Electrical Stimulation for Critically Ill Post-Covid-19 Patients: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Electrical Stimulation for Critically Ill Post-Covid-19 Patients (NCT05198466), a randomized phase 2 study. The primary outcome is Gastrocnemius Muscle Endurance (Muscle Sustained Contraction) in Response to Electrical Stimulation.

2. Clinical Question

3. Trial Design

The registry identifies NCT05198466 as a phase 2, randomized, double-masked, parallel-group trial. Its title is Electrical Stimulation for Critically Ill Post-Covid-19 Patients, and the official title describes a proof-of-concept randomized controlled trial of electrical stimulation therapy for recovery of hospital-acquired weakness in critically ill COVID-19 patients. Baylor College of Medicine is listed as sponsor. The record lists COVID-19, muscle atrophy and muscle weakness as conditions.

The recorded enrollment is 19. The primary outcome summaries list 10 participants in Active E-Stim and 8 in Electrical Stimulation - Sham. The registry does not explain the relationship between these arm-level outcome counts and the enrollment figure, or state which participants were included in the outcome summaries. The status is COMPLETED. The recorded start date is 2021-08-18 and the primary completion date is 2022-08-18.

The study rationale describes prolonged bed rest and paralytic use during intensive care as circumstances associated with muscle loss and functional impairment. It presents lower-extremity electrical stimulation as a potentially practical option when conventional mobility programs are challenging for critically ill patients. The stated purpose is to assess feasibility and proof-of-concept effectiveness. These are aims, not findings.

Interpretation of the assigned groups is constrained by the intervention descriptions. Although the registry labels one group Active E-Stim and the other Electrical Stimulation - Sham, both descriptions say participants receive a sham electrical stimulation device for 1 hour daily for 4 weeks (phase II). The record does not clarify whether this wording is an error or accurately describes the devices used. It is therefore not possible to confidently characterize the treatment contrast from these descriptions alone.

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 Gastrocnemius Muscle Endurance (Muscle Sustained Contraction) in Response to Electrical Stimulation, measured over an average of 4 weeks (Phase II).

The primary endpoint is titled Gastrocnemius Muscle Endurance (Muscle Sustained Contraction) in Response to Electrical Stimulation. It is a continuous measure reported in miliVolts, with the registry identifying the summary parameter as the mean and the spread as the standard error. The timeframe is an average of 4 weeks (Phase II).

The endpoint description says gastrocnemius muscle endurance in response to 5 minutes of electrical stimulation therapy will be assessed using surface electromyography and a validated non-invasive device, identified as the Delsys Trino Wireless EMG System, MA, US. Surface electromyography records electrical activity associated with muscle contraction. In general, measuring the muscle response during stimulation can provide a physiological indicator related to sustained contraction and muscle endurance. It is not itself a direct measure of mobility, independence, symptoms, or recovery after discharge.

The registry describes the measure and its intended assessment, but the posted arm-level summaries alone do not show whether a difference between assigned groups is statistically distinguishable from sampling variation. No estimable two-arm comparison is reported. The endpoint should therefore be read as a physiological outcome with descriptive arm summaries, not as a demonstrated effect on broader functional outcomes.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry reports a continuous primary outcome summarized by a mean and standard error. It does not report an estimable comparison between the trial groups. The concepts below explain how such results are generally interpreted; they do not imply that a particular unreported analysis was performed.

What does a mean describe?

For a continuous measure, the mean is a summary of the observed values in a group. It gives a central value on the measurement scale, here miliVolts. A mean does not show the full distribution of individual measurements. Participants may have values close to the mean or spread widely around it, and that pattern cannot be recovered from the mean alone. The registry reports no individual-level outcome values or additional description of the distribution.

How is a standard error different from a standard deviation?

A standard error describes the uncertainty in an estimated mean, rather than the variability of individual observations. In general, it is used to show how precisely the mean has been estimated under the assumptions of the analysis. A standard deviation, by contrast, describes variation among observations. The registry identifies the reported spread as a standard error, so it should not be read as a range containing most individual participants’ measurements.

Standard errors for separate groups do not directly answer whether the group means differ. A comparative analysis estimates a contrast and quantifies its uncertainty. That uncertainty may be expressed with a confidence interval. In general, a confidence interval represents values for the underlying effect that are compatible with the data and the analysis assumptions. A narrow interval indicates greater precision than a wide interval, but neither guarantees that an estimate is unbiased or clinically important. No comparative confidence interval is reported in this registry record.

Why is a direct comparison needed?

Random allocation is intended to create groups that can be compared, on average, while reducing systematic differences in treatment assignment. It does not remove the need to report the actual comparison, its uncertainty, and the analysis population. A direct estimate might compare group means, or use another method specified by the analysis plan. The registry record does not report the method used for a comparative analysis, and it states that a two-arm comparison for this continuous endpoint is missing or not estimable.

