Investigational Study of the Ekso for High-Dosage Use by Individuals With SCI in a Non-Clinical Environment: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Investigational Study of the Ekso for High-Dosage Use by Individuals With SCI in a Non-Clinical Environment (NCT02566850), a na na study. The primary outcome is Number of Study Participants With Adverse Events.

2. Clinical Question

3. Trial Design

The registry describes an investigational study of the Ekso Bionics powered exoskeleton for high-dosage use by people with spinal cord injury in a non-clinical environment. It is a single-group, non-randomized study, with an Ekso Users group and no control group. Masking is listed as none. The intervention is a device, rather than a medication or procedure.

Enrollment is listed as four. The brief summary describes a study of safety and health effects in a home setting over an extended period ranging from 12-42 months. The primary outcome timeframe is through study completion, for a maximum possible duration of 42 months. These descriptions identify the intended setting and duration; they do not establish how long each participant actually used the device or how much exposure each participant received.

The registry status is terminated. The reason for termination is not reported in the registry record, so termination should not be interpreted as evidence about safety, effectiveness, recruitment, or any other cause. The primary outcome is the number of participants with adverse events. Secondary outcomes listed include quality of life, bowel and bladder function, spasticity, spinal cord independence, strength, and perceived exertion. Outcome measurement names alone do not establish that results were collected or analyzed.

There are no analyses reported in the registry record. Consequently, the design and posted event counts can be described, but there is no reported inferential analysis or group comparison to interpret. The absence of a comparator is especially important: any change over time, if measured, could not be separated from other influences using a randomized control contrast in this design.

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 dropout from original 4 participants

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

Population: four males with SCI

6. Primary Endpoint

The registry lists the primary outcome as Number of Study Participants With Adverse Events, measured over through study completion for a maximum possible duration of 42 months.

The primary endpoint is the number of study participants with adverse events. It is a participant count, not a count of all event episodes: a person who experiences more than one event would still contribute as a participant with an event. The stated timeframe runs through study completion, for a maximum possible duration of 42 months. The endpoint description says it is intended to evaluate the safety of a subject walking with a lay spotter in a non-clinical environment.

Safety endpoints are used to record whether participants experience unwanted events while taking part in a study. A participant-based measure gives a direct count of people affected, while event-level measures can describe how many events occurred. Those measures answer different questions and should not be treated as interchangeable. The registry record identifies the primary measure as a count of participants, but does not report event-level detail, severity grading beyond the serious-versus-other classification in the posted counts, or exposure time for each person.

The posted results list four participants at risk, with zero serious adverse events and zero other adverse events. This describes the recorded counts for this group. It does not establish that no event could occur with greater exposure, in other settings, or among other people. The registry record does not report an uncertainty interval or a statistical test for this endpoint.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

There are no statistical analyses reported in the registry record. The method descriptions below are general explanations of how this kind of endpoint can be understood; they should not be read as a description of analyses that the study actually performed.

What does a participant count measure?

A count of participants with an event asks how many people experienced at least one event during the specified observation period. It does not count repeated events separately. For example, event frequency and the number of people affected are distinct quantities: repeated episodes in one participant may raise the event total without changing the number of participants affected. Here, the primary endpoint is explicitly a count of participants, and the posted safety data separately identify serious and other adverse events.

Counts are often useful for a direct safety description, but they depend on the group size and the period in which events could be observed. A count by itself is not a rate. A rate requires an exposure denominator, such as time under observation, and the record does not report participant-specific follow-up or device-use exposure. The maximum possible duration does not show that every participant was observed for that full period.

Why does a zero count require caution?

General statistical explanation: a sample is only one realization from a broader process. If an event is infrequent, a small study can observe no events even when the event remains possible. As a result, zero observed events should not be interpreted as proof of zero risk. An uncertainty interval can express how much imprecision accompanies an estimate, but no such interval is reported for this endpoint. No estimate should be reconstructed from the count alone in this interpretation.

The absence of events also does not show that the study had sufficient size or follow-up to detect a particular level of risk. Sample-size planning and observed information are different concepts. The registry record does not report a sample-size justification or a statistical plan, and no analyses are reported. Any planning illustration associated with a page cannot be treated as a study design target or as observed power.

What can a single-group design establish?

