Human Participant Study of Prototype Non-medicated Multilayer Foam Dressings on Intact Skin: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Human Participant Study of Prototype Non-medicated Multilayer Foam Dressings on Intact Skin (NCT06700850), a randomized na study. The primary outcome is Number of Participants With Acceptable Dressing Presence at Day 7.

2. Clinical Question

This is a device-performance question on healthy, intact skin, not a question about treatment of a wound or a medical condition. The planned comparisons keep dressing shape and placement site paired: rectangle dressings are compared on knees, and square dressings on thighs. That structure matters when interpreting the question. Participants received both dressings in each pair, so the comparison is not simply between separate groups of people assigned to receive only one dressing. The side receiving each dressing was randomized within each pair.

The stated aim is framed as non-inferiority: the prototypes were to be assessed for whether their ability to remain acceptably present was not worse than that of the established comparison devices. A non-inferiority conclusion requires a prespecified margin and an appropriate estimate with uncertainty. The margin and the comparative results are not reported in the registry record, so the stated aim cannot be evaluated from the reported information alone.

3. Trial Design

The registry describes an open-label, prospective, comparative study, with randomized allocation and no masking. It lists 135 participants, a status of completed, and a phase of NA. The listed condition is healthy. The study was sponsored by Smith & Nephew, Inc. The registry dates are 2024-10-28 for study start and 2025-01-21 for primary completion.

The design descriptions indicate that each participant received a rectangle prototype and a rectangle marketed dressing, one on each knee. The assignment of the two dressings to right or left knee was randomized in a 1:1 ratio. Each participant also received a square prototype and a square marketed dressing, one on each thigh, with right-versus-left assignment randomized in a 1:1 ratio. This gives a within-participant comparison for each shape and placement site. It is important not to read the four dressing placements as four independent groups of participants: the described comparisons involve the same participants, and observations from one person may be related.

There is a registry-level design-label tension: allocation is listed as randomized, while the model is listed as single group. The detailed descriptions clarify that dressing side was randomized within each comparison pair, but the registry record does not explain the model label. The record also does not report further details about randomization sequence generation, concealment, or how the open-label design was managed during outcome assessment.

Acceptable dressing presence was assessed at Day 7 for the primary endpoint. Other listed outcomes include acceptable presence at Day 1 and Day 3, presence of dressing, pad integrity, pad lift, border lift, and dressing comfort. The record says additional performance, safety, and potential device-issue data were collected up to 7 days. Detailed schedules for assessments and the analysis plan are 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.

Before assignment: Prior to application of the four different dressings (two prototype and two marketed dressings), a physical skin assessment occurred to ensure skin was healthy, intact \& hair free. Upon eligibility confirmation, the investigator would apply the appropriate dressing to the randomized right/left knee (rectangle dressing) and right/left thigh (square dressing). All participants would receive all dressings (i.e., each participant is their own control with the comparator dressing).

Overall Study

Analysis population for the primary outcome, as defined in the registry: Full analysis set (FAS) included all participants of the Safety Population with at least one post baseline assessment.

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.

Population: Safety Population (SP) included all participants in the investigation that received at least one of the test products, regardless of the number of further assessments.

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants With Acceptable Dressing Presence at Day 7, measured over Day 7.

The primary endpoint is the number of participants with acceptable dressing presence at Day 7. It is based on a yes/no assessment. A “yes” means the dressing was in place, no border lift had reached the pad, and the pad was not exposed. This definition makes the endpoint a binary measure of whether the dressing met the stated presence criteria at the assessment time.

The endpoint is relevant to the study’s stated performance question because it focuses on whether a dressing remains acceptably positioned and intact on the body through the specified assessment. The criteria combine border lift and pad exposure into one judgment. A dressing can therefore fail the definition if either specified issue is present, even if other aspects of its performance are acceptable. The endpoint does not, by itself, describe comfort, the degree of lifting, or the timing of any change between assessments.