A p-value, when reported, addresses how unusual data at least as incompatible with a specified null hypothesis would be under the model assumptions. It does not measure the probability that the null hypothesis is true, the size of an effect, or its clinical importance. Since no comparative p-value is posted, there is no reported hypothesis-test result to interpret. The absence of a p-value is not evidence of no difference.

What can arm summaries establish?

Arm-level means and standard errors support a descriptive account of the reported outcome summaries. They do not establish that a between-group difference is real, important, or attributable to the assigned stimulation. The interpretation also depends on what the named groups actually received, how outcomes were measured and handled, and who contributed data. The registry’s identical sham wording for both arm descriptions leaves the treatment contrast unclear. Details about outcome completeness and analysis populations are not reported in the registry record.

What does the design description add?

The trial is registered as randomized, double-masked and parallel. In general, randomization assigns participants to groups by chance, masking aims to reduce the influence of knowledge of assignment, and a parallel design follows separate groups under their assigned conditions. These labels describe design intentions; they do not verify how allocation, masking or follow-up operated in practice. Further operational details are not reported in the registry record.

The trial is identified as phase 2 and proof-of-concept. Those descriptions frame the study’s stated purpose, but they do not substitute for a prespecified statistical plan or a comparative result. The registry does not report a sample-size justification, a statistical analysis plan, an interim analysis plan, or a primary analysis population. These elements should not be inferred from the design label or the number of participants recorded.

How should planning illustrations be read?

In general, sample-size planning asks how many participants per arm would be needed to detect a chosen effect under stated assumptions. The registry’s planning assumptions specify a two-sided significance level of 0.05, equal allocation, a normal approximation, and target effects expressed as fractions of the observed effect. Such figures are planning illustrations, not observed power and not estimates of what this trial proved. No resulting sample-size values are reported in the registry record. Because the comparison is not estimable, planning based on an observed effect would also need cautious interpretation; it does not resolve the missing comparative analysis.

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("Active E-Stim", "Electrical Stimulation - Sham")
n   <- c(10, 8)
m   <- c(363.04, 359.55)
sp  <- c(1.56, 2.04)
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  Active E-Stim  10  363.040  4.933  359.511  366.569
CARM  Electrical Stimulation - Sham  8  359.550  5.770  354.726  364.374

11. Multiplicity, Missing Data and Analysis Populations

The registry reports 3 outcome measures and identifies Plantar Oxyhemoglobin as a secondary outcome. It reports 0 analyses. The information in the registry record does not provide a complete analysis of all listed outcomes, identify which measures were formally tested, or describe any adjustment for multiple comparisons. A multiplicity strategy is not reported in the registry record.

Multiplicity matters when several outcomes or hypotheses are examined. In general, the more opportunities there are to find an apparently notable result, the more important it is to interpret each result in light of the analysis plan and the number of comparisons. Without a stated testing strategy and full outcome results, it is not possible to assess how the reported findings relate to a prespecified hierarchy or adjustment procedure.

Missing outcome data and analysis populations are also not described. The record gives an enrollment figure and arm-level counts for the primary outcome summaries, but does not explain the difference between those figures, how missing measurements were handled, or whether all randomized participants were included in an analysis. It does not report reasons for unavailable outcomes, imputation methods, or sensitivity analyses. These details are not reported in the registry record.

These omissions limit assessment of selection bias and robustness. If measurements are unavailable for some participants, the way that missingness relates to outcome or group assignment can affect interpretation. General methods for handling missing data rely on assumptions, which should be stated and examined rather than presumed. The registry record does not provide the information needed to evaluate those assumptions for this trial.

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.

The registry’s adverse-event figures list 0 serious events among 10 participants at risk in Active E-Stim and 0 among 8 at risk in Electrical Stimulation - Sham. Other adverse events are also listed as 0 in both groups, and deaths are listed as 0 in both groups. No top serious-event terms are listed.

These are recorded counts for the groups and risk denominators stated in the registry. They mean that the posted record lists no events in these categories; they do not establish that risk is absent. With a small trial and no further information about adverse-event definitions, collection methods, follow-up completeness, or reporting thresholds, the figures cannot precisely characterize uncommon harms. The registry does not report additional detail about event severity, timing, relatedness, or exposure duration beyond the intervention description. Safety interpretation should remain limited to the recorded counts and the completeness of the available reporting.

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

The results establish that the registry posts arm-level summaries for the primary muscle-endurance measure: means of 363.0 miliVolts and 359.6 miliVolts, with standard errors of 1.56 and 2.04, respectively. They also establish that the registry lists no estimable two-arm comparison for this continuous endpoint and no analyses. The record therefore does not supply a comparative estimate with which to judge the direction, magnitude, or precision of a treatment effect.

The posted summaries do not establish that electrical stimulation improved or failed to improve gastrocnemius muscle endurance. Descriptive values from separate groups are not a substitute for a direct analysis. The reported absence of an estimable comparison must not be treated as evidence that the groups were equivalent, nor as evidence that they differed.

