Clinical Study on Silk Sericin Wound Dressing for Split-thickness Skin Graft Donor Sites Treatment: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Clinical Study on Silk Sericin Wound Dressing for Split-thickness Skin Graft Donor Sites Treatment (NCT01539980), a na phase 1, phase 2 study. The primary outcome is Clinical Efficacy of Wound Dressing Containing Silk Sericin for Split-thickness Skin Graft Donor Site Treatment.

2. Clinical Question

The study concerns split-thickness skin graft donor sites treated with a wound dressing containing silk sericin. Its central question is whether the dressing is associated with the time required for complete epithelialisation, measured in days within 14 days after operation. The endpoint description defines completion using wound closure and the dressing’s spontaneous separation without pain, alongside the absence of fluid leakage and the ability to expose the wound to the environment without pain.

The study summary also raises questions about pain levels, infection, and adverse events, and lists proinflammatory cytokines (IL) and liver enzyme (AST) among secondary outcomes. The summary frames these as comparisons with Bactigras®. However, the registry record identifies a Sericin scaffold intervention and a single-group model; it does not describe a Bactigras® arm. A comparator group’s identity and treatment allocation are not reported in the registry record. Thus, the stated comparative questions cannot be matched to a documented like-for-like treatment comparison.

The population is described in terms of the donor sites rather than participant characteristics. Age, eligibility criteria, clinical setting, and other participant details are not reported in the registry record. The enrollment is 30, but the record does not supply a participant-level description or explain how many contributed data to each outcome.

In practical statistical terms, the record establishes the study’s intended clinical focus, but not whether the observed healing time, pain, infection, or safety outcomes differed between treatments. No outcome analyses are reported in the registry record. The clinical question is therefore best understood as an intended assessment of healing and related outcomes, with the comparative element limited by the absence of a documented comparator group.

3. Trial Design

The registry identifies this as a completed Phase 1 and Phase 2 study sponsored by Chulalongkorn University. The recorded enrollment is 30. The study began in 2012-08, and primary completion was recorded in 2014-03. These details describe the planned and recorded scope, but do not establish how many participants completed follow-up or contributed to each analysis.

The design is recorded as single group, with allocation marked NA and masking marked single. A single-group model does not, by itself, provide a concurrent control group for comparing outcomes between treatments. The registry names the intervention as a Sericin scaffold, categorized as a device. It does not give an arm description. Although the study summary refers to comparison with Bactigras®, the record does not identify a Bactigras® arm or explain how any comparison was conducted. The allocation and treatment details needed to interpret a comparative estimate are therefore not reported in the registry record.

The primary outcome is a continuous measure in days, summarized by a mean and standard deviation in the outcome specification. The timeframe is within 14 days after operation. Other listed outcomes concern clinical safety, pain levels, proinflammatory cytokines (IL), and liver enzyme (AST). The record lists five outcome measures but no outcome analyses.

The registry record does not report the statistical analysis plan, the sample-size justification used when the study was designed, or whether there were interim analyses. It also does not report details of masking procedures, follow-up completeness, or analysis populations. These omissions matter because a completed study’s design labels do not show how observations were collected, handled, or analyzed. The recorded design and enrollment can be described, but the methods used to draw efficacy conclusions cannot be reconstructed from 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

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 Clinical Efficacy of Wound Dressing Containing Silk Sericin for Split-thickness Skin Graft Donor Site Treatment, measured over Within 14 days after operation.

The primary endpoint measures the time, in days, from completion of the surgical procedure until the donor-site dressing spontaneously peels off without causing pain, with the wound described as completely closed, without fluid leakage, and able to be exposed to the environment without pain. The timeframe is within 14 days after operation. The registry also states that this duration should not exceed 14 days.

This endpoint is intended to capture healing as a time-based outcome rather than as a single observation of wound status at an unspecified visit. In general, a time-to-event measure can represent how long it takes for a defined event to occur. In this study, the event is the endpoint’s specified completion of epithelialisation. A shorter observed time would describe earlier completion under that definition, but the registry record does not report the observed mean or standard deviation, so the actual timing cannot be characterized.

