RESCU System for Robust Upper Limb Prosthesis Control: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for RESCU System for Robust Upper Limb Prosthesis Control (NCT04043234), a na phase not stated study. The primary outcome is Mean Daily Prosthesis Use Duration.

2. Clinical Question

The clinical question is whether daily use differs when the same participants use RESCU rather than the standard pattern recognition system. The study description frames prosthesis use as a proxy for user satisfaction: it assumes that a person who is more satisfied with a prosthetic solution may use it more in daily life. That is the study's stated rationale, not a direct measurement of satisfaction. Use duration can also reflect circumstances other than satisfaction, so it should be interpreted as a behavioral measure rather than a direct satisfaction score.

The registry also lists measures of activity, functional status, prosthesis experience, satisfaction, pain, socket comfort, and residual-joint range of motion. These outcomes could give context to use duration, but their results are not reported in the registry record. The primary result is likewise not reported, so the registry does not establish whether use duration was higher, lower, or similar across the described evaluation periods.

3. Trial Design

The registry identifies a single-case experimental design in which participants act as their own controls. Each participant first uses the control device and is then transitioned to the experimental device. The study summary describes use of both systems over a 35-day period. This sequential, within-person approach differs from a parallel-group trial, where separate groups are assigned to different systems at the same time.

The control system is described as including a commercially available pattern recognition controller. The experimental system uses the same components as the control system but differs by incorporating eight IBT Element Electrodes and RESCU control software. The standard system is described as including at least two controllable DoFs, with examples such as a hand, wrist, or multi-articulated hand. The registry's arm description gives additional device components, but fuller device specifications are not reported in the registry record.

Allocation is recorded as NA, and masking is recorded as none. The study is marked completed, with a start date of 2023-11-07 and primary completion date of 2023-12-19. These registry fields describe status and design; they do not establish that every participant completed every planned measure. Participant-level completion details are not reported in the registry record.

Because control use precedes experimental use, observed differences may reflect more than the control software. For example, change over time, learning, adaptation, or differences in the periods being compared could affect measured use. These are general considerations for sequential designs, not claims about what happened in this study. The registry describes a single-case design intended to address a limited patient population, but the design rationale and its analysis procedures are not reported in further detail in the registry record.

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:

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 Mean Daily Prosthesis Use Duration, measured over Baseline, 4 weeks.

The primary endpoint is mean daily prosthesis use duration, measured in hours. For the experimental intervention, the registry defines it as the average number of hours the prosthesis was used daily over the four-week evaluation period. For the control intervention, it is the average number of hours of daily use before the evaluation period, at baseline.

The stated reason for measuring use is that it serves as a proxy for user satisfaction. The underlying assumption is that people who are more satisfied with a prosthetic solution will use it more in daily life. This makes duration a practical measure of use in everyday settings, but it does not directly ask participants how satisfied they are. The registry separately lists PROMIS Satisfaction Short Form 8a and other subjective measures; their results are not reported in the registry record.

Use duration can depend on factors other than satisfaction, including routine, opportunity to use the prosthesis, device fit, and the demands of daily activities. These are general interpretive considerations, not reported explanations for any participant's use. The registry does not report primary endpoint values, variation across participants, or an estimated comparison between baseline control use and experimental use. The measure's definition is reported, but its observed result and precision are not.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical concepts in this discussion are general unless explicitly tied to the registry. The registry describes a continuous primary measure: mean daily use duration in hours. A continuous outcome can take values along a scale rather than being limited to categories. Reporting a mean gives a summary of the observations, while a measure of spread describes how much observations differ around that summary. The registry identifies standard deviation as the dispersion measure for the primary outcome, but no outcome mean or standard deviation is reported in the registry record.

A standard deviation describes the spread of observed values in the data, not the precision of the estimated mean. A confidence interval is commonly used to express uncertainty around an estimated effect or mean. Its width depends on the amount and variability of information and on the analysis assumptions. A narrow interval indicates greater statistical precision than a wide interval, but precision is not the same as clinical importance. In this record, an interval for the primary comparison is not reported, so the uncertainty around any effect cannot be assessed.

The single-case design calls for care in defining the comparison. Participants serve as their own controls, with control use preceding experimental use. This makes within-person observations relevant, but it does not remove the possibility that outcomes change with time or experience. General analytical approaches for repeated observations can account for within-person dependence and trends, but the registry does not report which approach was used. It also does not report whether the primary comparison was based on each person's average, a pooled summary, or a model using repeated daily observations.