The clinical scope is also narrow. The primary outcome is a physiological measure obtained with surface electromyography in response to stimulation. It is not a direct measure of a participant’s ability to walk, perform daily activities, leave hospital, or maintain function after discharge. The record does not report results for such outcomes. Its stated interest in feasibility and proof-of-concept effectiveness does not itself demonstrate feasibility or effectiveness.

The trial’s group descriptions create further uncertainty: both state that a sham electrical stimulation device is used. The registry record does not clarify the treatment contrast. As a result, even an arm-level difference would need the assigned interventions to be understood before it could be attributed to active stimulation. The available information supports a cautious descriptive account, not a treatment conclusion.

Finally, a completed registry status indicates the recorded trial status, not that every planned analysis or outcome result is available. Missing comparative results, unreported analysis methods, and limited detail on missing data and analysis populations constrain what can be learned. The registry record does not report enough information to determine whether the unreported elements were not conducted, were not estimable, or were simply not entered.

14. Why This Trial Matters Statistically

This trial addresses a practical measurement and design question in a setting where conventional mobility programs may be challenging. The registry’s rationale focuses on muscle deconditioning among critically ill patients with COVID-19 and proposes lower-extremity electrical stimulation as a possible approach. A physiological endpoint such as gastrocnemius muscle endurance can help frame a focused proof-of-concept question, but its interpretation depends on transparent measurement and comparative analysis.

Statistically, the record illustrates the difference between reporting group summaries and answering a randomized-trial question. The means and standard errors describe each named group, but the key inferential quantity is a between-group comparison with uncertainty. That comparison is not estimable in the posted results. Without it, readers cannot assess how precisely the observed data distinguish among possible effects.

The record also shows why clear intervention descriptions matter. Randomization can support a causal comparison when the assigned treatments and analysis are sufficiently documented. Here, the Active E-Stim and sham group descriptions both refer to a sham device. That ambiguity complicates interpretation of the treatment contrast, independently of the missing statistical comparison.

Small proof-of-concept trials can provide useful early information, but their role should not be overstated. Planning illustrations based on an observed effect are not evidence of observed power, and arm-level summaries do not establish effectiveness. Complete outcome reporting, clear analysis populations, and a transparent statistical plan are important for distinguishing an inconclusive record from evidence of no effect or evidence of an effect. Those details are not reported in the registry record.

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.

The main limitation is that the registry reports no estimable two-arm comparison for the primary continuous endpoint and lists 0 analyses. The posted arm means and standard errors cannot replace that missing comparative result. No comparative confidence interval or p-value is reported, so the precision of any between-group effect cannot be assessed.

The intervention contrast is unclear because both arm descriptions state that participants receive a sham electrical stimulation device for 1 hour daily for 4 weeks (phase II). The registry does not clarify whether the description for Active E-Stim is inaccurate or whether both groups received the same type of device. This uncertainty limits interpretation of the trial’s randomized comparison.

The primary outcome summaries list 10 participants in Active E-Stim and 8 in Electrical Stimulation - Sham, while recorded enrollment is 19. The registry does not explain the outcome analysis population or the relationship between these figures. Reasons for missing or unavailable outcome values, methods for handling missing data, and sensitivity analyses are not reported in the registry record.

Further limitations include the absence of a reported statistical analysis plan, sample-size justification, interim analysis information, and multiplicity strategy. Although the registry lists 3 outcome measures and names Plantar Oxyhemoglobin as a secondary outcome, comprehensive results and analysis details are not reported. The adverse-event counts are recorded, but further detail on collection, follow-up, and event characterization is not available in the registry record.

Finally, the primary endpoint is a physiological measure. The record does not report results for broader functional outcomes that would directly describe mobility or daily activity. These limitations constrain both statistical and clinical interpretation.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Electrical Stimulation for Critically Ill Post-Covid-19 Patients — NCT05198466.
• Registry record last updated 2023-03-07; status last verified 2023-02.
• Results first posted 2023-01-18.
• 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

NCT05198466 is a completed phase 2 randomized, double-masked, parallel-group trial sponsored by Baylor College of Medicine. Its stated focus is electrical stimulation for recovery of hospital-acquired weakness in critically ill patients with COVID-19. Recorded enrollment is 19; the primary outcome summaries list 10 participants for Active E-Stim and 8 for Electrical Stimulation - Sham.

The primary endpoint is gastrocnemius muscle endurance in response to electrical stimulation, measured in miliVolts and summarized by means and standard errors at an average of 4 weeks (Phase II). The registry posts arm-level summaries but says a two-arm comparison is missing or not estimable, and lists 0 analyses. It also lists 0 serious events, 0 other adverse events, and 0 deaths in each arm.

Interpretation is limited by the absence of comparative results, unreported analysis and missing-data details, and arm descriptions that both refer to a sham device. The registry record does not establish a treatment effect.