This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for The General Use of Robots in Stroke Recovery: the Anklebot (NCT02249832), a na na study. The primary outcome is Mean Change From Baseline in Gait Speed (m/Sec) on the 10 Meter Walk Test at Comfortable Pace..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02249832 |
| Phase | NA |
| Condition | Stroke |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 55 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Northwell Health |
| Results posted | Yes |
2. Clinical Question
Population
People with stroke were enrolled in a study whose stated purpose concerned chronic hemiparetic gait. Participants were classified by average admission gait speed on the comfortable-pace 10 Meter Walk Test: low, moderate, or high functioning. The registry record lists enrollment of 55.
Intervention
All participants received seated robot-assisted ankle therapy using the MIT anklebot. The registry describes eighteen 1 hour sessions, scheduled 3x/week for 6 weeks. The study purpose was to assess isolated robot-assisted training of the ankle joint.
Comparator
The record describes a single-group study, not a randomized comparison. It does not list a separate control group or a like-for-like comparator. The gait-speed categories are participant strata, not treatment arms receiving different interventions.
Primary question
The primary outcome concerns mean change in comfortable-pace gait speed on the 10 Meter Walk Test. The record describes comparing gait speeds across the three baseline-function strata at baseline, discharge at week 6, and follow-up at overall week 18. Numerical results for those comparisons are not reported in the registry record.
3. Trial Design
This completed study is recorded as a single-group intervention study with enrollment of 55. The intervention was seated robot-assisted ankle therapy, described as a device-based treatment. All participants received the therapy; the registry does not describe a randomized allocation or a separate untreated or active comparison group. Allocation and phase are listed as NA, and masking is listed as none.
The treatment schedule was eighteen 1 hour sessions, 3x/week for 6 weeks. The listed assessment period begins at baseline, includes discharge at week 6, and extends to a 3 month follow-up, described as overall week 18. The record gives start as 2013-06, primary completion as 2019-02, and status as completed.
Participants were stratified using average admission gait speed on the comfortable-pace 10 Meter Walk Test. The described categories were low functioning, below 0.4 m/sec; moderate functioning, 0.4 m/sec-0.8 m/sec; and high functioning, above 0.8 m/sec. These are baseline-function groups, not randomized study arms. Because each group received the same intervention, comparisons between them describe outcomes across baseline gait-speed strata rather than treatment effects against a control.
The registry does not report the rationale for the enrollment target, a protocol-defined statistical analysis plan, or whether additional analyses were prespecified. The precise method for comparing the strata and timepoints is not reported in the registry record. Consequently, the design description supports understanding the treatment schedule and measurement plan, but not a detailed reconstruction of how the primary analysis was conducted.
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: All participants received eighteen sessions of seated anklebot training. Upon analysis, subjects were stratified based on average admission gait speed on the 10 Meter Walk Test at comfortable pace according to well standardized gait speed performance groups: low (\<0.4m/sec), moderate (0.4m/sec-0.8m/sec) and high (\>0.8m/sec) functioning.
Overall Study
| Stage | Seated Robotic Ankle Therapy |
|---|---|
| STARTED | 55 |
| COMPLETED | 42 |
| NOT COMPLETED | 13 |
Reasons for not completing this period:
| Reason | Seated Robotic Ankle Therapy |
|---|---|
| Withdrawal by Subject | 3 |
| Lost to Follow-up | 10 |
Analysis population for the primary outcome, as defined in the registry: Subjects were stratified according to clinically established gait speed impairment levels based on average admission gait speed on the 10 Meter Walk Test at comfortable pace.