The record gives a sample-size planning description based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. These are planning assumptions, not a description of the trial's own design or a report of observed power. The registry record does not report the planning outputs or the underlying observed effect used for such illustrations. A planning calculation cannot replace an observed effect estimate, and it should not be interpreted as evidence that the study had a particular probability of detecting an effect.

The equal-allocation planning assumption also differs conceptually from the described within-person sequence. Planning illustrations that treat two arms as equally allocated do not, by themselves, characterize the information structure of a single-case design with sequential measurements. In a within-person study, repeated measurements from the same participant are related rather than independent. General methods may model that dependence, but the analysis method, covariance assumptions, and any adjustment for trends are not reported in the registry record.

The term over-dispersion is generally used when observed variability is greater than a model assumes. In a study with repeated daily use measurements, differences between people and fluctuations within a person could contribute to variability. If an analysis assumed less variation than the data contain, its uncertainty estimates could be too optimistic. This is a general statistical concern; the registry does not report whether over-dispersion was assessed or whether the data exhibited it.

Multiple measurements and outcomes can also create multiplicity. If many hypotheses are tested, the chance of at least one apparently unusual result can increase. A prespecified primary outcome can help distinguish the main question from supporting outcomes, but interpretation still depends on which analyses were planned, how many were conducted, and whether adjustments were used. The registry lists eight outcome measures and reports zero analyses. It does not describe an analysis plan, multiplicity adjustment, hierarchy of secondary outcomes, or interim analyses. Those details are not reported in the registry record.

Missing observations matter for both the estimated mean and its uncertainty. If data are missing, the result may depend on which participants or days contributed observations and on why measurements were unavailable. General methods include complete-case analyses and approaches that make assumptions about missing values; each requires transparent reporting. The registry does not report missing-data counts, reasons for missingness, imputation methods, or the analysis population for the primary outcome. No assumptions about missingness can therefore be attributed to this study.

Finally, a statistically detectable difference and a practically important difference are separate ideas. Statistical methods quantify compatibility between data and a model or hypothesis; they do not determine whether a difference matters to participants. That judgment would require an interpretable effect estimate and relevant context. Since the primary outcome values and comparison are not reported, neither statistical evidence nor the practical magnitude of any difference can be evaluated from the registry record.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Experimental", "Control")
n   <- c(2, 2)
m   <- c(3.81, 6.83)
sp  <- c(1.77, 2.55)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Experimental  2  3.810  1.770  -12.093  19.713
CARM  Control  2  6.830  2.550  -16.081  29.741

11. Multiplicity, Missing Data and Analysis Populations

The registry lists eight outcome measures: the primary measure of mean daily prosthesis use duration and secondary measures covering activity, upper-extremity functional status, prosthesis experience, satisfaction, pain, socket comfort, and residual-joint range of motion. It reports zero analyses. The outcome list identifies what was planned or registered, but does not show which outcomes were collected, analyzed, or reported as results.

When several outcomes or comparisons are examined, multiplicity can make isolated findings more likely to appear notable by chance. A clear analysis plan can specify which outcome is primary, how secondary outcomes will be interpreted, and whether any adjustment is planned. The registry does not report a multiplicity strategy, the number of comparisons intended, or whether secondary analyses were exploratory. It also does not report interim analyses or a detailed statistical analysis plan.

The registry does not give missing-data counts or explain whether all enrolled participants contributed data to each measure. It does not report how missing daily-use observations, incomplete questionnaires, or other unavailable measurements were handled. It also does not define an analysis population for the primary endpoint. Without these details, readers cannot determine which observations entered an estimate or assess whether missingness could have affected its interpretation.

These omissions do not establish that data were missing, that analyses were conducted, or that a particular adjustment was needed. They mean those matters are not reported in the registry record. The registry's status of completed should not be taken as a substitute for outcome-level analysis and missing-data reporting.

12. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The registry reports zero serious adverse events in the Experimental group among 4 participants at risk, and zero serious adverse events in the Control group among 4 participants at risk. It also reports zero other adverse events in each group among 4 participants at risk, and zero deaths in each group. These are the safety figures recorded for the listed groups.

Zero reported events means that the registry lists no events in those categories during the reported observation. It does not prove that a device has no risk or establish the safety of a system in other settings or populations. With a small study population, uncommon events may not be observed even if they can occur. The registry does not provide additional details about the duration or completeness of safety surveillance, event definitions, or how events were attributed to a device.

The participant groups are part of a sequential, within-person design, not independent randomized arms. The same individuals may be represented under both group descriptions, so the at-risk figures should not be added to infer a count of distinct participants. The registry reports no top serious adverse-event terms. Safety findings should therefore be read narrowly as the event counts entered in the registry, not as a comprehensive assessment of risks.

