Home Study of an Advanced Upper Limb Prosthesis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Home Study of an Advanced Upper Limb Prosthesis (NCT01551420), a non-randomized na study. The primary outcome is Change in Quality of Life (QOL) Scale.

2. Clinical Question

3. Trial Design

The registry describes a completed, parallel, nonrandomized study of an advanced upper limb prosthetic device. Masking was none. Enrollment is listed as 52. The sponsor was the VA Office of Research and Development. The listed start date is 2012-04-01 and the primary completion date is 2017-12-19. These record details describe the study's administrative design and timeline, but do not establish how many participants completed training or entered home use.

The study had two parts. All participating subjects were to enroll in Part A for supervised training. Subjects meeting eligibility requirements were invited to Part B, the home-use portion. The objective described home use over 3 months and also included assessing the logistical support requirements used during home use. The primary endpoint timeframe is baseline and after 9-12 weeks of home use at the end of Part B. The registry record does not report the number invited to Part B, the number who accepted, or the number who completed it.

The listed arms were an IMU-controlled advanced upper limb prosthetic device and an EMG-PR-controlled advanced upper limb prosthetic device. The arm descriptions indicate different eligibility descriptions: upper limb amputation for the IMU arm and TR or TH upper limb amputation for the EMG-PR arm. The registry marks allocation as nonrandomized and explicitly cautions that the arms are not a like-for-like control comparison. Therefore, the design does not support treating the two arms as interchangeable groups that differed only by chance assignment.

The study included a continuous primary outcome and a range of secondary functional, satisfaction, and health-related measures. The registry lists 10 outcome measures and 42 analyses. A protocol-level description of how those analyses were selected, adjusted, or prioritized is not reported 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.

In-laboratory (Part A)

Reasons for not completing this period:

Screened for Part B Eligibility

Reasons for not completing this period:

Home Use (Part B)

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 Change in Quality of Life (QOL) Scale, measured over baseline and after 9-12 weeks of home use (end of Part B).

The primary endpoint was change in the Quality of Life (QOL) Scale summary score from baseline to the end of Part B. The stated timeframe was baseline and after 9-12 weeks of home use. The scale consists of 16 questions about satisfaction with independent living and self-care activities. Each item is rated from 1, Terrible, to 7, Delighted. The average of the 16 items forms the summary score, with higher values reflecting higher satisfaction. The primary outcome is the net change in that summary score.

This endpoint is used to describe participants' satisfaction in areas of daily life that the study considered relevant to home use of an advanced prosthetic device. In general, a change score compares a participant's follow-up value with their baseline value, so the focus is on change over the specified period rather than the follow-up score alone. The registry record does not explain the rationale for selecting this scale over other measures, specify how incomplete item responses were handled, or report the observed mean change, its standard deviation, or an interval estimate.

The endpoint is a continuous score, and the registry identifies the summary measure as a mean with standard deviation. A group mean describes the average score change; a standard deviation describes the spread of individual values around that mean. Neither quantity, by itself, gives the full distribution of participant experiences. No numerical primary-endpoint result is reported in the registry record, so the direction and precision of the observed change cannot be assessed from the record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is continuous: it is a numerical summary score formed by averaging 16 QOL items. The registry identifies the analysis measure as a mean and the measure of spread as a standard deviation. In general, a mean provides a summary of the average score in a group, while a standard deviation describes how widely individual scores vary around that average. The mean alone does not show whether most participants had similar changes or whether the average reflects a wide range of individual changes.

For a change outcome, the key quantity is the difference between the follow-up and baseline scores as defined by the analysis. The record calls the primary outcome the net change in the summary score between baseline and the end of Part B. In general, a change score can help describe how measurements shifted over time among participants with both measurements. Its interpretation depends on which participants contribute measurements and how missing follow-up data are handled. Those details are not reported in the registry record.

Uncertainty around an estimated mean is commonly expressed with a confidence interval. In general, a confidence interval shows a range of values compatible with the data and the method used to calculate it; a narrower interval indicates greater precision under that method. It is not a guarantee that the true value lies within the interval. The registry record does not report a confidence interval for the primary outcome, so its precision cannot be evaluated from the record. A p-value, which in general summarizes how surprising data would be under a specified null hypothesis and model, is also not reported for this endpoint.

Interpretation of change over time requires attention to the study's participation pathway. All participating subjects were to take part in supervised training, while only eligible subjects were invited to home use. The primary endpoint is timed to the end of Part B. This means that the group contributing home-use follow-up may not be identical to the full group that began training. The number entering each part, completing each assessment, and contributing to the primary analysis is not reported in the registry record. Without these details, the population represented by any endpoint estimate cannot be fully characterized.

The two arms were not randomly assigned. In general, random allocation helps balance both measured and unmeasured characteristics on average, whereas nonrandom allocation can leave groups with systematic differences. The registry explicitly states that the arms are not a like-for-like control comparison. The arm descriptions also specify different amputation eligibility. If outcome estimates were compared between arms, interpretation would require care about baseline differences, selection into the home-use portion, and other possible sources of confounding. The registry record does not report the baseline outcome values or a statistical adjustment strategy.