General statistical explanation: a single-group study can describe what was observed among its participants, but it does not directly estimate what would have happened to comparable participants under another condition. Without a concurrent comparator, changes in health or function may reflect the device, the passage of time, other care, changes in circumstances, or measurement variation. Random allocation can help balance such influences between groups; no random allocation or separate comparison group is reported.

Masking is listed as none. In general, awareness of the intervention can affect participant reports, behavior, care, or outcome assessment, depending on how a measure is collected. That possibility is relevant when interpreting outcomes, but the registry record does not describe the assessment procedures well enough to say how much it affected any result.

Why are the listed analyses important?

There are 11 outcome measures listed, including the primary safety outcome and secondary measures spanning quality of life, bowel and bladder function, spasticity, independence, strength, and perceived exertion. The registry record reports no analyses. Therefore, it does not provide effect estimates, uncertainty intervals, or test results for those measures. Listing an outcome is not the same as reporting its observed result.

For outcomes measured repeatedly over time, an analysis would also need to clarify which visits or timepoints were used and how within-person measurements were handled. For count or binary outcomes, the analysis would need to specify the population included, the treatment of missing observations, and the method used to quantify uncertainty. Those choices are not reported in the registry record. In particular, the endpoint's participant count cannot reveal whether any repeated assessments or event timing were incorporated into a statistical model.

General statistical explanation: when count variability exceeds what a simple model assumes, over-dispersion can make conventional uncertainty estimates too narrow. A method suited to the data structure may be needed. The posted information does not include a model, variability assessment, or inferential result, so no claim about over-dispersion or model adequacy can be made for this study.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Ekso Users")
n      <- c(3)
events <- c(0)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Ekso Users  3  0  0.0  0.0  70.8  0.0  56.1  0.6  60.2

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 11 outcome measures, including a primary safety endpoint and secondary measures related to quality of life, bowel and bladder function, spasticity, spinal cord independence, strength, and perceived exertion. It reports no analyses. No multiplicity adjustment or hierarchy for interpreting multiple outcomes is reported in the registry record.

General statistical explanation: when many outcomes or comparisons are examined, the chance of at least one apparently notable result can rise. A prespecified hierarchy, adjustment, or clear distinction between primary and exploratory outcomes can help readers interpret a collection of findings. Here, because no analyses or outcome results are reported, there is no set of statistical findings on which to assess the impact of multiplicity. The existence of several listed measures alone does not show that all were analyzed.

Missing-data handling is not reported in the registry record. The primary-outcome population description refers to one dropout from the original four participants, while the adverse-event group lists four at risk. The record does not explain the dropout's timing, the extent of available follow-up, or the method used to handle missing measurements. It also does not describe whether secondary outcomes were collected for every participant or at every planned assessment.

The analysis populations and any rules for inclusion or exclusion are not reported in the registry record. No statistical plan, interim-analysis procedure, or sample-size justification is reported either. These omissions mean that the posted counts can be described, but the reader cannot determine whether they reflect a prespecified analysis population, how missing observations influenced other outcomes, or whether any unreported analysis choices were made.

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 serious adverse-event figures list four participants at risk and zero participants affected. The other adverse-event figures likewise list four at risk and zero affected, and the death count is zero. No serious adverse-event terms are listed. These figures are counts for the Ekso Users group, not a comparison with another group.

General statistical explanation: a zero observed count in a small group does not mean that an event is impossible or that a broader risk is known to be zero. The precision of a safety estimate depends on the amount of information observed, including the number of participants and their observation time. Although the primary timeframe permits a maximum possible duration of 42 months, actual follow-up and device exposure by participant are not reported in the registry record.

The distinction between serious and other adverse events is retained in the posted data; the record does not provide additional event descriptions or explanations. The counts should therefore be read as a narrow description of recorded events, not as a complete characterization of every possible harm or as evidence about how the device compares with another approach.

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

The posted results establish a limited descriptive fact: the registry records zero serious adverse events and zero other adverse events among four participants at risk in the Ekso Users group, with zero deaths. The study was designed as a single-group investigation, and no comparator is reported. The numbers therefore describe the recorded experience of this group rather than a contrast between the device and another intervention.

