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 Effectiveness Study of Santyl Ointment to Treat Pressure Ulcers (NCT01208220), a randomized na study. The primary outcome is Quicker Filling of the Wound With Good Tissue (vs. Treatment With NPWT Alone).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01208220 |
| Phase | NA |
| Condition | Pressure Ulcer, Soft Tissue Necrosis Lower Limb |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 2 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Louisiana State University Health Sciences Center Shreveport |
| Results posted | Yes |
2. Clinical Question
Population
The registry describes people with a wound that had not responded to standard treatments and lists pressure ulcer and soft tissue necrosis of the lower limb among the conditions. The enrollment is listed as 2. The record does not provide further participant characteristics or describe the analyzed population.
Intervention
The intervention combines Santyl collagenase ointment with negative pressure wound therapy (NPWT). The arm description says collagenase was applied TIW with NPWT. The registry does not define the abbreviation TIW in the posted description.
Comparator
The comparison group received NPWT alone, described as NPWT changed TIW. The registry identifies the study as randomized, with a parallel design and no masking.
Primary question
The primary question is whether the combination is associated with a greater percentage of red granulation tissue at 2 weeks than NPWT alone. The endpoint title describes this as quicker filling of the wound with good tissue. The posted arm values are 75.0% for the combination and 80.0% for NPWT alone, each with n of 1. These limited entries do not establish whether the treatments differ reliably.
3. Trial Design
The study is registered as a randomized, parallel-group trial with no masking. The two listed treatment groups are NPWT alone and Santyl ointment with NPWT. The sponsor is Louisiana State University Health Sciences Center Shreveport. The registry lists enrollment as 2 and gives the study status as terminated. The listed start is 2010-06 and the primary completion is 2011-12.
The brief summary says the investigators aimed to study whether combining a medication and a device would help wounds heal faster than treatment with the device alone. It describes use of a vacuum device and special tests to assess whether the combined treatments were working better than one treatment alone. The registry does not provide a fuller account of the clinical procedures, eligibility criteria, treatment duration, or reasons for termination.
The arm descriptions state that NPWT was changed TIW in the comparator group and that collagenase was applied TIW with NPWT in the combination group. The abbreviation is not defined in the record. Allocation concealment, details of the randomization process, and whether participants or outcome assessors knew the assigned treatment are not reported in the registry record; the masking field is listed as none.
The primary outcome was recorded at 2 weeks into the study. A secondary outcome concerns removal of harmful fluids in wound tissue. The record lists 2 outcome measures, but it does not provide posted analysis records. This means that the design information and the limited arm-level outcome entries should be distinguished from a complete report of the trial conduct and statistical 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
| Stage | Negative Pressure Wound Therapy | Santyl Ointment and NPWT |
|---|---|---|
| STARTED | 1 | 1 |
| COMPLETED | 1 | 1 |
| 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.
| Characteristic | Unit | Negative Pressure Wound Therapy | Santyl Ointment and NPWT | Total |
|---|---|---|---|---|
| Participants analysed | 1 | 1 | 2 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 1 | 1 | 2 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 |
| Age, Continuous | years | 52 (SD 0) | 57 (SD 0) | 54 (SD 3) |
| Sex: Female, Male: Female | Participants | 1 | 1 | 2 |
| Sex: Female, Male: Male | Participants | 0 | 0 | 0 |
| Region of Enrollment: United States | participants | 1 | 1 | 2 |
6. Primary Endpoint
The registry lists the primary outcome as Quicker Filling of the Wound With Good Tissue (vs. Treatment With NPWT Alone), measured over 2 weeks into study.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Percentage of red granulation tissue |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the percentage of red granulation tissue at 2 weeks into the study. The registry’s title for the outcome describes quicker filling of the wound with good tissue, comparing the combination with NPWT alone. Granulation tissue is a feature of the wound bed, so measuring its proportion offers a way to describe wound appearance at the specified assessment time.
