on average. This study has no listed comparator and no randomized allocation.

The adverse-event counts and listed terms are likewise descriptive. They do not establish causality or comparative safety. The record does not provide enough information to determine event attribution or how safety outcomes compare with those under another approach.

Thus, the defensible interpretation is limited: the registry describes the planned clinical question and study structure, but the primary outcome result needed to answer that question is not reported in the registry record. No treatment-effect conclusion should be drawn from the design description or from the safety entries alone.

14. Why This Trial Matters Statistically

This study illustrates a basic distinction between a defined outcome and a reported outcome. The registry provides a specific primary endpoint, including its clinical threshold and timeframe, but does not report the endpoint result. A clear definition is necessary for meaningful analysis, yet it cannot substitute for the event count, the analyzed denominator, and an estimate of uncertainty.

It also illustrates why enrollment does not automatically tell a reader how much information is available for an endpoint. Follow-up losses, withdrawals, and deaths are listed in the primary outcome entry, but the analysis population and handling of those cases are not described. Without those details, the relationship between the enrolled group and the endpoint result remains unclear.

The single-group design is another important statistical feature. Descriptive outcome data can be useful for documenting experience after device use, but they do not provide a contemporaneous estimate of what would have happened under another treatment. A registry reader should distinguish post-market observation from a randomized comparative trial, and distinguish each from evidence about causation.

Finally, the record makes visible the difference between planning illustrations and actual trial evidence. Statistical assumptions can illustrate the scale of a hypothetical future study, but they are not observed outcomes and do not repair missing endpoint reporting. Interpretable clinical evidence requires the result itself, its denominator, a transparent analysis approach, and enough detail to understand uncertainty and missing data.

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 immediate limitation is that the registry record does not report the primary endpoint count or the analyzed denominator. Although the primary endpoint is defined, its frequency and precision cannot be assessed. The listed enrollment of 50 does not resolve this because endpoint status and analysis inclusion are not reported.

The record lists follow-up loss, consent withdrawal, and deaths in the primary outcome entry but does not explain their timing, overlap, or analytical handling. This leaves uncertainty about how much outcome information was available and whether missingness could have affected the result. Methods for imputation or sensitivity analysis are not reported in the registry record.

The single-group, unmasked design has no concurrent comparator and no randomized allocation. It can therefore support neither a direct comparison with another repair approach nor a causal attribution of outcomes to MIROMESH. The record also does not report participant baseline characteristics, eligibility criteria, detailed follow-up procedures, or the criteria and adjudication process for reoperation.

The registry lists multiple outcomes and analyses but does not provide details of prespecification, multiplicity control, or the statistical analysis plan. The record does not report a sample-size justification for the trial or an interim-analysis plan. These omissions limit assessment of whether the analyses were aligned with a prespecified strategy. The adverse-event entries are also limited: event attribution, timing, and detailed ascertainment are not reported, and there is no comparator for interpreting the figures.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Miromatrix Biological Mesh for Hiatal Hernia Repair — NCT02436681.
• Registry record last updated 2019-09-20; status last verified 2019-09.
• Results first posted 2019-09-18.
• 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

NCT02436681 is a completed, prospective, single-group post-market evaluation of MIROMESH for hiatal hernia repair. Enrollment is listed as 50; the study start is recorded as 2015-08 and primary completion as 2018-07. The record lists no masking, no allocation, and no study phase.

The primary endpoint is the number of participants with a hernia recurrence requiring reoperation within 2 years. The registry defines the endpoint and describes imaging used to assess recurrence, but does not report the primary event count, analysis denominator, or an uncertainty estimate. It lists 8 outcome measures and 4 analyses, without details sufficient to assess multiplicity or analysis populations.

The safety entry lists serious and other adverse-event figures and 2 deaths, but does not establish attribution or provide a comparator. The record therefore describes the design and endpoint but does not provide the primary result needed to quantify recurrence requiring reoperation.