Stroke Gait Rehabilitation Using Functional Electrical Stimulation: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Stroke Gait Rehabilitation Using Functional Electrical Stimulation (NCT01668602), a non-randomized na study. The primary outcome is Change in Motor Evoked Potentials (MEP) Amplitude Measure in milliVolt (mV) of FastFES Versus Fast Walking After 3 Training Sessions in Cohort 2.

2. Clinical Question

3. Trial Design

This is a prospective interventional study listed as completed, with a parallel model, non-randomized allocation, and no masking. Emory University is named as the sponsor. The condition is cerebrovascular accident. The listed start is 2013-08 and primary completion is 2019-05-01. The study is not identified as having a drug phase.

The brief summary describes two cohorts of people with chronic stroke. Cohort 1 is described as receiving 18 sessions of fast treadmill walking with functional electrical stimulation, called FastFES. Cohort 2 is described as participating in FastFES and fast walking without FES. Its arm description specifies 3 sessions of each intervention. The primary outcome concerns Cohort 2 and compares changes following these interventions.

The summary also says that interested participants could complete both cohorts sequentially, with at least 3-weeks between switching. This does not make the study a randomized crossover trial: allocation is listed as non-randomized, and masking as none. The registry record does not explain how cohort assignment was decided or establish that the order of Cohort 2 interventions was randomized.

Enrollment is listed as 24, while the brief summary says 55 individuals will be assigned to a cohort. These are both statements in the registry record, and their relationship is not explained there. The record lists 6 outcome measures and 0 analyses. Numerical primary-outcome results and a statistical analysis plan are not reported in the registry record.

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

Analysis population for the primary outcome, as defined in the registry: This analysis includes participants in Cohort 2 who had complete data for this assessment. There were issues with data collection during the training sessions and stimulus artifact causing noise in data, resulting in incomplete data for some participants.

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 Change in Motor Evoked Potentials (MEP) Amplitude Measure in milliVolt (mV) of FastFES Versus Fast Walking After 3 Training Sessions in Cohort 2, measured over Baseline, week 3 (after 3 sessions of one intervention), week 6 (after 3 sessions of the other intervention).

The primary endpoint is change in motor evoked potential (MEP) amplitude, measured in milliVolt (mV), in the transverse abdominal (TA) muscle. The registry describes the endpoint as a mean and identifies standard deviation as its measure of dispersion. Measurements are scheduled at baseline, week 3 after 3 sessions of one intervention, and week 6 after 3 sessions of the other intervention.

MEP amplitude is used as a measure of corticospinal excitability. The record describes transcranial magnetic stimulation (TMS) as the non-invasive assessment technique. Electrical activity in muscles is collected with surface electromyography (EMG) sensors. TMS is delivered using two Magstim 200 stimulators connected via a BiStim module, and the endpoint description says that an average of 10 TMS-evoked responses is used to compare mean peak-to-peak amplitudes in response to suprathreshold TMS delivered to the hotspot.

In general, an endpoint like this translates a physiological response into a continuous measurement that can be compared across assessment times and interventions. It is not itself a direct measure of walking ability. The registry record uses it to assess corticospinal excitability in the context of gait rehabilitation; it does not report numerical endpoint results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record describes a mean for the continuous primary outcome and standard deviation as the dispersion measure. It does not report the statistical test, model, covariates, handling of repeated measurements, or method used to estimate a FastFES-versus-fast-walking contrast. These elements are not reported in the registry record, so a particular analysis should not be attributed to the study.

What does a mean describe?

In general, a mean represents the arithmetic center of a set of measurements. For a change-from-baseline endpoint, the mean change would describe the average measured change in the analyzed participants. It does not show how widely individual measurements vary, whether all participants changed in the same direction, or whether the average is precise. Those questions require additional information, such as a dispersion measure and an uncertainty interval. The numerical mean changes are not reported in the registry record.

What does standard deviation add?

In general, standard deviation describes the spread of observations around their mean. A larger standard deviation indicates more variability among measured values, while a smaller one indicates that values are more concentrated around the mean. Standard deviation is not the same as the uncertainty around a mean or a treatment contrast. Precision also depends on the amount of usable data and the analysis design. The registry lists standard deviation as the dispersion measure but does not report its value for the primary endpoint.

How should the repeated assessments be understood?

The endpoint is assessed at baseline, week 3 after 3 sessions of one intervention, and week 6 after 3 sessions of the other intervention. In general, measurements taken repeatedly from the same participant are related rather than independent. Statistical methods for repeated observations can account for that dependence, but the registry record does not say whether such a method was used. It also does not report whether an intervention sequence was randomized or how any order effect was addressed. The record's description of a parallel model and its mention of participants potentially completing cohorts sequentially do not resolve those analysis details.