As a general statistical point, a percentage endpoint expresses a measured feature relative to the wound area or another defined whole. Its interpretation depends on how the feature and its denominator were assessed. The registry does not report the measurement procedure, the denominator used, assessor training, or whether assessment was blinded. These details matter because visual or image-based assessments can be affected by measurement choices and observer judgment.
The posted result is 80.0 for NPWT alone and 75.0 for Santyl ointment with NPWT, with n of 1 for each group. The unit is given as percentage of red granulation tissue. No measure of variability or confidence interval is posted. The result is a description of the recorded endpoint values, not a complete estimate of comparative treatment effect. The registry does not report whether this endpoint was assessed at additional times or how it relates to wound closure or other clinical outcomes.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted primary-outcome entries are 80.0% for NPWT alone and 75.0% for Santyl ointment with NPWT. Each group has n of 1. These values describe the entries recorded for the endpoint at 2 weeks; they do not support a reliable estimate of the average difference between treatment groups. No confidence interval, standard error, or variability measure is reported.
The numbers should not be read as evidence that either treatment caused a particular outcome. Random allocation can help make groups comparable in a sufficiently informative trial, but the registry’s very limited outcome entries do not show the uncertainty that would be needed to judge a treatment contrast. The status is terminated, and the record does not explain why recruitment or study activity ended.
No formal comparative analysis is posted. In particular, the record does not supply a test statistic, p-value, adjusted estimate, or model-based result. The skip note says values are missing or not estimable for a two-arm comparison for this count-other endpoint. Consequently, there is no sponsor-reported comparative estimate to interpret, and no recalculated comparison is appropriate from the posted summary information.
As a general statistical principle, an observed value is not itself evidence of a reproducible treatment effect. A confidence interval, when available, describes the range of effect values compatible with the data and the analysis assumptions; its width conveys precision. Here, the registry does not report an interval, and the arm-level entries are too limited to characterize between-participant variation. A reader therefore cannot use these values to distinguish a real group difference from variation in measurement or chance.
The secondary outcome concerns removal of harmful fluids in wound tissue, but no result for it is included in the record. The listed safety counts show no reported serious or other adverse events among the participants at risk in either group, but those sparse counts do not characterize safety across a broader population. Overall, the record documents a trial question and a small set of outcome entries, not a conclusive assessment of comparative effectiveness or safety.
9. Statistical Methods Explained
The registry identifies the study as randomized and parallel, with no masking. Those design labels describe how treatment groups were intended to be formed and followed. Randomization is generally used to reduce systematic differences between groups at assignment, while a parallel design assigns participants to a treatment group that is followed alongside the comparator. The record does not describe the randomization sequence, allocation concealment, or implementation, so those aspects cannot be assessed.
What does the endpoint summarize?
The primary endpoint is a percentage of red granulation tissue, assessed at 2 weeks. A group summary can describe the observed endpoint values, but a treatment comparison also needs information about how much values vary among participants. The posted arm results give a value and n for each group, but no dispersion estimate. With no reported variability information, precision cannot be quantified from the registry entries.
As a general matter, a confidence interval combines an estimated effect with its uncertainty under a stated statistical model. It can show whether the estimate is precise or remains compatible with a broad range of effects. A p-value addresses compatibility of data with a specified null hypothesis under model assumptions; it does not measure clinical importance or the probability that a treatment works. Neither a confidence interval nor a p-value for the primary comparison is reported in the registry record.
Why is no comparison available?
The skip note states that values are missing or not estimable for a two-arm comparison for the count-other endpoint. The record lists n of 1 in each arm and contains no analysis records. A comparison requires an estimable effect and an appropriate account of uncertainty. The posted entries do not provide the information needed for a reliable inferential comparison, and no model or test is reported. It would be inappropriate to derive a new treatment contrast or an uncertainty estimate from these entries.
The outcome is expressed as a percentage, but the registry does not provide individual observations, a standard deviation, or another measure of spread. General statistical methods for percentages depend on how measurements were obtained and on the distribution of values. If values are clustered or more variable than a model assumes, standard errors can be understated; this is a general concern about over-dispersion. The registry does not report enough detail to evaluate whether that issue arose or which modeling approach would be suitable.
