Multicentric RCT Comparing High Purity Type I Collagen-Skin Substitute vs dHACM in Treatment of Diabetic Foot Ulcers: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Multicentric RCT Comparing High Purity Type I Collagen-Skin Substitute vs dHACM in Treatment of Diabetic Foot Ulcers (NCT07046403), a randomized na study. The primary outcome is Percentage Change in Wound Area.

2. Clinical Question

3. Trial Design

The registry describes a completed, randomized, parallel-group clinical trial conducted at multiple centers. It lists the allocation as randomized and the masking as single. The record does not specify who was masked, how randomization was generated, or whether allocation was concealed. The phase is recorded as NA. The sponsor is Adichunchanagiri Institute of Medical Sciences, B G Nagara.

The registry lists enrollment of 120 and reports 60 participants in each arm. One arm received High Purity Type-I Collagen-based Skin Substitute with standard of care; the other received Dehydrated Human Amnion/Chorion Membrane with standard of care. Both interventions are classified as devices. The record’s descriptions identify wound coverage followed by a padded dressing, but both descriptions end before the complete dressing details are given. The protocol’s full definition of standard care is not reported in the registry record.

The primary outcome was percentage change in wound area, assessed through week 5. The record also lists outcomes related to histopathology, capillary density, complete wound closure, time to closure, partial healing, number of applications, adverse events, and patient-reported quality of life. The posted outcome results include group summaries for the primary wound-area measure and several secondary outcomes. The registry status is completed. The listed start date is 2025-07-05 and the listed primary completion date is 2025-09-09.

The registry record does not describe the statistical analysis plan in enough detail to identify the prespecified model, analysis population, handling of missing observations, or any interim analyses. It also does not report the trial’s original sample-size justification. Those omissions limit how fully the posted group summaries can be connected to the protocol’s intended analysis.

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 Percentage Change in Wound Area, measured over 5 weeks.

The primary endpoint is percentage change in wound area, summarized as a mean with a standard deviation. It is intended to quantify change in the measured area of the ulcer over the assessment period, rather than simply record whether complete closure occurred. The registry describes assessments at 1, 2,3, and 4 weeks, and week 5, with manual measurement using digital photography; the primary outcome timeframe is listed as 5 weeks.

Using a continuous measure can retain information about the degree of change across participants. A measure of percentage change also expresses change relative to the wound area used as its starting reference, although the registry record does not specify the exact calculation or reference value. The reported mean describes the group average, while the standard deviation describes the spread of individual measurements around that average. Neither statistic alone shows the full distribution of outcomes or whether each participant improved.

At 5 weeks, the posted mean percentage change was 81.5 with a standard deviation of 12.3 in the collagen-based substitute arm, and 64.2 with a standard deviation of 14.1 in the membrane arm. The unadjusted mean difference, expressed as membrane arm minus collagen-based substitute arm, was -17.3, with a confidence interval from -22.03 to -12.57. The registry does not report the details needed to determine how measurements at earlier visits contributed to this primary comparison.

7. Results Posted in the Registry

• Human Amnion/Chorion Membrane and SOC: mean 64.20 versus 81.50 on control; difference -17.30 (95% CI -22.03 to -12.57), standardized effect d = -1.31; z-test p = <0.001.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Histopathological Analysis - Capillary Density (Vessels Per mm²)

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Human Amnion/Chorion Membrane and SOC: mean 29.40 versus 45.60 on control; difference -16.20 (95% CI -19.27 to -13.13), standardized effect d = -1.89; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Human Amnion/Chorion Membrane and SOC than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Percentage of Participants to Obtain Complete Wound Closure

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Human Amnion/Chorion Membrane and SOC: 51.7% (31/60) versus 83.3% (50/60) on control; risk difference -31.7 percentage points (95% CI -47.4 to -15.9), risk ratio 0.62 (0.47–0.81); unadjusted two-proportion z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the proportion with the event is statistically lower for Human Amnion/Chorion Membrane and SOC than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Time to Achieve Complete Wound Closure

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Human Amnion/Chorion Membrane and SOC: mean 28.80 versus 22.20 on control; difference 6.60 (95% CI 4.52 to 8.68), standardized effect d = 1.14; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Human Amnion/Chorion Membrane and SOC than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The posted secondary results address different aspects of wound healing rather than repeating the primary outcome. Their overall direction is consistent with the primary group-mean pattern: the collagen-based substitute arm has the higher reported capillary-density mean, the higher count for complete wound closure, and the lower mean time to closure. These endpoints are related in subject matter but measure distinct processes and use different scales. Agreement in direction can make a pattern more coherent, but it does not make the outcomes interchangeable or independently confirm the primary finding.

