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 Study of Cellutome System for Treatment of Individual Lesions in EB Pts (NCT02670837), a non-randomized na study. The primary outcome is Percentage of Grafts Successfully Treated.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02670837 |
| Phase | NA |
| Condition | Epidermolysis Bullosa |
| Allocation | Non-Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 34 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Masonic Cancer Center, University of Minnesota |
| Results posted | Yes |
2. Clinical Question
Population
People with epidermolysis bullosa and individual persistent wounds. The registry record describes local wound treatment in the context of epidermolysis bullosa, including wounds that may remain after hematopoietic cell transplantation. Enrollment was 34.
Intervention
Epidermal cells were harvested with the CelluTome system and transferred to a wound using an Adaptic non-adherent silicone dressing. The described graft source was either an HCT donor or the participant’s own intact skin patch. The protocol descriptions specify up to 3 harvest sites and treated wound sites on day 0.
Comparator
The registry describes a graft-from-HCT-donor group and a self-donor-from-intact-skin-patch group. Allocation was non-randomized, and the record flags that the arms are not a like-for-like control comparison. It does not establish that the groups provide an unbiased estimate of the effect of one graft source versus the other.
Primary question
What percentage of grafts met the registry’s definition of successful treatment at 12 weeks after grafting? A graft was considered successful if the body surface area affected by the wound was at least 50% lower at 12 weeks relative to baseline. The registry record does not report the observed percentage or its 95% confidence interval.
The clinical question is therefore about a short-term wound-area criterion following epidermal grafting, rather than a randomized comparison of treatments. The registry also lists secondary outcomes concerning lesion-free skin, graft longevity, changes in IScorEB and IScoreEB assessment scores, and scar-free healing at donor sites. Results for these outcomes are not reported in the registry record.
3. Trial Design
This completed study evaluated the CelluTome Epidermal Harvesting System for treating individual lesions in people with epidermolysis bullosa. The registry lists 34 participants enrolled. The study started on 2016-08-04, reached primary completion on 2023-03-16, and has completed status. Its phase is listed as NA.
The design is recorded as parallel, non-randomized, and unmasked. The described graft-source groups were grafts from an HCT donor and grafts taken from the participant’s own intact skin patch. In both descriptions, harvested epidermal cells were transferred to the recipient wound using an Adaptic dressing. The HCT-donor description refers to a donor whose hematopoietic graft was given to the recipient; the self-donor description refers to harvesting from the subject being treated.
Because allocation was not randomized, differences between the groups cannot automatically be interpreted as effects caused by graft source. Group membership may be associated with participant or clinical characteristics, and the registry record does not report an adjustment strategy that would address such differences. The record itself cautions that the arms are not a like-for-like control comparison. Masking is listed as none, so the record does not describe masking of participants, clinicians, or outcome assessors.
The primary outcome was the percentage of grafts considered successfully treated at 12 weeks after grafting. The record defines success using a threshold for reduction in wound-affected body surface area relative to baseline. It lists five secondary outcomes, including lesion-free skin, graft longevity, assessment-score changes, and scar-free donor-site healing. Results and analysis details for these outcomes are not reported in the registry record. A prospective sample-size justification, interim analysis plan, and full statistical analysis plan are also 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.
Overall Study
| Stage | Graft From HCT Donor | Donor | Self-Donor |
|---|---|---|---|
| STARTED | 17 | 17 | 0 |
| COMPLETED | 15 | 17 | 0 |
| NOT COMPLETED | 2 | 0 | 0 |
Reasons for not completing this period:
| Reason | Graft From HCT Donor | Donor | Self-Donor |
|---|---|---|---|
| Death | 2 | 0 | 0 |
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 | Graft From HCT Donor | Donor | Total |
|---|---|---|---|---|
| Participants analysed | 17 | 17 | 34 | |
| Age, Categorical: <=18 years | Participants | 15 | 10 | 25 |
| Age, Categorical: Between 18 and 65 years | Participants | 2 | 7 | 9 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 |
| Sex: Female, Male: Female | Participants | 8 | 15 | 23 |
| Sex: Female, Male: Male | Participants | 9 | 2 | 11 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 1 | 1 | 2 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 16 | 16 | 32 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 1 | 1 | 2 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): White | Participants | 15 | 12 | 27 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 1 | 4 | 5 |
| Region of Enrollment: United States | participants | 17 | 17 | 34 |
6. Primary Endpoint
The registry lists the primary outcome as Percentage of Grafts Successfully Treated, measured over 12 weeks after grafting.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | 95% Confidence Interval |
| Unit | Percentage of grafts |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the percentage of grafts successfully treated at 12 weeks after grafting. The registry defines an individual graft as successful if the body surface area affected by the wound is at least 50% lower at 12 weeks than at baseline. The endpoint therefore reduces wound-area change to a threshold-based classification: a graft either meets the stated criterion or does not. The reported outcome would be a percentage of grafts, together with a 95% confidence interval according to the registry description.
