A Transparent Elasticized Adhesive Occlusive Compression Bandage for Use as an Arterial Tourniquet: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Transparent Elasticized Adhesive Occlusive Compression Bandage for Use as an Arterial Tourniquet (NCT02592655), a randomized na study. The primary outcome is Radiologist Limb Occlusion Assessment.

2. Clinical Question

The study also sought to characterize safety through mapping interface pressures between skin and tourniquet. The posted safety figures include adverse-event counts, but the registry record does not report interface-pressure results. The stated aim was to compare investigational and control devices, not to establish effects in patients receiving emergency treatment. The trial was a randomized-sequence crossover: participants were assigned an intervention sequence and were intended to receive all interventions. This design makes within-participant comparison possible in principle, but the record does not describe the statistical method used to account for repeated measurements or give a completed comparative analysis.

3. Trial Design

The registry describes a randomized-sequence, assessor-blind crossover study. Its official title identifies a windlass tourniquet, a pneumatic tourniquet, and an elastic adhesive bandage for tourniquet use. The intervention list names a pneumatic tourniquet, one windlass tourniquet, two windlass tourniquets, and tape in 5 cm and 10 cm widths. The brief summary says the devices would be applied to the upper thigh and that all interventions would be applied in one visit. A minimum washout of five minutes was planned between applications.

The record lists enrollment of 19, while the brief summary describes twenty five (anticipated). These are different descriptions: one is the enrollment entry and the other is the anticipated enrollment in the summary. The record does not explain the difference. It describes the pneumatic device as representative of usual care in hospital settings and the windlass device as representative of prehospital and military usual care. The investigational tape was expected to create circumferential pressure when tightly wrapped around a limb.

The primary endpoint was assessed with duplex and color flow ultrasound after each tourniquet application. A still image was saved for later assessment by a blinded outcome assessor. The 5 cm tape was discontinued after the 4th participant because its width was considered unacceptably narrow after stretching; the record calls this a mechanical failure even if occlusion was observed. Its data were not evaluated by the radiologist. No follow-up visit was anticipated. The registry record does not report details of the randomization sequence generation, allocation concealment, washout assessment, or the statistical model for the crossover data.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: Each participant receives a different intervention each period. 19 Participants randomly allocated to unique sequences of four interventions. No participants were lost once enrolled. 5 minute minimum washout period between interventions.

First Tourniquet, Left Thigh.

Second Tourniquet Right Thigh.

Third Tourniquet, Left Thigh.

Fourth Tourniquet Right Thigh.

Analysis population for the primary outcome, as defined in the registry: One ultrasound image from one of the participants of the pneumatic tourniquet (ATS) group failed to capture anatomy and was therefore not included in the analysis. One ultrasound image from one of the participants of the windlass tourniquet (SOFTT-W) group failed to capture anatomy and was therefore not included in the analysis.

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: "One Windlass" indicates the participants received only one windlass tourniquet because it appeared to be effective. "Two Windlass" describes the participants that received two windlass tourniquets because one did not appear to be effective. The total describes all participants. All participants received both the pneumatic and tape tourniquet.

6. Primary Endpoint

The registry lists the primary outcome as Radiologist Limb Occlusion Assessment, measured over For 1 sustained minute after application of each tourniquet intervention..

The primary endpoint, titled Radiologist Limb Occlusion Assessment, measures whether a tourniquet application produces sustained absence of distal blood flow at the popliteal artery. Duplex and color flow ultrasound were used to assess flow for 1 sustained minute after application of each intervention to the middle upper thigh. If no flow was observed for that interval, the application was classified as successful occlusion. A still image was saved for later evaluation by the blinded assessor.

This endpoint is a binary assessment: flow was either observed or not observed during the specified assessment interval. In general, a binary endpoint gives a direct count of participants meeting a defined criterion, but it does not describe the magnitude of blood-flow change or the pressure needed to achieve occlusion. The study separately planned interface-pressure mapping as safety information; the registry record does not report those measurements.

The 5 cm tape was discontinued after the 4th participant because stretching left it considered unacceptably narrow. Its data were not evaluated by the radiologist, even if occlusion had been observed. The record also notes that one ultrasound image in the pneumatic-tourniquet group and one in the windlass-tourniquet group failed to capture anatomy and were not included in the analysis. The registry record does not report the resulting endpoint counts, the analyzed denominator for each intervention, or a comparative effect estimate.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical interpretation depends first on what was measured and how the comparisons were organized. This was a randomized-sequence crossover study, and the primary endpoint was a binary ultrasound assessment after each intervention. The registry record describes the design and measurement procedure, but does not report the primary outcome counts or the method used to compare interventions.

What does a binary endpoint represent?

A binary endpoint assigns each assessment to one of two categories. In this study, no observed popliteal flow for 1 sustained minute was classified as successful occlusion; observed flow would not meet that criterion. For a binary outcome, analysts commonly report the count meeting the criterion and the denominator assessed, then compare the proportions between interventions. Those summaries are not reported in the registry record, so no observed event rate or effect estimate can be stated.

