NMES Efficacy on Patients With NBPP: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for NMES Efficacy on Patients With NBPP (NCT01999465), a randomized na study. The primary outcome is Change From Baseline in Upper Extremity Muscle Strength.

2. Clinical Question

The clinical question concerns whether adding standard electrical stimulation to the study’s home-use arrangement is associated with a different change in biceps strength than using a sham device. Both groups were part of the same program, and the registry describes parents as performing the device-based therapy at home. The posted primary outcome focuses on biceps strength; it does not by itself describe every aspect of arm function or movement.

The study description also mentions active range of motion as a goal, but the primary endpoint listed in the registry is change in upper extremity muscle strength. The record lists four outcome measures, while secondary outcome results are not posted. Consequently, the primary comparison can be interpreted on its own, but the available information does not support a broader conclusion about every intended functional outcome.

3. Trial Design

This was a randomized, parallel-group study with a triple-masking classification in the registry. The arms were a standard NMES device cohort and a sham NMES device cohort. The record does not identify which specific people were included in the triple-masking classification, so it is not possible to specify from the registry whether masking applied to participants, caregivers, outcome assessors, investigators, or another combination. The endpoint description does identify the occupational therapists as blinded.

The registry lists enrollment of 20 participants and a study status of completed. The study start is recorded as 2013-11, and the primary completion date is 2018-01-31. The phase is listed as NA. The record describes participants as newborns aged 3-9 months who were already involved in the University of Michigan Brachial Plexus program.

Parents were trained to administer the assigned device at home. The description specifies use for 30 minutes each day, with monthly follow-up appointments with research occupational therapists during the three month study period. The strength evaluation was scheduled at enrollment and at the 3-month follow-up clinic visit. The listed device interventions are standard NMES and sham NMES; further device-setting details are not reported in the registry record.

For the primary outcome, posted arm summaries include 9 participants in the Standard NMES Cohort and 5 in the Sham NMES Cohort. The endpoint description reports that one participant in the standard cohort and two in the sham cohort were lost to follow-up at 3 months. The registry does not describe the randomization sequence, allocation concealment, the rationale for the planned enrollment, or a detailed protocol for follow-up and treatment adherence. These omissions limit assessment of how the design was implemented beyond the features explicitly recorded.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: One in the Standard NMES cohort was lost of follow-up and two in the sham cohort were lost of follow-up at 3 months.

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 From Baseline in Upper Extremity Muscle Strength, measured over Baseline to 3-month..

The primary endpoint is change from baseline to 3-month follow-up in upper extremity muscle strength, assessed through biceps strength. An occupational therapist conducted the evaluation at enrollment and the 3-month clinic visit. The registry describes the assessor as one of two blinded occupational therapists.

Strength was graded using the British Medical Research Council (MRC) scale, which ranges from 0, described as the minimum score and not testable, through 5, described as the maximum score and normal strength. Higher scores indicate better strength. The registry also states that MRC grade 2 or higher is functional in terms of muscle power. This is a graded clinical assessment, rather than a direct measurement of force in physical units.

The posted endpoint summaries report a median of 1 and a full range from 0 to 5 in each cohort. The reported comparison uses a Wilcoxon (Mann-Whitney) test. Because the scale is ordinal, medians and rank-based comparisons can describe the distribution without requiring the score differences between adjacent grades to have equal meaning. However, a median and full range do not show how many participants had each score or how individual scores changed. The registry does not post a confidence interval for the between-group comparison.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a change in an ordinal muscle-strength grade. Ordinal measures have an order, but the distance between neighboring categories need not be equal. A move from one grade to the next cannot automatically be treated as the same amount of change everywhere on the scale. The MRC system is described as ranging from 0 to 5, with higher values representing better strength. Its ordered categories make it natural to report medians and to consider rank-based comparisons, while also making it important not to treat the scale as a precise continuous measure without justification.

What does a median and full range communicate?

The median identifies the central ordered value in a group’s observations. The full range gives the lowest and highest observed values, but does not show how observations are distributed between those endpoints. In this trial, the posted median is 1 in each cohort, and the full range is 0 to 5 in each cohort. Those summaries do not reveal the number of participants at each grade, whether values cluster near the median, or whether many participants had different changes that balance out in the summary.

