Study of Phasix™ Mesh for VHWG Grade 3 Midline Hernia Repair: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study of Phasix™ Mesh for VHWG Grade 3 Midline Hernia Repair (NCT02720042), a na na study. The primary outcome is Number of Participants With One or More Surgical Site Occurrence Within 3 Months of Index Procedure.

2. Clinical Question

The study’s stated purpose is to collect additional data on safety and performance of Phasix™ Mesh in people requiring this type of repair. Its primary endpoint is a participant count for a composite of specified surgical site occurrences, rather than a comparison between treatments. The registry also lists secondary outcomes concerning occurrences through 24 months, hernia recurrence, surgical site infection, pain, device-related adverse events, reoperation and patient-reported quality of life.

Because the study has no control arm, it cannot directly estimate how outcomes would differ under another repair strategy. Its results, when reported, describe outcomes among participants treated with the mesh in this investigation. The registry record does not report the primary endpoint count or a statistical comparison, so the primary question cannot be answered from the record details.

3. Trial Design

NCT02720042 is a prospective, multi-center, single-arm clinical investigation of Phasix™ Mesh for VHWG Grade 3 midline hernia repair. The registry classifies the study as post-market and records the phase as NA. Its allocation is also recorded as NA, and masking is listed as NONE. The intervention is the device Phasix™ Mesh; the arm description says patients were treated with the mesh for hernia repair.

The registry lists enrollment as 84. The recorded study start is 2016-03-23, primary completion is 2017-07-31, and status is COMPLETED. These registry fields describe the study record; they do not establish which participants contributed data to each outcome or analysis. The analysis populations, follow-up completeness and outcome-specific denominators are not reported in the registry record.

The primary outcome is the number of participants with one or more surgical site occurrences within 3 months of the index procedure. The registry lists secondary outcomes covering surgical site occurrence within 24 months, hernia recurrence, surgical site infection, pain change from baseline to 24 months, device-related adverse events, reoperation due to the index hernia repair, Carolinas Comfort Scale results at 1, 3, 12 and 24 months, and EQ-5D change from baseline to 24 months. The record lists 12 outcome measures overall, but detailed results for those measures are not reported in the information available for this analysis.

With no randomized or concurrent control arm, this design is descriptive rather than a controlled treatment comparison. It can report observed event counts and patient-reported outcomes in the studied group if those results are available, but it does not by itself separate treatment effects from other explanations for outcomes. Further information about study conduct, eligibility, follow-up procedures beyond those stated for the primary outcome, or the statistical analysis plan is 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.

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 Number of Participants With One or More Surgical Site Occurrence Within 3 Months of Index Procedure, measured over 3 Months.

The primary endpoint is the number of participants with one or more surgical site occurrences within 3 months of the index procedure. The registry defines a surgical site occurrence as hematoma, seroma, surgical site infection, wound dehiscence, skin necrosis or fistula requiring intervention. For analysis, the aggregate outcome is based on whether there is evidence of a surgical site occurrence in the same location as the index procedure. The record states that occurrences are assessed by physical examination at each study visit through 3 months.

This endpoint combines several types of complications into a participant-level outcome. As a general statistical concept, a composite can capture whether a participant experiences any event from a prespecified group, rather than focusing only on a single complication type. The result should therefore be interpreted as the occurrence of at least one qualifying event, not as the total number of complications or as a measure of severity. The registry record does not report the primary endpoint count, its denominator, or an uncertainty interval, so the observed frequency and its precision cannot be assessed from the record details.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The study is a single-group investigation, not a randomized comparison. That distinction determines what the results can estimate. If outcome data are reported, the direct descriptive target is the frequency of each outcome among the analyzed participants treated with Phasix™ Mesh. Without a control group, the study cannot estimate a between-group treatment contrast. Other features of the participants, their care or the course of the condition could also contribute to observed outcomes.

What does a participant count represent?

The primary endpoint is a count of participants with one or more qualifying surgical site occurrences within 3 months. It is not a count of every event. A participant with multiple qualifying occurrences still meets the participant-level endpoint; event-level totals would be a different measure. The registry definition combines hematoma, seroma, surgical site infection, wound dehiscence, skin necrosis and fistula requiring intervention, at the same location as the index procedure. The record says assessment is by physical examination at each study visit through 3 months.

For a binary outcome, a participant is classified as having or not having the defined event during the specified window. A proportion can describe the fraction with the event among participants with evaluable data. To interpret such a proportion, readers need both the number meeting the definition and the denominator included in that analysis. The registry record does not report the primary outcome count or its denominator. The enrollment field alone does not establish the number assessed or analyzed for that endpoint.

What would an uncertainty interval tell readers?

General explanation: a confidence interval gives a range of estimates compatible with the observed data under the chosen statistical method and its assumptions. For a single-group event proportion, it can communicate how precisely the event frequency is estimated. A narrower interval generally indicates greater precision, while a wider interval indicates more uncertainty. It does not account automatically for systematic differences from a target population, missing outcome data or the lack of a comparator. No confidence interval for the primary endpoint is reported in the registry record.

