This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Comparison of Skin Substitutes Used in Burn Care (NCT00676013), a na na study. The primary outcome is Burn Scar Comparison.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00676013 |
| Phase | NA |
| Condition | Burns |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 158 |
| Arms in the primary outcome | n/a |
| Lead sponsor | The University of Texas Medical Branch, Galveston |
| Results posted | Yes |
2. Clinical Question
Population
The registry describes people with burns who received grafting. Scar assessment was defined for each site grafted with a skin substitute. The study enrolled 158 participants, but further eligibility details and the characteristics of the enrolled population are not reported in the registry record.
Intervention
The procedures named are AlloDerm, Integra, Homograft, and Autograft. The arm description says these procedures were used on four separate sites on each patient. The record does not report how the sites or procedures were assigned, or whether every participant received each procedure as described.
Comparator
The procedures can be understood as the potential comparators for assessing scar outcomes, but the registry classifies the study as a single-group model and does not report randomized allocation. It therefore should not be read as a randomized, like-for-like comparison between independent treatment groups. Details of any planned within-person comparisons are not reported in the registry record.
Primary question
The stated question is whether dermal layers used under skin grafts are associated with differences in burn scarring. The primary outcome is the Vancouver Scar Scale score, assessed two years post burn injury. The scale covers redness or vascularity, hardness, pigmentation, and scar height; lower scores indicate less severe scarring. The posted results do not report the scores or comparative estimates needed to answer the question.
3. Trial Design
This is a single-group study of grafting procedures in burn care. The registry lists AlloDerm, Integra, Homograft, and Autograft, and describes their use on four separate sites on each patient. That description suggests assessment across grafted sites within participants, but the record does not explain how treatment was allocated to sites, whether site characteristics were balanced, or how the site-level observations were analyzed. Allocation is listed as NA, and masking is listed as none. The record therefore does not establish a randomized comparison or blinded scar assessment.
The listed enrollment is 158. The study status is terminated. Its recorded start is 1997-12 and its primary completion is 2011-01. The phase is listed as NA. The sponsor is The University of Texas Medical Branch, Galveston. The registry describes burns as the condition and identifies a single primary outcome measure, Burn Scar Comparison.
The primary outcome was intended to be assessed two years post burn injury. The measure is a mean Vancouver Scar Scale score, with standard deviation as the stated dispersion. Although the record names the procedures and describes the site arrangement, it does not report the analysis plan, the number of sites with usable assessments, or the timing and handling of any incomplete assessments. It also does not report a protocol rationale for the enrollment target. The registry record does not give a detailed account of why the study was terminated.
Because the design is not described as randomized and no comparative score estimates are posted, the named procedures should not be treated as if they came from balanced, independently assigned groups. Differences between sites could reflect procedure choice, site characteristics, or other factors; the record does not provide enough detail to separate these explanations.
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: Patients were enrolled before their surgical procedure. After consent was obtained. After the surgical site was identified, the site was randomized to receive the various skin products.
Overall Study
| Stage | Alloderm, Integra, Homograft, Autograft |
|---|---|
| STARTED | 158 |
| COMPLETED | 157 |
| NOT COMPLETED | 1 |
Analysis population for the primary outcome, as defined in the registry: Each site grafted with a skin substitute was analyzed with a Scar 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.
| Characteristic | Unit | Alloderm, Integra, Homograft, and/or Autograft |
|---|---|---|
| Participants analysed | 158 | |
| Age, Categorical: <=18 years | Participants | 158 |
| Age, Categorical: Between 18 and 65 years | Participants | 0 |
| Age, Categorical: >=65 years | Participants | 0 |
| Sex: Female, Male: Female | Participants | 48 |
| Sex: Female, Male: Male | Participants | 110 |
| Region of Enrollment: United States | participants | 158 |
6. Primary Endpoint
The registry lists the primary outcome as Burn Scar Comparison, measured over 2 years post burn injury.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | units on a scale |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is burn scarring measured with the Vancouver Scar Scale. The registry says the scale assesses redness or vascularity, hardness, pigmentation, and scar height. Each item is scored from 0 to 3, and the item scores are summed for a total from 0 to 12. Lower totals are described as better and higher totals as worse. The total score is reported as the measure used in the burn community.
The endpoint is intended to capture several visible and physical features of a scar in a single score. Using a common total can make scar assessments across grafted sites easier to describe, while retaining the component categories in the underlying assessment. The listed timeframe is two years post burn injury, and the registry defines the population for the outcome as each site grafted with a skin substitute that received a scar assessment.