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.
| Characteristic | Unit | Seated Robotic Ankle Therapy |
|---|---|---|
| Participants analysed | 55 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 33 |
| Age, Categorical: >=65 years | Participants | 22 |
| Sex: Female, Male: Female | Participants | 18 |
| Sex: Female, Male: Male | Participants | 37 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 8 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 6 |
| Race (NIH/OMB): White | Participants | 40 |
| Race (NIH/OMB): More than one race | Participants | 1 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | participants | 55 |
6. Primary Endpoint
The registry lists the primary outcome as Mean Change From Baseline in Gait Speed (m/Sec) on the 10 Meter Walk Test at Comfortable Pace., measured over baseline, discharge (week 6), 3 month FU (overall week 18).
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Error |
| Unit | m/sec |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is described as mean change from baseline in comfortable-pace gait speed on the 10 Meter Walk Test, measured in m/sec. The test records the time or speed associated with walking a set distance; expressing the result as speed gives a continuous measure of walking performance. The registry identifies measurements at baseline, discharge at week 6, and 3 month follow-up at overall week 18.
Gait speed is relevant to the study’s stated question because the purpose was to assess whether isolated robot-assisted ankle training improves chronic hemiparetic gait after stroke. The baseline gait-speed categories also describe different starting levels of walking performance, allowing the registry’s stated analysis to compare outcomes across low, moderate, and high functioning groups.
There is an important reporting distinction: the endpoint title describes change from baseline, while the detailed description says mean gait speeds were compared across the three groups at the three timepoints. The registry does not provide the numerical estimates or fully specify the contrast used to represent change. It therefore does not establish from the record alone whether the reported analysis focused on within-group change, between-group differences at each timepoint, or another comparison. The primary outcome values are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies the outcome of interest and the assessment schedule, but does not report numerical primary outcome results. There is therefore no posted estimate of mean gait-speed change, no estimate of differences across the baseline-function groups, and no measure of uncertainty for those outcomes in the registry record. The direction, size, and precision of the primary result cannot be interpreted from the record.
The study’s single-group structure matters for interpretation. Participants all received seated robot-assisted ankle therapy, while low, moderate, and high gait-speed categories were formed from baseline performance. Comparing outcomes across those categories can describe how results vary with starting gait speed, but it is not a randomized comparison of therapy with no therapy or with another treatment. Differences over time cannot, on this design description alone, be separated from other explanations for change.
The primary outcome title refers to change from baseline, whereas the detailed description refers to comparing mean gait speeds among the strata at baseline, discharge, and follow-up. Those descriptions do not specify the precise effect estimate or statistical contrast. A change score, a comparison at a follow-up timepoint, and a comparison of trajectories answer related but distinct questions. The registry does not report enough analysis detail to determine which interpretation is appropriate.
For a continuous outcome, an estimate should be read alongside its uncertainty. A confidence interval, when reported, describes a range of values compatible with the data and the analysis assumptions; it does not guarantee that the true value lies within that range. The record does not give a confidence interval or standard error for the primary outcome results. Although the endpoint lists standard error as its dispersion measure, no corresponding outcome values are reported.
The registry lists enrollment of 55 and records 55 at risk for each of the safety counts. Enrollment should not be mistaken for the number assessed at every outcome timepoint: the number contributing to each gait-speed analysis is not reported in the registry record. Missing follow-up results, if any, cannot be assessed from the information recorded.
The posted safety counts are separate from the gait-speed efficacy outcome. The record reports 1 serious adverse event among 55 at risk, 2 other adverse events among 55 at risk, and 0 deaths. These counts describe recorded events in the treated group; they do not provide a comparative risk estimate because no control group is described. The record also lists worsening baseline ankle pain as a serious adverse event term at 1.8%. These safety entries should not be used to infer the primary gait-speed result.
Planning calculations based on an observed effect are described as illustrations, not as the original trial design. Such calculations do not show the power achieved by the completed study. Their stated two-arm equal-allocation assumption also does not match the registry’s single-group design. Without reported primary outcome estimates and analysis details, neither the effect nor its precision can be evaluated.
9. Statistical Methods Explained
The primary measure is continuous: gait speed is recorded in m/sec, and the endpoint is described as a mean. A mean gives the arithmetic average of the measured values within the group being analyzed. It can be useful for describing a group’s typical level, but it does not show how widely individual observations vary. That is why a measure of dispersion or uncertainty is important alongside a mean.
