SR-WBV Training for Frail Elderly in the Skilling up Stage: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for SR-WBV Training for Frail Elderly in the Skilling up Stage (NCT01704976), a randomized na study. The primary outcome is Physical Functional Performance.

2. Clinical Question

The study’s brief summary describes an aim to examine longer-term effects during a 4-week “skilling up” phase, focusing on physical functional performance and strength. Its title also mentions dance therapy. However, the listed arm descriptions identify an SR-WBV intervention and an SR-WBV sham; they do not describe a dance therapy arm. The record therefore does not establish a direct comparison between vibration and dance therapy.

The primary endpoint concerns lower-extremity function relevant to everyday tasks. Secondary outcomes concern isometric knee-extension force and rate of force development on both sides. These measures address aspects of strength and force production, but no results for them are reported in the registry record. The clinical question can therefore be described from the registered aims and endpoints, but the posted information does not answer whether the arms differed in physical function or strength.

3. Trial Design

This was a randomized, parallel-group study with single masking. The registry lists an enrollment of 27 and a status of completed. The study start is recorded as 2012-09, and primary completion as 2014-07. The record names Bern University of Applied Sciences as sponsor and lists the phase as not applicable.

The two arm descriptions specify a 4-week intervention period. The intervention arm received SR-WBV at 5 Hz with noise 4; the sham arm received SR-WBV at 1 Hz with noise 1. The record does not identify who was masked, describe how randomization was generated or concealed, or explain whether masking was assessed. Those procedural details are not reported in the registry record.

The primary outcome was physical functional performance measured after 4 weeks using the Short Physical Performance Battery. The primary outcome is summarized in the record as a median with an inter-quartile range, but the group values and a treatment comparison are not reported. The registry lists four secondary outcomes: isometric maximum voluntary contraction for right and left knee extension, and isometric rate of force development for right and left knee extension.

The brief summary refers to vibration and dance therapy, while the listed interventions and arm descriptions concern SR-WBV and sham SR-WBV. The actual arm descriptions are the clearest account of the registered comparison; a dance therapy arm is not described there. Further details about participant eligibility, treatment frequency, adherence, follow-up beyond the stated endpoint, and analysis procedures are not reported in the registry record. The record lists five outcome measures and five analyses, but it does not provide enough information to determine which analysis corresponds to each outcome or how results were handled.

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

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 Physical Functional Performance, measured over after 4 weeks.

The primary endpoint is physical functional performance after 4 weeks, measured with the Short Physical Performance Battery (SPPB). The record describes three components: standing balance, usual walking speed, and the ability to stand from a chair. Balance is assessed through semi-tandem, side-by-side, and full tandem stands. Together, these tasks cover lower-extremity function used in activities relevant to independent living.

The stated score ranges from 0 (worst performance) to 12 (best performance). The registry describes SPPB 0-6 as “Poor performance,” SPPB 7-9 as “Intermediate performance,” and SPPB 10-12 as “High Performance.” These categories give context for interpreting a score, while a group comparison would be needed to describe how the arms differed after treatment.

The registry specifies a median and inter-quartile range as the summary measures for this endpoint. A median describes the middle of the observed scores after ordering them; the inter-quartile range describes the spread of the central part of the observations. These summaries can be useful when an outcome’s distribution is skewed or when extreme values make a mean less representative. That is a general statistical consideration, not a reported rationale for the registry’s choice.

The endpoint is relevant to the study’s stated focus on physical function, but its result is not reported in the registry record. Without group summaries, an effect estimate, or uncertainty around a comparison, the endpoint definition alone cannot show the size or precision of any difference.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Randomization assigns participants to study arms by chance. In general, random allocation aims to make the groups comparable with respect to both measured and unmeasured characteristics, although chance imbalances can remain, especially in a study with limited enrollment. The registry labels this study randomized but does not report the sequence-generation method, allocation concealment, or whether randomization was stratified. Those details are not reported in the registry record.

A parallel-group design means that participants are assigned to one arm and assessed under that assigned arm, rather than crossing between treatments. The record describes an intervention and a sham group. The intervention is SR-WBV at 5 Hz with noise 4, while the sham is described as SR-WBV at 1 Hz with noise 1. Because both arm descriptions use SR-WBV, this is not described as a comparison with no device intervention. The registry does not report whether the sham setting was intended to mimic the experience of the intervention or whether its credibility was evaluated.

Single masking means that masking was recorded at one level, but the registry does not specify whose knowledge of group assignment was restricted. In general, masking can reduce the influence of treatment expectations on behavior, measurement, or assessment. Its effectiveness depends on the procedures used and whether the treatment can be distinguished. Without the identity of the masked party or details of masking procedures, the extent to which masking could have reduced bias cannot be assessed.

What does the primary summary measure describe?

The registry describes the primary outcome using a median and inter-quartile range. A median is the central observation after values are ordered. The inter-quartile range describes the spread from the lower to the upper quartile. These summaries focus on the distribution of scores without requiring that it be symmetric. In general, they are useful when a distribution may be skewed or include unusually high or low observations. The registry does not state why these summaries were selected or report the values for either arm.