The outcome is continuous in the registry’s statistical classification, with the mean as the summary measure and standard deviation as the measure of spread. However, the posted results do not report a mean score, standard deviation, or comparison between procedures. The endpoint definition therefore explains what was intended to be measured, but does not establish which procedure had a lower score or how precise any difference may have been.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry describes a clinically interpretable scar measure but does not post the primary outcome values. There are no reported Vancouver Scar Scale means or standard deviations for the named procedures, and no reported difference between procedures, confidence interval, or p-value for the scar outcome. Consequently, the posted results do not quantify the direction, size, or precision of a scar-score contrast. The study’s stated objective cannot be resolved from the outcome results in the registry record.
The design description also limits what a reader can infer. The record calls the study a single-group model, lists allocation as NA, and describes four procedures at separate sites on each patient. It does not report random assignment of procedures to sites or a statistical analysis that accounts for sites belonging to the same person. Those details matter because sites from one participant may share characteristics. If site observations are related, treating them as fully independent can make uncertainty estimates too small. This is a general statistical concern, not a claim about an analysis that the registry does not describe.
The outcome is intended to be a mean score, but a mean alone would not show how variable the scores were. The standard deviation would describe spread among observations; an uncertainty interval around a comparison would address how precisely the contrast was estimated. Neither the descriptive scores nor comparative uncertainty estimates are reported in the registry record. A statement of statistical significance, if one were available without an effect estimate and uncertainty interval, would also not communicate the size or practical relevance of a difference.
The safety results list 9 participants affected by serious adverse events and 3 affected by other adverse events, each with 158 at risk in the listed group. These are reported counts, not a comparison of safety between the four procedures. The record does not assign the adverse events to a particular grafting procedure or provide procedure-specific risk estimates. The serious-event terms include several events at 1.3% and 0.6%, but the entries do not establish the total burden of each event category beyond the listed terms.
The study is marked terminated, but that status alone does not explain why it ended or whether termination affected outcome collection. The record does not report a reason, missing-outcome counts, or an account of the analyses completed before termination. No inference about the scar outcome should be drawn from the study status itself. Overall, the registry supports describing the study question, design labels, endpoint definition, and posted safety counts, but not a conclusion about comparative scar scores.
9. Statistical Methods Explained
The primary outcome is classified as continuous and summarized using a mean and standard deviation. In general, a mean describes the central level of a set of measurements, while the standard deviation describes how dispersed the measurements are around that mean. For the Vancouver Scar Scale, the score has an ordered range from 0 to 12, with lower scores described as better. Reporting both a mean and a measure of spread would help readers understand the observed scores, but those outcome summaries are not reported in the registry record.
What a comparison would estimate
In general, a comparison between procedures could be expressed as a difference in average scar scores. The sign would indicate which procedure had the lower average, given that lower scale scores are described as better. The magnitude would describe the size of the observed contrast in score units. A confidence interval would show the range of values compatible with the data under the chosen statistical model and would communicate precision. A p-value would address how compatible the observed data are with a specified null hypothesis under that model. These are general explanations; the registry does not report a scar-score contrast, confidence interval, or p-value.
The study description says that grafted sites were assessed within each patient. In general, measurements from the same person can be correlated: a participant’s health, injury, healing, or other shared characteristics may affect more than one site. A method that recognizes this dependence can produce more appropriate uncertainty estimates than a method that assumes every site is unrelated. Possible approaches for repeated or clustered measurements include paired analyses or models that account for within-person correlation. The registry record does not identify which approach, if any, was used, and the site assignment and analysis details are not reported.
Why the design details matter
Random allocation can help balance known and unknown characteristics across treatment groups, while masking can reduce the influence of knowledge of treatment on assessment. The registry lists allocation as NA and masking as none. These labels do not provide enough information to infer the exact site-assignment process or whether scar assessors knew which procedure had been used. In a site-based design, the clinical features of each grafted site may also be relevant to outcome. The record does not describe how such features were measured or addressed analytically.
The registry lists one primary outcome measure and one analysis. This count does not specify the model, the comparison structure, covariates, assumptions, or the method for estimating uncertainty. Those statistical details are not reported in the registry record. It is therefore not possible to determine whether the posted analysis was a simple comparison of means, a paired analysis, or another approach.
Over-dispersion and score distributions
In general, over-dispersion means that observed variability is greater than a statistical model expects. When variability is underestimated, estimated standard errors can be too small and confidence intervals too narrow. The Vancouver Scar Scale is bounded, and its distribution may not necessarily be well described by a normal model; this is a general consideration for bounded scores, not a finding about this study. Reviewing the distribution, variability, and model assumptions would help assess whether a mean-based analysis adequately represents the data. The record does not report the score distribution or diagnostic checks.
