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 Prospective Randomized Double Blind Clinical Trial of Polyhexamethylene Biguanide Impregnated Foam Dressing (NCT00618787), a randomized phase 2 study. The primary outcome is Percentage Change in Wound Surface Area (cm2) at Week 4 Compared to Week 0..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00618787 |
| Phase | Phase 2 |
| Condition | Wounds |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Triple |
| Enrollment | 45 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Tyco Healthcare Group |
| Results posted | Yes |
2. Clinical Question
Population
Subjects with chronic wounds. The primary outcome population is identified as per protocol; further eligibility details are not reported in the registry record.
Intervention
COPA AMD, described in the trial summary as a PHMB-impregnated foam dressing.
Comparator
COPA, described in the trial summary as regular foam dressing.
Primary question
How did median percentage change in wound surface area from Week 0 to Week 4 compare between the two dressing groups?
The registry record describes a prospective, randomized, double-blind pilot trial involving subjects with chronic wounds. Its primary endpoint is the percentage change in wound surface area at Week 4 compared with Week 0. Wound area was measured at study visits as longest length multiplied by widest width at right angles, in cm2. The endpoint description says compiled data were used to determine the median percentage decrease in wound area between groups and between visits.
The posted medians are 34.9 for COPA AMD and 27.8 for COPA. These are group summaries, not results for every participant, and the posted ranges are broad. The registry record does not include a comparative p-value or confidence interval for the primary endpoint, so the precision of a between-group contrast cannot be assessed from a formal comparison in the record. The registry’s primary outcome population is per protocol; details of how that population was defined are not reported in the registry record.
3. Trial Design
This is a randomized, parallel-group phase 2 trial listed as completed. The registry record reports an enrollment of 45 and describes the study as multicenter, prospective, double blind, and a pilot trial. It compares two devices: COPA AMD and COPA. The brief description identifies COPA AMD as a PHMB-impregnated foam dressing and COPA as regular foam dressing.
The record labels masking as triple, while the trial description says double blind. It does not identify which participants, investigators, assessors, or other roles were masked, or explain the difference between these descriptions. Random allocation is reported, but the method used to generate the allocation sequence, conceal assignments, or maintain masking is not reported in the registry record. The record identifies a parallel model, meaning participants were assigned to one of the two groups rather than described as crossing between treatments.
The study start is listed as 2008-02 and primary completion as 2009-04. The primary outcome compares wound surface area at Weeks 0 and 4, and its analysis population is listed as per protocol. Pain is listed as a secondary outcome. The registry record does not report the planned follow-up beyond the primary endpoint, the treatment schedule, or the criteria for entering or leaving the per-protocol population.
The posted primary outcome includes 19 participants in the COPA AMD group and 21 in the COPA group. The adverse-event summaries use risk-group counts of 22 and 23, respectively. These are different denominators for different reported summaries; reasons for the difference between outcome and safety counts are not reported in the registry record. A planned sample-size justification and the rationale for the enrollment target are also not reported.
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 | COPA AMD | COPA |
|---|---|---|
| STARTED | 22 | 23 |
| COMPLETED | 19 | 21 |
| NOT COMPLETED | 3 | 2 |
Reasons for not completing this period:
| Reason | COPA AMD | COPA |
|---|---|---|
| Adverse Event | 0 | 1 |
| Withdrawal by Subject | 2 | 1 |
| Lost to Follow-up | 1 | 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 | COPA AMD | COPA | Total |
|---|---|---|---|---|
| Participants analysed | 22 | 23 | 45 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 16 | 21 | 37 |
| Age, Categorical: >=65 years | Participants | 6 | 2 | 8 |
| Age Continuous | years | 56.4 (SD 15.28) | 55.1 (SD 11.01) | 55.8 (SD 13.13) |
| Sex: Female, Male: Female | Participants | 5 | 3 | 8 |
| Sex: Female, Male: Male | Participants | 17 | 20 | 37 |
| Region of Enrollment: Canada | participants | 22 | 23 | 45 |
6. Primary Endpoint
The registry lists the primary outcome as Percentage Change in Wound Surface Area (cm2) at Week 4 Compared to Week 0., measured over Weeks 0 and 4.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Full Range |
| Unit | Percentage change |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the median percentage decrease in wound surface area at Week 4 compared with Week 0. At each visit, the area was measured by multiplying the longest wound length by its widest perpendicular width, with the result expressed in cm2. The endpoint therefore describes change in a measured wound dimension over the specified interval, rather than a count of wounds or a time-to-event outcome.
A percentage-change measure expresses change relative to a participant’s starting area, which can help describe change across wounds with different initial sizes. The median is the middle value in an ordered set, so it describes a typical observation without being as strongly influenced by extreme values as the mean can be. These are general statistical properties; they do not establish that the measurement captures every aspect of wound status.