The endpoint’s operational definition is important. Spontaneous dressing separation, absence of pain during separation, wound closure, absence of fluid leakage, and exposure without pain are all included in the description. Those criteria should guide interpretation; the endpoint is not simply a general assessment of wound appearance. The record does not report how assessors applied the criteria, whether assessments were blinded, how timing was recorded, or how observations after the stated timeframe were handled.

The endpoint is specified as a mean with standard deviation, although its time-based nature may raise questions about how incomplete observation or differing follow-up is handled. The registry record does not report those analysis details or the primary endpoint result.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation starts with the design and the outcome definition. Here, the design is recorded as single group, allocation is NA, and masking is single. Those labels do not describe a randomized comparison. The intervention is listed as a Sericin scaffold, but the record does not identify a comparator arm, even though the study summary refers to Bactigras®. As a result, a treatment contrast cannot be reconstructed from the registry entries.

What does the mean describe?

The primary outcome is specified as a mean in days, with standard deviation as its measure of dispersion. In general, the mean is the arithmetic average of the observed values included in an analysis. It gives a central summary, but can be affected by particularly long or short observations. The standard deviation describes the spread of individual values around the mean. A small spread indicates observations are more tightly clustered; a larger spread indicates greater variability. Neither summary is reported for the primary endpoint in the registry record.

The endpoint is time to a defined healing event. Its definition combines the spontaneous peeling off of the dressing without pain with wound closure, no fluid leakage, and ability to expose the donor site without pain. In general, analyzing a time-based outcome requires clarity about when observation starts, how the event is assessed, and what is done when the event is not observed during follow-up. The registry specifies the period as within 14 days after operation, but does not report the analysis approach for incomplete follow-up or unobserved events. It also does not state whether the mean was calculated only among participants with an observed event or by another method.

What would an uncertainty interval add?

In general, a confidence interval expresses the uncertainty around an estimated quantity under a specified statistical model. It provides a range of values that are compatible with the observed data and method, rather than only a single point estimate. For a comparison, an interval around the treatment difference would help readers assess both the estimated direction and the precision of that difference. No confidence interval, treatment difference, or primary outcome estimate is reported in the registry record. Without an estimate and its uncertainty, the endpoint cannot be statistically interpreted for magnitude or precision.

A p-value, in general, summarizes how unusual data at least as incompatible with a null hypothesis would be under the assumptions of a particular test. It does not describe the size of an effect, the probability that a treatment works, or the clinical importance of a result. The registry record reports no test statistic or p-value for the outcome analyses. The stated sample-size assumptions refer to a two-sided significance level of 0.05, but this planning assumption is not a reported analysis result and does not reveal what statistical test, if any, was used for the trial outcomes.

Why does the design matter?

In general, a concurrent comparator can help separate changes associated with one treatment from changes that might occur over time or under usual care. A single-group study does not offer that direct concurrent contrast unless other design or analysis features are documented. The record does not report such features. Its stated comparison with Bactigras® therefore cannot be treated as a documented controlled comparison. The single masking label also does not identify who was masked or how masking was implemented, and those details are not reported in the registry record.

Sample-size planning is distinct from outcome analysis. The planning assumptions describe an illustration using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with an effect defined as a stated fraction of an observed effect. For time-to-event tables, the assumptions specify total events; for other outcomes, they specify participants per arm. These assumptions describe hypothetical planning, not the trial’s observed design or evidence. The registry record does not report the original sample-size justification, a calculated participant target, or the observed effect used for such planning. Planning illustrations are not observed power and cannot substitute for estimates and uncertainty from the trial.

Why can over-dispersion matter?

In general, over-dispersion occurs when observed variability is greater than a statistical model assumes. It can make standard errors too small if the model does not account for the extra variation, leading to uncertainty that appears narrower than warranted. This concept is relevant when choosing models for variable outcomes, but the registry record does not identify a model, report an over-dispersion assessment, or provide outcome data from which to assess it. It should not be assumed that over-dispersion occurred in this study.