A confidence interval, in general, describes the range of effect estimates reasonably compatible with the observed data under a statistical model. Its width reflects precision: less precise estimates generally have wider intervals. No confidence interval for the primary comparison is reported. A p-value, in general, assesses how unusual data at least as incompatible with a specified null hypothesis would be if that hypothesis and the statistical assumptions were true. It does not measure the probability that the null hypothesis is true, and it does not measure clinical importance. No primary-outcome p-value is reported in the registry record.

Why does the crossover design matter?

In a crossover design, the same participant can contribute measurements under multiple interventions. In general, analyses should account for the dependence among measurements from the same participant rather than treating every assessment as independent. The randomized sequence helps distribute intervention order, while the sequence and timing can still matter if responses differ by period or carry over from an earlier application. The record states that a minimum washout of five minutes was allowed between applications, but does not report tests of carryover, period effects, or the statistical model used to account for repeated assessments.

The crossover design can be efficient when within-participant comparisons are appropriate, because participants serve as their own comparison. That general feature does not guarantee unbiased or precise estimates: missing observations, order effects, and the choice of analysis can affect interpretation. The record does not report whether every participant completed every planned intervention or give the sequence-specific completion information needed to assess this.

How should the missing assessments be understood?

The record identifies two images that failed to capture anatomy, one in the pneumatic-tourniquet group and one in the windlass-tourniquet group, and says they were not included in the analysis. It also says the 5 cm tape was discontinued after the 4th participant and its data were not evaluated by the radiologist. These statements identify reasons that some observations were unavailable for the primary assessment. The registry record does not report the full number assessed for each intervention, a missing-data assumption, or a sensitivity analysis. In general, missingness can affect a comparison if the chance of an unavailable measurement is related to the outcome or differs across interventions.

What do the planning assumptions mean?

The stated sample-size planning assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is expressed as a stated fraction of the observed effect. In general, a sample-size calculation estimates the sample needed to meet a target statistical criterion if its assumptions hold. Planning illustrations are not evidence that the trial had a particular probability of finding an effect, and they are not observed power. The record does not state the trial's own sample-size justification, or give numerical planning estimates in the available information.

What is not reported about the analysis?

The record does not report the primary-outcome comparison method, adjustment for multiple comparisons, a prespecified analysis population, or an approach to handling missing primary outcomes beyond the exclusions described. It also does not report interim analyses. Those details matter because multiple comparisons can increase the chance of false-positive findings if not accounted for, while a clearly specified analysis population and missing-data strategy help readers understand which observations contribute to each estimate. These are general statistical considerations, not claims about analyses performed in this study.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome was assessed after each intervention, and the registry record describes several interventions and outcome categories or time points. The available information does not reduce these assessments to one comparison. No multiplicity adjustment or hierarchy of primary comparisons is reported in the registry record. In general, testing multiple comparisons can increase the chance of at least one apparently notable result by chance; an analysis plan may address that issue by specifying primary comparisons or an adjustment strategy. The record does not say whether either approach was used.

Missingness is described for the ultrasound outcome. One image in the pneumatic-tourniquet group and one in the windlass-tourniquet group failed to capture anatomy and were excluded from analysis. The 5 cm tape was discontinued after the 4th participant because it was considered unacceptably narrow after stretching, and its data were not evaluated by the radiologist. These are distinct reasons for unavailable endpoint assessments. The record does not give complete analyzed denominators, report a formal missing-data method, or describe sensitivity analyses.

The record does not identify a prespecified analysis population, such as an intention-to-treat or per-protocol population, and does not state how the crossover measurements were analyzed. It also does not report whether all participants completed all interventions. The registry record does not report interim analyses. Without these details, readers cannot determine how the analysis handled incomplete sequences, missing images, or multiple intervention comparisons, or whether the reported analysis followed a prespecified plan.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The posted adverse-event figures list zero serious adverse events, zero other adverse events, and zero deaths for the pneumatic tourniquet, windlass tourniquet, and 10 cm tape groups. For the 5 cm tape, the figures list zero serious adverse events, zero other adverse events, and zero deaths among the 4 participants shown at risk. The registry record lists no top serious-event terms.

These counts describe what was recorded in the listed groups; they do not establish that no harms are possible. The study was small, involved healthy human subjects, and assessed applications in one visit, with no follow-up visit anticipated. The record does not report the duration or method of adverse-event surveillance beyond those details. In general, a zero observed event count does not rule out an event occurring in other settings or in a larger population.

The adverse-event figures should also be read separately from the interface-pressure assessment, which the study summary describes as a source of safety data but for which results are not reported in the registry record. No causal attribution details or additional safety analyses are reported. These figures are therefore a limited account of recorded adverse events, not a complete characterization of safety.

