Adherence and Perspiration While Wearing Lower Limb Prostheses: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Adherence and Perspiration While Wearing Lower Limb Prostheses (NCT03900845), a randomized na study. The primary outcome is Adherence.

2. Clinical Question

The clinical motivation is management of sweat and prosthesis security while maintaining residual-limb skin health and comfort. The registry describes both a chamber assessment and field measurements during participants’ usual activities at home, work, and in the community. The primary endpoint is the amount of slippage measured after the chamber protocol; skin hydration, transepidermal water loss, and satisfaction are listed as secondary outcomes.

The posted primary results give mean slippage of 1 millimeter for DAE-RED, 8 millimeters for As-Prescribed (RX), and 3 millimeters for Perforated Liner (PERF). Since the endpoint defines slippage as loss of adherence, lower values correspond to less measured slippage. The registry also reports an overall regression test and tests for each pair of systems. These results address measured slippage in this study context; they do not by themselves establish effects on everyday mobility, skin health, comfort, or prosthesis security outside the measured conditions.

3. Trial Design

The registry describes a randomized, unmasked crossover study. In a crossover design, participants receive or use more than one study condition, so comparisons can be made across conditions experienced by the same people. The registry states that all participants will wear all three study prostheses in the environmental chamber and in field settings. It does not report the randomization sequence, the procedure used to assign sequence, or whether the statistical model accounted for the within-participant structure.

For the chamber assessment, the environmental conditions were 35 degrees Celsius and 50% relative humidity. The primary endpoint was measured after a 90-minute rest-walk-rest protocol: a 30-minute seated acclimation, a 30-minute treadmill walk, and a 30-minute seated rest outside the chamber. For field measurements, participants were to wear all three study prostheses in their home, work, and community environments for two weeks. The record does not clarify whether that duration applies to each prosthesis or to the field-measurement period overall.

The registry lists enrollment as 20. The brief summary describes a plan to recruit 25 below-knee amputees, so the planned recruitment figure and the listed enrollment are not the same. The record does not explain that difference. The primary results report n of 8 for each prosthesis condition, but do not explain how those outcome counts relate to enrollment or whether all randomized participants contributed data to every condition.

The study is marked completed, with a start date of 2019-02-17 and a primary completion date of 2022-06-28. Its phase is listed as NA. The sponsor is the Seattle Institute for Biomedical and Clinical Research. The registry does not report a masking procedure, consistent with its designation of NONE.

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: Twenty eligible individuals (17 male, 3 female) were enrolled in the study. All considered themselves moderately active community ambulators. Twelve individuals terminated before randomization: one withdrew due to health issues, one did not feel strong enough to complete the protocol, one left the country, five had prosthetic fitting issues, and four were lost to follow up after consent.

First Intervention (2 weeks)

Second Intervention (2 weeks)

Third Intervention (2 weeks)

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 Adherence, measured over After the 90-minute rest-walk-rest protocol where subjects enter our environmental chamber for a 30-minute seated acclimation and a 30-minute treadmill walk and then exit the chamber for a 30-minute seated rest..

The primary endpoint is adherence, measured as the amount of slippage in millimeters. The registry defines slippage as the distance between a mark on the skin and the proximal border of the liner. It treats slippage as loss of adherence: a larger measured distance means more movement between the skin mark and liner border during the assessment.

The measurement followed the chamber-based rest-walk-rest protocol. Participants completed seated acclimation in the chamber, treadmill walking, and seated rest outside the chamber before the endpoint was assessed. The chamber was set at 35 degrees Celsius and 50% relative humidity, conditions selected in the study description to evaluate the systems where profuse sweating may occur. This is a specific, protocol-based measure; it is not a direct measure of all aspects of comfort, skin health, or security during daily life.

The registry reports the endpoint as a mean with standard error. Mean slippage was 1 millimeter for DAE-RED, 8 millimeters for As-Prescribed (RX), and 3 millimeters for Perforated Liner (PERF). The reported standard errors were 1, 4, and 2 millimeters, respectively. A standard error describes uncertainty in an estimated mean; it is not the range of individual measurements. The record does not report confidence intervals for these means.

Slippage is used because it operationalizes adherence as a measurable distance. However, the record does not report a threshold defining a clinically important difference in slippage or a threshold for acceptable adherence. The endpoint therefore supports comparison of the measured values, but the practical importance of a particular difference is not established by the posted endpoint description alone.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Several statistical ideas help place the posted adherence results in context. The registry identifies the trial as randomized and crossover, and lists linear regression as the method for the reported tests. It does not describe the full regression specification, so the role of participant-level correlation, period, sequence, or other covariates is not reported in the registry record.

