Robotic Pedaling Therapy for Targeted Neural Plasticity: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Robotic Pedaling Therapy for Targeted Neural Plasticity (NCT03300258), a randomized na study. The primary outcome is Change in Six Minute Walk Test (6MWT) Distance.

2. Clinical Question

3. Trial Design

The registry describes a randomized, parallel-group study with no masking. Its stated focus was robotic pedaling therapy for targeted neural plasticity after stroke. The intended stroke comparison was robotic training versus duration-matched aerobic pedaling. In the robotic group, participants with stroke were to perform novel tasks on a robotic recumbent cycle; in the aerobic group, participants with stroke were to pedal for a duration matched to the robotic program.

The brief summary describes a pilot study and plans to enroll 40 adult stroke patients and 80 healthy controls. The registry lists enrollment as 44. These figures describe different parts of the record: the summary gives planned numbers, while the enrollment field gives the recorded overall enrollment. The record does not explain the difference or report the number assigned to each stroke group. It also describes healthy participants used for device testing and protocol development, including a healthy comparison group and additional pilot participants. Their roles should not be confused with the intended randomized comparison in patients with stroke.

The registry lists the study start as 2019-06-01 and primary completion as 2022-06-29. Its status is terminated. The record does not explain why the study was terminated or state whether all intended activities were completed. It lists robotic therapy and aerobic therapy as device interventions.

Planned assessments included behavioral measures and functional magnetic resonance imaging, with scans before and after training described in the brief summary. The listed secondary outcomes include brain activity, Timed Up-and-Go, self-selected and fastest comfortable walking speeds, and center-of-pressure characteristics. The record does not report results for these measures. It also does not report the actual treatment duration, adherence, or participant flow through the randomized comparison.

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: Original study plan required re-evaluation and the decision was made to pivot to developing tests and exercises on healthy population. A clinical trial was not conducted.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Healthy Pilot Group participants were enrolled and the study team learned that the protocol was insufficient to test the hypothesis. No data were collected for this measure.

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 Six Minute Walk Test (6MWT) Distance, measured over Baseline and at 5 weeks.

The primary endpoint is change in Six Minute Walk Test distance, with assessments described at baseline and at 5 weeks. The registry characterizes the test as a series of laps along a 30 m straight path in a level hallway. Distance covered during a timed walk is used as a measure of walking capacity: it records how far a participant can walk under the test conditions. In general, a change from baseline can describe whether measured walking distance differs after a period of training, while a comparison between groups can help distinguish changes associated with each assigned program.

For a randomized comparison, the key statistical quantity would ordinarily be the difference in change between the robotic and aerobic groups. That comparison needs observed outcome data and a clearly specified analysis population and method. The registry record reports neither a numerical result nor a group-level comparison. Instead, it states that Healthy Pilot Group participants were enrolled and that the study team found the protocol insufficient to test the hypothesis; no data were collected for this measure. Thus, although the endpoint and assessment times are named, there is no observed primary-outcome change to interpret.

The endpoint’s stated population also warrants care in reading the record. The study’s overall focus was stroke recovery, but the primary-outcome description attributes the decision not to collect the measure to the healthy pilot group. The record does not clarify how that population description relates to the planned stroke-group comparison.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies a randomized allocation, parallel model, and no masking. In general, random allocation is intended to make treatment groups comparable, on average, with respect to measured and unmeasured factors at the point of assignment. A parallel design assigns participants to a group and compares outcomes across groups rather than having every participant receive each intervention in sequence. These design features support a planned comparison, but they do not by themselves show that allocation occurred, that groups were balanced, or that the outcome data were analyzed. The record does not describe the randomization procedure or allocation concealment.

What would the primary comparison estimate?

The named endpoint is change in Six Minute Walk Test distance between baseline and 5 weeks. For the intended clinical comparison, an analysis might estimate the change in each group and then compare those changes, or use another prespecified method that accounts for baseline measurements. In general, the choice of method affects the exact interpretation and precision of the estimate. The registry does not report the statistical model, the contrast definition, or whether the analysis was intended to adjust for baseline values. Because the endpoint data were not collected, none of these possible approaches can be evaluated against observed results.

The registry’s endpoint description identifies a simple series of laps along a 30 m straight path in a level hallway. It does not report test procedures beyond that description, such as assessor training, standardized encouragement, handling of interruptions, or rules for invalid tests. Such details can matter for reproducibility and measurement consistency. Their absence from the record does not prove they were absent from the protocol; it means they are not reported in the registry record.

What do estimates and uncertainty usually convey?

In general, an effect estimate gives the magnitude and direction of a comparison on the outcome’s scale. A confidence interval conveys uncertainty around that estimate; a narrower interval generally indicates greater precision under the model, while a wider interval indicates less precision. A p-value addresses compatibility with a null hypothesis under specified assumptions and is not itself a measure of clinical importance or the probability that a hypothesis is true. These concepts require an estimate and analysis. No estimate, interval, or p-value for the primary outcome is reported, so they cannot be used to characterize this study’s primary result.