The primary analysis population is described as the Full Analysis Set, including all participants in the Safety Population with at least one post-baseline assessment. The registry record does not provide the number of participants included in this endpoint analysis, the Day 7 counts by dressing, or a comparative estimate. It therefore establishes how the outcome was defined, but not the observed frequency of acceptable presence or the precision of a difference between prototype and marketed dressings.

For a comparative non-inferiority question, the outcome definition is only one part of the evidence. Interpretation also depends on the prespecified comparison method, non-inferiority margin, and uncertainty around the treatment contrast. Those details and results are not reported in the registry record. The endpoint definition should not be mistaken for a finding that either dressing did or did not meet the study aim.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a binary endpoint mean?

A binary endpoint places each assessment into one of two categories. In this study, acceptable dressing presence is recorded as yes or no at Day 7. The “yes” category requires the dressing to be in place, with no border lift reaching the pad and no pad exposure. This definition makes the endpoint straightforward to classify, but it compresses several features into a single outcome. It does not indicate how much a border lifted when the criterion was not met, or whether the dressing remained comfortable.

With a binary endpoint, descriptive results commonly report the number meeting the criterion and the number assessed. Comparative methods can then estimate a difference or another contrast between the dressing conditions. The registry record does not report the observed endpoint counts, the comparative effect measure, or the method used. No numerical comparison can be reconstructed from the endpoint definition alone.

Why does the paired arrangement matter?

For each body site, a participant received both the prototype and the corresponding marketed dressing. The two dressings were assigned to opposite sides, and the side assignment was randomized in a 1:1 ratio. This is a paired structure: each participant contributes observations under both dressing conditions for a given comparison. Measurements from the same person may be related because they share participant characteristics. An analysis that treats all dressing observations as independent could fail to reflect that relationship.

Pairing can be useful because comparisons within the same participant can reduce the influence of characteristics that are shared across that person’s two sites. It does not remove every possible source of variation, and the two sites may still differ. The registry record does not report the statistical analysis used to account for pairing, nor does it explain how the two comparison pairs were handled together or separately.

What does non-inferiority require?

The stated primary aim is to show that the prototype dressings are not worse than the established marketed dressings for acceptable presence at Day 7. In general, a non-inferiority analysis defines a margin before examining results. The margin sets the largest disadvantage that would still be considered compatible with the study objective. A suitable estimate and confidence interval are then interpreted in relation to that margin. A non-significant result from a conventional superiority test would not, on its own, demonstrate non-inferiority.

The registry record does not report the non-inferiority margin, the statistical test, the confidence level, or the primary comparison results. It is therefore not possible to assess whether the analysis met a non-inferiority criterion. The stated objective should be read as the question the study set out to address, not as evidence that the objective was achieved.

How should uncertainty be considered?

A point estimate summarizes the observed contrast, while a confidence interval communicates uncertainty around that estimate under the analysis assumptions. A narrow interval generally indicates greater precision than a wide interval, but precision is distinct from whether an effect meets a clinical or study-defined criterion. For this study, no comparative estimate or interval is reported in the registry record. The degree of statistical uncertainty around the primary comparison is therefore not available.

Randomized side assignment helps avoid systematic assignment of the prototype to one side, but randomization does not guarantee that all relevant features are balanced in a particular study. Open-label status means masking was listed as none. The registry record does not report whether outcome assessment was conducted by a person unaware of the dressing assignment or what steps were taken to limit assessment bias.

What can the sample-size assumptions tell readers?

The registry record includes a description of a sample-size planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It states that the effect to detect is a specified fraction of the observed effect. These are described as planning assumptions, not as the trial’s own design or a measure of the study’s observed power. The record does not report a protocol sample-size justification or the assumptions used when the study was designed.

In general, sample-size planning explores how many observations might be needed under chosen assumptions to detect a specified effect with a chosen probability. A retrospective illustration based on an observed effect is not evidence that a study had a particular probability of finding a result before it was conducted. It also cannot replace the observed effect estimate and its uncertainty. No sample-size illustration values are included in the registry entries.