What does a crossover design contribute?

General statistical explanation: a crossover design allows a participant to experience multiple conditions. When the same participant contributes measurements under different conditions, comparisons may use within-person information and can account for stable characteristics that differ between people. This can be useful when outcomes vary substantially across participants. The registry says all participants will wear all three study prostheses, but does not report the order of use, washout arrangements, or how the analysis handled repeated measurements. Those details matter because period effects, order effects, or carryover could affect observed values if not addressed appropriately.

What does a mean and standard error describe?

The registry reports mean slippage and standard error for each condition. A mean is a central summary of the measured values. A standard error describes the estimated precision of that mean, given the data and the method used to calculate it. It should not be read as a description of the range of individual observations. The posted standard errors are 1 millimeter for DAE-RED, 4 millimeters for As-Prescribed (RX), and 2 millimeters for Perforated Liner (PERF). The record does not report confidence intervals around the means or contrasts.

General statistical explanation: a confidence interval expresses a range of values compatible with a data-based estimate under a stated method and confidence level. It can show both the direction and precision of an estimated contrast. The registry record does not provide confidence intervals for the reported comparisons, so readers cannot use those results to assess a range of plausible contrast magnitudes. A p-value alone does not replace an estimate with a confidence interval.

How should the regression tests be read?

The registry reports a linear regression test across the three conditions, p = .037, and pairwise regression tests with p = 0.031, p = 0.220, and p = 0.510. The overall test evaluates evidence against a null hypothesis of no condition differences under its model. Pairwise tests evaluate the specified pairs. The record does not provide regression coefficients, standard errors for contrasts, model diagnostics, or a description of the exact null hypotheses. It also does not state whether the regression was fitted to participant-level observations, condition summaries, or a model that explicitly represents the crossover.

General statistical explanation: a p-value depends on the model assumptions and the analysis plan. It is not the probability that the null hypothesis is true, and it does not measure clinical importance. Estimates and confidence intervals, alongside a transparent model description, are needed to assess magnitude and precision. The posted means give descriptive context, but they do not supply adjusted contrasts.

Why can over-dispersion matter?

General statistical explanation: over-dispersion occurs when observed variability is greater than a statistical model expects. It can make standard errors too small if a model assumes less variability than is present, which in turn can affect confidence intervals and hypothesis tests. Over-dispersion is most often discussed for count or event data. The primary adherence outcome is a continuous measure, and the registry does not report an over-dispersion assessment. It would not be appropriate to claim that over-dispersion was present or was a problem in this analysis.

What does multiplicity mean for these results?

The registry lists an overall test, pairwise comparisons, secondary outcomes, and 8 analyses. Testing multiple hypotheses can increase the chance of obtaining at least one small p-value by chance when all null hypotheses are true. General statistical explanation: multiplicity procedures can control that risk, but the choice depends on the planned testing hierarchy and inferential goal. The record does not report a hierarchy, adjustment method, or adjusted p-values. Thus, the listed p-values should be interpreted as reported tests without assuming that they account for all analyses.

How should planning calculations be distinguished from observed results?

The stated planning illustration assumptions are a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. Such calculations are planning illustrations, not observed outcomes and not observed power. The registry record does not report the resulting participant-per-arm values in the registry record described for this analysis. Nor does it report the trial’s own sample-size justification. These planning assumptions therefore cannot be used to infer the original design rationale or whether the study was adequately sized.

In short, the posted means and regression p-values support a descriptive reading of measured slippage and the reported tests. Interpretation of precision, adjusted effects, crossover-specific analysis, and multiplicity requires methods details that are not reported in the registry record.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Dynamic Air Exchange - Rising Edge Design (DAE-RED", "As-Prescribed (RX)", "Perforated Liner (PERF)")
n   <- c(8, 8, 8)
m   <- c(1, 8, 3)
sp  <- c(1, 4, 2)
sd  <- sp * sqrt(n)      # standard errors converted to SDs
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Dynamic Air Exchange - Rising Edge Design (DAE-RED  8  1.000  2.828  -1.365  3.365
CARM  As-Prescribed (RX)  8  8.000  11.314  -1.458  17.458
CARM  Perforated Liner (PERF)  8  3.000  5.657  -1.729  7.729

11. Analyses Reported by the Sponsor

The registry reports the sponsor’s own analyses as linear regression tests. The overall test across DAE-RED, As-Prescribed (RX), and Perforated Liner (PERF) has p = .037. The pairwise tests have p = 0.031 for DAE-RED versus As-Prescribed (RX), p = 0.220 for As-Prescribed (RX) versus Perforated Liner (PERF), and p = 0.510 for DAE-RED versus Perforated Liner (PERF).

