ECoG Direct Brain Interface for Individuals With Upper Limb Paralysis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for ECoG Direct Brain Interface for Individuals With Upper Limb Paralysis (NCT01393444), a na na study. The primary outcome is Number of Participants Able to Successfully Control of a Variety of External Devices Using Neural Data Recorded With ECoG.

2. Clinical Question

The study’s stated purpose was to demonstrate whether individuals with upper limb paralysis could achieve direct brain control of assistive devices using an ECoG-based brain-computer interface. The devices participants would attempt to control included computer cursors, virtual reality environments, and assistive devices such as hand orthoses or surface functional electrical stimulators.

This is a feasibility question about observed device control in a group receiving the ECoG intervention. It is not a comparative question about whether ECoG performs better than another approach: the registry record specifies a single group and no control arm. Nor does the primary question, as registered, quantify how much control participants achieved or compare performance across device types. The primary outcome is a participant count, while a secondary outcome also concerns the number able to achieve direct brain control. The registry record does not report the observed primary outcome result, so it does not establish how many participants achieved control.

3. Trial Design

NCT01393444, titled “ECoG Direct Brain Interface for Individuals With Upper Limb Paralysis,” is listed as a completed study sponsored by the University of Pittsburgh. Its official title describes an acute ECoG direct brain interface study. The registry record lists enrollment of 6 and gives a start date of 2011-05 and a primary completion date of 2015-04.

The design is single-group, with no control group and no other arms. Allocation is listed as NA, and masking is listed as NONE. The Direct Brain Interface Users group received implantation of ECoG sensors on the brain surface to record neural activity. As a result, the design can describe what happened among participants in that group, but it cannot directly compare their outcomes with an untreated, sham, or alternative-treatment group.

The planned primary outcome was the number of participants able to successfully control a variety of external devices using neural data recorded with ECoG. The timeframe was up to 29 days of device implantation. Participants were to attempt control of computer cursors, virtual reality environments, and assistive devices including hand orthoses or surface functional electrical stimulators. A secondary outcome concerns the number able to achieve direct brain control of assistive devices using an ECoG-based brain-computer interface system.

The registered primary-outcome population includes people with limited or no ability to use one or both hands due to cervical spinal cord injury, brachial plexus injury, brainstem stroke, muscular dystrophy, cerebral palsy, ALS, or another motor neuron disease. The conditions list also includes tetraplegia and spinal cord injury. These descriptions indicate the intended clinical setting, but the registry record does not report the characteristics of the participants who contributed outcome data.

Although the study status is completed, the registry record does not report a primary-outcome result, the number analyzed, or an analysis plan. The completed status therefore indicates the recorded study status, not that the registry contains enough outcome information to assess the primary question.

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: This study did not include "arms" or group assignments.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Individuals with limited or no ability to use one or both hands due to cervical spinal cord injury, brachial plexus injury, brainstem stroke, muscular dystrophy, cerebral palsy or amyotrophic lateral sclerosis (ALS) or other motor neuron disease.

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: All individuals were English speaking, with a disability of at least one hand/arm, but no other health issues which would interfere with or be made worse by study participation.

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants Able to Successfully Control of a Variety of External Devices Using Neural Data Recorded With ECoG, measured over Up to 29 days of device implantation.

The primary endpoint is a count: the number of participants who were able to successfully control a variety of external devices using neural data recorded with ECoG. The planned attempts involved computer cursors, virtual reality environments, and assistive devices such as hand orthoses or surface functional electrical stimulators. The timeframe was up to 29 days of device implantation.

A participant count is a direct way to describe whether the intended task was achieved within the study group. It can make a feasibility outcome readily interpretable: the result would indicate how many participants met the study’s criterion for successful control. However, the registry record does not define a detailed success threshold, describe whether success required control of every device or any device, or report the observed count. Those details are not reported in the registry record, so the endpoint’s operational definition and result cannot be evaluated from this entry.

