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 The Effect of OASIS Ultra on Critical Sized Wound Healing (NCT01848821), a non-randomized phase 1 study. The primary outcome is Change in Wound Size From Baseline to Final Wound Evaluation up to 60 Days Later.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01848821 |
| Phase | Phase 1 |
| Condition | Traumatic Wound, Infective Wound, Iatrogenic Critical Sized Wound Defects |
| Allocation | Non-Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 7 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Massachusetts General Hospital |
| Results posted | Yes |
2. Clinical Question
Population
The registry record concerns critical-sized wound defects, with conditions listed as traumatic wound, infective wound, iatrogenic critical-sized wound defects, and wound healing. Enrollment was 7. Further participant characteristics and eligibility details are not reported in the registry record, so the population cannot be described more specifically.
Intervention
OASIS Ultra, a device, was applied to one half of the wound in the described OASIS arm. The study aim was to evaluate wound-healing speed and quality, including the histological composition of the dermal substitute.
Comparator
The record describes standard therapy on the other half of the wound as wound VAC only in one arm description. Another description specifies non-stick mesh and wound VAC. Allocation was non-randomized, and the registry cautions that the arms are not a like-for-like control comparison.
Primary question
The primary outcome was change in wound size from baseline to final wound evaluation up to 60 days later, measured in cm^2. The registry record does not report the numerical change for either arm or a comparison between them, so the outcome question cannot be answered from the posted results.
3. Trial Design
This completed Phase 1 pilot study was sponsored by Massachusetts General Hospital. The registry lists a start date of 2013-05, primary completion in 2015-07, and enrollment of 7. It describes the study as non-randomized, single-masked, and using a parallel model. The identity of the masked party is not reported in the registry record.
The arm descriptions indicate a within-wound arrangement: OASIS Ultra was applied to one half of a wound, while standard therapy was applied to the other half. The standard-therapy description includes non-stick mesh and wound VAC; another description refers to wound VAC only. The record does not explain the discrepancy between these descriptions. Although the design model is listed as parallel, the descriptions of the intervention specify wound halves. The registry explicitly warns that this is not a randomized comparison and that the arms are not a like-for-like control comparison. The basis for assigning treatment to each half is not reported in the registry record.
The study aim was to assess healing speed and quality and to examine histological features, including cellular recruitment, collagen deposition, and neovascularization. The investigators also described an interest in the potential for later skin graft application. These are stated aims and hypotheses, not evidence that the expected effects occurred. The record lists wound-size change as the primary outcome and histological inflammation and repair score changes as secondary outcomes. It does not give outcome values, analysis results, or participant-level details. Further protocol information, including masking procedures and the rationale for the design, is 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 | OASIS | Standard Therapy |
|---|---|---|
| STARTED | 7 | 7 |
| COMPLETED | 7 | 7 |
| NOT COMPLETED | 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.
Population: A total of 7 patients with 10 wounds were enrolled in the study.
| Characteristic | Unit | OASIS Half of Wound | Standard Therapy Half of Wound | Total |
|---|---|---|---|---|
| Participants analysed | 7 | 7 | 7 | |
| Age, Customized: Years | years | 51.4 (SD 24.1) | 51.4 (SD 24.1) | 51.4 (SD 24.1) |
| Sex/Gender, Customized: Female | participants | 1 | 1 | 1 |
| Sex/Gender, Customized: Male | participants | 6 | 6 | 6 |
| Region of Enrollment: United States | participants | 7 | 7 | 14 |
| Days from first debridement to OASIS application | days | 6 (4.25 to 6) | 6 (4.25 to 6) | 6 (4.25 to 6) |
6. Primary Endpoint
The registry lists the primary outcome as Change in Wound Size From Baseline to Final Wound Evaluation up to 60 Days Later, measured over Baseline, Final Wound Evaluation up to 60 Days Later.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Inter-Quartile Range |
| Unit | cm^2 |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is change in wound size from baseline to final wound evaluation up to 60 days later, with wound area measured in cm^2. The record specifies the median and inter-quartile range as the planned summary. It describes high-resolution digital photographs with a measurement scale, taken at baseline and during serial wound evaluations in the operating room, at the bedside, and in the clinic. The images were to be uploaded to wound-tracing software, and wound area calculated from the tracing. Only the baseline measure and final wound evaluation were used to define the primary outcome.