The endpoint is titled as a change from baseline to 3-month follow-up, and the outcome description says the change in biceps MRC grade was examined. The registry does not provide individual baseline and follow-up scores or a fuller breakdown of change values. Without those details, readers cannot inspect the pattern of change within each cohort or assess whether the same summary arose from similar participant-level trajectories.

What does the Wilcoxon (Mann-Whitney) test assess?

The Wilcoxon (Mann-Whitney) test is a rank-based method for comparing observations between two independent groups. It orders the observations and evaluates whether values from one group tend to rank higher or lower than values from the other group. It avoids requiring a normal distribution for the raw outcome, which can be useful when the outcome is ordinal or its distribution is not well represented by a mean and standard deviation.

The test is not always simply a test of whether two medians differ. If the group distributions have different shapes or spreads, a rank-based result can reflect more than a location shift. The registry reports the method and a p-value of 0.40, but does not report a test statistic, confidence interval, or enough detail to inspect the shape of each group’s outcome distribution. The test result therefore cannot, by itself, establish the size or clinical importance of a difference.

Why are uncertainty intervals useful?

A confidence interval describes the uncertainty around an estimated effect under a specified statistical method. It can show whether the data are consistent with a narrow range of effects or with a much wider range. A p-value alone does not give this range. No confidence interval for the primary between-group effect is reported in the registry record, so the precision of an estimated difference is not directly available. The absence of an interval also means that readers cannot use the posted result to judge whether effects of particular sizes are compatible with the data.

For ordinal outcomes, an effect estimate could be expressed in several ways, each with a different interpretation and assumptions. The registry does not report an effect estimate beyond the arm summaries and p-value. It is therefore important not to infer a numerical between-group difference from the medians or to treat the shared full range as an estimate of equivalence.

How should the planning figures be understood?

Sample-size figures in the page are planning illustrations based on the observed effect, rather than a record of the trial’s original design justification. The stated assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation; the effect to detect is expressed as a stated fraction of the observed effect. Such calculations describe a hypothetical planning scenario under those assumptions. They are not observed power and do not show the probability that the completed study detected an effect.

The registry does not report the original sample-size justification or the assumptions used when the study was designed. Planning calculations based on an observed effect can be especially sensitive to how uncertain that observed effect is. They should not be interpreted as evidence that the original enrollment was adequate or inadequate, nor as a substitute for a confidence interval around the observed comparison.

What can and cannot be assessed from the design record?

Randomization is intended to create groups that are comparable on average with respect to factors that could influence outcomes. Its protection depends on implementation and on how participants are retained and analyzed. The registry identifies the study as randomized, parallel, and triple masked, but does not report the sequence-generation method, concealment procedures, or the specific parties covered by the masking classification. The endpoint description states that occupational therapists were blinded, but the record does not detail how masking was maintained or assessed.

The endpoint summaries include fewer participants than the enrolled total, and the record notes losses to follow-up in both cohorts. Missing observations can reduce precision and may affect comparability if missingness is related to group or outcome. The registry does not report an imputation method, a missing-data sensitivity analysis, or a clearly defined analysis population. These omissions make it difficult to determine whether the reported comparison preserves the randomized assignment or relies on only observed endpoint values.

10. Analyses Reported by the Sponsor

The registry reports the sponsor’s primary comparison using a Wilcoxon (Mann-Whitney) test, with a p-value of 0.40. It also reports a median of 1 and a full range from 0 to 5 for each cohort. The record does not report an independent recalculated effect estimate or p-value for comparison with that analysis. It therefore does not support a direct assessment of whether an independent calculation agrees with the sponsor’s result.

The reported test should be read alongside its outcome summaries and the available endpoint counts: 9 participants in the standard cohort and 5 in the sham cohort. The record also states that one standard-cohort participant and two sham-cohort participants were lost to follow-up at 3 months, but does not describe the analysis population or missing-data handling. These details matter when interpreting any test result because they determine which observations contribute to the comparison.