For a continuous endpoint, the analysis method should match the outcome distribution and the study design. A simple comparison of means, for example, would require a defined comparison group and relevant assumptions. The record does not report such a method, does not define a comparator arm, and does not provide outcome summaries. No method should therefore be attributed to the study beyond the recorded mean and standard deviation specification.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Sericin Scaffold")
n   <- c(30)
m   <- c(12)
sp  <- c(5)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Sericin Scaffold  30  12.000  5.000  10.133  13.867

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary outcome and secondary outcomes concerning clinical safety, pain levels, proinflammatory cytokines (IL), and liver enzyme (AST). The study summary also mentions epithelialisation time, pain, infection, and adverse events. Considering multiple outcomes can create multiplicity: in general, the more hypotheses tested, the greater the chance that at least one result may appear statistically noteworthy by chance if each test is interpreted separately. Methods such as prespecifying a primary outcome or adjusting for multiple comparisons can address different multiplicity concerns, but the registry record does not report a multiplicity strategy.

The record identifies five outcome measures and zero outcome analyses. It does not report which secondary outcomes were formally analyzed, whether outcome definitions changed, how repeated measurements were handled, or whether any adjustment was made for multiple testing. The analysis plan and any interim-analysis plan are not reported in the registry record. The study summary’s hypotheses should not be mistaken for a complete statistical analysis plan.

Missing-data handling is also not described. In general, missing observations can affect interpretation when their occurrence is related to participant characteristics or outcomes. For a time-based endpoint, incomplete observation may leave the event time unknown; for pain or laboratory outcomes, missing assessments may change which observations contribute to an estimate. The registry record does not report missingness, reasons for missing data, imputation methods, or sensitivity analyses.

Analysis populations are not reported in the registry record. It is not stated whether all enrolled participants, only participants who received the intervention, or another defined group contributed to each outcome analysis. The recorded enrollment of 30 should therefore not be assumed to be the denominator for every endpoint. Without outcome-specific denominators and missing-data methods, the completeness and comparability of the analysis sets cannot be assessed.

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 3% reporting threshold.

Most frequent non-serious adverse event terms

The registry’s serious-adverse-event summary reports 0 affected among 30 at risk for the Sericin Scaffold group. It also gives figures of 2 affected among 30 at risk for an “other” group, but the treatment identity of that group is not reported in the registry record. The counts are presented without a comparative analysis, uncertainty estimate, or explanation of how the groups were defined. They should not be interpreted as a treatment effect.

No serious adverse event terms are listed in the record. That absence of listed terms is not the same as a complete narrative of safety findings: event definitions, ascertainment procedures, follow-up duration, and the relationship of events to treatment are not reported in the registry record. Death information is also not reported in the registry record.

Safety counts require context. In general, a count depends on who was monitored, for how long, what qualified as an event, and whether all participants had comparable observation. The “at risk” figures do not establish that follow-up was complete or equivalent across groups. The listed counts can be described as recorded, but the available information is insufficient to draw a reliable comparative safety conclusion.

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

The registry record establishes that a completed Phase 1 and Phase 2 study evaluated a Sericin scaffold for split-thickness skin graft donor sites, with a recorded enrollment of 30. It defines the intended primary endpoint as time to complete epithelialisation within 14 days after operation and identifies pain, safety, proinflammatory cytokines (IL), and liver enzyme (AST) among other outcomes. These registry entries clarify what the study set out to examine.

The record does not report the primary outcome result or analyses for the listed secondary outcomes. No mean healing time, standard deviation, estimated treatment difference, confidence interval, or test result is included. Therefore, the record does not establish the size, direction, or precision of an effect on healing time. The hypotheses in the study summary are not findings, and the safety counts alone do not answer the efficacy questions.

The design information further limits comparative interpretation. The record describes a single-group model and names the Sericin scaffold intervention, but does not describe a Bactigras® arm. The summary’s comparative language cannot fill in that missing design detail. Without an identified comparator and a reported analysis, no controlled treatment contrast can be assessed.

These limitations do not show that the dressing is ineffective or that it is effective. They show that the available registry information is insufficient to determine either. Likewise, the recorded serious-adverse-event counts do not establish comparative safety, because the “other” group is not identified and event ascertainment and analysis details are absent.

In general, clinical interpretation should distinguish a study’s intention, its design, and its reported results. The record describes the first two only partially and does not provide outcome analyses. A careful reader can understand the endpoint and the questions of interest, but cannot use this record alone to quantify an outcome difference or judge its precision.

