Utility of Restrata With Split Thickness Skin Graft to Reconstruct the Forearm Donor Site: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Utility of Restrata With Split Thickness Skin Graft to Reconstruct the Forearm Donor Site (NCT04829331), a randomized na study. The primary outcome is Tendon Exposure.

2. Clinical Question

The trial was intended to examine the association between use of Restrata in forearm flap reconstruction and donor-site healing and function. Its primary endpoint focused on tendon exposure, a wound finding assessed at a specified post-operative time. The comparison is between a grafting approach that includes Restrata and grafting alone; the registry record identifies randomized allocation and a parallel-group design.

The clinical question can therefore be framed as a comparison of the frequency of tendon exposure between the assigned approaches. The record describes the endpoint as a percentage of participants with tendon exposure, but does not include the number of affected participants, the denominator used for the primary analysis, or a comparison estimate. It also does not report how tendon exposure was assessed or whether the endpoint was defined using specific clinical criteria.

The registry lists an enrollment of 5 and a terminated status. These details provide context for the record but do not establish why the trial was terminated, how many participants completed follow-up, or whether the planned endpoint was assessed for every enrolled participant. Those details are not reported in the registry record.

3. Trial Design

The registry describes a randomized, single-masked, parallel-group trial of Restrata with a split-thickness skin graft versus a split-thickness skin graft alone. Participants were assigned to one of two treatment groups according to the randomized allocation. The record does not identify which people involved in the trial were masked, or describe how allocation was generated or concealed.

The recorded enrollment is 5. The trial status is terminated. The start date is 2021-04-09, and the primary completion date is 2022-01-01. The registry record does not explain the termination or report whether these dates correspond to the actual conduct of the study exactly as planned. It also does not give the number randomized to each arm, the number who received the assigned intervention, or the number followed through the primary assessment.

The primary endpoint is tendon exposure, assessed at four weeks post-operatively. The intervention is listed as a device, and the condition is recorded as Wound Heal. The brief summary describes an interest in donor-site healing and function. The record lists two outcome measures, but does not provide details for the second measure in the available outcome information.

For interpretation, randomization is intended, in general, to reduce systematic differences between treatment groups at the point of assignment. A parallel-group design means the groups are compared after assignment rather than each participant serving as their own treatment comparison. Masking can, in general, reduce the influence of knowledge about treatment assignment on assessment or care; however, because the registry does not identify who was masked, the scope of masking cannot be characterized.

The record does not report the protocol, detailed eligibility criteria, recruitment setting, sample-size justification, or planned analysis population. It also does not report whether the actual trial conduct differed from the registered design. These omissions limit assessment of how closely the trial’s implementation can be compared with its registered plan.

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 Tendon Exposure, measured over 4 weeks post-operatively.

The primary endpoint is tendon exposure, recorded as the number of participants with the event and described as the percentage of participants with tendon exposure. Its stated timeframe is four weeks post-operatively. The endpoint is intended to capture a wound finding at the forearm donor site after reconstruction.

In general, a binary endpoint classifies each participant according to whether the defined event occurred. Reporting the number of participants with the event alongside the number assessed makes the observed frequency interpretable. A percentage expresses that frequency relative to an eligible denominator, but the registry record does not report the primary endpoint’s event counts, denominator, or percentage for either treatment group. It therefore does not permit a direct comparison of tendon-exposure frequency.

The registry record also does not describe the clinical criteria for identifying tendon exposure, who assessed it, or how missing assessments were handled. These details matter because a clear and consistently applied outcome definition supports comparable assessment across groups. A fixed assessment time can make the intended comparison more specific, but the record does not clarify whether the assessment window allowed visits outside the stated time or how such visits were treated.

As a general statistical matter, the endpoint is clinically interpretable as a participant-level event, but interpretation of a group comparison depends on both the event counts and the number of participants evaluated. Without those results, no estimate of the direction or size of the primary-outcome contrast can be described. The registry record does not report a primary endpoint analysis.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does randomization contribute?

In general, randomization assigns participants to treatment groups using a chance-based process. Its purpose is to reduce the likelihood that assignment is systematically related to participant characteristics that could also affect the outcome. It does not guarantee that groups will be identical, particularly when enrollment is limited. The registry identifies the allocation as randomized, but does not report the sequence-generation method, allocation concealment, or any implementation details. The intended protection of randomization can therefore be described, but its execution cannot be evaluated from the record.

A parallel-group design compares outcomes between separate groups assigned to the study approaches. For a participant-level binary endpoint such as tendon exposure, the usual descriptive starting point is the number with the event and the number evaluated in each group. A comparison may then express the contrast in a chosen way, such as a difference in event frequencies or a relative measure. Those are general approaches; the registry record does not report a primary-outcome analysis or specify the planned effect measure.

What does the endpoint measure?