No discrepancy between a sponsor analysis and a recalculated analysis is identified in the registry record. That does not add an independent validation of the analysis; it means only that the record does not present a conflicting calculation. The sponsor’s reported analysis remains the available inferential result, and its precision cannot be judged fully without an effect estimate and confidence interval.

11. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures and reports two analyses. It posts no secondary outcome results. The primary endpoint is change from baseline to 3-month follow-up in upper extremity muscle strength. The study description also identifies active range of motion as a goal, but the record does not provide secondary results for that or the other listed outcome measures. Other endpoint comparison values are described as missing or not estimable in the registry record.

When a study examines multiple outcomes or performs multiple analyses, the chance of at least one apparently notable result can increase if no adjustment or prespecified hierarchy is used. This is a general statistical concern, not evidence that the result in this trial is misleading. The registry does not report a multiplicity plan, a hierarchy among outcomes, or whether any adjustment was used. It is therefore not possible to determine how the reported p-value fits into a broader family of planned tests.

The study enrolled 20 participants, but the primary endpoint summaries list 9 in the standard cohort and 5 in the sham cohort. The endpoint description reports one loss to follow-up in the standard cohort and two in the sham cohort at 3 months. The registry does not explain the difference between total enrollment and the endpoint counts, give a complete disposition of participants, or state whether missing observations were imputed, excluded, or handled by another method. It also does not report a sensitivity analysis to show how conclusions might change under alternative assumptions about missing outcomes.

The analysis population is not specified in enough detail to determine whether the comparison followed the randomized assignment for all participants or used only participants with observed endpoint values. The randomization method and analysis plan are also not reported in the registry record. These gaps limit assessment of both missing-data bias and the role of multiplicity. The posted primary result can be described, but it should not be treated as a complete account of all planned analyses or outcomes.

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 reports serious adverse events for 10 participants at risk in the Standard NMES Cohort and 7 in the Sham NMES Cohort. The serious adverse event count is 0 in each cohort. It also reports 0 other adverse events in each cohort, with 10 and 7 participants at risk, respectively. Deaths are reported as 0 in both cohorts. No serious adverse event terms are listed.

These figures describe what was recorded among the participants identified as at risk in each cohort. They do not establish that the risk of an adverse event is zero, and they do not show that the groups have identical safety profiles. A count of zero in a study with limited participant numbers can coexist with uncertainty about events that might occur in a larger group or under different observation conditions. The registry does not report detailed event definitions, observation time for safety outcomes, or further information about how adverse events were collected.

The safety counts are not identical to the primary endpoint analysis counts. The record does not explain that difference, so the endpoint and safety denominators should not be treated as interchangeable. The reported counts are best read as a description of recorded adverse events within the stated at-risk groups, rather than as a precise estimate of comparative risk.

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

The results establish that the registry contains a randomized comparison of standard and sham NMES and reports a primary strength outcome. In the posted summaries, both cohorts have a median of 1 and a full range from 0 to 5. The registry’s Wilcoxon (Mann-Whitney) test has a p-value of 0.40. These are the observed summaries and inferential result reported for the primary endpoint.

They do not establish that the two interventions have the same effect. A failure to find a statistically compelling difference is not proof of equivalence, and the registry does not report an equivalence margin or analysis. The same median and range can conceal different distributions of participant scores, and no detailed distribution or confidence interval is reported. The p-value alone does not tell how large a difference might remain compatible with the observations.

The result also cannot support a conclusion about every goal mentioned in the study description. Active range of motion is mentioned as a goal, but secondary outcome results are not posted. Nor does the primary strength result provide a complete picture of how participants used the affected arm in everyday activities. The primary endpoint measures biceps strength on an ordinal scale, not all dimensions of arm function.

Missing follow-up observations are relevant to interpretation. The record notes losses to follow-up in both cohorts, and the primary outcome summaries include 9 standard-cohort participants and 5 sham-cohort participants. The analysis population and missing-data approach are not reported. This makes the extent to which the posted comparison represents all randomized participants uncertain.