The measure is a count, not a continuous score of control quality, speed, accuracy, duration, or independence. It also does not, by itself, show whether the outcome differs from what would occur without the intervention. Such a comparison would require a comparator group or other suitable design, and this study had no control group. The endpoint is therefore suited to describing achievement within the Direct Brain Interface Users group, but the registry record does not supply the result needed to make that description.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary outcome as a number of participants, with the unit listed as participants and the parameter described as NUMBER. This is a count outcome: it records how many participants meet the endpoint definition. The record’s secondary outcome is also a participant count, focused on achieving direct brain control of assistive devices. The registry lists 2 outcome measures and 0 analyses.

What can a count endpoint tell readers?

In general, a count is straightforward to understand, but its interpretation depends on the definition of success and on who was assessed. For a participant-level binary outcome, each person is classified as having met or not met the stated criterion. The count of those meeting it should be interpreted alongside the number assessed. If the denominator is missing, readers cannot determine the observed proportion from the count alone. If the success criterion is unclear, readers may not know whether participants needed to control every device, one device, or meet another threshold. The registry record does not report a detailed criterion or the primary endpoint count and denominator.

The outcome description names several kinds of devices participants would attempt to control. In general, outcomes involving different tasks can be affected by how each task is defined, how many attempts are made, and whether success is assessed consistently. The registry record does not report those assessment details. It also does not state whether the primary endpoint required success across device types or whether a successful attempt on any one type would qualify.

Why does the design matter?

In general, a single-group design describes results within the group that received the intervention. It does not provide a direct estimate of the difference between intervention and control groups. Without a comparator, differences from an alternative approach cannot be estimated from the trial design. Changes over time, task practice, or other influences cannot be separated from the intervention using a treatment contrast that the study does not contain. This study is registered as SINGLE GROUP, has allocation listed as NA, and has no control group.

Masking is listed as NONE. In general, masking can reduce the influence of knowledge about group assignment on some aspects of assessment or reporting. The registry record does not describe whether outcome assessors were masked or give further details about how control was evaluated. The listed masking field therefore should not be expanded into an assumption about specific assessment procedures.

What does uncertainty mean for a binary outcome?

In general, a confidence interval gives a range of values compatible with the data under the statistical model and procedure used. It expresses uncertainty about an estimate; it does not guarantee that the true value lies in the interval, and it does not measure the importance of the outcome. With a small group, estimates for binary outcomes can be imprecise, particularly when the event count is low or at an extreme. The registry record lists enrollment of 6, but does not report the primary outcome count, analyzed denominator, or confidence interval. Therefore, no interval for the primary endpoint can be interpreted from this record.

For a binary outcome, different methods can yield different intervals, especially with limited data. A method should be selected to suit the estimand, outcome structure, and sample size. The registry record does not report an interval method or a statistical analysis plan. It is therefore not possible to attribute any particular interval procedure to the study.

What do the planning assumptions represent?

The record describes planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It states that the effect to detect is a stated fraction of the observed effect, and that the non-time-to-event illustrations refer to participants per arm for a specified power level. These are planning assumptions, not evidence that this single-group study used a two-arm design. In particular, equal allocation between two arms does not describe the registered study, which had one group and no control group.

In general, a sample-size illustration asks how many participants might be needed under specified assumptions to detect an effect using a chosen design and statistical method. Its answer depends on the assumed effect, variability, significance level, power, allocation, and model. An illustration based on an observed effect is conditional on that effect being available and a future design being appropriate. It is not a report of the study’s enrollment rationale and is not observed power. The registry record does not report the trial’s own sample-size justification or a design plan that corresponds to the two-arm assumptions.

For count outcomes, over-dispersion is a general concern when counts vary more than a statistical model assumes. In general, a model that understates variability can produce intervals that are too narrow and tests that are too optimistic. This concept is relevant to count-data analyses, but the primary endpoint is described as a number of participants, not a repeated-event count. The registry record does not report a count model, an over-dispersion assessment, or an analysis using such a model.

Statistical significance and clinical meaning are also distinct in general. A significance test addresses compatibility of data with a specified null model, while the size and precision of an estimate describe the range of plausible effects. For this registry entry, no primary result or analysis is posted, so neither statistical significance nor endpoint precision can be evaluated. The purpose statement describes what the study sought to demonstrate; it is not a statistical finding.