What does the planning illustration represent?
The stated planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, a normal approximation, and an effect to detect set as a stated fraction of the observed effect. Such calculations are planning illustrations, not evidence about the trial’s achieved power. They describe hypothetical future design requirements under the chosen assumptions; they do not alter the uncertainty in this trial’s posted outcomes. Numerical planning results are not reported in the registry record.
In general, sample-size planning depends on the target effect, outcome variability, significance level, desired power, allocation, and analytic method. A planning estimate based on an observed effect can be unstable when the observed data are sparse. The registry does not report a protocol-based sample-size justification or say whether the trial’s own enrollment target was set using these assumptions. The planning assumptions should therefore not be interpreted as the original design rationale.
How should the design and analysis be separated?
Randomization is a design feature, not a substitute for reporting outcome data and a statistical analysis. A complete analysis would ordinarily explain the analyzed population, the handling of missing outcome measurements, the chosen effect measure, uncertainty estimation, and any prespecified adjustment or subgroup procedures. Those details are not reported in the registry record. The posted values are descriptive entries and cannot resolve those methodological questions.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 2 outcome measures and 1 secondary outcome, concerning removal of harmful fluids in wound tissue. It does not provide a results entry for that secondary outcome. No analysis records are posted. The record does not report a multiplicity plan, such as how interpretation would account for examining more than one outcome or multiple tests. Without a reported analysis plan and results, it is not possible to assess whether multiplicity was addressed.
Missing-data handling is not reported in the registry record. The posted primary outcome includes n of 1 in each arm, but the record does not explain whether these are all randomized participants, all participants with an available assessment, or another analysis population. It also does not describe withdrawals, missed visits, exclusions, or reasons for missing measurements. No assumption or imputation method is reported.
The analysis population is likewise not reported. The record does not say whether results were intended to follow an intention-to-treat approach, a per-protocol approach, or another definition. Those distinctions affect what a group comparison estimates, especially when participants do not complete assigned treatment or outcome assessment. With no posted analysis records and no missing-data description, the scope and completeness of the results cannot be determined from the registry record.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Negative Pressure Wound Therapy | 0 | 1 | 0.0% |
| Santyl Ointment and NPWT | 0 | 1 | 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 |
|---|---|
| Negative Pressure Wound Therapy | 0 of 1 |
| Santyl Ointment and NPWT | 0 of 1 |
The adverse-event entries list 1 participant at risk in each group. Serious adverse events affected 0 in the NPWT group and 0 in the Santyl ointment with NPWT group. Other adverse events affected 0 in each group. These counts describe what is entered in the registry for the listed groups; they are not evidence that adverse events are impossible or that safety is established.
The death values are not reported in the registry record. No serious adverse-event terms are listed. Because the number at risk is limited and the record does not provide detailed event definitions, observation periods, or a fuller safety analysis, the entries offer only a narrow description of the recorded events. They cannot characterize uncommon harms or establish comparative safety.
As a general statistical point, a zero event count in a small group can coexist with substantial uncertainty about the underlying event risk. The absence of recorded events should therefore be interpreted in light of how many participants were observed and for how long. The registry does not provide enough detail to extend these counts beyond the participants and reporting recorded in the trial.
12. What the Result Does, and Does Not, Mean
The record documents a randomized comparison of NPWT alone with Santyl ointment plus NPWT for pressure ulcers and related wound conditions. Its primary endpoint was the percentage of red granulation tissue at 2 weeks. The posted values are 80.0% for NPWT alone and 75.0% for the combination, with n of 1 in each group. The trial is listed as terminated.
Those values are not a dependable estimate of how the treatments compare in a wider group of people. There is no posted confidence interval, variability measure, or inferential analysis. The registry also does not report enough information to assess outcome measurement, missing data, or the analyzed population. The observations may describe what was recorded for the listed groups, but they cannot establish a general treatment effect.
