Vacuum Assisted Closure as a Treatment for Open Fractures: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Vacuum Assisted Closure as a Treatment for Open Fractures (NCT00582361), a randomized na study. The primary outcome is Healing of Orthopaedic Trauma Open Fractures.

2. Clinical Question

The clinical question is about wound readiness for closure, not a broad measure of recovery or every possible consequence of the fracture. The endpoint captures a specific stage in wound care: adequate healing to permit closure after the initial fracture treatment. The registry record also reports serious and other adverse-event counts, but these are separate from the primary wound-healing endpoint. The results therefore describe the posted measurements for each group; they do not, by themselves, establish whether any observed group difference is attributable to the assigned dressing strategy.

3. Trial Design

The registry record describes a prospective, randomized, comparative study of a negative-pressure vacuum device for traumatic wounds associated with open fractures. Allocation was randomized, the model was parallel group, and masking was listed as none. The groups received either a standard wound dressing or a VAC device following initial treatment of the open fracture. The study is marked completed, and its phase is listed as not applicable.

The registry lists enrollment of 63. For the primary endpoint, the Standard Dressing Group has a reported count of 23 and the Vacuum Assisted Closure Group has a reported count of 35. Those endpoint counts do not account for the enrollment figure, and the registry record does not explain the difference. The safety results use different group counts: 25 for the Standard Dressing Group and 38 for the Vacuum Assisted Closure Group. These counts should be read as reported for their respective outcomes rather than treated as interchangeable denominators.

The registry records a start date of 2001-06 and a primary completion date of 2008-09. It identifies the University of Alabama at Birmingham as sponsor. The planned comparison was between two wound-management approaches after initial fracture treatment. The record does not report details of the randomization sequence, allocation concealment, procedures for delivering the interventions, adherence, or crossover between groups. It also does not describe a masking procedure; masking is recorded as none.

Although the trial is randomized, the registry record does not provide a posted statistical analysis for the primary outcome. It lists zero analyses. It therefore supplies descriptive group results but not a reported test, confidence interval, or adjusted estimate for the primary comparison. Random allocation is relevant to how groups are formed, but it does not replace a clearly reported analysis of the outcome.

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

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.

6. Primary Endpoint

The registry lists the primary outcome as Healing of Orthopaedic Trauma Open Fractures, measured over from surgery to wound closure.

The primary endpoint is healing of orthopaedic trauma open fractures, measured in days from surgery to wound closure. The endpoint description defines healing as the wound being adequately healed to permit closure. It is therefore a time measure tied to a clinical milestone in wound management. It is not described as time to complete recovery, fracture union, or return to usual activity.

The registry reports the endpoint as a mean with a full range for each group. The Standard Dressing Group has a reported mean of 3.2 days, with a full range of 2.0 to 9.0 days. The Vacuum Assisted Closure Group has a reported mean of 4.0 days, with a full range of 2.0 to 11.0 days. The endpoint counts are 23 and 35, respectively. No standard deviation or confidence interval is posted for these group summaries.

Using a wound-closure milestone gives a defined outcome that can be expressed in elapsed days and compared descriptively across the randomized groups. However, interpreting a mean alone can be difficult when individual times vary. The full range conveys the observed span but does not show how values are distributed within that span. The registry record does not describe how the endpoint was assessed, how the timing was recorded, or how cases without an observed closure time were handled. Those details would help readers evaluate measurement consistency and the completeness of the endpoint data.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The study is described as randomized and parallel group. In a randomized trial, assignment is intended to make the comparison groups similar on average with respect to factors that could affect the outcome. Randomization does not guarantee exact balance in a particular trial, and its value depends on how assignment was generated and concealed. The registry record does not report those procedures, so the method of randomization cannot be assessed in detail. The parallel-group description indicates that the groups were assigned to different wound-management approaches rather than being described as a crossover comparison.

What does the reported mean describe?

A mean is an average of the observed endpoint values in a group. For this outcome, the values are days from surgery until the wound was adequately healed to permit closure. The registry reports means of 3.2 days for the Standard Dressing Group and 4.0 days for the Vacuum Assisted Closure Group. A mean offers a compact summary, but it does not show whether most observations were close to that value or whether a small number of longer times influenced it. The record does not provide a standard deviation or other measure that describes the typical distance of individual observations from the mean.

The reported full ranges are 2.0 to 9.0 days for the Standard Dressing Group and 2.0 to 11.0 days for the Vacuum Assisted Closure Group. A range reports only the endpoints of the observed values. It does not reveal the distribution between those endpoints, and it can be sensitive to individual extreme observations. The registry record does not provide a histogram, quantiles, or participant-level data from which the shape of the distributions could be assessed.

Why does distribution matter?