They do not establish that use of the device prevents adverse events, that risk is absent, or that the same experience would occur in a larger or different population. General statistical explanation: a small sample can provide little precision about uncommon events. Without an uncertainty estimate, the range of plausible underlying event rates cannot be read from the posted counts alone. The record also does not provide participant-specific exposure or follow-up, which limits interpretation of the observation period.

The registry lists secondary outcomes addressing quality of life, bowel and bladder function, spasticity, independence, strength, and perceived exertion. Their results are not reported in the registry record, and no analyses are reported. It is therefore not possible to infer changes in these measures, their precision, or whether any apparent change would be attributable to device use.

The record identifies the study as terminated but does not report why it ended. The dropout reference also lacks detail about timing and handling. Neither point should be used to infer an unreported cause or outcome. The most defensible interpretation is that the registry contains a small set of descriptive safety counts and insufficient reported analysis to support broader conclusions about safety, health effects, or comparative performance.

14. Why This Trial Matters Statistically

This study is statistically notable for the gap between a broad research aim and the limited outcome information reported. Its stated purpose concerns safety and health effects during extended use in a non-clinical setting, while the primary endpoint is a participant count for adverse events. The registry also lists measures covering several functional and quality-of-life domains. However, the registry record reports no analyses, so the listed outcomes do not yield reported estimates of change or uncertainty.

The single-group design makes the distinction between description and comparison central. Counts can document what was observed among participants, but without a comparator they cannot isolate the effect of the device from other influences. The small enrollment also makes it important to avoid interpreting a zero event count as a precise estimate of risk. These are general issues of study design and statistical precision, not evidence that an unreported event or effect occurred.

The record also illustrates why denominator and follow-up details matter for safety interpretation. It lists four participants at risk, describes one dropout from the original four in the primary-outcome population field, and allows a maximum possible duration of 42 months. It does not explain how the dropout relates to the at-risk count or report individual observation times. Readers therefore cannot assess exposure differences or reconstruct an event rate.

For biostatistical interpretation, the key lesson is to distinguish a recorded count from an estimate of a broader risk, and an outcome listing from an analyzed result. Transparent reporting of analysis populations, missing-data handling, actual follow-up, statistical methods, and uncertainty would be needed for a more informative assessment. 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 enrollment is four, and the design has one group without a randomized comparator. The posted event counts are consequently limited to a very small group and do not support a comparative estimate. No uncertainty interval is reported in the registry record, so the precision of the safety counts is not quantified.

The intended duration is described as ranging from 12-42 months, and the primary timeframe allows a maximum possible duration of 42 months. Actual participant-level follow-up and device exposure are not reported. The record also does not explain how the dropout mentioned in the primary-outcome population description relates to the four participants listed at risk. This limits assessment of completeness and exposure.

The registry status is terminated, but the reason is not reported in the registry record. The record does not report the statistical plan, sample-size justification, analysis populations, interim analyses, or missing-data procedures. No analyses are reported, and results for the listed secondary outcomes are not reported. These gaps prevent assessment of functional outcomes, statistical uncertainty, and how analysis decisions may have affected results.

Finally, the study description concerns a non-clinical environment and the brief summary refers to a home setting. The record does not describe enough about participant characteristics, implementation, adherence, or outcome assessment to determine how broadly the observations apply. These limitations do not imply a particular unreported result; they define what can and cannot be concluded from the registry information.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Investigational Study of the Ekso for High-Dosage Use by Individuals With SCI in a Non-Clinical Environment — NCT02566850.
• Registry record last updated 2023-09-28; status last verified 2023-09.
• Results first posted 2023-09-28.
• 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 terminated, single-group study of the Ekso Bionics powered exoskeleton in people with spinal cord injury. Enrollment is listed as four, masking as none, and no randomized allocation or comparator group is reported. The stated primary outcome counts participants with adverse events through study completion, for a maximum possible duration of 42 months.

The Ekso Users group has four participants listed at risk, with zero serious and zero other adverse events and zero deaths. The registry lists 11 outcome measures and reports no analyses. Secondary measures address quality of life, bowel and bladder function, spasticity, independence, strength, and perceived exertion, but their results are not reported in the registry record. The reason for termination, participant-level follow-up, missing-data handling, and statistical analysis methods are also not reported. The counts are descriptive and do not establish a comparative effect or a precise broader safety estimate.