Why does over-dispersion matter?

General explanation: over-dispersion occurs when observed variability is greater than a statistical model expects. If an analysis assumes less variability than the data contain, its uncertainty estimates may be too small. This is especially relevant to count outcomes analyzed with models that make assumptions about the distribution of events. The primary endpoint is a participant-level binary count, and the registry record does not report a model or an over-dispersion assessment. It would therefore be inappropriate to claim that over-dispersion was tested, found or addressed.

What statistical analysis is documented?

The registry record lists no analyses. The statistical plan, including any model choice, covariate adjustment, confidence-interval method, hypothesis tests, interim analyses and prespecified analysis populations, is not reported in the registry record. Those details should not be inferred from the endpoint definitions or from the study’s completed status. The registry’s outcome descriptions identify what was intended to be measured, but they do not establish how each outcome was analyzed.

How should planning illustrations be read?

The stated planning assumptions describe illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. For non-time-to-event outcomes, the illustrations are expressed as participants per arm for 80% power or other listed planning targets; time-to-event illustrations use total events. These are planning calculations, not observed trial outcomes, and not observed power. They also do not describe the actual single-arm design, which has no allocation between two study arms. The numerical planning results are not reported in the registry information.

In general, sample-size calculations depend on assumptions about the effect to detect, variability or event frequency, significance threshold, power target and analysis method. Changing those assumptions changes the planned sample size. A planning illustration cannot establish that a study was adequately powered for an outcome unless its assumptions and relationship to the actual design are justified. The registry record does not report the study’s own sample-size justification.

Finally, outcomes measured at different follow-up times can have different analysis denominators because participants may have incomplete follow-up. General statistical practice requires clear reporting of the eligible population, number assessed and handling of missing values for each outcome and time point. Those details are not reported in the registry record, so no specific missing-data method or analysis population can be attributed to this investigation.

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("Phasix™ Mesh")
n      <- c(84)
events <- c(22)
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  Phasix™ Mesh  84  22  26.2  17.2  36.9  18.0  36.5  18.0  36.5

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 12 outcome measures, including a primary surgical site occurrence endpoint and secondary outcomes covering complications, recurrence, pain, device-related adverse events, reoperation and patient-reported quality of life. When a study evaluates multiple outcomes, the chance of at least one apparently notable result can increase if many statistical tests are conducted. General methods for addressing multiplicity include prespecifying a primary outcome, adjusting significance thresholds or treating secondary analyses as exploratory. The registry record does not report whether any multiplicity strategy was prespecified or used. It lists no analyses, so no testing hierarchy or adjustment can be inferred.

The primary outcome is defined for assessment through 3 months, while some secondary measures extend to 24 months. Follow-up at different times can lead to different numbers of evaluable participants. The registry record does not report the outcome-specific denominators, completeness of follow-up, reasons for missing data or methods used to handle missing observations. It is therefore not possible to determine whether analyses used complete cases, imputation, another approach or a particular rule for classifying unobserved outcomes.

The record also does not report analysis populations, such as whether results were based on all enrolled participants, treated participants or participants with available outcome data. These distinctions matter because exclusions or incomplete follow-up can affect which participants contribute to an estimate. Without outcome counts, denominators and analysis methods, neither the influence of missingness nor the robustness of findings can be evaluated. These omissions are not evidence that a particular method was or was not used; the relevant details are not reported in the registry record.

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 2% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: incisional hernia (6.0%), stomal hernia (4.8%), abdominal wall abscess (3.6%), device related infection (2.4%), post procedural pneumonia (2.4%).

The registry lists 40 affected in the serious adverse-event group among 84 at risk, and 35 affected in the other adverse-event group among 84 at risk. It also lists 3 deaths. These are descriptive safety figures for the study group, not comparisons against another treatment. The record details do not establish whether a participant could be counted in both adverse-event groups, nor do they describe the timing, duration or individual clinical circumstances of the events.

The listed serious-event terms are Incisional Hernia at 6.0%, Stomal Hernia at 4.8%, Abdominal Wall Abscess at 3.6%, Device Related Infection at 2.4%, Post Procedural Pneumonia at 2.4% and Postoperative Wound Infection at 2.4%. These percentages should be read as registry-listed term frequencies, not as evidence that the terms are mutually exclusive or as a controlled comparison. The record does not report the corresponding counts for each term in the information.

Serious adverse events and the primary surgical site occurrence endpoint are different reporting concepts. The primary endpoint has its own specified event definition and 3-month window; the serious adverse-event listing is not a substitute for that result. No causal attribution or comparative safety conclusion follows from the listed counts alone. Further details about event definitions, attribution and follow-up are not reported in the registry record.