The record does not include numerical recalculated contrasts or confidence intervals that can be compared with those sponsor-reported tests. The posted means and standard errors are not a substitute for a model-based estimate that accounts for the crossover design. The registry does not explain the regression model specification or how repeated measurements were treated. As a result, it is not possible to assess numerical agreement between the sponsor’s tests and a recalculation from the posted summary statistics.

The registry does not flag a discrepancy between the sponsor analysis and a recalculation. That absence does not establish that the analyses are equivalent; the information needed to make that comparison is not reported in the registry record. The sponsor-reported tests should therefore be read as the analyses recorded by the study, with their model and multiplicity details unresolved.

12. Multiplicity, Missing Data and Analysis Populations

The registry reports an overall test across the three prosthesis conditions and pairwise tests for the three possible pairs. It also lists 8 analyses and 3 secondary outcomes. The record does not describe a prespecified testing hierarchy, state which tests were primary versus exploratory, or report an adjustment for multiple testing. The pairwise p-values are therefore best treated as the values reported for those comparisons, without assuming family-wise or false-discovery control.

Multiplicity is relevant because a set of tests creates more opportunities for a small p-value than a single test. General statistical explanation: an adjustment may change the threshold for interpreting tests or the p-values themselves, depending on the method. Since neither the method nor adjusted results are reported, no multiplicity-adjusted conclusion can be drawn from the record. The overall p-value and pairwise p-values should not be conflated: they test different hypotheses and may be subject to different planned inferential roles.

The registry does not report the number of participants included in each regression analysis, how missing measurements were handled, or whether any participants were excluded from an analysis. Although the primary results list n of 8 for each condition, the record does not explain whether these are complete-case counts, the number contributing to a specific analysis, or another summary. It also does not describe an intention-to-treat population, a per-protocol population, or any other analysis population.

For a crossover study, it is relevant to know how incomplete sequences or missing condition measurements were treated. The registry record does not report that information. It also does not state whether missingness was assessed as potentially related to measured or unmeasured factors. Without those details, the effect of missing observations on the estimated means and tests cannot be determined. No assumption about missing-at-random, imputation, or complete-case analysis should be made from the posted information.

These reporting gaps limit assessment of the inferential plan. They do not invalidate the listed values, but they mean the p-values cannot be interpreted as if the adjustment strategy and analysis population were fully documented.

13. 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 adverse-event figures are reported by sequence groups, not by the three prosthesis conditions. For PERF, Then RX, Then DAE-RED, the registry lists 2 at risk for serious adverse events and 0 affected; it also lists 2 at risk for other adverse events and 0 affected, with 0 deaths. For DAE-RED, Then RX, Then PERF, it lists 6 at risk for serious adverse events and 0 affected; it also lists 6 at risk for other adverse events and 0 affected, with 0 deaths.

These figures indicate that no serious adverse events, other adverse events, or deaths were recorded in the listed groups. They should not be read as showing that no adverse events could occur or that risk is absent. The denominators are small, and the registry does not provide detail about event ascertainment, exposure time by prosthesis, or whether these groups cover every participant who contributed to the efficacy results.

Because the adverse-event group labels describe sequences, the counts cannot be attributed to one prosthesis condition from the information reported. The record also provides no serious adverse-event terms. These figures are a limited safety summary and should be interpreted separately from the adherence means and regression tests.

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

The result describes measured slippage under a specific chamber protocol and reports tests comparing three prosthesis conditions. The mean values are 1 millimeter for DAE-RED, 8 millimeters for As-Prescribed (RX), and 3 millimeters for Perforated Liner (PERF). Since the endpoint defines slippage as loss of adherence, these values indicate the observed amount of movement measured by the protocol, rather than a direct assessment of every aspect of prosthesis performance.

The registry’s overall regression test is p = .037. The pairwise p-values are 0.031, 0.220, and 0.510 for the comparisons listed in the record. These statistics provide evidence from the reported tests, but the model specification and adjustment for multiple comparisons are not reported. The record also does not provide confidence intervals for the means or comparisons, so the precision and range of plausible contrast sizes cannot be evaluated from the posted results.

The outcome does not establish how participants experienced skin comfort, how secure the prostheses felt in everyday settings, or whether their mobility changed. The registry includes skin hydration, transepidermal water loss, and satisfaction as secondary outcomes, but values for those outcomes are not reported in the registry record described for this analysis. Nor does the primary endpoint establish the clinical importance of any measured slippage difference; a meaningful-change threshold is not reported in the registry record.