The comparison is non-randomized and unmasked. In general, random allocation can help balance measured and unmeasured participant characteristics across treatment groups, while masking can reduce some kinds of measurement or assessment bias. Neither protection is listed for this study. This does not establish that bias occurred, but it means the comparison should be interpreted with those design features in mind. The registry does not report adjustment methods intended to address them.

What do planning illustrations mean?

In general, sample-size planning asks how much information a study would need to detect a chosen effect under specified assumptions. The planning illustration described for this study uses a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It considers an effect defined as a stated fraction of the observed effect. These are planning assumptions, not evidence that the trial was designed or analyzed that way. The registry's sample-size justification is not reported. Such illustrations are not observed power and do not replace an estimate with an uncertainty interval.

The record's listed outcome and analysis counts do not supply a statistical model. It lists 6 outcome measures and 0 analyses. A reported outcome count indicates the breadth of registered measurement, not the number of statistically independent questions or the analysis strategy. In general, multiple outcomes and comparisons can raise multiplicity concerns: when many hypotheses are tested, the chance of at least one apparently notable result can increase. The registry record does not report a multiplicity adjustment or a hierarchy for interpreting outcomes.

Finally, the complete-data population and the stated data-collection difficulties matter to any analysis. In general, excluding incomplete measurements can alter an estimate if the availability of data is related to participant characteristics or the outcome. Statistical approaches can address missingness under specified assumptions, but those assumptions and methods must be described to assess their appropriateness. The registry record does not report imputation, a missing-data model, or a sensitivity analysis for the primary outcome.

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("Three Sessions of FastFES", "Three Sessions of Fast Walking")
n   <- c(12, 12)
m   <- c(0.058, 0.013)
sp  <- c(0.11, 0.2)
sd  <- sp      # posted standard deviations
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  Three Sessions of FastFES  12  0.058  0.110  -0.012  0.128
CARM  Three Sessions of Fast Walking  12  0.013  0.200  -0.114  0.140

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 6 outcome measures, including the primary MEP amplitude outcome and secondary outcomes involving change in peak anterior ground reaction force (AGRF) after training. It lists 0 analyses. The registry record does not report which outcomes were analyzed, how many comparisons were planned, or whether a formal hierarchy determined which findings would be treated as primary. A multiplicity adjustment is not reported in the registry record.

In general, evaluating multiple outcomes or comparisons creates more opportunities for chance findings. Adjustment methods can control aspects of that risk, while a prespecified hierarchy can distinguish confirmatory questions from exploratory ones. The registry record does not state whether either approach was used. The posted record therefore does not support a claim that the reported outcome set was adjusted for multiplicity.

For the primary endpoint, the analysis population is described as Cohort 2 participants who had complete data for the assessment. The record attributes incomplete data for some participants to issues with data collection during training sessions and stimulus artifact causing noise. It does not report how many primary-outcome observations were missing, whether the reasons differed across interventions, or whether missing values were imputed or otherwise handled. These details are not reported in the registry record.

In general, a complete-case analysis uses only participants with the needed observations. Its interpretation depends in part on why data are missing; if missingness is related to the outcome or participant characteristics, the analyzed group may not represent everyone eligible for measurement. The record does not report a missing-data assumption, sensitivity analysis, or comparison of participants with complete and incomplete assessments. A sample-size justification and a formal statistical analysis plan are also not reported in the registry record.

12. 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.

Most frequent non-serious adverse event terms

The registry lists serious adverse event counts separately for Cohort 1 FastFES training, Cohort 2 FastFES, and Cohort 2 fast walking. The at-risk counts for serious events are 2, 20, and 19, respectively; the corresponding serious event counts are 0, 0, and 0. Deaths are listed as 0 for each group. No top serious event terms are listed.

Other adverse event counts are also recorded: 0 among 2 at risk in Cohort 1, 0 among 20 at risk for Cohort 2 FastFES, and 1 among 20 at risk for Cohort 2 fast walking. These are the registry's group-specific counts, not evidence from a randomized safety comparison. In particular, the listed at-risk counts are not identical across all groups, and the study is non-randomized.

In general, a count of zero means no event of that category was recorded in the listed group; it does not establish that an event could never occur. The counts also do not, by themselves, establish whether an event was caused by an intervention. The registry record does not provide further detail about event definitions, observation duration, or attribution. Safety counts should therefore be read as descriptive registry entries, not as a causal comparison or a complete estimate of risk.

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

The study addresses a physiological question about gait rehabilitation after stroke: whether MEP amplitude, used as a measure of corticospinal excitability, changes differently after FastFES and fast walking. The endpoint is collected using TMS and EMG, and the primary comparison is described for Cohort 2 after 3 sessions of each intervention. This provides a defined measurement question, but numerical results are not reported in the registry record.