The registered primary endpoint concerns participants with tendon exposure at four weeks post-operatively. The description uses percentage language, while the listed outcome type is a count of participants. These are compatible representations of a binary endpoint: the event count is the numerator, and the number assessed is needed to interpret it as a percentage. The registry does not provide those primary-endpoint counts or denominators. It also does not report the endpoint definition, assessment procedures, or rules for classifying uncertain findings.

In general, a confidence interval describes the range of values reasonably compatible with an estimated effect under the statistical model and its assumptions. A narrow interval indicates greater precision than a wide interval, while neither width nor location alone resolves questions about clinical importance. No confidence interval for the tendon-exposure comparison is reported, so precision cannot be evaluated. A p-value, if reported, would address compatibility with a specified null model; it would not measure the probability that a treatment works. No primary-outcome p-value is reported in this record.

How should a small study be understood?

In general, estimates based on few participants can be unstable: a small change in the observed event count may substantially change the estimated frequency. Sparse data also make it difficult to distinguish a real group difference from random variation. This is a general statistical limitation, not a calculation of this trial’s precision. The registry lists an enrollment of 5, and no primary-outcome counts or uncertainty estimates are available to quantify the issue for the endpoint.

A sample-size justification is intended to explain the planning assumptions behind enrollment, including the target effect, variability or event frequency, and desired operating characteristics of the planned analysis. Such a justification is not reported in the registry record. Any sample-size figures presented as planning illustrations should be understood as calculations under stated assumptions, not as observed power or evidence that an effect was detected. The record does not report a trial-specific sample-size rationale.

What does the safety comparison show statistically?

The safety information reports counts of participants at risk and participants affected. The general principle is to interpret an event count together with its denominator and to avoid treating a zero count as proof of zero underlying risk. When counts are sparse, conventional large-sample approximations may be unreliable; exact methods can sometimes be considered, depending on the question and the analysis plan. The registry does not report a safety analysis method, effect estimate, or interval, so no inferential comparison can be reconstructed from the posted safety counts alone.

Over-dispersion is a general concern for some count outcomes: it occurs when observed variability exceeds what a simple model assumes, and may call for a model that accommodates that extra variability. The primary endpoint is described as participants with an event rather than a rate of repeated events, and the registry does not report a count-model analysis. There is therefore no basis in the record for claiming that an over-dispersion adjustment was used or was needed.

What is not specified?

The registry record reports zero analyses. It does not report a statistical analysis plan, a named analysis population, a method for handling missing data, or an approach to adjusting for baseline characteristics. It also does not report interim analyses, stopping rules, or a multiplicity procedure. These are distinct design and analysis decisions, and one should not infer their use from the randomized designation or the posted outcome description. With no primary results and no analysis details, the methods used to compare the groups cannot be assessed.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures, but only the tendon-exposure endpoint is described in the available outcome details. The second outcome’s definition, timing, and results are not reported in the registry record. The record reports zero statistical analyses. It does not state whether one outcome was designated as the sole basis for inference, whether any secondary outcomes were tested, or whether an adjustment for multiple comparisons was planned.

In general, multiplicity arises when several outcomes, time points, groups, or analyses are examined. Repeated testing can increase the chance of a chance finding if results are interpreted as though only one test had been conducted. A prespecified testing strategy or adjustment can help address that issue, but the record does not report one. The primary endpoint has a stated four-week post-operative timeframe, while the broader count of outcome measures alone does not reveal how many comparisons were intended.

Missing-data methods are also not reported. The registry does not give the number assessed for tendon exposure, the number missing, the reasons for any missing assessments, or how missing outcome values were treated. The analysis population is not reported: it is not stated whether the planned analysis included all randomized participants, only those who received the assigned approach, or another group. No interim analyses or related decision rules are reported. These omissions prevent assessment of whether missingness or multiple testing could have affected the interpretation of the planned or observed results.

11. 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

Serious events with the highest arm-level rate: infection (33.3%).

The registry reports 1 serious adverse event among 3 participants at risk in the Restrata-with-a-split-thickness-skin-graft group and 0 among 2 participants at risk in the split-thickness-skin-graft-alone group. Other adverse events are listed as 0 among 3 at risk and 0 among 2 at risk, respectively. Deaths are listed as 0 in both groups. These are descriptive counts; they do not by themselves establish a comparative safety effect or a causal relationship to treatment.

In general, an adverse-event count should be read together with its at-risk denominator, the observation period, and the event definition. A zero count means no event was recorded among the listed participants at risk; it is not proof that no event could occur. With a small study, the counts provide limited information about uncommon events and cannot support a precise estimate of comparative safety.

Infection is listed among the top serious terms at 33.3%. The registry record does not report the denominator or identify the treatment arm associated with that term. It is therefore not possible to interpret that percentage as an arm-specific rate from the record. Detailed event timing, narratives, and relatedness assessments are also not reported.