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

This investigation describes a prospective, multi-center, single-arm study of Phasix™ Mesh for VHWG Grade 3 midline hernia repair. The registry records enrollment as 84 and identifies a primary endpoint based on surgical site occurrences through 3 months. It also lists secondary outcomes and descriptive safety information. Those features show what the study was intended to examine and what safety figures the record lists.

The primary endpoint result itself is not reported in the registry entries. Without the event count, analysis denominator and an estimate of uncertainty, readers cannot determine the observed primary endpoint frequency or how precisely it was estimated. The listed safety figures also do not provide a comparison with another repair strategy. They should be understood as observations in the study group, not as estimates of comparative effects.

As a general statistical distinction, an outcome observed after treatment does not by itself show what would have occurred without that treatment or under an alternative. A concurrent comparator can help estimate such a contrast, subject to the design and analysis; this investigation has no separate comparator arm. Its record therefore cannot establish that the device caused an outcome or that outcomes would differ from those under another approach.

The record also does not report statistical analyses, uncertainty intervals, detailed outcome results, analysis populations or missing-data methods. The listed sample-size assumptions describe planning illustrations, not evidence of observed power or trial effectiveness. Conclusions should remain limited to the study design, defined endpoints and descriptive safety figures that the registry records. Additional outcome and analysis details are needed to assess the primary endpoint, the precision of estimates and the completeness of follow-up.

14. Why This Trial Matters Statistically

This trial is statistically notable because its primary endpoint is a participant-level composite in a single-arm post-market investigation. The endpoint combines several specified surgical site occurrences, each requiring intervention under the registry definition, and focuses on whether a participant experienced at least one qualifying event within 3 months. Understanding the unit of analysis prevents a participant count from being mistaken for a count of all complications.

The design also clarifies the boundary between descriptive evidence and comparative evidence. A single-group study can characterize outcomes among treated participants, but it does not include a control arm from which to estimate a treatment contrast. That distinction is important when reading safety counts and when considering what conclusions the record can support. The listed safety figures are observations in the study group, not comparative estimates.

The record’s outcome list spans clinical events and patient-reported measures, with some outcomes extending through 24 months. In general, outcomes with different definitions and follow-up windows require clear reporting of their denominators, missingness and analysis methods. The registry entries do not provide those results or methods, which limits assessment of precision and completeness.

Finally, planning calculations must be separated from observed evidence. The stated assumptions describe two-arm planning illustrations, whereas the investigation itself is single-arm. Such illustrations may help explain hypothetical sample-size planning under specified assumptions, but they do not demonstrate observed power or replace the unreported outcome estimates. The statistical significance of the study record lies partly in recognizing these distinctions and not reading more into descriptive information than its design supports.

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 central limitation for interpreting the primary outcome is that its result is not reported in the registry entries. The registry defines the endpoint and assessment window, but does not give the number of participants meeting the definition, the denominator analyzed or an uncertainty estimate. The primary question therefore cannot be answered from these details.

The study has no comparator arm and is not a randomized comparison. As a result, even complete outcome counts would describe the study group rather than establish a contrast with another treatment or repair strategy. The registry record also does not report eligibility criteria in detail, baseline characteristics, the statistical analysis plan or analysis populations. These omissions limit assessment of who contributed to the results and how applicable any estimates would be beyond the participants studied.

The record lists safety counts and serious-event terms, but does not report detailed event timing, individual overlap across categories, attribution methods or additional event-level information. It also does not report outcome-specific follow-up completeness, reasons for missing observations or methods for handling missing data. These details are particularly relevant when interpreting measures collected at multiple follow-up times.

Although planning assumptions are described, the study’s own sample-size justification is not reported in the registry record. The listed planning illustrations are not evidence of observed power and are based on two-arm assumptions that do not match the single-arm study design. The registry also lists 12 outcome measures but does not report analyses or a multiplicity strategy. These limitations mean that neither the primary endpoint’s precision nor the interpretation of multiple outcomes can be assessed from the available record details.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Study of Phasix™ Mesh for VHWG Grade 3 Midline Hernia Repair — NCT02720042.
• Registry record last updated 2020-09-25; status last verified 2020-09.
• Results first posted 2020-06-17.
• 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

NCT02720042 is a completed, prospective, multi-center, single-arm, post-market investigation of Phasix™ Mesh for VHWG Grade 3 midline hernia repair. The registry records enrollment as 84, a start date of 2016-03-23 and primary completion on 2017-07-31. Masking is listed as NONE and allocation as NA.

The primary endpoint is the number of participants with one or more surgical site occurrences within 3 months of the index procedure. The registry also lists secondary outcomes involving complications, recurrence, pain, reoperation, device-related adverse events and quality of life. Its safety information lists 40 affected in the serious adverse-event group among 84 at risk, 35 affected in the other adverse-event group among 84 at risk, and 3 deaths.

The primary endpoint result, detailed outcome analyses, analysis populations and missing-data methods are not reported in the registry record. The single-arm design supports descriptive reporting, not a controlled treatment comparison.