The findings are specific to the trial’s participants, prosthesis conditions, chamber setting, protocol, and field-measurement plan. The registry does not provide enough information to determine how representative participants were of all people with lower-limb amputation or how the crossover analysis addressed participant, period, and sequence effects. The results should not be generalized beyond the measured outcomes and conditions without additional evidence.

In statistical terms, the posted information supports a descriptive comparison and a summary of the sponsor-reported tests. It does not support a complete assessment of effect precision, multiplicity, missing data, or the relevance of the measured slippage to broader clinical outcomes.

15. Why This Trial Matters Statistically

This study raises a statistical challenge common to device comparisons: the outcome is measured repeatedly as the same participant uses multiple conditions. A crossover design can make within-person comparisons informative, but it also makes the analysis structure important. The registry identifies the design as crossover and the reported method as linear regression, yet does not describe how participant-level dependence or period and sequence effects were handled. That omission limits independent interpretation of the reported p-values.

The endpoint is also a concrete measurement rather than a broad patient-centered outcome. Slippage in millimeters gives a measurable indication of adherence loss under the chamber protocol. The posted means make the direction of the observed values understandable, while the missing confidence intervals and model details leave uncertainty about the precision of comparisons. This illustrates why effect estimates and intervals are useful alongside significance tests.

The study’s environmental and field contexts also raise questions about what an endpoint can represent. Chamber measurements occurred under specified heat and humidity, while field measurements were intended to take place in home, work, and community environments. The primary result described in the registry is the chamber-based adherence measure; the record does not provide field outcome values. It is therefore important to distinguish a controlled measurement from outcomes during ordinary activities.

Finally, the registry lists both an enrollment of 20 and a recruitment plan for 25, while each condition’s primary outcome count is n of 8. The record does not reconcile these figures. Transparent accounting of the participant flow and analysis population would help readers understand how enrollment translated into the reported outcome summaries. These design and reporting details are central to assessing precision and generalizability, not merely technical appendices.

16. 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 limitation is incomplete reporting of the analysis. The registry gives mean values, standard errors, and p-values but does not provide confidence intervals for the means or comparisons, regression coefficients, the full model specification, or diagnostics. It does not explain whether the regression analysis accounted for within-participant correlation, period, sequence, or carryover in this crossover study. The precision and robustness of the reported comparisons therefore cannot be fully assessed.

The participant counts are also not fully reconciled. Enrollment is listed as 20, while the brief summary describes a plan to recruit 25 below-knee amputees. The primary outcome lists n of 8 for each prosthesis condition. The record does not explain the difference among these figures, report participant flow, or state how many participants contributed data to each analysis. The handling of missing observations and the definition of the analysis population are not reported in the registry record.

The record does not state whether the reported pairwise tests were adjusted for multiplicity, or how the overall and pairwise tests fit within the planned analysis strategy. It does not report a sample-size justification for the trial. The stated planning illustration assumptions are not a substitute for the trial’s design rationale, and no resulting planning values are described in the registry record for this analysis.

The endpoint is a protocol-specific measure of slippage after the chamber assessment. The record does not give a threshold for clinical importance. While field measurements and secondary outcomes are described, their results are not included in the primary adherence details. Thus, the posted primary result cannot establish outcomes for everyday use, skin health, comfort, or satisfaction. The adverse-event counts are small and grouped by sequence, which limits attribution to any one prosthesis condition.

17. Related Tutorials

18. Related Statistical Calculators

19. Sources

• ClinicalTrials.gov: Adherence and Perspiration While Wearing Lower Limb Prostheses — NCT03900845.
• Registry record last updated 2026-01-27; status last verified 2026-01.
• Results first posted 2026-01-27.
• 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.

20. Record Summary

The registry record describes a completed, randomized, unmasked crossover study of three lower-limb prosthetic suspension systems: DAE-RED, As-Prescribed (RX), and Perforated Liner (PERF). It lists enrollment as 20 and identifies adherence, measured as slippage in millimeters after a chamber-based rest-walk-rest protocol, as the primary outcome. Mean slippage was 1 millimeter, 8 millimeters, and 3 millimeters, respectively, with standard errors of 1, 4, and 2 millimeters.

The registry reports a linear regression test across the three conditions with p = .037 and pairwise tests with p = 0.031, p = 0.220, and p = 0.510. Confidence intervals and full model details are not reported in the registry record. The record also lists secondary outcomes concerning skin hydration, transepidermal water loss, and satisfaction, but their results are not included in these primary-outcome details. Adverse-event counts are reported by sequence group and show zero affected in the listed categories.