Why might binary data need careful modeling?

Binary outcomes are often analyzed with methods designed for proportions or paired binary observations. The choice depends on the trial’s comparison structure and analysis plan. Over-dispersion is a general statistical issue that arises when observations vary more than a chosen model expects; if ignored, uncertainty can be understated. That general concern does not establish that over-dispersion occurred in this study. The registry record does not report a model, diagnostic checks, or an over-dispersion assessment.

For this study, the most important methodological details available are the binary endpoint definition, the within-participant placement of paired dressings, and the randomized side assignment. The analysis method, non-inferiority margin, uncertainty estimates, and handling of missing assessments are not reported in the registry record. Those omissions limit assessment of whether the statistical approach matched the design and the stated objective.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary endpoint at Day 7 and additional outcomes including acceptable dressing presence at Day 1 and Day 3, presence of dressing, pad integrity, pad lift, border lift, and dressing comfort. Examining multiple outcomes or assessment times can raise multiplicity concerns: when many statistical questions are tested, the chance of at least one apparently notable finding can increase. A prespecified hierarchy or adjustment can help clarify which comparisons are confirmatory and how results should be interpreted. The registry record does not report a multiplicity strategy or a detailed statistical analysis plan.

The available registry entries do not give the number assessed at Day 7, the counts with missing endpoint assessments, or the reasons assessments may have been missing. The primary population is described as including participants in the Safety Population with at least one post-baseline assessment. The record does not report how participants without a Day 7 assessment were handled, whether any imputation was used, or whether sensitivity analyses were conducted. These details matter because missing outcomes can affect the interpretation of a comparative result.

The record describes a Full Analysis Set for the primary endpoint but does not report the analysis population size or a separate per-protocol population. For non-inferiority questions, population definitions and missing-data assumptions can be particularly consequential; a detailed protocol and analysis plan are needed to assess them. The registry record does not report those details or the primary comparative results. No claim about the consequences of missing data or multiplicity can therefore be made from the information available.

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 non-serious adverse event terms

The safety summaries list serious adverse events affecting 0 of 135 participants in each of the displayed groups: all participants, prototype rectangle dressing on knee, marketed rectangle dressing on knee, prototype square dressing on thigh, and marketed square dressing on thigh. Deaths are listed as 0 in each of those groups. The registry record also lists other-event counts of 6 for all participants, 11 for the prototype rectangle dressing on knee, 7 for the marketed rectangle dressing on knee, 6 for the prototype square dressing on thigh, and 4 for the marketed square dressing on thigh.

These are group-level counts, and the dressing-specific group records refer to comparisons made within the same study population. They should not be added as though they represented distinct sets of participants. The record does not provide event descriptions for these other-event counts in the information, so their nature, severity, timing, and relationship to a particular dressing cannot be characterized. The group summaries also do not establish that an event was caused by a dressing.

Zero serious events recorded in a group means none were reported for that group in the registry summary; it does not establish that risk is absent. These safety counts are descriptive and do not supply the missing primary endpoint comparison or a statistical estimate of relative safety.

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

The registry record documents a completed, open-label study of prototype and marketed multilayer foam dressings on healthy, intact skin. Its primary endpoint was acceptable dressing presence at Day 7, defined using border lift and pad exposure criteria. Participants received paired prototype and marketed dressings for each shape and site, with side assignment randomized. These details describe the intended comparison and how the outcome was defined.

The record does not report the primary outcome counts or comparative analysis. It therefore does not show whether the prototypes met the stated non-inferiority aim, how large any difference was, or how precisely that difference was estimated. The absence of a reported comparative result is not evidence that the dressings performed similarly, and it is not evidence that they differed. The non-inferiority margin and analysis method are also not reported, so the stated objective cannot be independently evaluated.