The SPPB score combines information about balance, walking speed, and chair stands. Its stated range is 0 (worst performance) to 12 (best performance). The registry also gives performance categories: 0-6 is “Poor performance,” 7-9 is “Intermediate performance,” and 10-12 is “High Performance.” A score’s meaning depends on how it is distributed in the study population, and a comparison between arms requires reported group data and a defined analysis. Those results are not reported in the registry record.

How should an effect estimate and interval be read?

In general, an effect estimate expresses the size and direction of a comparison between study arms. A confidence interval expresses uncertainty around that estimate under the assumptions of the statistical method. A narrower interval indicates greater precision, while a wider interval indicates more uncertainty. An interval is not a guarantee that the true effect lies within its limits, and it does not by itself determine whether an effect matters clinically.

The registry record does not report an effect estimate or confidence interval for the primary endpoint. It therefore does not allow readers to assess either the magnitude of a between-arm difference or its precision. A p-value, if reported, would address compatibility with a statistical null model under the analysis assumptions; it would not convey the size or practical importance of an effect on its own. No primary outcome p-value is reported in the registry record.

What do the planning assumptions mean?

The stated planning illustrations use a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. They are described as calculations based on the observed effect, with the effect to detect set to a stated fraction of that effect. The stated illustration approach is not a report of the trial’s original sample-size justification. That justification, including any rationale for the planned enrollment, is not reported in the registry record.

Sample-size planning asks how many participants would be needed under specified assumptions to detect a particular effect with a chosen probability, if the assumptions hold. That probability is a planning property, not “observed power” calculated after the trial. Planning illustrations based on an observed effect can change substantially when the assumed effect changes, and their relevance depends on the reliability of the effect estimate and the assumptions used. The registry record does not report a numerical effect estimate for the primary outcome, so the planning assumptions alone cannot establish the trial’s ability to answer its primary question.

The record does not state whether over-dispersion, departures from a normal approximation, or other distributional features were considered. In general, over-dispersion means that variability is greater than a model expects. If it is ignored, standard errors and uncertainty estimates may be too small. This is a general explanation; the registry does not report an over-dispersion assessment for this study.

What analysis details are unavailable?

The record lists five analyses and five outcome measures, but does not report model specifications, covariate adjustment, handling of baseline values, or the precise contrast used for the primary endpoint. It also does not explain how missing measurements, protocol deviations, or participants who did not complete the intervention were handled. Those details are important for understanding how an estimate was produced and which participants contributed to it. They are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary outcome and four secondary outcomes. Considering several outcomes can raise a multiplicity issue: when many hypotheses are tested, the chance of at least one apparently unusual result can increase. In general, a study may address this by prespecifying a primary comparison, adjusting inference across tests, or treating secondary results as exploratory. The registry record does not report whether any multiplicity strategy was planned or used.

The record lists five outcome measures and five analyses, but it does not identify the statistical method for each analysis or explain how the primary and secondary analyses relate to one another. It also does not report whether there were additional time points or subgroups considered in the analysis. The primary endpoint is described at after 4 weeks, and the record notes that the primary outcome has several categories or time points and was not reduced to one comparison. No single primary comparison is therefore available for interpretation from the posted results.

Missing-data handling is not reported in the registry record. The record does not state how many primary outcome measurements were missing, why any were missing, or whether missing values were imputed, excluded, or handled through a model. In general, missingness can affect an estimate if the availability of measurements is related to participants’ outcomes or group assignment. Without counts and methods, the potential influence cannot be assessed.

The analysis population is also not reported. The registry does not say whether the primary analysis included everyone as randomized, only participants who completed treatment, or another defined group. The adverse-event at-risk counts are not the same as the overall enrollment figure, but the record does not explain the difference or connect those denominators to the primary outcome analysis. Thus, the number of participants contributing to the primary endpoint and the treatment of exclusions are not reported in the registry record.

11. 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.

The registry lists zero serious adverse events among 13 participants at risk in the intervention group and zero among 11 at risk in the sham group. It also lists zero other adverse events in each group, using the same at-risk counts. No serious adverse event terms are listed. Death counts are not reported in the registry record.

These entries describe the events recorded in the registry, not evidence that the interventions carry no risk. In general, an event count of zero in a study does not establish that an event is impossible; the ability to detect uncommon events depends on the amount and duration of observation. The registry does not report detailed adverse-event definitions, collection procedures, observation duration for safety, or reasons for the at-risk denominators.

The overall enrollment is recorded as 27, whereas the safety entries list 13 and 11 participants at risk in the respective groups. The record does not explain why these denominators differ from enrollment or whether they reflect the safety analysis population. No conclusions about comparative safety can be drawn from the zero counts alone, particularly without fuller information about follow-up and event ascertainment.

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

The registry record describes a randomized comparison of two SR-WBV settings in frail older people, with an SPPB assessment after 4 weeks. It defines the primary outcome and lists secondary measures of knee-extension force and force development. These details show the study’s intended focus and the outcomes selected to examine it.