In general, wound area is a direct measurement of wound size. Comparing a baseline measure with a later measure can describe how the measured area changed over the specified observation period. A median summarizes the middle of the observed values, while the inter-quartile range describes the spread of the central part of those values. These summaries can be useful when measurements vary substantially or are not well represented by a mean and standard deviation.
The registry record does not report the median change, inter-quartile range, number of evaluable wounds, or any estimate comparing treatment conditions. It therefore describes how the endpoint was intended to be measured, but does not show the observed wound-size results.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes a small pilot study with enrollment of 7 and a non-randomized comparison. It identifies wound-size change as the primary outcome, but does not report a numerical outcome estimate, confidence interval, test statistic, or p-value. Consequently, the posted results do not establish the size or precision of any difference between OASIS Ultra and standard therapy. The absence of a reported estimate is not evidence that the treatments had equal outcomes, nor does it show that either treatment had a particular effect.
The interpretation is also constrained by the design. The registry states that allocation was non-randomized and explicitly cautions that the arms are not a like-for-like control comparison. Random allocation can, in general, help balance measured and unmeasured factors between groups. Without it, differences in wound characteristics, treatment placement, or other factors could influence a comparison. The available record does not explain how treatment was allocated to wound halves or whether the analysis accounted for the within-wound structure.
The record lists a median and inter-quartile range for the primary outcome, but the actual values are not reported in the registry record. No inferential analysis is listed: the registry records 0 analyses. The two named secondary outcomes concern changes in histological acute inflammation and repair scores from baseline to the skin-grafting procedure, but their numerical results are also not reported. The total number of outcome measures is 3, including the primary wound-size measure.
The investigators’ stated hypotheses concerned faster healing and the re-establishment of a dermis. They also described anticipated potential benefits in healing time, wound quality, and hospital stay. These statements describe the study rationale and expectations; they are not reported findings. The registry record does not provide results for healing time, hospital stay, histology, or skin-grafting readiness.
Overall, the record permits a description of the pilot’s question, design, and planned measurements, but not a quantitative conclusion about wound healing. Even if numerical results were available, the non-randomized design and the record’s own warning about comparability would require careful interpretation. Any estimate from such a study would be descriptive and uncertain, rather than a definitive treatment-effect estimate.
9. Statistical Methods Explained
What does the primary summary describe?
The registry specifies the median and inter-quartile range for change in wound size. In general, the median is the middle value after observations are ordered. It is less affected by extreme observations than the arithmetic mean. The inter-quartile range describes the spread of the central portion of the observations and gives a sense of how much participant measurements vary. Neither summary alone establishes whether an observed change is attributable to treatment.
The registry record does not report the median or inter-quartile range for either treatment condition. It also does not state how many measurements contributed to a result or provide a confidence interval. A confidence interval, in general, expresses the uncertainty around an estimate in a way that reflects both the observed data and the statistical method. Without a reported estimate and interval, the magnitude and precision of the primary outcome cannot be assessed.
What does the photographic measurement involve?
The endpoint description says that high-resolution photographs included a measurement scale and were taken at baseline and during serial wound evaluations. Wound area was calculated using wound-tracing software. In general, tracing-based measurement turns an image into an area estimate, but the result can depend on image quality, scale placement, the boundary chosen for tracing, and consistency in measurement. The registry does not report procedures for training or blinding the people who traced images, checks of measurement agreement, or how uncertain wound boundaries were handled. These details are not reported in the registry record.
The primary outcome uses baseline and final evaluation measurements, with the final evaluation occurring up to 60 days later. The record does not report the actual timing of each final evaluation or explain how an outcome was handled if a final measurement was unavailable. Serial evaluations are described as part of data collection, but the primary outcome description limits its calculation to baseline and final wound evaluation.
How should the comparison be understood?
The study is listed as non-randomized, and the registry cautions that the arms are not a like-for-like control comparison. The arm descriptions place the intervention and standard therapy on wound halves. In general, when treatments are applied to different parts of the same wound, measurements from those parts may be related rather than independent. A statistical analysis should reflect the actual assignment and measurement structure. The record does not report how the analysis handled that structure, and no analysis results are listed. The design model is recorded as parallel, but the record does not explain how that label relates to the described wound-half application.