The secondary outcomes listed in the registry also cover histopathological analysis, achieving at least 50% wound healing, number of applications, adverse events, and patient-reported quality of life using the Diabetic Foot Ulcer Scale - Short Form. The registry record does not provide posted numerical results for all of these listed domains in the available outcome summaries. Where a result is not reported, its direction and precision cannot be inferred from the primary endpoint or from the other secondary outcomes.

Each secondary comparison is unadjusted in the posted results. When many outcomes are examined, the chance of seeing at least one apparently unusual result by chance can increase. Multiplicity procedures can address that concern, but the registry record does not report a prespecified adjustment strategy or a hierarchy of outcomes. Consequently, individual secondary p-values carry less weight than a result designated as primary in advance, especially when the full analysis plan and missing-data procedures are not reported.

The secondary findings are therefore best treated as supportive descriptive evidence that may motivate further study, not as a substitute for the primary comparison or as a complete account of all measured outcomes. The record does not provide enough detail to determine how much the secondary analyses were prespecified, whether all planned outcomes are posted, or whether their interpretation accounts for correlations among measures and repeated assessment.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Histopathological Analysis
• Histopathological Analysis - Capillary Density (Vessels Per mm²)
• Percentage of Participants to Obtain Complete Wound Closure
• Time to Achieve Complete Wound Closure
• Percentage of Participants Achieving ≥50% Wound Healing
• Mean Number of Applications of HPTC / dHACM
• Number of Participants With Adverse Events
• Patient-Reported Quality of Life Assessed Using Diabetic Foot Ulcer Scale - Short Form (DFS-SF)

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is continuous: it is a percentage-change measure summarized with a mean and standard deviation. A mean is an average that gives a concise description of the group’s central result. A standard deviation describes how dispersed the individual measurements are around that mean. When data are reasonably represented by a mean and standard deviation, these summaries help compare group averages, but they do not reveal skewness, outliers, or the shape of the participant-level data. The registry record does not provide individual observations or distributional plots.

What does the mean difference represent?

The posted primary contrast is the mean in the membrane arm minus the mean in the collagen-based substitute arm. A negative estimate therefore indicates that the posted mean is lower in the membrane arm for the outcome as recorded. The estimate is -17.3, with a confidence interval from -22.03 to -12.57. This contrast is unadjusted: it is a direct comparison of the reported group summaries, rather than a result adjusted for baseline factors or other covariates. The registry record does not report a covariate-adjusted primary analysis.

What does the p-value tell the reader?

The unadjusted p-value for the primary contrast is <0.001. In general, a p-value measures how compatible the observed result is with a specified null model, assuming that model and the analysis assumptions hold. It does not measure the size or importance of the difference. It also does not give the probability that the null model is true. Because the registry record does not report the full statistical plan, the exact model and assumptions underlying the sponsor’s primary analysis are not reported in the registry record. The displayed comparison is an unadjusted calculation from the posted summary statistics.

Why do confidence intervals matter?

A confidence interval presents a range of estimates compatible with the data under the calculation’s assumptions. Its width reflects precision: narrower intervals indicate less statistical uncertainty in the estimated contrast, while wider intervals indicate more. The primary interval from -22.03 to -12.57 lies on the negative side of zero, which is consistent with the direction of the reported mean difference. A confidence interval does not capture every possible source of uncertainty. For example, it does not by itself address bias from missing observations, measurement differences, or departures from the analysis assumptions.

How should the secondary outcomes be understood?

For continuous outcomes, such as capillary density and time to complete closure, the registry reports group means, standard deviations, mean differences, confidence intervals, and unadjusted p-values. A mean difference is interpreted according to the order of subtraction used for that outcome. For capillary density, the reported contrast is membrane minus collagen-based substitute, so a negative difference corresponds to a lower reported mean in the membrane arm. For time to closure, the contrast is positive, corresponding to a higher reported mean time in the membrane arm.