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("Direct Brain Interface Users")
n      <- c(3)
events <- c(3)
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  Direct Brain Interface Users  3  3  100.0  29.2  100.0  43.9  100.0  39.8  99.4

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists 2 outcome measures: a primary measure counting participants able to control a variety of external devices using ECoG neural data, and a secondary measure counting participants able to achieve direct brain control of assistive devices. It lists 0 analyses. No analysis plan is reported in the registry record, including any approach to handling multiple outcomes or multiple device tasks.

In general, multiplicity arises when several outcomes, comparisons, time points, or analyses are examined. Without a prespecified strategy, repeated testing can increase the chance of a false-positive finding. Adjustments or a clear hierarchy can help address this issue, but the appropriate approach depends on the planned questions and analysis. The record does not report whether such a strategy was used. The existence of more than one registered outcome does not establish that a particular multiplicity problem occurred; it means the analysis approach is not documented in this entry.

Missing-data methods are also not reported in the registry record. The primary outcome timeframe is up to 29 days of device implantation, but the record does not describe whether all participants completed the planned assessments, how incomplete device-control attempts were handled, or how participants without an assessable outcome would be classified. These details matter because an outcome count can depend on who was assessed and how missing observations are treated.

The analysis population is not reported in the registry record. Enrollment is listed as 6, but the number contributing data to the primary endpoint is not given. The record also does not describe exclusions, withdrawals, or a distinction between enrolled participants and participants included in an analysis. Accordingly, the endpoint denominator and the relationship between enrollment and analysis cannot be established from this entry.

12. Safety Results

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

Other (non-serious) adverse events

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

Most frequent non-serious adverse event terms

The registry reports adverse-event counts for the Direct Brain Interface Users group. Serious adverse events affected 0 of 6 participants at risk. Other adverse events affected 1 of 6 participants at risk. These are counts of participants affected, as recorded in the safety fields; they are not event rates calculated for a time period.

The record gives the same at-risk count for serious and other adverse events, but does not provide further detail about monitoring duration, event definitions, severity grading, or how events were attributed. The primary outcome timeframe was up to 29 days of device implantation; the record does not establish that each safety figure covers an identical observation period. Serious adverse-event terms are not listed. Deaths are not reported in the registry record, so the absence of a death count should not be interpreted as confirmation that no deaths occurred.

These figures should be read as registry-recorded counts, not as proof that the intervention is safe or unsafe. In general, a small study may be unable to characterize uncommon adverse events precisely, and a count alone does not describe an event’s nature, duration, or relationship to an intervention. The registry entry does not provide enough safety detail to make those assessments.

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

The study was designed to examine whether people with upper limb paralysis could use neural activity recorded by ECoG to control external devices. The registered primary endpoint makes this a feasibility question expressed as a participant count. The planned tasks included control of computer cursors, virtual reality environments, and assistive devices such as hand orthoses or surface functional electrical stimulators, during up to 29 days of device implantation.

The registry record does not report the observed primary endpoint result. It therefore cannot establish how many participants successfully controlled devices, how often success occurred among those assessed, or how precisely that outcome was estimated. The completed status does not fill this gap. Nor can the study’s stated purpose be treated as a result: the purpose describes the question investigators set out to address, not what the data showed.

The single-group design also sets an important boundary on interpretation. There was no control group, so the record cannot provide a direct comparison with an alternative intervention or with no intervention. Even if an outcome count were reported, it would describe participants in the study group and would not by itself establish that ECoG caused the observed outcome. The registry record also does not report a detailed success threshold, assessment procedure, or analysis plan.

The safety entry records 0 of 6 at risk affected by serious adverse events and 1 of 6 at risk affected by other adverse events. These counts should be considered separately from the primary endpoint, whose result is not reported. The registry does not list serious event terms, and deaths are not reported in the registry record. The safety fields therefore offer limited descriptive information rather than a comprehensive assessment.