What does the standard error describe?
The endpoint identifies standard error as its dispersion measure. In general, a standard error describes the precision of an estimated quantity, such as a mean, under the statistical model used. It is not the same as the standard deviation, which describes variation among individual observations. A smaller standard error generally indicates a more precise estimate, but precision also depends on the analysis and the observations included. The registry record does not report numerical standard errors for the primary outcome.
A confidence interval is another way to express uncertainty around an estimate. In general, it gives a range of values compatible with the observed data under stated assumptions and a specified procedure. A narrow interval indicates greater precision than a wide interval, all else being equal. Confidence intervals are not reported for the primary outcome in the registry record, and the confidence level and interval method are not reported there either.
What comparison is being described?
The endpoint title says mean change from baseline, while the descriptive text says mean gait speeds were compared across low, moderate, and high baseline-function groups at baseline, discharge, and follow-up. These formulations are not interchangeable. A mean change compares a later measurement with baseline; a comparison of group means at a particular timepoint compares the groups at that time; and a comparison of change across groups asks whether the amount of change differs by baseline category. The record does not identify the exact primary contrast or provide the analysis procedure.
In general, repeated measurements from the same participant are correlated: a participant’s measurements over time are not independent observations. An analysis of measurements at multiple timepoints should account for that dependence when estimating uncertainty. The registry does not report whether a repeated-measures model, separate timepoint analyses, or another approach was used. The analysis model and its assumptions are not reported in the registry record.
Why does baseline stratification need careful reading?
The three groups were defined using average admission gait speed on the same comfortable-pace walking test that supplies the outcome. In general, grouping participants by a baseline measurement can make later group comparisons sensitive to starting values and to measurement variability. Participants in different baseline categories may have different room for observed change, and random variation in the baseline measure can affect change scores. This is a general statistical consideration, not a claim about what occurred in this study. The record does not report analyses addressing baseline adjustment or regression to the mean.
The listed categories use cut points below 0.4 m/sec, from 0.4 m/sec to 0.8 m/sec, and above 0.8 m/sec. The record calls these clinically established gait-speed performance groups, but does not identify the source or further explain how borderline values were handled. No assumptions about category assignment beyond the stated cut points can be made.
What can planning calculations tell the reader?
In general, sample-size planning depends on the effect a study is designed to detect, the variability of the outcome, the chosen significance level, the allocation, and the analysis method. The registry’s planning assumptions describe illustrations based on a fraction of the observed effect, a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Those are planning illustrations, not evidence that the completed study had a particular power. The two-arm, equal-allocation assumption does not correspond to the described single-group trial, so those calculations should not be read as a reconstruction of its design.
Over-dispersion is relevant in statistical settings where observed variability exceeds what a model assumes; if ignored, uncertainty can be understated and tests can be poorly calibrated. This trial’s primary outcome is a continuous gait-speed measure, and the record does not report an over-dispersion analysis or suggest that such a model was used. No claim about over-dispersion in these data can be made from the registry record.
More generally, statistical significance and clinical importance are different concepts. A test result evaluates compatibility with a null hypothesis under assumptions; an effect estimate describes the magnitude and direction of an outcome; and an uncertainty interval indicates precision. None of these primary-result quantities is reported in the registry record. The statistical test, model specification, handling of covariates, and decision threshold for the primary analysis are also not reported. Consequently, the stated endpoint and schedule can be explained, but the numerical findings and their inferential basis cannot be reconstructed.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 3 outcome measures and 3 analyses. The primary measure is comfortable-pace gait speed on the 10 Meter Walk Test. The listed secondary measures are change in fast-pace gait speed on the 10 Meter Walk Test and change in distance walked on the 6 Minute Walk Test at comfortable pace. The record does not report whether these outcomes were tested as a family, whether a multiplicity adjustment was used, or how the primary and secondary analyses were prioritized. A multiplicity procedure and its rationale are not reported in the registry record.