The complete-closure outcome is a count of participants meeting the stated outcome. The registry reports 50 participants in the collagen-based substitute arm and 31 in the membrane arm, with 60 at risk in each arm. The posted risk difference is -0.317, with a confidence interval from -0.474 to -0.159, again oriented as membrane minus collagen-based substitute. The record also gives relative-risk and odds-ratio estimates. These are different ways to describe a comparison of binary outcomes; they are not interchangeable with a mean difference. A risk difference describes an absolute contrast in event proportions, while relative measures describe the relationship between the proportions on a relative scale.

In general, over-dispersion matters when observed variation is larger than assumed by a statistical model. A model that understates variation can make standard errors too small and confidence intervals too narrow. The registry record does not report an over-dispersion assessment or enough methodological detail to determine whether such an issue arose. Similarly, the record does not report whether the continuous outcomes were checked for influential observations or whether alternative analyses were used.

What is not documented about the analysis?

The record identifies randomized allocation, single masking, and a parallel design, but those design labels do not reveal the analysis method. The randomization procedure, concealment, identity of the masked parties, and planned adjustment factors are not reported in the registry record. The record does not describe how repeated wound-area measurements were handled, whether the primary comparison used only the 5-week measurement, or whether a model used measurements across visits. Details on missing-data handling, analysis populations, center-level adjustment, and sensitivity analyses are also not reported. These omissions matter because different defensible analysis choices can yield different estimates or uncertainty, especially when outcomes are measured repeatedly or are unavailable for some participants.

11. Confidence Intervals and Precision

The primary mean difference is -17.3, with a confidence interval from -22.03 to -12.57. This interval gives a range of values consistent with the unadjusted comparison and its assumptions. Because the interval does not include zero, the posted estimate is not centered on no difference. Its width still matters: the interval allows a range of possible magnitudes, rather than identifying the true contrast with certainty. The p-value is reported as <0.001, but that does not replace the interval’s information about magnitude and precision.

The confidence interval is based on the posted group summaries, and the registry does not state its confidence level or the exact analysis method in the record. It should therefore be interpreted as the interval reported for the comparison, without assigning an unreported coverage level or assuming that it accounts for every design feature. In particular, the record does not say whether center clustering, repeated measurements, missingness, or other covariates were included in the interval calculation.

Other continuous comparisons also have intervals. Capillary density has a reported mean difference of -16.2, with a confidence interval from -19.27 to -13.13. Time to complete wound closure has a reported mean difference of 6.6 days, with a confidence interval from 4.52 to 8.68. For complete wound closure, the reported risk difference is -0.317, with a confidence interval from -0.474 to -0.159. Each interval concerns its own outcome and scale, so widths should not be compared directly across outcomes as if they conveyed the same amount of practical uncertainty.

Precision is not the same as generalizability or clinical importance. A relatively narrow interval can still accompany uncertain measurement or limited follow-up, and a statistically clear group contrast does not establish the effect’s durability. The registry record does not report longer-term follow-up results or sufficient detail to assess the precision of any subgroup estimate.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning display illustrates how many participants per arm might be needed under stated assumptions if the effect to detect were a chosen fraction of the observed effect. For the primary outcome, the rows for 100% of the observed effect, 75% of the observed effect, and 50% of the observed effect give participants-per-arm figures for 80% and 90% power. The 80% column represents a design targeting an 80% chance of detecting the specified effect under the planning assumptions if that effect is real; the 90% column represents a higher target chance under those same assumptions.

The calculation assumes a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It uses the observed effect as its reference, then considers the stated fractions of that effect. Smaller effects are harder to distinguish from random variation and therefore require more participants under the same assumptions. The primary-outcome illustration lists 10 and 13 participants per arm for 100% of the observed effect, 17 and 22 for 75% of the observed effect, and 37 and 50 for 50% of the observed effect, with the first figure in each pair corresponding to the 80% power target.