Randomization is a method for assigning treatments by chance. In general, it can reduce systematic allocation differences, though it cannot guarantee balance in a small study. Here, the registry states that allocation was non-randomized. The method used to choose which half received OASIS Ultra, and whether the choice was consistent across participants, is not reported in the registry record. The stated caution about comparability should therefore remain central to interpretation.
What can planning illustrations tell readers?
In general, a sample-size illustration estimates how many participants might be needed under specified assumptions to detect an effect at a chosen significance level and power. Such an illustration is not the same as a description of the trial’s original planning, and it does not show the probability that the observed study result is true. The record’s planning assumptions describe a two-sided significance level of 0.05, equal allocation, a normal approximation, and effects expressed as fractions of the observed effect. The registry does not report the study’s own sample-size justification or planning assumptions.
Planning figures based on an observed effect are conditional illustrations: they depend on the effect used as their starting point and on the assumptions of the calculation. They should not be read as observed power. Sample-size estimates are planning quantities, not evidence that an effect was detected or that a result is precise. The numerical outcome estimate needed to interpret any effect-based illustration is not reported in the registry record.
What is not available for statistical assessment?
The registry lists 0 analyses. It does not report a statistical analysis plan, model specification, covariate adjustment, confidence intervals, hypothesis tests, or handling of missing measurements. It also does not identify an analysis population or explain whether every enrolled participant contributed to each outcome. These omissions prevent an assessment of the analysis choices and their consequences. General statistical concepts can clarify what the planned summaries mean, but they cannot replace missing outcome results or analysis details.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary outcome of change in wound size and two secondary outcomes: change in histological acute inflammation score and change in histological repair score, both from baseline to the skin-grafting procedure. The record gives 3 as the total number of outcome measures and lists 0 analyses. Numerical results for these outcomes, their analysis methods, and any inferential conclusions are not reported in the registry record.
In general, multiplicity arises when several outcomes or statistical tests are examined. Considering many results can increase the chance that at least one appears notable by chance. Researchers may address this through prespecified outcome priorities or statistical adjustments. The registry does not report whether a multiplicity strategy was planned or used, or whether the secondary outcomes were intended to support formal hypothesis tests. It would not be appropriate to infer such a strategy from the outcome list alone.
Missing-data methods and analysis populations are also not described. The record does not say whether all enrolled participants had complete baseline and final wound measurements, how unavailable measurements were handled, or whether analyses included everyone enrolled. For the histological outcomes, it does not report how many participants had a skin-grafting procedure or contributed measurements. Those details are not reported in the registry record.
In general, missing outcomes can affect both the estimate and its precision, especially when the reasons for missingness are related to wound status or follow-up. Without counts and handling rules, the extent and potential impact of missing data cannot be assessed. No imputation method, sensitivity analysis, or defined analysis population is reported.
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 |
|---|---|---|---|
| OASIS | 0 | 7 | 0.0% |
| Standard Therapy | 0 | 7 | 0.0% |
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 |
|---|---|
| OASIS | 0 of 7 |
| Standard Therapy | 0 of 7 |
The safety record lists 7 participants at risk for serious adverse events in the OASIS group and 0 serious adverse events. For standard therapy, it also lists 7 participants at risk and 0 serious adverse events. Other adverse events are listed as 0 in each group, with 7 at risk in each. No top serious adverse-event terms are listed.
These figures describe what was recorded in the registry; they do not establish that no adverse events occurred outside the recorded categories or observation period. The record does not report the observation period for these safety counts or provide details about how events were collected. The deaths entries are not reported in the registry record.
The groups each have 7 participants at risk in the safety listing, but the record’s non-randomized design and warning about comparability still apply. The counts should not be treated as a randomized estimate of relative safety, and the groups should not be combined into a new total. A zero count in this small pilot is a descriptive finding, not proof that an event cannot occur or that the safety profiles are equivalent.
12. What the Result Does, and Does Not, Mean
This record establishes that a completed Phase 1 pilot study examined OASIS Ultra in critical-sized wound defects and specified wound-size change as its primary outcome. It also documents an intended histological assessment and gives a description of photographic wound-area measurement. These details help clarify the research question and the outcomes the investigators intended to study.
The posted record does not report numerical primary or secondary outcome results. It therefore cannot show how much wound size changed, how variable the measurements were, whether the treatment conditions differed, or how precisely any difference was estimated. The investigators’ stated expectations about healing speed, dermal re-establishment, wound quality, and hospital stay should be understood as hypotheses or anticipated possibilities, not as demonstrated findings.