The posted median percentage decreases are 34.9 for COPA AMD and 27.8 for COPA. The posted full ranges are -74.8 to 94.7 and -167.0 to 97.6, respectively. Because the outcome is framed as percentage decrease, a negative value indicates an increase rather than a decrease in area. The ranges therefore indicate substantial variation in observed changes, including both decreases and increases. The registry record does not report a confidence interval for either median or for a between-group contrast, nor does it give a formal comparative test for this endpoint.
The endpoint description specifies Weeks 0 and 4, but does not report a detailed measurement manual, assessor training, or procedures for handling wounds with measurements that could not be obtained. These details matter when interpreting the consistency and reproducibility of wound-area measurements.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The primary outcome is reported as a median percentage decrease in wound surface area from Week 0 to Week 4. The median is 34.9 in the COPA AMD group and 27.8 in the COPA group. These numbers describe the center of each group’s observed distribution; they do not, on their own, estimate how precisely the groups differ or establish that any observed contrast is attributable to the dressing.
The full range for COPA AMD is -74.8 to 94.7, and the full range for COPA is -167.0 to 97.6. A negative percentage decrease corresponds to an increase in area. The ranges thus include participants with increases as well as participants with decreases, and they are wide relative to the median values. Since a full range records the most extreme observations, it is sensitive to individual values and does not show how observations are distributed between the endpoints. No interquartile range or standard deviation is posted for this outcome.
The outcome counts are 19 for COPA AMD and 21 for COPA, while the overall enrollment is 45. The primary endpoint is defined for the per-protocol population. The registry record does not explain why the reported endpoint counts differ from enrollment, whether participants were excluded from the per-protocol analysis, or how missing Week 0 or Week 4 measurements were handled. Those omissions limit assessment of the completeness and representativeness of the endpoint summaries.
No formal between-group estimate, confidence interval, or p-value is posted for the primary endpoint. Accordingly, the registry record does not quantify the uncertainty around a treatment contrast or provide a formal test of the difference between groups. The numerical ordering of the two medians should be read descriptively, not as evidence of a statistically established difference. No adjustment for baseline wound area or other participant characteristics is reported.
The trial is described as a pilot, and the registry record does not report a sample-size justification. Pilot studies can provide descriptive information and help identify practical issues for later research, but a small study may leave substantial uncertainty around group comparisons. This is a general consideration, not a claim about the trial’s intended design beyond its registry description. The record’s posted information supports a description of the observed medians and ranges, but does not establish a precise or causal comparative effect.
9. Statistical Methods Explained
The primary endpoint is a group median for percentage decrease in wound surface area between Week 0 and Week 4. The measurement is based on wound length multiplied by width at right angles. A median summarizes the central position of observations: after ordering the values, it identifies the middle. As a general statistical concept, the median is less affected by very large or very small observations than the arithmetic mean, though it does not describe the spread by itself.
What does the full range tell the reader?
The registry record reports a full range for each group. A full range gives the smallest and largest recorded values; it is not a confidence interval. The COPA AMD range is -74.8 to 94.7, and the COPA range is -167.0 to 97.6. Since the outcome is stated as percentage decrease, negative values represent an increase in measured wound area. The ranges show that observations varied widely and included both increases and decreases. They do not show how common values near either endpoint were, or how the other observations were distributed. General statistical practice often pairs a median with a measure of spread that describes the central portion of the distribution, but such a measure is not reported for this outcome.
Why is a confidence interval useful?
In general, a confidence interval communicates uncertainty around an estimated quantity, such as a median or a between-group contrast. It can help distinguish a precise estimate from one compatible with a broad range of possibilities. No confidence interval is reported for the primary endpoint or for a comparison between groups. The full ranges cannot substitute for those intervals because they describe the observed extremes, not uncertainty about the estimated group values or contrast.
What can randomization contribute?
As a general design principle, random assignment is intended to reduce systematic differences between groups at the point of allocation. It does not guarantee that groups will be identical, particularly in a small study, and it cannot address bias introduced after assignment by missing outcomes, departures from assigned treatment, or measurement procedures. The registry record says allocation was randomized, but the sequence-generation and allocation-concealment methods are not reported. Masking is labeled triple in the registry record and double blind in the study description; the roles masked and the procedures used are not reported.
What does the posted analysis establish?
The endpoint is described as per protocol, but the criteria for that population and the handling of participants who did not complete the relevant visits are not reported. The posted group medians and ranges are descriptive summaries. The registry record does not post a comparative effect estimate, confidence interval, or p-value for the primary endpoint. It therefore does not provide a formal estimate of the uncertainty around the difference between groups. The absence of a reported test should not be interpreted as evidence that the groups are equivalent or different.