14. Why This Trial Matters Statistically

This study is statistically notable because its stated clinical questions are comparative, while the registered design is a single group and the intervention record identifies only a Sericin scaffold. That mismatch is important: the wording of a research question does not itself create a comparator or establish that a controlled treatment contrast was performed. Clear alignment between the question, design, and analysis is necessary for a comparative estimate to be interpretable.

The primary endpoint also illustrates why operational definitions matter. “Time to complete epithelialisation” is linked to a particular set of conditions: spontaneous dressing separation without pain, complete wound closure, no fluid leakage, and exposure to the environment without pain. Different definitions or assessment procedures could lead to different event times. The registry states the endpoint definition, but does not report how assessors applied it or how timing was handled in the analysis.

The record shows why design labels and outcome reporting must be read together. It records enrollment of 30 and a completed study, but reports zero outcome analyses. Enrollment and completion do not, by themselves, demonstrate that results are available, that every participant contributed data, or that uncertainty around an effect is small. Without estimates, denominators, and uncertainty intervals, statistical precision cannot be judged.

The safety information offers a related lesson. Counts without a clearly identified comparator, event definitions, follow-up details, and analysis do not support a comparative safety conclusion. The reported figures can be accurately described, but their meaning depends on context the registry record does not provide.

For clinical researchers and statisticians, the key issue is transparent reporting. A clear account of the analysis population, missing observations, outcome methods, and uncertainty would allow readers to distinguish a descriptive result from a treatment comparison. In this record, the endpoint and study aim are identifiable, while the evidence needed to evaluate the stated comparative questions is not reported.

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.

Several trial-specific limitations constrain interpretation. Most importantly, the registry record describes a single-group model and does not document a comparator arm, although the study summary refers to Bactigras®. The treatment identity of the “other” group in the serious-adverse-event summary is not reported in the registry record. This prevents linking those figures to a named comparator or treating them as a like-for-like comparison.

The primary endpoint is described in detail, but its results are absent. The registry specifies a mean and standard deviation in days and a timeframe within 14 days after operation, yet reports neither summary statistic nor any analysis result. How the endpoint was assessed, how the event time was recorded, and how incomplete observation was handled are not reported in the registry record.

The enrollment is 30, but outcome-specific denominators and analysis populations are not reported. The record does not describe participant characteristics, eligibility criteria, follow-up completeness, or missing-data methods. These omissions prevent assessment of who contributed to the endpoint and whether observations were available consistently across outcomes.

The registry records single masking but does not identify who was masked or how masking was implemented. It also does not report the statistical analysis plan, interim analyses, multiplicity procedures, or the study’s original sample-size justification. The stated planning assumptions are hypothetical and should not be treated as a description of the actual study design or as evidence of observed precision.

Finally, the safety summary does not list serious adverse event terms, and death information is not reported in the registry record. Event definitions, monitoring procedures, and follow-up duration are also absent. These reporting gaps mean that the available counts cannot establish comparative safety or provide a complete safety profile.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Clinical Study on Silk Sericin Wound Dressing for Split-thickness Skin Graft Donor Sites Treatment — NCT01539980.
• Registry record last updated 2015-04-02; status last verified 2015-04.
• Results first posted 2015-04-02.
• 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.

19. Record Summary

NCT01539980 is a completed Phase 1 and Phase 2 study sponsored by Chulalongkorn University, with enrollment of 30. The study began in 2012-08, and primary completion was recorded in 2014-03. The registry describes a single-group model, allocation marked NA, single masking, and a Sericin scaffold intervention.

The primary endpoint is time to complete epithelialisation in days within 14 days after operation, specified as a mean with standard deviation. The study summary raises comparative questions involving Bactigras®, pain, infection, and adverse events, but the registry does not describe a Bactigras® arm. Secondary outcomes include clinical safety, pain levels, proinflammatory cytokines (IL), and liver enzyme (AST).

No outcome analyses are reported in the registry record. The serious-adverse-event summary lists 0 affected among 30 at risk for Sericin Scaffold and 2 affected among 30 at risk for an unidentified “other” group. No serious adverse event terms are listed; death information is not reported in the registry record. The available information describes the study’s aim and selected design details, but does not provide an efficacy estimate or a documented comparative analysis.