The record does not show whether the combination improves wound healing, whether NPWT alone is preferable, or whether either approach changes outcomes beyond the measured endpoint. The primary outcome is a tissue-percentage measure at a specified time, and no link between that measure and wound closure or longer-term outcomes is reported. The secondary outcome has no posted result.
Likewise, the safety entries do not establish that either treatment is safe or unsafe. No adverse events are listed among those at risk, but the number observed is limited and death data are not reported. The record’s value is in documenting the study question, design labels, outcome definition, and limited posted results. Its main statistical message is the lack of information needed for a precise comparative conclusion.
13. Why This Trial Matters Statistically
This trial is a useful example of why an outcome value and a treatment comparison are not the same thing. The registry contains a percentage for each treatment group, but a comparative conclusion requires a measure of effect together with an assessment of uncertainty. Without a reported analysis or variability information, the arm entries cannot establish whether the observed values reflect a reproducible difference.
The record also illustrates the importance of registration details beyond the primary endpoint. The randomized and parallel labels provide a basic design description, while the absence of reported allocation details, analysis methods, and analysis populations leaves important questions unanswered. A clearly stated endpoint does not by itself reveal how the measurements were obtained or how missing assessments were handled.
Termination status and limited enrollment are relevant context for readers evaluating the evidence. The registry does not give the reason for termination or a protocol-based sample-size rationale. The stated planning assumptions describe an illustration, not observed power and not necessarily the trial’s original plan. Keeping those concepts separate prevents a hypothetical planning calculation from being mistaken for evidence about the trial’s evidential strength.
Finally, the safety counts emphasize how zero recorded events should be interpreted in context. Counts without a substantial evidence base or detailed follow-up cannot establish the absence of harm. For clinical researchers, the record underscores the importance of reporting participant flow, endpoint measurement, analysis populations, missing-data handling, uncertainty estimates, and complete safety follow-up alongside group results.
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 posted primary outcome is based on n of 1 in each group, and no dispersion estimate is available. This limits what can be inferred about variation in the endpoint and prevents a precise estimate of comparative uncertainty. The registry marks a two-arm comparison as not estimable for this endpoint and contains no analysis records.
The record does not describe the outcome-assessment method, the denominator for the percentage, assessor blinding, or the timing and conduct of assessments beyond the stated 2-week timeframe. It also does not report baseline wound characteristics, eligibility details, treatment adherence, participant flow, or reasons for study termination. These omissions restrict assessment of comparability, measurement reliability, and generalizability.
The primary outcome concerns granulation tissue, while the record does not provide a posted result for the secondary outcome on removal of harmful fluids. It does not state how the outcome measures were prioritized analytically or how multiplicity was handled. Missing-data methods and analysis-population definitions are not reported.
The safety entries are also limited: the counts at risk are small, death data are not reported, and details of event ascertainment and follow-up are absent. The status is terminated, but the reason is not reported in the registry record. Taken together, these trial-specific limitations mean that the record supports a description of the registered question and entries, but not a robust estimate of comparative effectiveness or safety.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Effectiveness Study of Santyl Ointment to Treat Pressure Ulcers — NCT01208220.
- Registry record last updated 2014-07-17; status last verified 2014-07.
- Results first posted 2014-07-17.
- 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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Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
NCT01208220 is a randomized, parallel, unmasked study sponsored by Louisiana State University Health Sciences Center Shreveport. It compares NPWT alone with Santyl collagenase ointment used with NPWT for chronic pressure ulcers and related wound conditions. The registry lists enrollment as 2 and status as terminated.
The primary endpoint is percentage of red granulation tissue at 2 weeks. The posted group values are 80.0% for NPWT alone and 75.0% for the combination, with n of 1 in each group. No comparative analysis or uncertainty estimate is reported. One secondary outcome is listed, but no result is posted. The safety entries report 0 serious and 0 other adverse events in each group; death data are not reported.