General statistical interpretation also depends on whether the chosen summary matches the data distribution and scientific question. A median is a reasonable way to describe a central value when observations may be skewed or contain extremes, but the registry record does not report distributional diagnostics or a prespecified rationale for this summary. The record says the median percentage decrease was analyzed, but does not describe any adjustment, model, or sensitivity analysis. These analysis details are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists Pain as a secondary outcome and reports three outcome measures overall. It does not give enough detail to identify all outcome measures or establish how many statistical comparisons were planned. No multiplicity strategy, such as prioritizing outcomes or adjusting interpretation for multiple tests, is reported in the registry record. In general, when several outcomes or comparisons are examined, the chance of at least one apparently notable result can increase; prespecified priorities and transparent reporting help readers interpret that possibility. No secondary-outcome numerical result or analysis is included in the posted information described for this trial.
The primary endpoint is identified as per protocol. The criteria for that population, the number of participants assessed for eligibility to the analysis, and reasons for any exclusions are not reported in the registry record. The posted endpoint counts are 19 for COPA AMD and 21 for COPA. The record does not explain how missing wound measurements were handled, whether any values were imputed, or whether participants were analyzed according to their randomized assignment in another population.
In general, missing outcome data can affect interpretation if the likelihood of missingness is related to wound change or differs between groups. A per-protocol summary may also differ from an analysis that retains all randomized participants. These are general considerations; the registry record does not report enough information to determine whether either issue affected these results. The record also does not report a prespecified statistical analysis plan, sensitivity analyses for missing data, or an explanation of deviations from such a plan. Consequently, the completeness and robustness of the primary endpoint analysis cannot be assessed 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 |
|---|---|---|---|
| COPA AMD | 0 | 22 | 0.0% |
| COPA | 2 | 23 | 8.7% |
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 |
|---|---|
| COPA AMD | 5 of 22 |
| COPA | 9 of 23 |
Most frequent serious adverse event terms
| Event term | Organ system | COPA AMD | COPA |
|---|---|---|---|
| cardiac stent implanted | Cardiac disorders | 0 of 22 | 1 of 23 |
| pulmonary embolus | Respiratory, thoracic and mediastinal disorders | 0 of 22 | 1 of 23 |
Most frequent non-serious adverse event terms
| Event term | Organ system | COPA AMD | COPA |
|---|---|---|---|
| Skin/Dermatologic (not including study wound) | Skin and subcutaneous tissue disorders | 2 of 22 | 2 of 23 |
| Head, eyes, ears, nose and throat | Ear and labyrinth disorders | 2 of 22 | 0 of 23 |
| Wound Infection | Skin and subcutaneous tissue disorders | 0 of 22 | 2 of 23 |
| Endocrine, metabolic and nutritional | Metabolism and nutrition disorders | 1 of 22 | 0 of 23 |
| Allergic and immunologic | Endocrine disorders | 0 of 22 | 1 of 23 |
| Musculoskeletal | Musculoskeletal and connective tissue disorders | 0 of 22 | 1 of 23 |
| Digestive/Gastrointestinal | Gastrointestinal disorders | 0 of 22 | 1 of 23 |
| Urogenital | Renal and urinary disorders | 0 of 22 | 1 of 23 |
| Hematopoietic/Lymphatic | Blood and lymphatic system disorders | 0 of 22 | 1 of 23 |
Serious events with the highest arm-level rate: cardiac stent implanted (4.3%), pulmonary embolus (4.3%).
The safety summary reports serious adverse events in 0 of 22 participants at risk in the COPA AMD group and 2 of 23 participants at risk in the COPA group. Other adverse events are reported for 5 of 22 and 9 of 23 participants, respectively. These are counts of participants reported as affected, alongside each group’s risk count; they are not the primary wound-area outcome counts.
The record lists cardiac stent implanted and pulmonary embolus among the top serious adverse-event terms, each with a reported 4.3%. It does not identify a group for each listed term in the information available, so those terms should not be assigned to a particular arm. Death counts are not reported in the registry record.
Safety counts describe events observed and recorded during the study, but the registry record does not give the observation period, event definitions, severity grading, or detailed attribution procedures. In general, small group counts can be unstable and do not by themselves establish whether an event was caused by an intervention. The different at-risk counts also mean that raw counts alone should not be treated as a complete comparison of safety. No conclusion about comparative safety can be drawn from these summaries alone.
12. What the Result Does, and Does Not, Mean
The registry record describes a randomized phase 2 pilot trial comparing COPA AMD, a PHMB-impregnated foam dressing, with COPA, regular foam dressing, in subjects with chronic wounds. The principal posted result is a median percentage decrease in wound surface area from Week 0 to Week 4: 34.9 for COPA AMD and 27.8 for COPA. The full ranges are -74.8 to 94.7 and -167.0 to 97.6, respectively, indicating that observed changes varied widely and included increases as well as decreases.