For outcomes measured more than once, the analysis also depends on how repeated observations are handled. General approaches can compare changes, model measurements over time, or use baseline values in an adjusted comparison. The methods should align with the research question and measurement schedule. Here, baseline and 5 weeks are named for the primary endpoint, but the registry does not report an analysis plan specifying how those observations would have been combined.

How should the planning assumptions be read?

The record describes a sample-size planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It also says the effect to detect is a stated fraction of the observed effect. These are planning assumptions, not results from the randomized comparison. A sample-size calculation estimates how many participants a hypothetical or planned study might require under its assumptions; it does not show how much power the completed study had, and it cannot replace an observed effect estimate.

That distinction is especially important in this record because no primary-outcome data were collected and no primary comparison is reported. Without a reported observed effect for the endpoint, a planning illustration tied to an observed effect does not supply evidence about the treatment contrast. The registry also does not report the original sample-size justification or explain whether the planning illustration matches the protocol’s design. Any sample-size figure should therefore be read only as a planning scenario, not as an observed property of the trial or a result.

Why might outcome distributions affect analysis?

As a general statistical matter, methods based on a normal approximation make assumptions about the behavior of estimates or errors. If outcome variability differs substantially from those assumptions, the resulting uncertainty estimates may be inaccurate. For count outcomes, over-dispersion means that variability exceeds what a simpler count model expects; methods that account for it can yield more appropriate standard errors and intervals. These are general considerations, not claims about this trial. The registry does not report a distributional assessment, over-dispersion, or a model choice for the listed outcomes.

For a walking-distance endpoint, investigators may consider the scale and distribution of the measured values, baseline-to-follow-up association, and the number of observations available. A model can be statistically well specified yet yield a highly uncertain result when data are sparse, and a larger sample cannot compensate for a measure that was not collected. Here, no endpoint values are reported, so distributional checks, model diagnostics, and precision assessments cannot be made.

The registry lists 0 analyses. This does not identify a particular statistical method that was used, nor does it establish whether analyses were conducted outside the posted record. It means no analysis is described in the registry record. Details such as the intended estimand, handling of protocol deviations, covariate adjustment, missing-data procedures, and sensitivity analyses are not reported in the registry record. Consequently, the design labels and planning assumptions should not be mistaken for a full statistical analysis plan or for evidence that the planned comparison was carried out.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 12 outcome measures, including the primary Six Minute Walk Test and secondary measures of brain activity, mobility, walking speed, and center-of-pressure characteristics. When several outcomes or comparisons are assessed, the chance of at least one apparently unusual result can increase if each is tested separately without accounting for multiplicity. In general, investigators may prespecify a primary endpoint, use a hierarchy, or apply an adjustment, depending on the scientific aims. The registry record does not report a multiplicity strategy or a detailed testing hierarchy beyond naming a primary outcome.

The record lists 0 analyses and does not report numerical results for the primary or secondary outcomes. It therefore offers no set of inferential tests on which to assess multiplicity, and no adjustment method can be identified. A list of outcomes alone does not show that each was collected, tested, or used to support a conclusion.

For the primary endpoint, the registry says no data were collected because the team found the protocol insufficient to test the hypothesis. This is not ordinary participant-level missingness in a measure that was collected for some participants but absent for others; the record describes the measure as not collected. It does not report whether other outcomes had incomplete observations, why any such observations might be missing, or how missing values were handled.

The registry does not report analysis populations, such as which participants were included in an intention-to-treat or per-protocol analysis. It also does not report participant flow by randomized group, exclusions, or the number with completed follow-up. These omissions limit assessment of how closely any analysis might reflect the randomized design. No interim-analysis plan or stopping rule is reported in the registry record.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The registry lists one adverse-event group, Non-Stroke Pilot Group, with 44 participants at risk. It records 0 participants affected by serious adverse events, 0 affected by other adverse events, and 0 deaths for that group. No serious adverse-event terms are listed.

These figures are a count as recorded for the named group. They should not be read as a complete safety result for every participant described in the study summary or for the planned randomized stroke groups: the registry does not list those groups in the adverse-event figures. The record also does not provide event rates over time, definitions of adverse events, exposure duration, or details of how events were collected. A recorded zero means no events are entered for the specified category and group; it does not establish that no events occurred in populations or periods not covered by that entry.

The study’s status is terminated, but the registry does not explain the reason. The adverse-event figures do not by themselves explain termination or establish a safety comparison between robotic and aerobic therapy. They are descriptive entries for the group and categories named in the record, not an analyzed comparison of risks.

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

The record establishes that the study was registered as a randomized, parallel-group comparison of robotic training and duration-matched aerobic pedaling, with no masking. It identifies a primary outcome, Six Minute Walk Test distance, assessed at baseline and at 5 weeks. It also describes a broader research aim involving behavioral measures and functional magnetic resonance imaging. These details clarify the intended question and the planned framework for studying it.

The record does not establish whether robotic training produced a larger, smaller, or similar change in walking distance compared with aerobic pedaling. The primary outcome description states that the measure was not collected because the protocol was considered insufficient to test the hypothesis. There is no reported estimate, confidence interval, or p-value for that outcome. No effect size or precision can therefore be inferred from the primary endpoint.