The study is informative as a recorded randomized comparison with a defined clinical measure and a reported rank-based analysis. Its result is limited by the lack of an effect interval, incomplete outcome reporting, and insufficient detail about missing data and analysis procedures. It does not establish a precise estimate of the difference between groups or resolve whether differences of meaningful size can be ruled out.

14. Why This Trial Matters Statistically

This trial illustrates why a test result should be considered together with outcome scale, descriptive summaries, precision, and participant flow. The primary endpoint uses an ordered clinical grading system, and the registry reports medians and full ranges rather than a mean and standard deviation. That presentation reflects the ordinal nature of the MRC grades, but it does not show the full distribution of participant scores.

The reported p-value of 0.40 is not a substitute for an effect estimate. Without a confidence interval or detailed score distribution, readers cannot determine how precisely the between-group difference has been estimated. Similar medians do not demonstrate that all participants changed similarly, and a non-significant test result is not an equivalence finding. These distinctions are central to interpreting clinical comparisons, particularly when the outcome is measured on a graded scale.

Participant flow also matters to statistical interpretation. The registry records enrollment of 20, while primary outcome summaries include 9 participants in the standard cohort and 5 in the sham cohort. Losses to follow-up are reported in both groups, but the analysis population and handling of missing data are not described. Without that information, the relationship between random assignment and the reported endpoint comparison is difficult to assess.

The record further demonstrates the difference between a trial’s original design justification and a planning illustration based on an observed effect. Such illustrations depend on their stated assumptions and are not observed power. Because the original sample-size rationale and multiplicity plan are not reported, the available results cannot answer every question about the study’s statistical design. These limitations do not erase the reported findings; they define how narrowly those findings should be interpreted.

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 registry record leaves several trial-specific uncertainties. It identifies the design as randomized and triple masked, but does not describe the randomization sequence, allocation concealment, or the parties included in the masking classification. The outcome description says the occupational therapists were blinded, but does not explain masking procedures. This limits evaluation of how the design features were implemented.

The primary endpoint summaries are available for 9 participants in the standard cohort and 5 in the sham cohort, while total enrollment is 20. The record reports one standard-cohort and two sham-cohort participants lost to follow-up at 3 months, but does not account for all participants between enrollment and the endpoint analysis. The analysis population, missing-data method, and sensitivity analyses are not reported. As a result, the potential influence of missing outcomes cannot be assessed from the registry alone.

The primary comparison is reported with a p-value but no confidence interval or between-group effect estimate. The median and range summaries do not show how scores are distributed, and participant-level baseline and follow-up values are not posted. That prevents a closer assessment of the magnitude and precision of the comparison or the pattern of change within each cohort.

The registry lists four outcome measures and two analyses, but posts no secondary results and does not report a multiplicity plan. The study description mentions active range of motion, yet the listed primary endpoint concerns muscle strength. The available record therefore does not show how all intended outcomes were measured, analyzed, or interpreted. The original sample-size justification and detailed statistical analysis plan are also not reported in the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: NMES Efficacy on Patients With NBPP — NCT01999465.
• Registry record last updated 2018-12-14; status last verified 2018-12.
• Results first posted 2018-12-14.
• 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

The registry describes a completed randomized, parallel-group study of standard versus sham NMES in infants aged 3-9 months with neonatal brachial plexus palsy. Enrollment was 20, and the study is classified as triple masked. Parents were trained to use the assigned device at home for 30 minutes each day, with monthly follow-up appointments during the three month study period.

The primary endpoint was change in biceps strength from baseline to 3-month follow-up, measured with the British Medical Research Council grading system. The posted summaries give a median of 1 and a full range of 0 to 5 in each cohort. The reported Wilcoxon (Mann-Whitney) p-value is 0.40. Primary endpoint counts are 9 in the standard cohort and 5 in the sham cohort, and the record notes losses to follow-up in both arms.

No confidence interval, detailed analysis population, or missing-data method is reported. Secondary outcome results and a multiplicity plan are not reported in the registry record. The safety record lists 0 serious adverse events, 0 other adverse events, and 0 deaths in each cohort.