These are planning illustrations based on the observed effect, not the trial’s original design assumptions. The original sample-size justification is not reported in the registry record. The listed illustrations are not observed power: they do not describe the probability that this completed trial detected an effect after its results were known. The sample-size curve should be read as a visual expression of the same relationship between the assumed effect and the required planning size, not as evidence about the actual probability of success in this trial.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = -17.300; pooled standard deviation σ = 13.231.
2. n = 2 × (1.96 + 0.842)² × 13.231² / -17.300² = 9.2, rounded up to 10 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- -17.3                      # observed difference in means
sigma <- 13.23064624272                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(7046403)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 10 (80% power), 13 (90% power)
 75% of observed effect: n per arm = 17 (80% power), 22 (90% power)
 50% of observed effect: n per arm = 37 (80% power), 50 (90% power)
power.t.test: 10.2 
Simulated power at n = 10 per arm: 0.784 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

Multiplicity arises when researchers test or estimate several outcomes, time points, subgroups, or contrasts. Even when each test uses a conventional threshold, considering many tests can increase the chance that at least one result appears compelling through random variation. A prespecified strategy might identify a primary endpoint, order key secondary outcomes, or adjust inference to reflect multiple comparisons. The registry identifies percentage change in wound area as the primary outcome and lists multiple secondary outcomes. However, the record does not report a multiplicity adjustment method, a testing hierarchy, or a detailed prespecified statistical analysis plan. The secondary p-values are explicitly unadjusted.

The primary outcome is described across assessments at 1, 2,3, and 4 weeks, and week 5, while its timeframe is listed as 5 weeks. The registry record does not state whether the primary analysis used only the week-5 value, modeled repeated observations, or applied another method to handle the visit sequence. It also does not report whether the earlier assessments were treated as separate inferential comparisons. Without those details, the extent of any time-point multiplicity cannot be assessed.

Missing data can affect both the estimated group difference and its uncertainty, particularly if the probability of an observation being missing is related to healing or treatment experience. The registry record does not report the amount or pattern of missing outcome data, the methods used to handle missing values, or sensitivity analyses examining different assumptions. It does not identify the analysis population, such as whether the primary comparison followed randomized assignment or included only participants with observed measurements.

The record reports randomized allocation, but randomization by itself does not answer how post-randomization events or incomplete observations were handled in the analysis. The record also does not describe protocol deviations or exclusions from the reported group summaries. These details are important for assessing whether the comparison preserves the advantages of the randomized design.

The record’s completed status indicates that the study is recorded as complete, but it does not establish that every planned outcome or analysis is reported. The registry lists several secondary domains, while some do not have numerical results in the posted outcome summaries. The reason for any unreported result is not reported in the registry record. These uncertainties call for cautious interpretation of the overall set of comparisons, particularly the secondary findings.

15. 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 serious-adverse-event figures are reported separately for the two arms. Among the 60 participants at risk in each arm, the registry reports zero serious adverse events in the collagen-based substitute arm and zero in the membrane arm. Deaths are reported as zero in both arms. No serious adverse-event terms are listed.

The registry also reports other, non-serious adverse events affecting 4 participants in the collagen-based substitute arm and 11 participants in the membrane arm, with 60 at risk in each arm. These figures describe the adverse-event counts recorded in the registry; they do not establish that every event was caused by the assigned device or that all events were captured in the same way. The record does not provide event descriptions for these other adverse events, their severity or timing, or details about how events were solicited and classified.

Zero reported serious events should not be read as proof that serious events cannot occur. Safety interpretation depends on the completeness of reporting, the observation period, and the definitions used. The registry record does not report enough detail to assess those aspects fully, and the listed follow-up for the primary outcome is 5 weeks.

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

The registry results describe a difference between the observed group averages for percentage change in wound area at 5 weeks. The collagen-based substitute arm had a reported mean of 81.5, while the membrane arm had a reported mean of 64.2. The unadjusted contrast, defined as membrane minus collagen-based substitute, was -17.3, with a confidence interval from -22.03 to -12.57. This describes the posted trial results on the stated measure and timeframe.

That finding does not establish that the same contrast would occur in every clinical setting or for every participant. The registry record does not report detailed participant characteristics, ulcer features, center-specific results, or subgroup analyses. It also does not describe the method for controlling differences in care across centers or the analysis approach for repeated measurements. Those limits restrict conclusions about how broadly the group averages apply.

The primary measure is not equivalent to complete wound closure, and a group mean does not indicate that each participant had the same outcome. The posted secondary outcomes provide additional perspectives, but they are distinct measures with their own uncertainties. Unadjusted secondary comparisons require caution when multiple outcomes are considered. The available results do not resolve whether the observed patterns persist after the stated follow-up period or under alternative assumptions about missing data.

Statistical evidence is also different from clinical importance. A p-value below a conventional threshold does not describe the value of a difference to patients, and the record does not provide a threshold for what would count as a clinically important change in wound area. The registry includes patient-reported quality of life among its listed outcomes, but the available outcome summaries do not report a numerical result for that measure.