General statistical context: a threshold endpoint can be easier to interpret clinically than a continuous change measure because it expresses whether a specified degree of improvement was reached. However, grafts just on either side of the threshold are classified differently even if their measured wound-area changes are similar. The percentage also depends on how grafts and their outcomes are counted, including how multiple treated sites within a participant are handled. Those operational details are not reported in the registry record.
The endpoint is assessed at a specified time point, 12 weeks after grafting. It does not by itself describe longer-term persistence of grafted skin; longevity is listed separately as a secondary outcome. The registry record does not report the observed number or percentage of successful grafts, the confidence interval, or details of missing outcome handling. Consequently, the endpoint’s definition is available, but its observed value and precision cannot be evaluated from the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record defines a primary outcome but does not report its numerical result. It therefore does not establish what percentage of grafts met the success criterion, nor how uncertain that percentage was. The stated criterion is a reduction of at least 50% in wound-affected body surface area at 12 weeks relative to baseline. Without the observed percentage and its 95% confidence interval, the result cannot be described as more or less frequent than any benchmark, or as precise or imprecise in numerical terms.
The record lists 34 participants enrolled and describes two graft-source groups, but the primary outcome is expressed as a percentage of grafts. The number of grafts evaluated and the relationship between grafts and participants are not reported in the registry record. That distinction matters: if a participant contributed multiple grafts, outcomes from grafts within the same person may be related rather than statistically independent. The registry does not report how this issue was handled in analysis.
The study is non-randomized and unmasked, and the registry explicitly cautions that the arms are not a like-for-like control comparison. General statistical context: in a non-randomized comparison, differences in outcomes may reflect differences in who received each graft source, as well as the grafting approach itself. Without random assignment or a reported adjustment plan, a contrast between groups should be read as descriptive rather than as a clean causal estimate. The registry record does not report an adjusted comparison or a statistical analysis of the primary endpoint.
The record lists six outcome measures and zero analyses. This means the registry data described for this study do not include analysis results for the listed outcomes. A completed status and a defined endpoint do not substitute for outcome estimates. The sponsor’s inferential analysis, if any, is not reported in the registry record, and no recalculated estimate can be discussed from the recorded information.
The adverse-event record lists zero participants affected by serious adverse events in each of its two groups, with 17 at risk in each group. It also lists 2 deaths in the Graft From HCT Donor group and 0 in the Donor group. These are registry counts; the record does not provide details about causes, timing, relationship to the procedure, or whether the deaths occurred among participants who received grafts. The counts should not be read as establishing a causal safety difference.
Overall, the registry supports a description of the study’s design, endpoint definition, and recorded safety counts, but not a quantitative conclusion about primary outcome frequency or group differences. The primary estimate, confidence interval, analysis population, and statistical methods used for outcome comparisons are not reported in the registry record.
9. Statistical Methods Explained
Statistical interpretation depends on distinguishing the outcome definition, the estimate, its uncertainty, and the design used to obtain it. In this study, the registry defines a binary graft-level success criterion at 12 weeks: wound-affected body surface area must be at least 50% lower than at baseline. It also specifies a percentage outcome and a 95% confidence interval. The observed percentage and interval are not reported in the registry record.
What a confidence interval would describe
General statistical context: a confidence interval expresses uncertainty around an estimated quantity under the assumptions of the analysis. For a percentage of successful grafts, the interval would indicate a range of values compatible with the observed data and chosen method. A narrower interval generally indicates greater precision, while a wider interval indicates less precision. An interval does not correct for non-random allocation, biased outcome assessment, missing data, or an inappropriate model. Since the interval itself is not reported, its width and the resulting precision cannot be assessed.
What the threshold endpoint captures
The primary outcome classifies each graft against a specified threshold rather than reporting only the amount of wound-area change. General statistical context: dichotomizing a continuous measurement can simplify interpretation, but it discards information about how far a value lies above or below the threshold. The percentage of successful grafts may also depend on the measurement method, the definition of the wound area, and how multiple graft sites are counted. Those measurement and counting details are not reported in the registry record.
Why the study design matters
Allocation is listed as non-randomized, masking as none, and the study model as parallel. The record also states that the arms are not a like-for-like control comparison. General statistical context: randomization aims to balance measured and unmeasured characteristics across groups on average. Without randomization, group differences can be entangled with participant characteristics, clinical circumstances, or treatment decisions. Masking can reduce some forms of assessment or management bias, but none is listed. These design features limit causal interpretation of any between-group contrast, even if an outcome estimate were available.