The result itself is not reported in the registry record. There are no primary endpoint group summaries, between-arm effect estimate, uncertainty interval, or primary outcome test result. Accordingly, the posted information cannot show whether physical functional performance differed between the intervention and sham groups, how large any difference was, or how precisely it was estimated. It also cannot establish whether the secondary strength outcomes differed.

The endpoint’s score range and performance categories help explain how SPPB results would be described. They do not substitute for the missing group data. Likewise, the randomized design is a method intended to support a fair comparison, but design labels alone do not demonstrate that allocation was implemented without bias or that the analysis preserved the advantages of randomization.

The registry’s brief summary mentions dance therapy, but the arm descriptions list SR-WBV and sham SR-WBV. Since no dance therapy arm is described, the record does not support interpreting the listed comparison as a test of vibration against dance therapy. Details about who was masked, participant adherence, missing measurements, and the primary analysis are also not reported.

The appropriate interpretation is therefore limited to the study’s registered design and outcome definitions. No claim that either intervention improved or failed to improve function can be drawn from these entries. The absence of posted results is not evidence of no effect; it means that the effect and its uncertainty cannot be evaluated from the registry record.

13. Why This Trial Matters Statistically

This study is statistically interesting because it combines a randomized comparison with an outcome intended to capture several aspects of lower-extremity function. The SPPB covers balance, walking speed, and chair stands, rather than measuring only one aspect of physical performance. Its scale and categories provide a framework for describing functional status, while the trial’s comparison would require the actual arm-level results and an appropriate analysis.

The two arms are described as different SR-WBV settings, including a sham setting. That detail matters for defining the estimand: the question represented by the comparison is not simply device use versus no device use, but the outcome under the listed intervention setting compared with the listed sham setting. The registry does not report enough information to assess how the sham was implemented or how participants experienced it.

The contrast between the study’s stated aim and the available record is also important. The brief summary mentions dance therapy, but the listed arms do not describe a dance therapy group. Clear alignment among the study question, intervention descriptions, outcomes, and analysis is essential for interpreting a trial. The record leaves that alignment uncertain.

From a statistical perspective, the primary endpoint results, uncertainty, missing-data approach, analysis population, and multiplicity strategy are all necessary to assess the strength of evidence. These details are not reported in the registry record. This makes the study useful as an example of how a clearly named endpoint and randomized design do not, by themselves, permit an efficacy interpretation when outcome results and analysis methods are unavailable.

The adverse-event entries also illustrate why denominators and observation procedures matter. Zero recorded events can only be interpreted in relation to who was monitored and how events were collected. The registry lists different at-risk counts from overall enrollment, without an explanation. That uncertainty limits the safety interpretation as well as the interpretation of the outcome analyses.

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 most important limitation for interpreting this trial is that the registry record does not report primary or secondary outcome results. Without group summaries and a comparison estimate, the magnitude, direction, and precision of effects cannot be evaluated. The endpoint’s measurement description is available, but the data needed to answer the clinical question are not.

The intervention descriptions also leave uncertainty about the trial’s intended comparison. The brief summary and official title mention dance therapy, while the listed arms describe two SR-WBV settings. A dance therapy arm is not described in the registry record. The record does not clarify this discrepancy, so the intervention contrast should be read from the arm descriptions rather than inferred from the title or summary.

Important design and conduct details are not reported: the randomization procedure, allocation concealment, identity of the masked party, participant eligibility criteria, treatment frequency, adherence, and follow-up beyond the primary endpoint. The record does not explain the sample-size rationale or identify the protocol’s statistical analysis plan. These omissions prevent assessment of whether planned methods were followed.

Analysis details are limited. The registry does not report the model, covariate adjustment, analysis population, missing-data handling, or any multiplicity strategy. It lists five outcome measures and five analyses without describing their correspondence. The statement that the primary outcome has several categories or time points and was not reduced to one comparison further limits interpretation of a single primary contrast.

The safety entries use at-risk denominators that differ from the recorded enrollment, and the reason is not reported. Death counts are also not reported. Consequently, neither the primary outcome nor the safety entries can be interpreted with the detail needed to assess the completeness of follow-up or the precision of comparisons.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: SR-WBV Training for Frail Elderly in the Skilling up Stage — NCT01704976.
• Registry record last updated 2019-02-12; status last verified 2019-01.
• Results first posted 2014-12-24.
• 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.

18. Record Summary

The registry record describes a completed randomized, single-masked, parallel-group study sponsored by Bern University of Applied Sciences. It records enrollment of 27, a study start of 2012-09, and primary completion in 2014-07. The population is described as frail older people, with poor performance status and muscle weakness listed as conditions.

The intervention arm received SR-WBV at 5 Hz with noise 4 for 4 weeks; the sham arm received SR-WBV at 1 Hz with noise 1 for 4 weeks. The primary outcome was physical functional performance after 4 weeks, measured with the SPPB and summarized in the record as a median and inter-quartile range. Four secondary outcomes concern isometric knee-extension force and rate of force development.

Primary and secondary outcome results, analysis details, missing-data methods, and the analysis population are not reported in the registry record. The adverse-event entries list zero serious and zero other adverse events in both groups, with death counts not reported. The brief summary mentions dance therapy, but the listed arm descriptions do not identify a dance therapy arm.