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 Clinical Study to Investigate the Safety and Effectiveness of RECELL for Repigmentation of Stable Vitiligo Lesions (NCT04547998), a na na study. The primary outcome is Incidence of ≥80% Study Area Repigmentation.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04547998 |
| Phase | NA |
| Condition | Vitiligo |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 25 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Avita Medical |
| Results posted | Yes |
2. Clinical Question
Population
Participants with stable vitiligo lesions. The registry record lists Vitiligo as the condition and identifies an ITT population for the primary outcome. It does not report additional eligibility details or describe the participants’ characteristics.
Intervention
Ablative laser resurfacing followed by RECELL and UVB. The record describes RECELL as a device used to prepare Spray-On Skin™ Cells for application to depigmented lesions.
Comparator
UVB alone, labelled the control intervention. Each participant is described as receiving both intervention conditions on portions of a depigmented lesion, with portions randomly allocated in the arm description.
Primary question
At Week 24, how many study areas reached at least 80% repigmentation, as evaluated by qualified members of a Central Review Committee? The observed count and any comparative estimate are not reported in the registry record.
The clinical question is framed around repigmentation of stable vitiligo lesions and the difference in treatment components between the two conditions. Both conditions include UVB; the investigational condition additionally includes ablative laser resurfacing and RECELL. The record therefore describes a comparison of treatment approaches within participants, rather than a comparison of separate groups of participants.
The title and brief description characterize the study as prospective, blinded, within-subject, and randomized. However, the record lists masking as NONE and allocation as NA, and its design model is SINGLE GROUP. These entries do not fully align with the descriptive wording. The registry record does not resolve the discrepancy, so the exact implementation of blinding and random allocation cannot be established from the record alone.
3. Trial Design
The record describes a prospective study in which each participant serves as their own control. Each participant is said to receive both the control intervention, UVB, and the investigational intervention, ablative laser resurfacing plus RECELL plus UVB. The arm description says the interventions are randomly allocated to portions of a depigmented vitiligo lesion. This within-participant arrangement is intended to compare treated areas while holding participant-level characteristics in common.
The registry lists enrollment as 25 and status as COMPLETED. The listed start date is 2020-09-10, and the primary completion date is 2022-06-28. The study phase is recorded as NA. Avita Medical is named as the sponsor. These record details describe the planned or registered study context; they do not establish how many participants contributed evaluable data to the primary outcome.
There are inconsistent design descriptors in the registry. The official title calls the study randomized and blinded, while the masking entry is NONE and the allocation entry is NA. The record also categorizes the model as SINGLE GROUP. Its arm description nevertheless says the two interventions were randomly allocated to portions of lesions within each participant. The registry record does not report enough detail to reconcile those entries or to determine exactly how sequence generation, allocation concealment, or blinding were carried out.
The record identifies secondary outcomes of Repigmentation Category and Color Matching, alongside three outcome measures and three analyses. The primary outcome is assessed at Week 24. Further details about follow-up beyond that timeframe, deviations from the planned design, or the conduct of the analyses are not reported in the registry record.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Before assignment: The design of this study is a within-patient comparison. Protocol enrollment is 25 (participants), with 50 interventions (2 per patient).
Overall Study
| Stage | Control Intervention (UVB) | Investigational Intervention (Ablative Laser Resurfacing + RECELL + UVB) |
|---|---|---|
| STARTED | 25 | 25 |
| COMPLETED | 25 | 25 |
| NOT COMPLETED | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: ITT
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
Population: Experimental: All Participants (within patient control)
| Characteristic | Unit | All Participants (Within Patient Control) |
|---|---|---|
| Participants analysed | 25 | |
| Age, Continuous | years | 41.0 (SD 12.5) |
| Sex: Female, Male: Female | Participants | 13 |
| Sex: Female, Male: Male | Participants | 12 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 6 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 19 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 3 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 2 |
| Race (NIH/OMB): White | Participants | 20 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Incidence of ≥80% Study Area Repigmentation, measured over Week 24.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | study areas |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the incidence of study areas with at least 80% repigmentation at Week 24. It is expressed as a number of study areas, not as a continuous measure of pigment change. The registry says qualified members of a Central Review Committee evaluated repigmentation, and identifies the primary outcome population as ITT.
A threshold endpoint turns a graded clinical observation into a count of areas meeting a prespecified category. Such endpoints can make a result easier to interpret in terms of reaching a defined degree of repigmentation. They also discard some detail: areas just below the threshold and areas with much less repigmentation are grouped together as not meeting it, while areas above the threshold are counted as meeting it.