Many standard methods for comparing means work best when their assumptions about the outcome distribution and variability are reasonably appropriate. Time measurements can be unevenly distributed, especially when a smaller number of observations take longer than most. Over-dispersion is a general term for variability greater than a model expects; when present, it can make standard errors too small if the analysis does not account for it. This is a general statistical consideration, not a claim that over-dispersion occurred in this trial. The posted group means and ranges do not provide enough detail to assess the distribution or choose a particular model.

For time-to-event outcomes, some participants may not have an observed event during follow-up. Such observations are often described as censored and require methods that account for incomplete event times. The registry describes the endpoint as days to wound closure but does not report whether any observations were censored, whether all wounds reached the endpoint, or how such cases were handled. It also does not state that a time-to-event method was used. The endpoint should therefore be interpreted according to the registry's stated summary, rather than assuming a particular analysis framework.

What would uncertainty estimates add?

A confidence interval is a statistical range calculated from data using a specified method. It conveys the precision of an estimate: a narrower interval indicates greater precision under that method, while a wider interval indicates more uncertainty. A confidence interval for the between-group difference would help show which comparative values are consistent with the data and analysis assumptions. No such interval is reported in the registry record. A p-value, also not reported, would summarize how unusual the data would be under a specified null hypothesis and statistical model; it would not measure the size or clinical importance of an effect.

The registry lists zero analyses, so it does not identify a test or model for the primary comparison. It does not report whether the analysis was intended to adjust for baseline characteristics, how an outcome population was defined, or how departures from the planned treatment assignment would be handled. Without those details, readers should not infer that the descriptive values were adjusted or that a particular inferential procedure was used.

How should planning illustrations be read?

Sample-size calculations are planning tools, not observations from a completed trial. The registry's planning assumptions describe illustrations based on a fraction of the observed effect, a two-sided significance level of 0.05, equal allocation, and a normal approximation. Those assumptions are not identified as the trial's own design justification. The actual planning values are not reported in the registry record. Such illustrations should not be interpreted as observed power or as evidence that the trial was designed with a particular sample-size target. A planning calculation depends on its assumptions, including the effect selected for detection and the variability model; it does not establish that the selected effect is true.

Overall, the available methodological information supports a straightforward reading of the registry: group-specific endpoint means and ranges were posted, but an inferential comparison and key analysis details were not. Descriptive summaries can clarify what was recorded, while uncertainty estimates and a transparent analysis plan would be needed for a fuller assessment of comparative evidence.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures, identifies one primary endpoint, and lists zero secondary outcomes posted. It also lists zero analyses. The registry record does not report a multiplicity procedure or explain how conclusions across outcomes were to be controlled. Multiplicity is a general concern when several outcomes or comparisons are tested: considering more tests can increase the chance of at least one apparently notable result by chance. The record does not provide enough information to determine whether this issue affected the study's analysis or interpretation.

Missing data handling is not reported in the registry record. For the primary endpoint, the posted group counts are 23 for the Standard Dressing Group and 35 for the Vacuum Assisted Closure Group, while enrollment is listed as 63. The record does not explain the relationship among these counts, identify reasons for unavailable endpoint data, or state whether missingness was addressed by an imputation or other method. No assumptions about missing outcomes should be inferred from the group summaries.

The registry also does not define the analysis population, such as whether participants were analyzed according to their randomized assignment or according to treatment received. It does not describe exclusions, adherence, crossover, or deviations from assigned treatment. The safety counts use separate group denominators, and the record does not explain how those populations were defined. These omissions limit assessment of whether outcome populations were comparable and how fully the posted results represent the randomized groups.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: infection (4.0%), nonunion (2.6%), required flap coverage (2.6%), amputation (2.6%).

The registry reports serious adverse events for 1 of 25 participants in the Standard Dressing Group and 4 of 38 participants in the Vacuum Assisted Closure Group. It reports no other adverse events in either group: 0 of 25 in the Standard Dressing Group and 0 of 38 in the Vacuum Assisted Closure Group. These are the posted counts for the safety outcomes, not the endpoint counts used for wound-healing time. Deaths are not reported in the registry record.

The serious-event terms listed are Infection at 4.0%, Nonunion at 2.6%, Required Flap Coverage at 2.6%, and Amputation at 2.6%. The registry does not identify the group attribution for each listed term, and these terms should not be assigned to a group based on the aggregate serious-event counts. The record also does not explain whether terms could overlap within a participant or how events were collected and classified.

These figures are descriptive. The registry record does not report a statistical comparison of adverse-event rates, follow-up duration for safety, or an analysis accounting for differences in observation. The counts alone do not establish whether the groups differed in safety, and they should not be interpreted as proof of either harm or safety.