Multiplicity matters when several outcomes, timepoints, groups, or contrasts are examined: the chance of at least one apparently notable result can increase as the number of tests grows. In general, an adjustment can control a chosen error rate, but may also affect precision or power. This is a general statistical consideration, not evidence that a particular error occurred in this study. The exact number of statistical tests cannot be inferred merely from the listed outcome and analysis counts.
The record identifies baseline, discharge at week 6, and follow-up at overall week 18, but does not report the number of participants contributing outcome data at each timepoint. Reasons for missing measurements, the method used to handle missing data, and any sensitivity analyses are not reported in the registry record. The analysis population, including whether analyses followed an intention-to-treat principle or used another population definition, is also not reported. These omissions limit assessment of possible attrition and of how the outcome estimates were constructed.
The registry does not report a complete statistical analysis plan, including prespecification of contrasts or correction for multiple comparisons. It is therefore not possible to determine whether reported analyses, if any, followed a prespecified hierarchy.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Seated Robotic Ankle Therapy | 1 | 55 | 1.8% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Seated Robotic Ankle Therapy | 0 of 55 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Seated Robotic Ankle Therapy | 2 of 55 |
Most frequent serious adverse event terms
| Event term | Organ system | Seated Robotic Ankle Therapy |
|---|---|---|
| worsening baseline ankle pain | Musculoskeletal and connective tissue disorders | 1 of 55 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Seated Robotic Ankle Therapy |
|---|---|---|
| neuropathic pain | Nervous system disorders | 1 of 55 |
| depression | Psychiatric disorders | 1 of 55 |
Serious events with the highest arm-level rate: worsening baseline ankle pain (1.8%).
The registry reports safety counts for the seated robotic ankle therapy group. Serious adverse events were recorded for 1 of 55 at risk. Other adverse events were recorded for 2 of 55 at risk, and deaths were recorded as 0. The listed serious adverse event term is worsening baseline ankle pain, reported as 1.8%.
These counts are descriptive. The record does not provide a separate control group, so the figures do not estimate how event frequency compares with an alternative treatment or with no intervention. Counts also do not by themselves establish whether an event was caused by the therapy. The adverse-event definitions, surveillance details, and attribution procedures are not reported in the registry record.
The phrase “at risk” identifies the denominator used for the safety entries; it should not be assumed to be the denominator for every gait-speed assessment. The record does not report outcome-specific follow-up counts. Serious and other adverse events are distinct categories in the registry, and the counts should not be combined. No further inference about comparative safety or the timing of events is supported by the reported entries.
12. What the Result Does, and Does Not, Mean
The registry record describes a completed, single-group study of seated robot-assisted ankle therapy after stroke. It gives the treatment schedule, gait-speed assessment points, and baseline gait-speed categories. It does not report numerical results for the primary gait-speed endpoint. Accordingly, the direction and size of the observed primary outcome, and how precisely it was estimated, are not reported in the registry record.
The design can describe what happened to measured gait speed among participants receiving the intervention and how measurements were considered across baseline-function strata. It cannot, without a comparison group, isolate the effect of the intervention from other explanations for changes over time. In general, changes may also reflect factors such as participants’ natural course, repeated testing, or other care; the record does not say whether or how these possibilities were addressed.
The low, moderate, and high categories represent baseline gait-speed groups, not randomized alternatives. Any differences among those groups could reflect their different starting gait speeds or other differences between participants. The registry does not report adjusted estimates or enough analysis detail to determine how baseline differences were handled.
The safety record includes 1 serious adverse event, 2 other adverse events, and 0 deaths among the stated risk groups. Those entries are descriptive and have no comparative control-group estimate. They do not answer the primary question about gait-speed change.