A parallel design means the registry presents groups rather than a crossover sequence. It does not, by itself, establish that groups are comparable. The registry record does not report a statistical adjustment strategy, matching procedure, or other method for addressing group differences. It also does not report the statistical test or model used for the primary endpoint.
Planning illustrations are not observed power
The registry’s sample-size assumptions describe a planning illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. This is not reported as the trial’s original design justification. The registry record does not report a prospective sample-size justification, and the numerical planning illustrations are not reported in the registry record.
General statistical context: a sample-size illustration estimates the number of participants per arm that would be needed under specified assumptions; it does not show that a study had a particular probability of detecting an effect after the study is complete. Such a calculation depends on the assumed effect and statistical model. It should not be called observed power. In this case, the available registry information does not give the numerical observed effect or the planning results needed to discuss the illustration further.
What can be concluded from the registry analysis record
The registry lists zero analyses. It does not report analysis populations, missing-data methods, handling of multiple grafts per participant, adjustment for baseline characteristics, multiplicity procedures, or an interim analysis plan. The full statistical analysis plan is not reported in the registry record. These omissions prevent a detailed assessment of whether the endpoint analysis accounted for clustering, incomplete follow-up, or other features of the data.
The endpoint definition and confidence-interval specification describe what the primary analysis was intended to summarize, but they do not reveal the result. Without the success percentage, interval, denominator, and analysis method, there is no basis to recalculate an effect or assess its precision. Any broader statistical explanation in this interpretation is general context, not a reconstruction of unreported analyses.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one primary outcome, the percentage of grafts successfully treated at 12 weeks, and five secondary outcomes: participants with lesion-free skin, longevity of grafted skin, percentage changes in IScorEB and IScoreEB assessment scores, and scar-free healing at donor sites. It records six outcome measures overall. Results for these outcomes are not reported in the registry record.
When a study assesses multiple outcomes, the chance of at least one apparently notable finding can increase if each outcome is tested separately without an appropriate plan. General statistical context: multiplicity procedures can help control that issue, while a prespecified hierarchy can clarify which outcomes are confirmatory and which are exploratory. A multiplicity adjustment or hierarchy is not reported in the registry record. The registry also records zero analyses, so no outcome-specific statistical results are available for evaluation.
The record does not report how missing measurements or withdrawals were handled, which participants or grafts were included in each analysis, or whether all treated grafts were assessed at 12 weeks. It does not report a method for handling multiple grafts from a participant. These details matter because the primary endpoint is defined per graft while enrollment is reported per participant. The analysis population and any imputation or sensitivity analyses are not reported in the registry record.
An interim analysis plan and a complete statistical analysis plan are also not reported in the registry record. These omissions do not establish that no such procedures existed; they mean their details cannot be assessed from the registry entry. As a result, the intended control of false-positive findings, missing-data effects, and analysis-population choices remains unclear.
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 |
|---|---|---|---|
| Graft From HCT Donor | 0 | 17 | 0.0% |
| Donor | 0 | 17 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Graft From HCT Donor | 2 of 17 |
| Donor | 0 of 17 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Graft From HCT Donor | 0 of 17 |
| Donor | 0 of 17 |
The registry lists two groups for adverse-event reporting: Graft From HCT Donor and Donor. Each group has 17 participants at risk for serious adverse events, and zero participants are recorded as affected by serious adverse events. The record also lists zero other adverse events in each group. These are counts as recorded, not estimates of comparative risk.
Deaths are listed separately: 2 in the Graft From HCT Donor group and 0 in the Donor group. The record does not report the timing or causes of these deaths, whether they were considered related to grafting, or the context needed to interpret them. The group labels and adverse-event counts do not establish that graft source caused the observed death counts.
General statistical context: zero recorded events in a group does not prove that the underlying event risk is zero. Counts from groups of this size can be imprecise, and interpretation depends on definitions, follow-up duration, completeness of reporting, and event attribution. Those details are not reported in the registry record. The record lists no top serious-event terms. These figures should therefore be read as a limited descriptive account, not as a comprehensive comparison or a causal safety assessment.
12. What the Result Does, and Does Not, Mean
The registry record describes a completed study of epidermal grafting for individual lesions in people with epidermolysis bullosa. It specifies the primary endpoint and its assessment time: a graft qualifies as successfully treated if wound-affected body surface area is at least 50% lower at 12 weeks relative to baseline. This definition identifies what the primary outcome was intended to measure.
The record does not report the percentage of grafts meeting that definition, its 95% confidence interval, or an analysis of differences between graft-source groups. It therefore cannot show how frequently the stated threshold was reached or how precise an estimate would be. The listed secondary outcomes also lack reported results. No treatment-effect estimate should be inferred from the endpoint definition, study completion status, or adverse-event counts.