Because the study is described as within-participant, the endpoint’s unit matters. The record specifies study areas, while the intervention assignment is described as applying to portions of lesions. The registry record does not report the observed count of areas meeting the threshold in either condition, the number of areas assessed, or a numerical contrast between conditions. Consequently, the endpoint definition can be explained, but the magnitude and precision of the observed outcome cannot be assessed from the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record defines a clinically interpretable primary outcome: the number of study areas reaching at least 80% repigmentation at Week 24, assessed by a Central Review Committee. It also identifies the ITT population. However, it does not report the observed primary outcome count, a comparison between intervention conditions, or an uncertainty estimate. The record therefore supplies the question and measurement approach, but not the numerical evidence needed to describe the observed repigmentation results.
The study is described as comparing UVB alone with ablative laser resurfacing plus RECELL plus UVB within participants. In a properly executed paired design, observations from the two conditions on the same participant may be statistically dependent. A paired analysis can account for that dependence, whereas an analysis that treats every area as independent could misstate uncertainty. The registry record does not report the analysis method or enough outcome detail to determine whether that dependence was handled appropriately.
The design information also needs cautious reading. The title and summary use randomized and blinded language; the arm description says portions were randomly allocated. At the same time, the allocation entry is NA, the masking entry is NONE, and the model is SINGLE GROUP. The record does not explain these differences. It would be unwarranted to infer the actual allocation procedure or assessor blinding from the descriptive title alone.
The listed enrollment is 25, but that does not establish the number of participants, lesions, or study areas included in the primary analysis. Nor does it show whether all enrolled participants completed Week 24 assessment. The record does not report missing outcome counts, exclusions, or analysis denominators. Without those details, the completeness and representativeness of the primary outcome cannot be judged.
The registry also lists secondary outcomes for Repigmentation Category and Color Matching, and records three outcome measures and three analyses. Their numerical findings and their relationship to the primary analysis are not reported in the registry record. No conclusion about consistency across endpoints, statistical significance, or the precision of effects can be drawn from those entries alone.
In short, the posted record supports a description of the study question and endpoint but does not provide the primary results required for an effect interpretation. It also does not provide an inferential analysis, confidence interval, or p-value for the described treatment comparison. The absence of those results in the registry record is not evidence of either benefit or lack of benefit; it limits what can be concluded from this record.
9. Statistical Methods Explained
Statistical interpretation depends on matching the method to the design, outcome, and unit of analysis. Here, the record describes treatment allocation to portions of lesions within participants, while the primary endpoint counts study areas meeting a repigmentation threshold. Those features raise design and analysis questions that cannot be answered fully from the registry entries.
Why does the within-participant design matter?
General statistical explanation: when two conditions are applied to different areas in the same participant, the two observations may be correlated because they share participant characteristics. A paired analysis uses that within-participant structure. It typically bases the contrast on the paired observations rather than treating the conditions as unrelated groups. Ignoring pairing can make uncertainty estimates inappropriate. The record does not identify the statistical test or model used, so it is not possible to say how the study’s analysis accounted for this structure.
The paired structure also means that an area-level count is not automatically an independent sample size. Areas belonging to the same participant may resemble one another more than areas from different participants. If multiple areas contribute for a participant, an analysis may need to account for clustering as well as pairing. The record does not report the number of areas per participant, the dependence structure, or a method for handling clustering. It is therefore not possible to assess whether the statistical unit matched the randomization unit.
What does the threshold endpoint represent?
The primary endpoint counts areas that reach at least 80% repigmentation by Week 24. General statistical explanation: converting a graded measurement to a threshold can simplify interpretation, but it loses information about the distance from the threshold and variation within each category. Results may depend on the chosen cut point. The record describes the threshold but does not report the underlying continuous measurements or explain how the threshold was selected.
The endpoint is a count, and the registry classifies its outcome type as count other. Count outcomes can sometimes show more variability than a simple model assumes. General statistical explanation: over-dispersion occurs when the observed variability exceeds the variability expected under a basic count model. If present, it can make standard errors too small unless the analysis accounts for it. The registry record does not report a distribution, dispersion estimate, or modeling approach, so over-dispersion cannot be evaluated.
What does a confidence interval add?
General statistical explanation: a confidence interval describes the uncertainty around an estimated effect under the assumptions of the analysis. It gives a range of effect values compatible with the data and method, rather than presenting only a point estimate. A narrow interval indicates greater precision than a wide interval, although neither width nor statistical significance by itself establishes clinical importance. No confidence interval or effect estimate for the primary comparison is reported in the registry record.
A p-value, if reported, would address how compatible the data are with a specified null hypothesis under the analysis assumptions. It would not measure the probability that a treatment works, nor would it describe the size or clinical relevance of an effect. The registry record does not report a p-value for the primary comparison, and the analysis plan is not reported in the registry record.
How should planning illustrations be understood?