These summaries do not establish that the dressings differ. The registry record does not post a comparative effect estimate, confidence interval, or p-value for the primary outcome. It also does not report a sample-size justification, the methods used to calculate the comparison, or a complete account of missing measurements and analysis-population definitions. Without those details, readers cannot assess the precision of a between-group contrast or how sensitive the result may be to analysis choices.
The results do not show what would happen for every participant, and a group median does not describe the whole distribution. Nor does a change in measured area capture every possible clinical outcome. Pain is identified as a secondary outcome, but a numerical result for it is not reported in the registry record. Safety summaries list adverse events, but their limited detail does not establish cause or support a definitive comparative safety assessment.
In general, a randomized design can support a causal comparison when allocation, follow-up, measurement, and analysis are adequately implemented and reported. The registry record does not provide enough methodological detail to evaluate all of those conditions. The appropriate reading is therefore descriptive: the posted group summaries show the observed medians and ranges in the reported endpoint populations, with substantial uncertainty about the comparative interpretation.
13. Why This Trial Matters Statistically
This trial is statistically informative as an example of why a group median should be read alongside its spread and analysis context. The primary outcome is reported as a median percentage decrease, while the full ranges extend from negative values, indicating increases in area, to positive values, indicating decreases. Reporting both the center and extremes makes clear that the participant-level observations were not uniform, but the range alone does not characterize the full distribution.
The endpoint population is per protocol, whereas the registry also reports overall enrollment and separate at-risk counts for safety summaries. Those denominators answer different questions. The record does not explain the relationship among them or describe exclusions and missing outcomes. Transparent definitions of analysis populations and reasons for missing data are important because readers need to understand which participants contribute to each result and how selection may affect interpretation.
The registry record reports randomization and masking, but does not provide operational details about allocation, concealment, or which roles were masked. These details help readers judge the risk of bias in treatment assignment and outcome assessment. The record also lacks a formal comparative estimate and measure of uncertainty for the primary endpoint. A numerical difference in group medians is not a substitute for those quantities.
Finally, the trial is identified as a pilot, but no sample-size justification or statistical analysis plan is reported. This limits assessment of what precision the study was designed to achieve and how outcomes were prioritized. These limitations do not erase the descriptive observations; they define what can responsibly be inferred from them. The study highlights the value of reporting effect estimates, uncertainty, analysis populations, missing-data handling, and safety follow-up in a way that allows independent statistical interpretation.
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 primary endpoint is reported for a per-protocol population, but the record does not define that population or explain why its counts are 19 and 21. Overall enrollment is 45, and safety risk counts are 22 and 23. The reasons for these differences, including any exclusions or missing Week 0 or Week 4 measurements, are not reported in the registry record. This makes it difficult to judge whether the endpoint summaries represent all randomized participants.
The registry record gives medians and full ranges but no confidence interval, formal comparison, or p-value for the primary outcome. It does not report the planned analysis method, any baseline adjustment, or sensitivity analyses. The full range is especially influenced by extreme observations and cannot show the distribution’s shape or the precision of the median. The endpoint measurement is described as length multiplied by width, but details about assessor procedures and measurement reliability are not reported.
The record describes masking as triple while the study summary says double blind, without specifying the masked roles or explaining the terminology. Allocation-sequence generation and concealment are also not described. The study is identified as a pilot, but its sample-size rationale and statistical analysis plan are not reported. Although Pain is listed as a secondary outcome, a numerical result for it is not reported in the registry record. The safety information does not specify the observation period or detailed event-assessment procedures, and deaths are not reported.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Prospective Randomized Double Blind Clinical Trial of Polyhexamethylene Biguanide Impregnated Foam Dressing — NCT00618787.
- Registry record last updated 2010-04-15; status last verified 2010-04.
- Results first posted 2010-04-07.
- 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 identifies NCT00618787 as a completed phase 2 randomized parallel-group pilot trial of dressings for chronic wounds. It reports enrollment of 45 and describes the study as prospective, multicenter, and double blind; masking is also labeled triple in the record. The comparison is COPA AMD, a PHMB-impregnated foam dressing, versus COPA, regular foam dressing.
The primary endpoint is median percentage decrease in wound surface area from Week 0 to Week 4, assessed in a per-protocol population. The posted medians are 34.9 for COPA AMD and 27.8 for COPA, with full ranges of -74.8 to 94.7 and -167.0 to 97.6. A comparative estimate and uncertainty interval are not reported. Pain is listed as a secondary outcome. The record also includes adverse-event counts, but details needed for a full comparative safety interpretation are limited. The study rationale for sample size, statistical analysis plan, missing-data methods, and per-protocol criteria are not reported in the registry record.