These results should be understood as a record of what was reported for this randomized comparison, not as individualized guidance. The registry does not report all methodological details needed to determine the robustness of the analyses or the completeness of outcome reporting. No conclusion about outcomes beyond the recorded measures and follow-up can be drawn from these summaries alone.

17. Why This Trial Matters Statistically

This trial is statistically interesting because it compares two active wound-care approaches using randomized allocation and reports a continuous primary endpoint alongside binary and time-based secondary outcomes. Those measures capture different features of healing. A continuous wound-area measure can describe the degree of change, while complete closure records whether a stated milestone was reached. Time to closure adds a timing dimension, and capillary density describes a tissue measure. Considering distinct endpoints can provide a broader picture than relying on one summary alone.

The primary result is reported as a mean difference with a confidence interval, allowing readers to consider both the direction and precision of the group contrast. The comparison is unadjusted, and the registry record does not describe the analysis model or the original sample-size justification. That makes transparency about methods especially important: a clear prespecified plan would help readers assess how the primary endpoint, repeated assessments, secondary outcomes, and missing observations were handled.

The registry also highlights a common distinction between planning calculations and observed trial evidence. The sample-size illustrations use the observed effect as a reference and vary the effect assumed for planning. They do not reconstruct the trial’s original design rationale or give observed power. This distinction helps prevent a post-result calculation from being mistaken for evidence that the study was adequately designed in advance.

Finally, the study shows why reporting completeness matters. The available results include several secondary comparisons, while the registry record does not provide numerical results for every listed secondary domain or detailed information about multiplicity, analysis populations, and missing data. Those omissions do not erase the posted findings, but they constrain the strength and scope of statistical conclusions that can be drawn from them.

18. 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 follow-up described for the primary outcome is 5 weeks, so the posted findings do not characterize longer-term wound outcomes. The record lists multiple centers but does not report how many centers participated, the distribution of participants across centers, or whether center effects were considered in the analysis. It also does not provide detailed baseline characteristics or wound features, limiting assessment of comparability and applicability to particular patient groups.

Although allocation is recorded as randomized and masking as single, the randomization method, allocation concealment, and identity of the masked parties are not reported in the registry record. The intervention descriptions are incomplete at the dressing details, and the record does not explain how standard care was standardized across centers. These gaps make it difficult to assess implementation consistency.

The primary endpoint is described at several visits, but the method used to combine or select measurements for the primary comparison is not reported. The registry does not identify the analysis population, report missing-data amounts or methods, or describe sensitivity analyses. It does not report whether center, baseline wound area, or other covariates were included. These details matter for interpreting both the estimate and its uncertainty.

The secondary results are unadjusted, and no multiplicity strategy is reported. The registry lists additional outcomes for which numerical findings are not available in the outcome summaries, including patient-reported quality of life. The reason for these missing result details is not reported in the registry record. The record also does not provide detailed adverse-event descriptions or ascertainment procedures. Together, these limitations mean that the posted results are informative as reported group summaries but do not provide a complete account of all planned analyses or sources of uncertainty.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Multicentric RCT Comparing High Purity Type I Collagen-Skin Substitute vs dHACM in Treatment of Diabetic Foot Ulcers — NCT07046403.
• Registry record last updated 2025-11-21; status last verified 2025-11.
• Results first posted 2025-11-21.
• 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.

22. Record Summary

The registry record describes a completed, randomized, single-masked, parallel-group, multicenter trial in patients with diabetic foot ulcers. It compares High Purity Type-I Collagen-based Skin Substitute with standard of care against Dehydrated Human Amnion/Chorion Membrane with standard of care. Enrollment is listed as 120, with 60 participants reported in each arm. The primary outcome is percentage change in wound area at 5 weeks.

The posted primary means are 81.5 for the collagen-based substitute arm and 64.2 for the membrane arm. The unadjusted mean difference, expressed as membrane minus collagen-based substitute, is -17.3, with a confidence interval from -22.03 to -12.57 and p < 0.001. Secondary summaries cover capillary density, complete wound closure, and time to closure. The record also reports adverse-event counts and lists additional outcome domains.

The registry record does not report the full statistical analysis plan, original sample-size justification, missing-data methods, analysis populations, or a multiplicity strategy. Those omissions limit interpretation beyond the posted summaries.