The registry’s sample-size assumptions describe a 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. The illustration is not the trial’s own design justification. It is not observed power and cannot substitute for an estimate of uncertainty in the trial results. The registry record does not report a protocol-based sample-size justification. Since the posted primary outcome does not include an observed effect estimate, the record does not allow a reader to interpret a planning illustration as evidence of the study’s ability to detect a scar-score difference.
When recalculated estimates are presented from summary statistics, they are simple unadjusted recalculations rather than the sponsor’s original analysis. No such comparative scar-score estimate is reported in the registry record. In general, a recalculation cannot account for clustering, covariate adjustment, or other design features unless the necessary information is available. The registry record does not provide enough detail to reconstruct an adjusted analysis or verify a model-based result.
For an appropriate interpretation, readers would need the procedure-specific score summaries, the number of assessed sites and participants, the comparison method, and an uncertainty estimate. They would also need information on whether the analysis accounted for within-person dependence and on how incomplete assessments were handled. These items are not reported in the registry record, so the statistical interpretation is necessarily limited to the design description and outcome definition.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one primary outcome measure and one analysis. It does not report whether there were additional planned outcomes, exploratory comparisons, or multiple comparisons among the four named procedures. If multiple contrasts are tested, the chance of finding an apparently unusual result can increase; general methods can adjust interpretation or testing to account for that multiplicity. The record does not report a multiplicity strategy, so it is not possible to tell whether any adjustment was planned or used.
Missing-data information is not reported in the registry record. The record does not state how many participants or grafted sites had a scar assessment at the planned time, whether assessments were missed, or how any missing scores were handled. It also does not report whether the analyses used only complete observations or included a method for incomplete data. These details matter because the observed scores may not represent all intended assessments if missingness is related to scarring or participant characteristics.
The population for the primary outcome is described as each site grafted with a skin substitute that was analyzed with a scar assessment. The registry does not define a broader analysis population, explain exclusions, or state how sites and participants were counted in the analysis. Because the study is not described as randomized, standard randomized-trial analysis populations cannot be assumed. Without a participant and site flow or an analysis-population definition, the relation between the listed enrollment and the number contributing to the primary outcome is not reported in the registry record.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| AlloDerm, Integra, Homograft, Autograft | 9 | 158 | 5.7% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 1% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| AlloDerm, Integra, Homograft, Autograft | 3 of 158 |
Most frequent serious adverse event terms
| Event term | Organ system | AlloDerm, Integra, Homograft, Autograft |
|---|---|---|
| Respiratory status compromised | Respiratory, thoracic and mediastinal disorders | 2 of 158 |
| hypoglycemia | Endocrine disorders | 2 of 158 |
| Aspiration and Death | Respiratory, thoracic and mediastinal disorders | 1 of 158 |
| Invasive infection and death | Infections and infestations | 1 of 158 |
| 90% burn admitted with renal failure, died | Renal and urinary disorders | 1 of 158 |
| leg ischemia | Vascular disorders | 1 of 158 |
| Invasive infection, Multi organ failure, death | Infections and infestations | 1 of 158 |
Most frequent non-serious adverse event terms
| Event term | Organ system | AlloDerm, Integra, Homograft, Autograft |
|---|---|---|
| Hematoma | Vascular disorders | 2 of 158 |
| Fall and open wound | Skin and subcutaneous tissue disorders | 1 of 158 |
Serious events with the highest arm-level rate: respiratory status compromised (1.3%), hypoglycemia (1.3%), aspiration and death (0.6%), invasive infection and death (0.6%), 90% burn admitted with renal failure, died (0.6%).
The registry lists 158 participants at risk for serious adverse events and 9 affected, and 158 at risk for other adverse events and 3 affected, in the combined group named AlloDerm, Integra, Homograft, Autograft. These counts should be read as reported safety summaries for the listed group, not as separate counts for each grafting procedure. The record does not say whether a participant could appear in both categories or whether the counts refer to unique people across the full observation period.
The listed serious adverse event terms include Respiratory status compromised and hypoglycemia, each reported as 1.3%; Aspiration and Death, Invasive infection and death, 90% burn admitted with renal failure, died, and leg ischemia, each reported as 0.6%. These percentages are reproduced as stated in the registry record. The terms are not linked to a specific procedure in the posted results, and they should not be interpreted as comparative rates across the four procedures. The record does not report a total death count in the safety group, despite death appearing in some event terms.
The event list is a safety description, not an estimate of causal risk. The registry does not provide treatment-specific exposure, timing, attribution, or a comparison group suitable for estimating differences in adverse-event risk.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a study of grafting procedures in burn care was undertaken and that scar assessment was intended at two years post burn injury. It identifies the Vancouver Scar Scale and explains how the total score is interpreted. It also gives a study enrollment, design labels, status, and selected safety summaries. These details describe the study question and the information that was posted.