The setting and population matter when interpreting the scope of the study. The listed participants were healthy, and the study concerned intact skin. The registry record does not establish how findings would apply to other populations or uses. The primary endpoint concerns dressing presence, not every aspect of performance. Secondary outcomes are listed, but their results are not reported in the registry entries.

The safety summaries report zero serious adverse events and zero deaths in each displayed group, alongside other-event counts. Those counts are descriptive and do not establish causal relationships or answer the primary performance question. Overall, the registry describes the design, objective, endpoint definition, and selected safety information, but it does not report the findings needed to determine comparative performance or precision.

13. Why This Trial Matters Statistically

This study is statistically interesting because its comparisons are paired within participants rather than based only on separate groups. Each participant received both members of a dressing pair at a given site, with right-versus-left assignment randomized. That design makes the unit of comparison and the dependence between observations important. A statistical analysis should reflect that structure rather than automatically treating every dressing placement as an unrelated observation.

The stated objective is non-inferiority, which requires more than observing similar-looking results. Interpretation depends on a prespecified margin, a suitable comparative estimate, and uncertainty around that estimate. The registry record does not report these elements or the outcome results. This illustrates why a study’s stated aim and endpoint definition are not enough to establish whether its objective was met.

The endpoint is binary and combines more than one physical criterion into an acceptable-presence classification. That provides a clear rule for a yes-or-no assessment, while leaving other dimensions—such as comfort and the specific components of dressing integrity—to separate outcomes. The registry lists several secondary outcomes, making prespecification and multiplicity handling relevant to interpretation; those analysis details are not reported.

Finally, the listed single-group model label sits alongside randomized allocation and detailed within-participant side randomization. The placement descriptions clarify the paired comparison, but the record does not explain the model label or provide a full statistical analysis plan. Readers should distinguish the randomized assignment feature from the statistical model used to estimate effects. The reported design information raises these considerations, while the absence of results prevents a conclusion about performance.

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 most consequential limitation of the registry information is that it does not report the primary Day 7 outcome counts or comparative results. Without these, the stated non-inferiority question cannot be evaluated. The non-inferiority margin, analysis method, confidence interval, and test result are also not reported in the registry record.

The detailed descriptions indicate paired dressing placements within participants, but the registry’s model field is listed as single group while allocation is listed as randomized. Side assignment is described as randomized in a 1:1 ratio for each comparison, yet the record does not explain the model designation or give enough statistical detail to assess how within-participant dependence was handled.

The study is open-label, with masking listed as none. The record does not say whether outcome assessors were masked or how the subjective elements of the presence assessment were managed. The endpoint definition is specific about border lift reaching the pad and pad exposure, but the registry entries do not report assessor procedures or reproducibility information.

The population is described as healthy and the skin as intact. The record does not provide outcome results for other populations or settings, and the study’s stated scope should not be extended beyond its described population. Although several additional outcomes are listed, their results, the multiplicity approach, and the timing and handling of missing assessments are not reported. The record also does not describe the other events in the safety summaries, limiting interpretation of those counts.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Human Participant Study of Prototype Non-medicated Multilayer Foam Dressings on Intact Skin — NCT06700850.
• Registry record last updated 2026-04-02; status last verified 2024-11.
• Results first posted 2026-04-02.
• 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 completed study evaluated two prototype non-medicated multilayer foam dressings against corresponding marketed dressings on healthy, intact skin. It lists an enrollment of 135 and describes randomized side assignment within paired comparisons: rectangle dressings on knees and square dressings on thighs. The study was open-label, with masking listed as none.

The primary endpoint was the number of participants with acceptable dressing presence at Day 7, defined as a dressing in place without border lift reaching the pad or pad exposure. The stated aim was to show that the prototypes were not worse than the established comparison dressings. The primary endpoint counts, comparative results, non-inferiority margin, and statistical analysis method are not reported in the registry record.

Safety summaries list zero serious adverse events and zero deaths in each displayed group, as well as other-event counts. The registry record does not provide descriptions of those other events in the information available for this account.