Without a reported effect estimate and its uncertainty, the record cannot establish the direction or size of a difference in mean change. It also cannot establish whether any observed difference would be precise, compatible with no difference, or practically meaningful. The absence of a listed analysis or numerical result should not be interpreted as proof of no effect or as evidence that the interventions are equivalent.

The design places limits on causal interpretation. Allocation is non-randomized, masking is none, and the registry does not describe an adjustment strategy. In general, observed differences in a non-randomized comparison may reflect intervention exposure as well as baseline differences, order, or other factors. The record does not provide enough information to judge how those possibilities were addressed.

The endpoint is a measure of corticospinal excitability, not a direct measure of walking performance or a patient-reported outcome. The registry also lists secondary outcomes concerning AGRF, but their numerical results are not reported in the registry record. Physiological measures can contribute to understanding rehabilitation, but an endpoint's statistical result alone would not establish a broad clinical benefit.

The primary population includes Cohort 2 participants with complete data, and data collection problems and stimulus artifact are reported as reasons for incomplete data. Together with the discrepancy between the enrollment field's 24 and the summary's 55 individuals, this means the available record leaves important questions about the analyzed population unanswered. The findings should be understood only within what the registry reports.

14. Why This Trial Matters Statistically

This study is statistically informative as an example of why design and outcome reporting matter alongside the choice of measurement. It asks a focused question about change in MEP amplitude after FastFES versus fast walking, with measurements at baseline, week 3, and week 6. The record defines the endpoint and the population with complete data, but does not report the numerical primary result or analysis method. Without those elements, readers cannot assess the estimated contrast or its precision.

The non-randomized allocation and lack of masking also deserve attention. Statistical comparisons do not remove design limitations by themselves. A clear account of allocation, intervention sequence, analysis population, repeated-measure handling, and adjustment would help readers judge how robust an estimate is. Those details are not reported in the registry record.

The record also illustrates the distinction between registered outcome measures, completed analyses, and reported results. It lists 6 outcomes and 0 analyses, while offering a description of the primary measure and noting incomplete data. That information helps identify what was intended to be measured and what data-quality challenges occurred, but it does not answer the primary statistical question.

Finally, the enrollment field and brief summary differ, and the registry does not reconcile the figures. Transparent clarification of the analyzed sample and the handling of incomplete assessments would be important for interpreting any eventual effect estimate. The value of the record is therefore in defining the study question and its limitations, not in supporting a conclusion about the comparative effect.

15. 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.

Several details needed to interpret the primary comparison are not reported in the registry record. Numerical MEP results, uncertainty estimates, and the statistical test or model are absent. The record also does not describe adjustment for covariates, handling of repeated measurements, treatment sequence, or a prespecified analysis plan. The listed analysis count is 0.

The non-randomized allocation and absence of masking limit the protection against group differences and assessment bias that randomization and masking can provide. The registry does not describe how participants were assigned to cohorts or whether the order of Cohort 2 interventions was controlled. Its parallel-model designation and its statement that participants could complete both cohorts sequentially are not reconciled in the record.

The enrollment field lists 24, whereas the brief summary describes 55 individuals. No explanation is given for the difference. The primary endpoint population is limited to Cohort 2 participants with complete data, and the record reports collection issues and stimulus artifact causing noise. The number of incomplete primary assessments, their distribution across interventions, and the missing-data methods are not reported in the registry record.

The primary endpoint is physiological and does not directly measure walking performance. The record lists secondary AGRF outcomes but does not give their numerical results. It also does not report a sample-size justification or multiplicity strategy. Together, these gaps make it impossible to assess the precision of the primary estimate, how missingness may affect it, or how the full set of outcomes was interpreted.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Stroke Gait Rehabilitation Using Functional Electrical Stimulation — NCT01668602.
• Registry record last updated 2021-03-10; status last verified 2021-02.
• Results first posted 2021-03-10.
• 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.

19. Record Summary

NCT01668602 is a completed, prospective interventional study sponsored by Emory University, listed for cerebrovascular accident. It is described as non-randomized, unmasked, and parallel. The study concerns FastFES, combining fast treadmill walking and functional electrical stimulation, and fast walking without FES.

The primary outcome is mean change in MEP amplitude in the transverse abdominal muscle, measured in mV and used as a measure of corticospinal excitability. The primary comparison is described for Cohort 2 after 3 sessions of each intervention, with assessments at baseline, week 3, and week 6. The primary analysis population consists of participants with complete data; collection issues and stimulus artifact are cited as reasons for incomplete data.

The enrollment field lists 24, while the brief summary describes 55 individuals. The registry record does not reconcile the figures. It lists 6 outcome measures and 0 analyses, and does not report numerical primary-outcome results, a statistical analysis plan, or a sample-size justification.