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

The registry record establishes that a randomized, single-masked, parallel-group trial was registered to compare Restrata with a split-thickness skin graft against a split-thickness skin graft alone. It identifies tendon exposure at four weeks post-operatively as the primary endpoint and describes a broader interest in donor-site healing and function. These design details clarify the intended comparison, but they do not provide the primary-outcome result.

The posted information does not report how many participants had tendon exposure in either group, the denominator assessed in each group, or a statistical comparison. It therefore cannot show the direction or magnitude of an observed difference, nor the precision of any treatment-effect estimate. The registry also does not report results for the second outcome measure or any statistical analyses. No conclusion about the effect of either approach on healing or function can be made from the primary-outcome information available.

The safety counts describe the events recorded among the listed participants at risk. They do not establish that the interventions caused or prevented events. The serious-event counts and the listed infection term should be read with their limited denominators and with the missing arm attribution for the infection percentage in mind. The record does not give enough detail to assess event relatedness or compare safety precisely.

The enrollment of 5 and terminated status are relevant context, but the registry does not state the reason for termination, the number completing follow-up, or whether the intended outcome assessment was completed. These gaps mean the status cannot be used to infer why results are absent or what the trial would have found with further enrollment. The findings that can be stated are limited to the registered design and the descriptive safety figures; claims about benefit, lack of benefit, or comparative effectiveness are not supported by the posted primary results.

13. Why This Trial Matters Statistically

This trial is statistically instructive because it pairs a clear randomized comparison with a sparse registry record. Randomization identifies the intended framework for comparing the treatment groups, while the primary endpoint specifies a participant-level wound outcome at a defined post-operative time. Those features help clarify the question the study was designed to address.

At the same time, an endpoint definition is not a result. Without event counts, denominators, and an estimate of the group contrast, readers cannot judge the observed pattern or its precision. This distinction is central to clinical-trial interpretation: a registered question, a completed assessment, a reported estimate, and evidence supporting a conclusion are not interchangeable. The record reports zero statistical analyses, so the intended comparison cannot be evaluated through inferential results.

The limited enrollment and safety denominators also illustrate why event counts need context. In general, small studies can describe what was recorded but often provide little precision for comparative estimates, especially when outcomes are uncommon. A zero count in a small group does not establish the absence of risk. The safety information is therefore best read descriptively rather than as a definitive comparison.

The terminated status and lack of an explanation further demonstrate the value of transparent reporting. The reason for termination, data completeness, missing-data handling, and analysis populations are not reported in the registry record. Without those details, readers cannot distinguish among possible explanations for absent primary results. The statistical lesson is to separate what the registration establishes—the intended design and endpoint—from what the results establish. In this record, the former is described more fully than the latter.

14. Limitations

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

The primary limitation for interpreting this trial is that the registry record does not report the primary endpoint results. Although tendon exposure is named as the primary measure and its assessment time is stated, there are no group-specific event counts, denominators, percentages, or comparison estimates. The endpoint’s clinical definition and assessment process are also not reported.

The record lists an enrollment of 5 and a terminated status, but does not report the number assigned to each group for the primary analysis, the number completing follow-up, or the reason for termination. It is not possible to determine from the record whether all planned assessments occurred or whether incomplete follow-up contributed to the absence of results.

Only limited safety counts are available. The registry does not report detailed event descriptions, timing, relatedness, or the arm attribution and denominator for the listed infection percentage. Such omissions restrict interpretation of the safety information beyond its descriptive counts.

Other trial details important to interpretation are not reported in the registry record, including detailed eligibility criteria, the identity of those masked, allocation procedures, a sample-size justification, an analysis plan, missing-data methods, analysis populations, multiplicity procedures, and interim analyses. The record lists two outcome measures but provides details for only one in the available outcome information. These limits prevent a comprehensive appraisal of the intended statistical methods and the completeness of outcome reporting.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Utility of Restrata With Split Thickness Skin Graft to Reconstruct the Forearm Donor Site — NCT04829331.
• Registry record last updated 2023-04-18; status last verified 2023-03.
• Results first posted 2023-04-18.
• 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.

18. Record Summary

The registry identifies NCT04829331 as a randomized, single-masked, parallel-group trial of Restrata with a split-thickness skin graft versus a split-thickness skin graft alone for forearm donor-site reconstruction. Enrollment is 5, and the status is terminated. The primary endpoint is tendon exposure at four weeks post-operatively, described as the percentage of participants with the event.

The registry record does not report primary-outcome results or statistical analyses. It lists 1 serious adverse event among 3 participants at risk in the Restrata-with-graft group and 0 among 2 at risk in the graft-alone group; other adverse events and deaths are listed as 0 in both groups. Infection is listed among the top serious terms at 33.3%, without reported arm attribution or denominator. The reason for termination and key analysis details are not reported.