The most defensible reading is that the registry describes the study’s intended population, intervention, tasks, design, and selected safety counts, but does not provide the primary outcome data needed to answer the central feasibility question. It does not support a conclusion that the interface succeeded or failed, nor a comparative claim about its performance.

14. Why This Trial Matters Statistically

This trial is statistically notable because its main question is a participant-level feasibility outcome in a single-group design. Such studies can be useful for describing whether a planned task was achieved under study conditions. A count of participants who meet a clear success criterion can communicate feasibility directly, provided the outcome definition, denominator, and assessment process are reported.

Those details are particularly important when the endpoint spans several device types. Controlling a cursor, a virtual reality environment, and an assistive device may involve different tasks and criteria. In general, combining such attempts into one success count requires a transparent rule for what qualifies. The registry record names the device types but does not report a detailed rule for combining or judging them.

The lack of a comparator also distinguishes descriptive evidence from comparative evidence. A single-group study can document outcomes among participants who received the intervention, but does not estimate a treatment contrast. That boundary is not a flaw by itself; it reflects the question the design can answer. It does mean that conclusions about relative performance or causal effects require evidence beyond the registered design and results available in this entry.

The registry record further illustrates why completion status, sample-size illustrations, and outcome results must be kept separate. A study can be marked completed without its endpoint result being present in the registry. A hypothetical planning illustration using a two-arm allocation does not describe the registered single-group design, and does not supply an observed effect or indicate observed power. Here, the primary outcome result and analysis are not reported.

For researchers, this record emphasizes the value of reporting success criteria, analyzed denominators, uncertainty, missing-data handling, and the analysis population alongside a feasibility count. Those elements allow readers to judge both the meaning of the result and its precision. Without them, even a clearly stated study aim cannot answer the statistical question the endpoint was designed to address.

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 primary limitation for interpreting this trial from its registry entry is that the observed primary outcome is not reported. The record states what participants were to attempt, but does not give the number who successfully controlled devices, the denominator assessed, or an uncertainty estimate. The study’s completed status cannot be used to infer those results.

The endpoint definition is also not detailed enough to establish exactly what counted as successful control. Several device types are named, but the registry record does not state whether participants needed to control all device types, any one type, or meet another criterion. It does not describe the number of attempts, assessment procedures, or how control quality was judged. This limits interpretation of the intended count even apart from the missing result.

The study had no control group, so it cannot provide a direct comparative estimate. The registry record lists a single group and no other arms. It also does not report the analysis population, withdrawals, missing outcome data, or a statistical analysis plan. The relationship between enrollment and the primary endpoint denominator is therefore unknown.

The timeframe is described as up to 29 days of device implantation, but the record does not give participant-level exposure or outcome-assessment durations. Safety information is limited to affected-participant counts: serious adverse events affected 0 of 6 at risk, and other adverse events affected 1 of 6 at risk. Serious event terms are not listed, and deaths are not reported in the registry record. The details needed to interpret event type, timing, and attribution are not reported.

Finally, the registered primary-outcome population includes cerebral palsy and other motor neuron disease, while the conditions list names other conditions, including ALS and spinal cord injury. The record does not report the actual participant diagnoses, so the enrolled group’s composition cannot be described from these fields.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: ECoG Direct Brain Interface for Individuals With Upper Limb Paralysis — NCT01393444.
• Registry record last updated 2016-12-12; status last verified 2016-10.
• Results first posted 2016-12-12.
• 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

NCT01393444 is a completed, single-group study sponsored by the University of Pittsburgh, with enrollment listed as 6. The registry record gives a start date of 2011-05 and a primary completion date of 2015-04. Allocation is listed as NA, masking as NONE, and no control group is described.

The intervention was implantation of ECoG sensors on the brain surface to record neural activity. The primary outcome was the number of participants able to control external devices using ECoG neural data, during up to 29 days of device implantation. The record lists 2 outcome measures and 0 analyses.

The primary outcome result and analysis population are not reported in the registry record. For safety, serious adverse events affected 0 of 6 at risk, and other adverse events affected 1 of 6 at risk. Serious event terms are not listed; deaths are not reported in the registry record.