The study’s non-randomized allocation and the registry’s explicit warning that the arms are not a like-for-like control comparison further limit what can be inferred. In general, an observed contrast in a non-randomized study may reflect differences in treatment as well as differences in the circumstances that led to treatment assignment. The record does not explain the allocation procedure or report an analysis that could clarify this issue.
The safety listings record 0 serious adverse events and 0 other adverse events in each group, with 7 at risk in each. Those figures are descriptive and do not establish equivalence or rule out uncommon harms. The death entries are not reported in the registry record.
Accordingly, the registry record supports a careful account of the pilot’s design and intended measurements, but not a conclusion about treatment benefit, lack of benefit, or comparative safety. Numerical outcome findings, analysis details, and further participant information are not reported in the registry record.
13. Why This Trial Matters Statistically
Pilot studies can be statistically informative by showing how a research question is operationalized, what measurements are planned, and which design features may affect interpretation. This record describes wound-area measurement from photographs, a baseline-to-final outcome, and histological assessments. It also makes clear that the study was non-randomized and cautions against treating the arms as a like-for-like control comparison.
That design information matters because statistical conclusions depend on how observations were generated. A comparison between treatment conditions is easier to interpret when assignment and analysis are clearly described. The registry record does not explain the allocation process or the analysis of measurements from wound halves. Those gaps make it difficult to determine what a treatment contrast would represent, even if numerical results were present.
The record also illustrates why outcome definitions and outcome results are distinct. A clear endpoint description tells readers what investigators intended to measure; it does not tell them what the data showed. Here, the primary measure is specified, but its numerical results and analyses are not reported in the registry record. The same distinction applies to the histological outcomes and the investigators’ hypotheses.
Finally, small pilot studies are often most useful as preliminary evidence about feasibility and measurement, rather than as definitive tests of comparative effects. General statistical interpretation should distinguish the purpose of a pilot from the strength of evidence its results can support. In this case, the absence of posted outcome analyses prevents even a descriptive assessment of the wound-size findings. The record is therefore informative about design and intent, while leaving the central quantitative question unresolved.
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.
Several limitations are specific to this record. Enrollment was 7, and allocation was non-randomized. The registry explicitly states that the arms are not a like-for-like control comparison. The record does not describe how a treatment was assigned to a wound half, how many wounds or measurements were available for each outcome, or how the within-wound arrangement was reflected in analysis.
The listed design model is parallel, while the arm descriptions refer to applying different treatments to halves of a wound. The record does not explain how these descriptions fit together. It also gives different descriptions of standard therapy: one refers to wound VAC only, while another includes non-stick mesh and wound VAC. The reason for this difference is not reported in the registry record.
Outcome reporting is incomplete. The primary outcome is described, but its median and inter-quartile range are not reported. The two secondary histological outcomes are named without numerical results, and the registry lists 0 analyses. The record does not report confidence intervals, statistical tests, missing-data handling, an analysis population, or the number of participants contributing data to each outcome. Details about masking, measurement reliability, and the timing of individual final evaluations are also not reported in the registry record.
The safety figures list 0 serious and 0 other adverse events in each group, but the observation period and event-collection procedures are not reported. Death entries are not reported in the registry record. These limitations mean that neither outcome magnitude nor precision, and neither comparative effectiveness nor comparative safety, can be established from the posted record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: The Effect of OASIS Ultra on Critical Sized Wound Healing — NCT01848821.
- Registry record last updated 2019-10-30; status last verified 2019-10.
- Results first posted 2019-10-30.
- 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
NCT01848821 is a completed Phase 1 pilot study sponsored by Massachusetts General Hospital, with enrollment of 7. The registry lists a start date of 2013-05 and primary completion in 2015-07. The study was non-randomized, single-masked, and recorded as using a parallel model.
The study compared OASIS Ultra with standard therapy as described for wound halves. The registry warns that the arms are not a like-for-like control comparison. The primary outcome was change in wound size from baseline to final evaluation up to 60 days later, summarized by median and inter-quartile range. Two secondary histological outcomes are listed.
Numerical outcome results and analyses are not reported in the registry record. Safety listings show 0 serious and 0 other adverse events in each group, with 7 participants at risk in each. The record does not report the deaths entries.