General statistical explanation: sample-size calculations use assumptions about the effect to detect, variability, allocation, and chosen error rates. A planning illustration based on an observed effect is a retrospective scenario, not evidence that the original study had adequate power. It is also not observed power. The record describes planning illustrations computed from the observed effect using a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It says the target effect is a stated fraction of the observed effect. The record does not report the trial’s own design justification, so these illustrations should not be attributed to the original protocol.
For time-to-event outcomes, the record says planning illustrations give a total number of events; for other outcomes, they give participants per arm. The primary endpoint is a count of study areas, and the record does not provide the numerical planning outputs or the observed effect needed to interpret such scenarios. Those figures should not be confused with enrollment, outcome denominators, or observed results.
What is needed to assess the analysis?
General statistical explanation: interpretation of a randomized comparison usually depends on the allocation method, analysis population, handling of missing data, outcome definition, and a prespecified analysis. For a within-participant study, details about pairing, area selection, and clustering are also important. The registry record identifies an ITT population for the primary endpoint but does not describe how ITT was defined or implemented, nor does it report the statistical model, missing-data procedures, or analysis assumptions. These omissions prevent independent assessment of whether the selected analysis appropriately reflects the study design.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary endpoint and the secondary outcomes Repigmentation Category and Color Matching. It also records three outcome measures and three analyses. Listing multiple outcomes creates a general multiplicity issue: when several hypotheses are tested, the chance of at least one apparently notable result can increase if no adjustment or hierarchy is used. The registry record does not report a multiplicity strategy, endpoint hierarchy, or whether any adjustment was applied. It is therefore not possible to determine how findings across outcomes were intended to be interpreted together.
The primary population is identified as ITT. The registry record does not define the analysis population in practical terms, describe how participants or study areas were retained in that population, or report the number included in the primary analysis. The enrollment entry of 25 is not a substitute for an analysis denominator.
Missing-data methods and missing outcome counts are not reported in the registry record. The record does not say whether participants with unavailable Week 24 assessments were excluded, imputed, or handled through another method. General statistical explanation: missingness can affect interpretation when the likelihood of an unavailable outcome is related to treatment or to the outcome itself. Without the amount and pattern of missingness, and the method used to address it, the direction or size of any impact cannot be assessed.
The protocol’s prespecified statistical analysis plan and any changes to it are not reported in the registry record. Nor is there information about interim analyses or rules for stopping analyses early. Those details should not be inferred from the completed status or from the count of analyses.
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 |
|---|---|---|---|
| Control Intervention | 0 | 25 | 0.0% |
| Investigational Intervention (RECELL) | 0 | 25 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Control Intervention | 0 of 25 |
| Investigational Intervention (RECELL) | 0 of 25 |
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 |
|---|---|
| Control Intervention | 1 of 25 |
| Investigational Intervention (RECELL) | 5 of 25 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Control Intervention | Investigational Intervention (RECELL) |
|---|---|---|---|
| Pruritus | Skin and subcutaneous tissue disorders | 0 of 25 | 2 of 25 |
| Vitiligo | Skin and subcutaneous tissue disorders | 1 of 25 | 1 of 25 |
| Scar | Injury, poisoning and procedural complications | 0 of 25 | 1 of 25 |
| Erythema | Skin and subcutaneous tissue disorders | 0 of 25 | 1 of 25 |
The registry reports adverse-event figures separately for the Control Intervention and the Investigational Intervention (RECELL). For serious adverse events, 0 of 25 participants at risk are listed as affected in each condition. Deaths are listed as 0 in each condition. For other adverse events, 1 of 25 at risk is listed as affected for the control condition, and 5 of 25 at risk for the investigational condition.
These are descriptive counts in the registry record. They should not be treated as a definitive comparison of safety between conditions. The record does not report an inferential analysis, a confidence interval, event timing, severity details for the non-serious events, or whether the same participant experienced events in both conditions. Because the design is described as within-participant, the participant-level relationship between the two conditions is particularly relevant to a formal comparison.
The registry lists no top serious adverse-event terms. A count of zero serious events in the posted record does not establish that no risk exists; it describes the reported events and observation in this study. The record does not provide follow-up detail sufficient to characterize how long participants were monitored for safety.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a study was registered to evaluate repigmentation of stable vitiligo lesions using RECELL with ablative laser resurfacing and UVB, compared with UVB alone. The comparison is described as within-participant, with the participant serving as their own control and interventions assigned to portions of a depigmented lesion. The primary outcome is the number of study areas reaching at least 80% repigmentation at Week 24.