The study’s non-randomized allocation and lack of masking are important when interpreting any comparison. The registry explicitly warns that the arms are not a like-for-like control comparison. General statistical context: observed differences between non-randomized groups may reflect participant selection or other group differences rather than the intervention alone. The registry does not report methods that would allow those sources of bias to be evaluated or adjusted for.
The record’s safety counts are descriptive. Zero serious adverse events are recorded among 17 at-risk participants in each listed group, while deaths are listed as 2 and 0, respectively. The registry does not report the circumstances or attribution of the deaths. These figures do not establish a causal relationship between grafting and any event, and should not be treated as a complete safety comparison.
In short, the record informs readers about the study structure, grafting approaches, endpoint definition, and recorded event counts. It does not supply the outcome estimates needed to judge the observed frequency of primary success, the precision of that estimate, or comparative effects. Statistical interpretation must remain within those limits.
13. Why This Trial Matters Statistically
This study raises statistical issues that are common in trials of procedures applied to individual lesions. The primary endpoint is expressed as a percentage of grafts, while enrollment is expressed as participants. The registry does not report the number of grafts evaluated or how multiple treated sites per participant were analyzed. If multiple graft outcomes from the same person are related, treating them as independent could misstate uncertainty. The analysis method is not reported in the registry record.
The endpoint also converts a wound-area measurement into a threshold-based success classification. That approach gives the outcome a clear criterion, but it can hide variation in the amount of change among grafts. Reporting both the proportion meeting the criterion and the underlying wound-area changes could provide complementary information; such results are not reported in the registry record.
Non-random allocation and no masking make careful interpretation essential. The registry notes that the arms are not a like-for-like control comparison. This means even a numerical difference between groups would not automatically isolate the effect of graft source. Design, analysis, and transparent reporting all matter in determining what a comparison can support.
Finally, a defined primary outcome is not the same as a reported result. The registry includes the success rule and a confidence-interval specification, but no outcome estimate or interval. That distinction is important for clinical research readers: a protocol-level description tells what was intended to be measured, while results are needed to assess the observed pattern and its uncertainty. In this record, the design and endpoint can be described, but the primary statistical finding cannot be evaluated.
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 central limitation for statistical interpretation is that the registry record does not report the primary outcome estimate or its 95% confidence interval. The success threshold and follow-up time are specified, but the percentage of grafts meeting the threshold is unavailable. Results for the listed secondary outcomes are also not reported.
The study is non-randomized and unmasked. The registry cautions that the groups are not a like-for-like control comparison. Consequently, any group contrast would be vulnerable to differences between participants or treatment circumstances, and the record does not report an adjustment strategy. The statistical analysis methods are not reported in the registry record.
Enrollment is given as 34 participants, but the primary endpoint is stated as a percentage of grafts. The number of grafts, the number assessed at 12 weeks, and the handling of multiple grafts per participant are not reported. Missing-data procedures, analysis populations, and outcome-assessment details are also not reported in the registry record. These gaps prevent assessment of the denominator and uncertainty underlying the primary estimate.
The registry describes adverse-event counts but not their timing, attribution, or cause. It lists 2 deaths in the Graft From HCT Donor group and 0 in the Donor group; the record does not explain whether these deaths were related to treatment. The counts alone cannot establish causality.
A prospective sample-size justification, interim analyses, multiplicity strategy, and complete statistical analysis plan are not reported in the registry record. The listed planning assumptions are an illustration based on the observed effect, not the trial’s own design justification. These reporting limitations leave important aspects of the intended and completed analyses unresolved.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Study of Cellutome System for Treatment of Individual Lesions in EB Pts — NCT02670837.
- Registry record last updated 2024-04-09; status last verified 2024-04.
- Results first posted 2024-03-12.
- 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
NCT02670837 is a completed, parallel, non-randomized, unmasked study of the CelluTome Epidermal Harvesting System for individual lesions in people with epidermolysis bullosa. The registry lists 34 participants enrolled and describes grafting with epidermal cells from an HCT donor or from the participant’s own intact skin patch. Grafting used an Adaptic dressing.
The primary endpoint is the percentage of grafts meeting a success criterion at 12 weeks after grafting: wound-affected body surface area at least 50% lower than at baseline. The registry specifies a 95% confidence interval but does not report the endpoint estimate or interval. It lists five secondary outcomes, with no results reported in the registry record.
The record lists zero serious adverse events among 17 at-risk participants in each of two groups, and deaths of 2 and 0, respectively. It does not report event attribution or analysis details. Allocation was non-randomized, and the record cautions that the arms are not a like-for-like control comparison. A full statistical analysis plan and prospective sample-size justification are not reported in the registry record.