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

The record establishes that a completed study was registered to examine RESCU system use in people with upper limb amputation, with participants acting as their own controls. It defines mean daily prosthesis use duration as the primary endpoint and describes a baseline control period followed by an experimental evaluation period. It also identifies a group of secondary measures relating to function, experience, satisfaction, pain, comfort, and range of motion.

The registry does not report the primary outcome values, an estimated difference, or the uncertainty around a comparison. It also does not report results for the listed secondary outcomes. As a result, the record cannot show whether daily use changed, how large any change was, whether participants had similar experiences, or whether any observed difference was precise. The study's stated hypothesis remains a hypothesis in the absence of reported results.

The sequential, within-person design can provide information about use in a person's own experience, but it does not make the periods equivalent or eliminate changes over time. General influences such as learning, adaptation, and daily circumstances could affect use. Without participant-level observations and a described analysis, those influences cannot be separated from a system-related difference.

These limitations do not establish that RESCU is beneficial or ineffective. They define what can and cannot be concluded from the registry record. In particular, the record does not support a claim about efficacy, satisfaction, or comparative safety beyond the specific event counts recorded. The study may have generated further data, but results beyond those registered are not reported in the registry record.

14. Why This Trial Matters Statistically

This study is statistically notable because it addresses a small clinical population with a single-case experimental design, rather than relying on a conventional parallel-group structure. In such designs, each participant can contribute a comparison across conditions. That can make detailed within-person patterns informative, especially when the population available for study is limited. It also makes transparent measurement over time and clear analysis of repeated observations especially important.

The primary endpoint is everyday use duration, a measure that connects device use to behavior outside a single clinic assessment. Its interpretation remains indirect: the study uses duration as a proxy for satisfaction rather than measuring satisfaction through that primary endpoint. The registered secondary outcomes include direct measures of functional status and subjective experience, which could help interpret use duration if their results and relationships were reported.

The record illustrates why design descriptions and outcome results need to be read separately. A hypothesis, an endpoint definition, and a completed study status do not supply an effect estimate. Statistical interpretation requires the observed outcome, a suitable analysis, and enough information to understand variability and uncertainty. These results are not reported in the registry record.

The design also emphasizes the importance of distinguishing planning assumptions from analysis of observed data. The registry describes planning illustrations based on an observed effect and a normal approximation, but such planning does not establish the precision or evidential strength of the actual study. That assessment would require the reported data and analysis. For this study, the statistical contribution described in the registry is therefore primarily its design and measurement framework, rather than a publicly reported estimate of comparative use.

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 main limitation for interpretation is that the registry record does not report primary outcome results. Without daily-use means, variability, an effect estimate, or an uncertainty interval, the comparison cannot be quantitatively assessed. The record likewise does not report results for any listed secondary outcome, despite describing measures that could add context.

The study enrolled 4 participants, and its single-case design means that broad generalization would require careful consideration even if results were available. The registry does not report participant characteristics beyond the condition labels, so readers cannot assess how the enrolled participants compare with other people who use upper limb prostheses. Participant-level outcomes and variation are also not reported.

The periods were sequential: control use was at baseline and experimental use was evaluated over four weeks. This structure may confound system differences with time, learning, adaptation, or other period-specific influences. The registry does not report methods for addressing order or time effects. Masking is recorded as none, and allocation is recorded as NA, consistent with the described non-randomized, within-person design.

Further details needed to judge the analysis are not reported in the registry record, including a full statistical analysis plan, missing-data handling, analysis populations, and multiplicity procedures. Safety interpretation is also limited to the recorded event counts, without fuller surveillance details. These are limitations of what can be concluded from the registry record and do not imply that unreported procedures or results were absent from the study itself.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: RESCU System for Robust Upper Limb Prosthesis Control — NCT04043234.
• Registry record last updated 2024-04-24; status last verified 2024-04.
• Results first posted 2024-04-24.
• 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

NCT04043234 is a completed study of the RESCU system for robust upper limb prosthesis control, sponsored by Infinite Biomedical Technologies. The registry describes a single-case experimental design in which participants used a commercially available pattern recognition control system before transitioning to RESCU. Enrollment was 4; the study start date was 2023-11-07, and primary completion was 2023-12-19.

The primary measure was mean daily prosthesis use duration in hours, comparing baseline control use with experimental use over four weeks. The registry lists seven secondary outcome names in addition to the primary measure, reports zero analyses, and does not report outcome results or a primary comparison estimate. It records zero serious adverse events, zero other adverse events, and zero deaths in both named groups. The registry record describes the design and planned measurements, but does not provide results sufficient to evaluate comparative use or uncertainty.