This absence of a primary comparison is different from a finding that the interventions had no difference. A null or inconclusive statistical result would require collected data and an analysis, with uncertainty characterized. In this case the primary measure has no recorded data, so the question remains unanswered by the posted primary outcome. The same caution applies to the secondary outcomes: their names and intended role do not substitute for results.

The record also does not clarify how many participants entered each planned group or how many completed the intended training and assessments. Total enrollment is listed as 44, while the brief summary describes plans for 40 stroke patients and healthy controls. The endpoint description refers to Healthy Pilot Group participants. Without a participant flow account, those details cannot be reconciled into a clear analysis population for the primary clinical comparison.

In general, a pilot study can inform whether procedures and measures are feasible, as well as help refine a later study. Here, the registry specifically reports that the team judged the protocol insufficient to test the hypothesis for the primary measure. The record does not describe the particular protocol problem or its consequences beyond the absence of data for that measure. Thus, the most defensible reading is that the registry documents a study intention and a limitation in the primary endpoint, rather than an estimate of comparative effectiveness.

13. Why This Trial Matters Statistically

This record illustrates why the existence of a registered design does not guarantee that a primary statistical question can be answered. The registry names a randomized comparison and a clinically interpretable endpoint, but also states that the outcome was not collected because the protocol was insufficient to test the hypothesis. Without the measurement, randomization cannot produce a primary treatment-effect estimate. Study design, measurement feasibility, and analysis are linked: a planned contrast is informative only if the outcome can be collected in the intended population and analyzed under a clear plan.

The record also highlights the importance of distinguishing study populations. The intended clinical comparison concerns adults with stroke, while the primary endpoint description attributes the lack of measurement to Healthy Pilot Group participants. The brief summary includes several healthy-control and pilot activities, and the total enrollment field does not describe group-specific enrollment. Clear reporting of which population was assessed for each outcome is essential for interpreting any result.

For biostatistical interpretation, the absence of estimates is itself a meaningful boundary. It prevents claims about magnitude, direction, and precision, and it prevents a conclusion that a null result was observed. A planning illustration based on an observed effect cannot bridge that gap. Planning calculations can help describe assumptions for a future comparison, but they are not evidence from participants and are not observed power.

Finally, the record makes visible the value of reporting analysis populations, outcome completion, and reasons for termination. Those details help readers understand whether a study reached its intended comparison and how much weight to place on recorded safety and outcome information. Their absence does not establish what happened, but it limits statistical evaluation. The key lesson is to separate a registered question, a collected outcome, an analysis, and an interpretable result; they are not interchangeable.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The primary limitation is that the registry explicitly reports no data for the Six Minute Walk Test. The study therefore has no reported primary-outcome estimate or comparison between the planned stroke groups. The stated reason is that Healthy Pilot Group participants were enrolled and the team judged the protocol insufficient to test the hypothesis, but the specific insufficiency is not described. This makes it difficult to assess whether the issue concerned the measure, the population, the intervention procedures, or another aspect of the protocol.

The record contains descriptions of planned populations and an overall enrollment of 44, but does not report group-specific enrollment or participant flow. The brief summary’s plan for stroke patients and healthy controls does not on its own establish how many were enrolled, randomized, treated, or assessed in each group. The primary outcome’s reference to healthy pilot participants adds uncertainty about the relationship between the planned clinical comparison and the outcome record.

The registry does not report treatment adherence, intervention exposure, outcome completion for measures other than the primary endpoint, or analysis populations. It also does not give the statistical analysis plan, the handling of protocol deviations, or methods for missing data. The absence of those details limits assessment of bias and reproducibility; it should not be treated as proof that no such procedures existed outside the registry.

The study is marked terminated, but the reason is not reported in the registry record. The adverse-event entry is limited to the Non-Stroke Pilot Group and does not provide a comparative safety analysis for the planned stroke groups. Finally, the record provides no numerical primary or secondary results, so no conclusions about effect magnitude, variability, or statistical uncertainty are possible.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Robotic Pedaling Therapy for Targeted Neural Plasticity — NCT03300258.
• Registry record last updated 2023-10-05; status last verified 2023-10.
• Results first posted 2023-10-05.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

The registry describes NCT03300258, Robotic Pedaling Therapy for Targeted Neural Plasticity, sponsored by the University of Wisconsin, Madison. It lists a randomized, unmasked, parallel design, enrollment of 44, and a terminated status. The study start is recorded as 2019-06-01, with primary completion on 2022-06-29.

The planned clinical comparison was robotic pedaling therapy versus duration-matched aerobic pedaling in participants with stroke. The primary outcome was change in Six Minute Walk Test distance at baseline and at 5 weeks. The registry states that no data were collected for this measure because the protocol was judged insufficient to test the hypothesis. It lists 12 outcome measures and 0 analyses, with no reported numerical primary-outcome result.

The adverse-event record lists the Non-Stroke Pilot Group, with 44 at risk and 0 serious adverse events, 0 other adverse events, and 0 deaths recorded. The record does not explain termination or report a safety comparison for the planned stroke groups. Overall, it documents the study’s intended design and outcomes but does not provide an analyzed primary comparison.