12. What the Result Does, and Does Not, Mean

The registry results establish what was posted for the primary endpoint: the Standard Dressing Group had a mean time to adequate wound healing for closure of 3.2 days, with a full range of 2.0 to 9.0 days; the Vacuum Assisted Closure Group had a mean of 4.0 days, with a full range of 2.0 to 11.0 days. The results also show the reported endpoint counts of 23 and 35. These are descriptive summaries of the recorded groups.

The results do not establish the size or precision of a comparative effect. No confidence interval, p-value, or statistical analysis of the primary comparison is reported in the registry record. The posted means should not be taken as proof that one approach shortens or lengthens time to closure, or as evidence that the groups are equivalent. A finding of similarity would require an appropriate analysis and enough precision to rule out differences that matter; neither is reported.

The endpoint addresses a specific wound-healing milestone. It does not, on its own, describe fracture union, longer-term function, complications beyond the posted safety outcomes, or other aspects of recovery. The adverse-event counts provide additional descriptive information, but the registry does not report a comparative safety analysis or deaths.

Interpretation is also constrained by the unexplained difference between total enrollment and the endpoint counts, as well as by the lack of reported information on missing data and analysis populations. Randomization is an important design feature, but it does not resolve these reporting gaps. The findings are best understood as registry-posted group summaries rather than a complete inferential evaluation of the comparative clinical question.

13. Why This Trial Matters Statistically

This trial is statistically interesting because it links a randomized comparison to a concrete wound-care milestone while illustrating the difference between descriptive results and a complete comparative analysis. The registry reports mean time to adequate healing for closure and the observed full range in each group. These summaries let readers see the scale and span of the recorded endpoint values without suggesting more certainty than the record supports.

The study also demonstrates why denominators matter. Overall enrollment is listed as 63, while endpoint and safety results use different group counts. Those numbers may reflect different outcome populations or data availability, but the registry record does not explain the reason. A clear account of who contributed to each analysis is essential for judging how representative the reported results are.

Another important statistical lesson is that randomization and analysis reporting serve different roles. Randomization is intended to support a fair comparison at the design stage. A prespecified and transparent analysis, with uncertainty estimates, is needed to show how the observed data inform that comparison. Here, the registry records random allocation but lists zero analyses and does not report a confidence interval or p-value for the primary outcome. The resulting group summaries can be read descriptively, but they cannot answer questions about comparative precision or statistical compatibility with a null effect.

Finally, the record distinguishes the primary healing endpoint from adverse-event reporting and planning assumptions. Safety counts, endpoint means, and sample-size illustrations answer different questions and should not be combined or treated as interchangeable evidence. Clear separation of observed outcomes, inferential estimates, and planning calculations is a useful principle for reading clinical trial registries.

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 registry record leaves several trial-specific limitations unresolved. It does not report the randomization procedure or allocation concealment, so the practical safeguards used to implement randomized assignment cannot be evaluated. Masking is listed as none, and the record does not describe how the wound-healing endpoint was assessed or whether assessment could have been influenced by knowledge of group assignment.

The primary endpoint is reported as a mean and full range, but no standard deviation, confidence interval, or inferential comparison is posted. The distribution of times cannot be evaluated from the mean and range alone. The registry does not say whether any participants had no observed closure time during follow-up or how such cases were treated in the analysis.

The reported counts also need clarification. Enrollment is 63, while the endpoint group counts are 23 and 35; the safety group counts are 25 and 38. The registry record does not explain these differences, define analysis populations, or report reasons for missing observations. It does not describe adherence, crossover, exclusions, or handling of deviations from assigned intervention.

For safety, the registry gives group counts and serious-event terms but does not report follow-up duration, event-collection methods, group attribution for each listed term, or a comparative analysis. Deaths are not reported in the registry record. Finally, no statistical analysis plan, multiplicity approach, or sample-size justification for the trial is reported. These gaps limit conclusions about precision, robustness, and the interpretation of both efficacy-related and safety outcomes.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Vacuum Assisted Closure as a Treatment for Open Fractures — NCT00582361.
• Registry record last updated 2013-08-14; status last verified 2012-05.
• Results first posted 2013-01-24.
• 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.

18. Record Summary

NCT00582361 is a completed, randomized, parallel-group trial sponsored by the University of Alabama at Birmingham. It compared standard wound dressing with a Vacuum Assisted Closure device following initial treatment of traumatic open fractures. Masking is listed as none; phase is listed as not applicable. The recorded start date is 2001-06, and the primary completion date is 2008-09. Enrollment is listed as 63.

The primary endpoint was days from surgery until the wound was adequately healed to permit closure. The registry reports group means and full ranges, with endpoint counts of 23 for standard dressing and 35 for VAC. It also reports serious and other adverse-event counts using separate group denominators. The record lists two outcome measures, zero secondary outcomes posted, and zero analyses. It does not report a statistical comparison, confidence interval, or p-value for the primary endpoint.