Planning calculations based on an observed effect are illustrations rather than observed power or proof that the study was adequately sized for its stated question. The assumptions describe equal allocation between two arms, whereas the trial is recorded as a single-group study. Without primary estimates, uncertainty intervals, analysis details, and outcome-specific follow-up information, the record does not support a conclusion about the magnitude, precision, or causal interpretation of gait-speed change.
13. Why This Trial Matters Statistically
This study is statistically notable for the distinction between a treatment evaluation and a description of change within a treated group. The registry records a single-group design, with participants stratified by admission gait speed rather than assigned to different treatments. That distinction determines what comparisons can mean: group differences describe variation across baseline-function categories, not randomized treatment contrasts.
The endpoint also illustrates why precise definition of an estimand matters. The title refers to mean change from baseline, while the detailed description refers to comparing mean gait speeds across strata at multiple timepoints. Those descriptions could lead to different estimates and interpretations. Without a specified contrast, model, and numerical result, readers cannot tell which question the reported analysis answers.
Repeated measurement and baseline-based grouping raise familiar analytical considerations. Measurements from one participant over time are related, and defining groups using a baseline measure can influence interpretation of subsequent changes. These are general issues for longitudinal continuous outcomes, not evidence of a particular analysis failure. The registry does not report how they were handled.
Finally, planning illustrations need to align with the actual design. The described planning assumptions use equal allocation between two arms, but the study is listed as single group. Such calculations may illustrate how assumed effect size relates to planning, but they do not establish the study’s observed power or recreate its design. Taken together, the record underscores why a complete analysis description and numerical estimates with uncertainty are essential for assessing a clinical outcome.
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 principal limitation for interpreting this trial from the registry record is the absence of numerical primary outcome results. Mean changes, group estimates, standard errors, and confidence intervals are not reported in the registry record. Without them, the gait-speed result’s magnitude, direction, and precision cannot be assessed.
The single-group design has no described randomized or like-for-like control comparison. The baseline gait-speed strata are not treatment comparators, so changes over time cannot be attributed to the intervention on the basis of the design description alone. The record does not report whether other care or relevant co-interventions were controlled or accounted for.
The endpoint description is not fully aligned: the title specifies change from baseline, but the narrative describes comparisons of mean speeds across groups at several timepoints. The exact contrast, statistical model, treatment of repeated measurements, and any baseline adjustment are not reported. The record also does not report outcome-specific participant counts, missing-data handling, analysis populations, or sensitivity analyses.
The registry lists 3 outcome measures and 3 analyses, but multiplicity procedures and the prespecified status of each analysis are not reported. The rationale for enrollment of 55 and the trial’s statistical plan are not reported in the registry record. Planning assumptions based on a two-arm equal-allocation design do not match the recorded single-group structure and should not be interpreted as the original design’s power assessment.
For safety, the available entries are counts in the treated group without a control comparison. The record does not report event timing, attribution methods, or detailed surveillance procedures. These limitations constrain both efficacy and safety interpretation.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: The General Use of Robots in Stroke Recovery: the Anklebot — NCT02249832.
- Registry record last updated 2021-03-09; status last verified 2019-11.
- Results first posted 2019-11-15.
- 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.
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18. Record Summary
The registry record identifies a completed, single-group study sponsored by Northwell Health, with enrollment of 55 and a device intervention described as seated robot-assisted ankle therapy using the MIT anklebot. The schedule was eighteen 1 hour sessions, 3x/week for 6 weeks. The listed assessments include baseline, discharge at week 6, and 3 month follow-up at overall week 18.
The primary endpoint concerns mean change in comfortable-pace gait speed on the 10 Meter Walk Test. Participants were classified by admission gait speed into low, moderate, and high functioning groups. The record does not report numerical primary outcome results or the detailed statistical analysis needed to interpret them.
Safety entries report 1 serious adverse event among 55 at risk, 2 other adverse events among 55 at risk, and 0 deaths. The registry lists no randomized comparator. Missing-data procedures, analysis populations, and multiplicity handling are not reported in the registry record.