Those design and endpoint details explain what the study set out to examine. They do not reveal the observed primary outcome. The registry record does not report how many study areas met the threshold, a numerical comparison between conditions, or an estimate of uncertainty. It is therefore not possible to say from this record whether one condition had more areas meeting the endpoint, how large any difference was, or how precisely it was estimated.
The adverse-event entries report zero serious adverse events and zero deaths in each listed condition, with other adverse events recorded as 1 in the control condition and 5 in the investigational condition. These figures are descriptive and do not, on their own, establish a comparative safety effect. The record does not give event-level details or a statistical safety comparison.
The study’s design labels also require caution. Descriptive text calls the study blinded and randomized, but the registry lists masking as NONE and allocation as NA, as well as a SINGLE GROUP model. The within-participant arm description says treatment portions were randomly allocated. The record does not reconcile these entries, so the exact design conduct cannot be confirmed from the registry alone.
Overall, the registry provides a study description and limited safety counts, but not the primary efficacy findings or enough methodological detail for an independent assessment of the treatment contrast. This should be read as a limitation of the available registry record, not as evidence that the intervention either does or does not produce repigmentation.
13. Why This Trial Matters Statistically
This study raises an important statistical issue: the treatment conditions are described as being applied to portions of lesions within the same participant. That approach can control for characteristics shared by the participant, but it creates paired observations that require analysis suited to their dependence. The unit receiving treatment, the unit assessed, and the unit used in the analysis need to align for the resulting uncertainty to be interpretable.
The primary outcome is also a threshold-based count of study areas. This makes the endpoint concrete, but it compresses graded repigmentation into whether an area crosses the at least 80% threshold. Statistical interpretation therefore depends not only on the number meeting that threshold, but also on how areas were assessed and how multiple areas within participants were handled.
The record’s inconsistent design descriptors illustrate why registry fields and narrative descriptions should be read together. It calls the study blinded and randomized in its title and summary, while the masking and allocation entries are NONE and NA. It also identifies the model as SINGLE GROUP despite describing control and investigational conditions within participants. These details affect how a comparison should be analyzed and how strongly it can support causal interpretation.
Finally, the distinction between a defined outcome and a reported result matters. The registry specifies what was to be measured and when, but does not report the primary outcome count or comparative estimate. Without those results, statistical significance, effect size, and precision cannot be evaluated. The safety counts add descriptive information, but they do not fill that gap or provide a formal comparative analysis.
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 principal limitation for interpreting this trial from the registry record is the absence of the primary outcome result. Although the endpoint, assessment time, unit, and ITT population are named, the observed count and comparative estimate are not reported in the registry record. No confidence interval or p-value is reported for the primary comparison.
Important design details are also unclear. The title and summary describe a blinded randomized study, and the arm description says intervention portions were randomly allocated. Yet the record lists allocation as NA, masking as NONE, and the model as SINGLE GROUP. The registry record does not explain these differences or provide details about sequence generation, concealment, or assessor blinding.
The record does not report how many study areas were assessed, how many were assigned to each condition, or how areas were distributed across participants. It also does not describe how the paired structure or possible clustering of multiple areas within a participant was handled. These omissions limit assessment of the analysis unit and uncertainty estimates.
Missing outcome information and analysis methods are not reported in the registry record. There is no account of unavailable Week 24 assessments, exclusions, the operational definition of ITT, or the method used to address missing data. The statistical analysis plan, multiplicity approach, and any interim analyses are also not reported in the registry record.
Finally, the safety information is limited to aggregate counts. Event descriptions, timing, participant overlap between conditions, and a comparative safety analysis are not reported in the registry record. These limitations prevent a fuller assessment of both effectiveness and safety from the registry entries alone.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Clinical Study to Investigate the Safety and Effectiveness of RECELL for Repigmentation of Stable Vitiligo Lesions — NCT04547998.
- Registry record last updated 2024-05-24; status last verified 2023-08.
- Results first posted 2023-09-21.
- 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.
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18. Record Summary
The registry record concerns a completed study of RECELL for repigmentation of stable vitiligo lesions, sponsored by Avita Medical. It lists enrollment as 25 and identifies UVB as the control condition and ablative laser resurfacing plus RECELL plus UVB as the investigational condition. The arm description says each participant served as their own control, with treatment conditions randomly allocated to portions of a depigmented lesion.
The primary outcome is the number of study areas reaching at least 80% repigmentation at Week 24, evaluated by a Central Review Committee in an ITT population. Secondary outcomes include Repigmentation Category and Color Matching. The primary outcome result and comparative estimate are not reported in the registry record.
The record lists zero serious adverse events and zero deaths in both conditions; other adverse events are recorded as 1 for control and 5 for the investigational condition. Design entries are not fully consistent: the title and description use randomized and blinded language, while allocation is NA and masking is NONE. The registry does not explain the discrepancy.