The registry lists 10 outcome measures and 42 analyses. In general, testing or estimating many outcomes can raise multiplicity concerns: the more results examined, the greater the chance that some appear notable by chance alone when multiple hypotheses are tested. This does not mean every result is misleading; it means that the analysis plan, hierarchy of outcomes, and any adjustment or interpretation strategy matter. Whether multiplicity adjustments were planned or applied is not reported in the registry record.

The registry also describes a sample-size planning illustration based on the observed effect. Its assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. For time-to-event tables, the stated quantity is the total number of events, while other planning values are expressed as participants per arm. These are planning illustrations, not observed power. The numerical planning values and the observed effect used for the illustration are not reported in the registry record. The registry does not report the trial's own design-stage sample-size justification.

In general, over-dispersion means that variation in the data is greater than a statistical model assumes. When that happens, standard errors and confidence intervals based on the less variable model can be too small, making results appear more precise than they are. For this continuous mean endpoint, the registry identifies the standard deviation as the spread measure, but does not report a model, residual diagnostics, or any assessment of over-dispersion. It is therefore not possible to determine whether this issue was relevant to a particular analysis.

Finally, a statistical estimate and its clinical meaning are separate questions. A confidence interval can describe precision, while the scale's content and a meaningful-change threshold would be needed to judge practical importance. The registry record does not report a threshold for meaningful change. It also does not report the primary estimate, so neither statistical precision nor practical importance can be assessed from the 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("Advanced Upper Limb Prosthetic Device IMU Controll", "Advanced Upper Limb Prosthetic EMG-PR Controlled")
n   <- c(17, 7)
m   <- c(5.8, 5.3)
sp  <- c(0.7, 0.6)
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  Advanced Upper Limb Prosthetic Device IMU Controll  17  5.800  0.700  5.440  6.160
CARM  Advanced Upper Limb Prosthetic EMG-PR Controlled  7  5.300  0.600  4.745  5.855

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 10 outcome measures and 42 analyses. Multiple outcomes and analyses can create more than one opportunity to observe an apparently notable result. In general, a prespecified hierarchy or multiplicity adjustment can help clarify how such results should be interpreted. The registry record does not report whether the 42 analyses were prespecified, whether any outcome hierarchy was used, or whether multiplicity adjustments were made. The count of analyses alone does not establish that the results were adjusted or unadjusted.

Missing-data handling is important because the primary endpoint requires a baseline measurement and a measurement at the end of Part B. The study included supervised training followed by an invitation to eligible subjects to enter home use. The registry record does not report how many participants completed each stage, how many had both endpoint measurements, why measurements might be missing, or whether any imputation or other missing-data method was used. It also does not report whether analyses were limited to completers or used another analysis population.

The analysis population is therefore not fully defined in the registry record. The enrollment listing is 52, but the record does not state how many of those enrolled contributed to the primary outcome analysis. Nor does it report how eligibility for Part B or withdrawal from home use was handled statistically. These omissions limit assessment of selection and attrition effects and of how broadly any estimated change would apply. Details of interim analyses and the full statistical analysis plan are not reported in the registry record.

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.

Most frequent non-serious adverse event terms

The registry reports zero serious adverse events in the IMU-controlled group, with 39 at risk, and zero serious adverse events in the EMG-PR-controlled group, with 13 at risk. It reports zero deaths in each group. For other adverse events, the record reports 5 affected in the IMU-controlled group, with 39 at risk, and 1 affected in the EMG-PR-controlled group, with 13 at risk. These are the counts recorded for the listed groups, not evidence that every possible event was absent.

The registry does not list serious adverse-event terms. The descriptions, timing, severity, relatedness, and resolution of the other adverse events are not reported in the registry record. The record also does not report how long each participant was observed for safety, or whether all participants had the same exposure to home use. Without those details, the counts cannot be interpreted as event rates over a common period.

Because allocation was nonrandomized and the registry cautions that the arms are not a like-for-like comparison, the counts should not be treated as a randomized comparison of device safety. The group sizes and eligibility descriptions differ, and the record provides no adjusted safety analysis. Zero recorded serious events is a description of the registry entries, not proof that serious events are impossible or that risk is absent.

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

The record establishes that the study was designed to examine home use of two advanced upper limb prosthetic device control configurations after supervised training. Its primary question concerned change in a QOL summary score about satisfaction with independent living and self-care activities. The scale's range and direction are specified: items run from 1, Terrible, to 7, Delighted, and higher summary values reflect higher satisfaction. The record also describes secondary measures and safety counts.

Those design details do not establish what happened to the primary score. The numerical change, standard deviation, confidence interval, and p-value are not reported in the registry record. It is therefore not possible to state whether the mean score rose or fell, how large any change was, how variable participants' scores were, or how precisely an estimate was determined. The record does not identify a threshold for meaningful change, so the clinical importance of a change cannot be assessed even if an estimate were available.