The record does not provide the primary scar scores or comparative estimates. It therefore does not show whether one procedure had lower average scar scores than another, how large any difference was, or how precisely a difference was estimated. The stated purpose includes scar formation, burn wound contractures, and functional outcomes of joints requiring grafts, but results for these outcomes are not reported in the registry record. A research objective is not itself evidence of an observed effect.
The four named procedures are described at separate sites on each patient, but the registry does not explain how treatment was assigned to sites or how the observations were analyzed. The single-group classification and lack of reported random allocation mean that the record does not establish a randomized, like-for-like comparison. Even if comparative scores were available, design and analysis details would be needed to assess whether site differences or within-person dependence could affect the estimate.
The safety counts describe participants affected in the combined group, not relative safety across procedures. The event terms and their reported percentages do not establish that any particular procedure caused an event or changed risk. Likewise, the terminated status does not explain the reason for termination or indicate what effect termination had on outcome collection.
Accordingly, the posted information supports a careful account of the study’s stated question, endpoint, design, and selected adverse-event counts. It does not support a conclusion about comparative effectiveness, scar reduction, contractures, joint function, or safety differences among procedures. Those conclusions would require outcome results and analysis details that are not reported in the registry record.
13. Why This Trial Matters Statistically
This study raises an important statistical issue for clinical research: the unit of treatment and the unit of analysis may differ. The description places four grafting procedures at separate sites on each patient, while the primary outcome is defined for each grafted site. When multiple sites belong to one participant, the observations may be related. Analysis must reflect the structure of the data if uncertainty estimates are to be trustworthy. The registry record does not report how this issue was handled.
The study also illustrates why a defined endpoint is not enough to evaluate comparative evidence. The Vancouver Scar Scale has a stated scoring range, component domains, direction of interpretation, and assessment timeframe. Those features help explain what the outcome is intended to capture. But without the observed scores, a comparison estimate, and its precision, the clinical question remains unanswered in the posted results.
Allocation and masking are also consequential design features. The record lists allocation as NA and masking as none, but does not describe the site-assignment process or assessor knowledge in detail. Such information is important for judging comparability and the possibility of measurement bias. It should not be assumed that procedures were assigned randomly or that assessments were blinded.
Finally, the record separates the existence of safety reporting from comparative safety evidence. The reported counts and serious-event terms provide descriptive information, but the combined group does not show how events differed by procedure. Together, these features make the study a useful example of why design structure, outcome reporting, and analysis transparency are necessary for interpreting clinical comparisons.
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 direct limitation is that the registry does not report the primary outcome values. No procedure-specific Vancouver Scar Scale means, standard deviations, contrasts, confidence intervals, or p-values are reported in the registry record. The planned endpoint and its interpretation are clear, but the posted results do not permit quantitative comparison of scar outcomes.
The design description is incomplete for assessing comparative validity. The study is labeled single group, allocation is listed as NA, and the arm description refers to procedures on four separate sites on each patient. The record does not explain how procedures were assigned to sites, whether site features differed, or whether the analysis accounted for the possibility that observations within a participant are related. Masking is listed as none, but assessor procedures are not described.
Outcome completeness and analysis populations are also unclear. The registry does not report how many sites had scar assessments, how many assessments were missing, or how missing scores were handled. It does not define exclusions or state how participants and sites contributed to the analysis. These gaps make it difficult to assess representativeness and the precision of any intended estimate.
The safety results are combined across the named procedures, and no procedure-specific adverse-event comparisons are reported. The registry also does not report the reason for termination, a detailed statistical analysis plan, a protocol-based enrollment justification, or a multiplicity strategy. These limitations are specific to the information recorded and should not be taken to establish what may or may not have been done outside the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Comparison of Skin Substitutes Used in Burn Care — NCT00676013.
- Registry record last updated 2019-12-16; status last verified 2018-08.
- Results first posted 2019-12-16.
- 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.
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18. Record Summary
NCT00676013 is titled Comparison of Skin Substitutes Used in Burn Care and is sponsored by The University of Texas Medical Branch, Galveston. The record lists burns as the condition, enrollment of 158, phase NA, a single-group model, allocation NA, masking none, and status terminated. The recorded start is 1997-12, with primary completion in 2011-01.
The listed procedures are AlloDerm, Integra, Homograft, and Autograft. The primary outcome is Burn Scar Comparison, measured with the Vancouver Scar Scale two years post burn injury and summarized as a mean with standard deviation. The record defines the score and its direction but does not report comparative scar results. Safety summaries list 9 participants affected by serious adverse events and 3 by other adverse events, with 158 at risk in each category. The registry does not report procedure-specific safety comparisons or the reason for termination.