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

This registry record describes a randomized-sequence, assessor-blind crossover study of pneumatic, windlass, and elastic adhesive tourniquet applications. Its primary endpoint was whether ultrasound showed no popliteal flow for 1 sustained minute after application. The record also describes interface-pressure mapping as a safety measure and provides selected adverse-event counts.

The posted information does not report the primary endpoint counts, comparative estimates, confidence intervals, or p-values. It therefore does not establish which intervention had more observed occlusions or how precise any difference might have been. The absence of those results is not evidence that interventions performed equally, nor does it establish that one was better. The registry record does not provide enough information to make a quantitative efficacy comparison.

The endpoint concerns an ultrasound assessment after tourniquet application to the upper thigh in healthy human subjects. It is not itself a report of outcomes in patients with hemorrhage or vascular injury. The study summary anticipates a single visit and no follow-up visit, so longer-term outcomes are not described. The 5 cm tape was discontinued after the 4th participant because it was considered unacceptably narrow after stretching, and the radiologist did not evaluate its data. This limits what can be learned about that intervention from the primary endpoint.

The safety counts list no adverse events or deaths in the named groups, but those counts do not prove that harm cannot occur. The record does not report interface-pressure results or enough surveillance detail to characterize all possible safety outcomes. Overall, the information documents a study design and measurement approach; it does not provide the primary comparative results needed to judge the observed efficacy or precision of the interventions.

13. Why This Trial Matters Statistically

This study raises statistical issues common to device comparisons in which each participant receives multiple interventions. A crossover design can support within-participant comparisons, but the analysis needs to reflect the dependence among repeated measurements and consider intervention order. The registry record states that the sequence was randomized and that a minimum washout of five minutes was planned. It does not report the statistical method or whether order and period effects were examined.

The endpoint is defined in operational terms: ultrasound assessment of popliteal flow for 1 sustained minute, with no observed flow classified as successful occlusion. Such a definition helps clarify what an endpoint count would represent. At the same time, the absence of the reported outcome counts and comparative estimates means readers cannot evaluate the effect size or its precision from this record.

Missing measurements and intervention discontinuation matter for interpretation. The record identifies image failures in two intervention groups and discontinuation of the 5 cm tape after the 4th participant. These circumstances make complete reporting of denominators and the handling of missing observations especially important. The registry record does not report full analysis denominators or a missing-data strategy.

The record also distinguishes between anticipated enrollment in the summary and the enrollment entry, without explaining the difference. Its sample-size planning assumptions are described, but the trial's own sample-size justification is not reported. Together, these details illustrate why design, analysis, and transparent reporting are all needed to interpret a clinical comparison. The posted information supplies the endpoint definition and selected safety counts, but not the comparative outcome results needed for a statistical conclusion.

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 does not report primary endpoint counts, effect estimates, confidence intervals, or p-values. Consequently, the comparative efficacy question cannot be evaluated quantitatively from the available record. The record also does not give analyzed denominators for each intervention or explain how the repeated measurements in the crossover design were modeled.

There is incomplete endpoint information for specific interventions. The 5 cm tape was discontinued after the 4th participant because it was considered too narrow after stretching; its data were not evaluated by the radiologist. One ultrasound image in each of the pneumatic-tourniquet and windlass-tourniquet groups failed to capture anatomy and was excluded. The record does not report whether there were other incomplete assessments or how missingness affected the analysis.

Several details needed to judge the statistical plan are not reported in the registry record, including a sample-size justification, the prespecified analysis population, the primary comparison hierarchy, any multiplicity adjustment, and the method used for crossover data. The brief summary's anticipated enrollment of twenty five differs from the enrollment entry of 19, and the record does not explain the difference.

The study involved healthy human subjects, tourniquet applications to the upper thigh, and a single visit; no follow-up visit was anticipated. These design features limit what the record can say about outcomes beyond the immediate ultrasound assessment and the safety information collected during the study. Interface-pressure results are not reported, despite being described as planned safety data. The listed zero adverse-event counts therefore do not provide a complete safety assessment.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: A Transparent Elasticized Adhesive Occlusive Compression Bandage for Use as an Arterial Tourniquet — NCT02592655.
• Registry record last updated 2017-08-24; status last verified 2016-01.
• Results first posted 2017-08-24.
• 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

The registry describes a randomized-sequence, assessor-blind crossover study of tourniquet devices in healthy human subjects. The primary endpoint was ultrasound assessment of popliteal flow for 1 sustained minute after application to the upper thigh; absence of flow met the study's occlusion criterion. Enrollment is listed as 19, while the summary describes twenty five (anticipated).

The 5 cm tape was discontinued after the 4th participant and was not assessed by the radiologist. One image each in the pneumatic-tourniquet and windlass-tourniquet groups failed to capture anatomy and was excluded. Listed adverse-event counts are zero for serious events, other events, and deaths in the named groups. The registry record does not report the primary outcome counts, comparative statistical results, or interface-pressure findings.