The study's nonrandomized design matters for any arm-to-arm interpretation. The registry cautions that the arms are not a like-for-like control comparison, and their descriptions specify different eligibility. Consequently, any observed difference between the arms would need to be interpreted in light of those design features; the registry record does not report an adjusted comparative analysis. The study also used an invitation to Part B for eligible subjects, so the population contributing home-use data may differ from the full group that entered supervised training. Participation and completion counts are not reported.

Likewise, the registry's adverse-event counts should be read as recorded counts, not as a complete account of safety or proof of equivalence between groups. The record does not provide event descriptions for serious events, exposure-adjusted rates, or comparative safety estimates. More generally, missing information about analysis populations, missing data, multiplicity, and statistical methods limits what can be inferred from the registry entry. The appropriate conclusion is that the record describes an intended evaluation and certain safety counts, while the primary outcome findings and their precision are not reported in the registry record.

14. Why This Trial Matters Statistically

This study raises statistical issues common to home-use evaluations of devices: the difference between an intervention's stated objective and a reported outcome, the interpretation of a nonrandomized comparison, and the importance of defining who contributed data. Its two-part structure is especially relevant. All participating subjects were to receive supervised training, but only eligible subjects were invited to home use, while the primary endpoint was timed to the end of that home-use period. Knowing the number who entered and completed each stage would help readers understand which participants the endpoint represents; those counts are not reported in the registry record.

The comparison also illustrates why arm labels do not by themselves make groups comparable. The registry identifies IMU and EMG-PR control configurations but explicitly warns that the arms are not a like-for-like control comparison. Their eligibility descriptions differ, and assignment was nonrandomized. Any arm contrast would therefore need an analysis and interpretation that recognize potential group differences rather than assuming randomization balanced them.

The QOL endpoint is a continuous summary of satisfaction ratings, which allows change to be described as a mean and its spread. But the score's definition is only one part of a statistical result. A useful interpretation also needs the observed estimate, its uncertainty, the analysis population, and the handling of incomplete assessments. Those primary results and methods are not reported in the registry record.

Finally, the registry lists many outcome measures and analyses and describes a planning illustration based on an observed effect. Distinguishing a planning illustration from an observed result is essential: planning values do not establish how informative the completed study's data were. The record does not provide the numerical illustration, the observed primary effect, or the trial's design-stage sample-size justification. These gaps make transparent reporting of analyses and results particularly important for readers assessing feasibility and future study design.

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.

Several limitations specific to this study follow from the information in the registry record. First, the two device-control groups were not randomized, and the registry cautions that they are not a like-for-like comparison. The arm descriptions also differ in eligibility. This restricts causal interpretation of any between-arm contrast and leaves uncertainty about whether group differences reflect the control configuration or other characteristics.

Second, the study's pathway from supervised training to invited home use makes the analysis population important. The record does not report how many subjects were eligible for Part B, accepted the invitation, completed home use, or contributed both baseline and endpoint measurements. Without these counts, selection into the home-use stage and attrition cannot be assessed. The method used to handle missing QOL items or missing follow-up scores is also not reported in the registry record.

Third, the record does not provide numerical results for the primary QOL endpoint or the listed secondary outcomes. It therefore offers no basis for evaluating the observed magnitude, variability, or precision of changes. A threshold for meaningful change is not reported either. Although 10 outcome measures and 42 analyses are listed, the protocol for choosing and adjusting analyses is not reported in the registry record.

Fourth, the safety record provides counts but not event descriptions for serious adverse events, event timing, exposure duration, or a comparative analysis. The absence of recorded serious events in the listed counts cannot establish absence of risk. Finally, the registry does not report the trial's design-stage sample-size justification, interim analyses, or full statistical plan. These limitations constrain interpretation of both the study's intended question and any claims about its results.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Home Study of an Advanced Upper Limb Prosthesis — NCT01551420.
• Registry record last updated 2019-04-30; status last verified 2019-04.
• Results first posted 2019-04-30.
• 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

NCT01551420 is a completed, nonrandomized, parallel study with no masking, sponsored by the VA Office of Research and Development. Enrollment is listed as 52. It examined supervised training and eligible subjects' subsequent home use of an advanced upper limb prosthetic device with IMU or EMG-PR controls. The primary endpoint was change in a 16-item QOL satisfaction summary score from baseline to the end of Part B, after 9-12 weeks of home use.

The registry lists 10 outcome measures and 42 analyses. It records zero serious adverse events and zero deaths in each group, and other adverse events affecting 5 in the IMU-controlled group and 1 in the EMG-PR-controlled group. The registry cautions that the nonrandomized arms are not a like-for-like comparison. Numerical results for the primary outcome, analysis populations, missing-data methods, and multiplicity procedures are not reported in the registry record.