This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Resident Posture Biofeedback Study (NCT06564519), a na na study. The primary outcome is Change in Percentage of Minutes Spent in the Upright Position During Laparoscopic Procedures.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT06564519 |
| Phase | NA |
| Condition | Postural; Strain, Healthy |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 13 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Wake Forest University Health Sciences |
| Results posted | Yes |
2. Clinical Question
Population
Surgical residents are the study population. The registry lists an enrollment of 13 and describes one group of resident participants. Further participant characteristics, such as age, training level, or specialty, are not reported in the registry record.
Intervention
All resident participants use a posture biofeedback device. The registry identifies the intervention as a device but does not report details such as its feedback mechanism, how often it is used, or whether participants receive other accompanying instruction.
Comparator
This is a single-group study, not a comparison between a device group and a separate control group. The primary endpoint compares the Tracking Phase (Days 1-14) with the Training Phase (Days 15-28). The registry does not describe a randomized allocation or a concurrent control condition.
Primary question
The study asks whether the cumulative percentage of minutes spent upright during laparoscopic procedures differs between the two phases. The endpoint is defined as the Training Phase percentage minus the Tracking Phase percentage. The registry record does not report the observed change, its uncertainty, or a statistical test result.
The registry’s stated rationale is that surgical ergonomics have been studied less often among residents than among attending surgeons, and that biofeedback paired with education could be directed toward residents. The primary question is specifically about posture during laparoscopic procedures, rather than a direct comparison of pain outcomes or a comparison with usual practice. The record also lists self-reported musculoskeletal pain outcomes, including a general pain score and scores for neck, right shoulder, and left wrist pain. These are secondary outcomes; the record does not report their numerical results.
Because the design has one group and the primary comparison is between phases, the clinical question is about change over time within the study, not the effect of the device relative to a separate untreated group. A change could be described only from the phase measurements, and the registry record does not provide those measurements or an estimated change. It also does not report whether any change was assessed at the participant level or only by combining measurements across procedures.
3. Trial Design
The registry describes the Resident Posture Biofeedback Study as a completed, single-group study with an enrollment of 13. The listed study intervention is the Posture Biofeedback Device, and the arm description says that all resident participants use it. The allocation entry is NA, the masking entry is NONE, and the phase entry is NA. These entries do not describe a randomized, masked comparison between separate intervention and control groups.
The study’s primary endpoint uses two sequential periods. During the Tracking Phase (Days 1-14), the cumulative percentage of minutes spent upright during laparoscopic procedures is recorded. During the Training Phase (Days 15-28), the corresponding cumulative percentage is recorded again. The primary outcome is defined as the Training Phase percentage minus the Tracking Phase percentage. The registry describes each period as two weeks. It does not explain the practical transition between phases, the device’s feedback schedule, or the criteria for which procedures contribute measurements.
The study began on 2024-09-26, reached primary completion on 2025-11-02, and has a registry status of COMPLETED. The record lists postural strain and healthy as conditions. It identifies Wake Forest University Health Sciences as the sponsor. The brief summary discusses the potential relevance of ergonomics and biofeedback for surgical residents, but a rationale is not itself evidence of an outcome.
The single-group structure means that the within-study phase comparison does not supply a concurrent control for changes that could occur over time for reasons other than the device. The registry does not report a randomization procedure, a control group, or masking. It also does not report the protocol’s sample-size justification, a statistical analysis plan, interim analyses, or a description of how participant-level observations were handled. Those details should not be inferred from the phase names or from the fact that the registry marks the study completed.
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.
Tracking Phase
| Stage | Residents |
|---|---|
| STARTED | 13 |
| COMPLETED | 13 |
| NOT COMPLETED | 0 |
Training Phase
| Stage | Residents |
|---|---|
| STARTED | 13 |
| COMPLETED | 12 |
| NOT COMPLETED | 1 |
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.
| Characteristic | Unit | Residents |
|---|---|---|
| Participants analysed | 13 | |
| Age, Continuous | years | 30.1 (SD 2.7) |
| Sex: Female, Male: Female | Participants | 12 |
| Sex: Female, Male: Male | Participants | 1 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 1 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 12 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Change in Percentage of Minutes Spent in the Upright Position During Laparoscopic Procedures, measured over Tracking Phase (Days 1-14) and Training Phase (Days 15-28).
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | percentage points of minutes |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the change in the cumulative percentage of minutes spent in an upright position during laparoscopic procedures. It compares the Training Phase (Days 15-28) with the Tracking Phase (Days 1-14), with the tracking-phase value subtracted from the training-phase value. The unit is percentage points of minutes. A positive value under this definition would indicate a higher cumulative upright percentage in the training phase; a negative value would indicate a lower one. This explains the direction of the measure, not the result of this study.
Posture during procedures is the behavior the device is intended to address, so measuring upright time gives a direct behavioral endpoint related to the study’s stated focus. Expressing the endpoint as a percentage makes the measure relative to the time captured during procedures, rather than a raw count of upright minutes. The registry does not provide the phase-specific percentages, the number or duration of procedures contributing data, or the observed difference. Therefore the size and precision of any change cannot be described from the registry record.
The endpoint is a phase-level comparison, but the record does not report whether its analysis preserves individual residents’ measurements, accounts for repeated procedures, or adjusts for procedure-level differences. Those choices affect how uncertainty should be estimated. The registry also does not state a threshold for a meaningful change. The endpoint can describe a difference in measured posture, but the record alone does not establish how such a difference relates to musculoskeletal pain or longer-term outcomes.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies the primary outcome and its comparison periods but does not report the numerical results. There is no posted estimate of the change in upright time, no confidence interval, and no p-value in the record. Consequently, the direction, size, and precision of the primary outcome cannot be assessed. The study status of COMPLETED does not substitute for a reported endpoint result.
The outcome definition sets the sign convention: the training-phase percentage minus the tracking-phase percentage. In general, a value above zero would represent a higher measured upright percentage in the training phase, while a value below zero would represent a lower value. No such observed value is reported, so neither direction can be attributed to this study. The same restraint applies to the secondary measures. The registry lists changes in self-reported musculoskeletal pain, including neck, right shoulder, and left wrist measures using CMDQ composite weighted scores, but it does not give their results.
Even if a phase difference were reported, this design would describe a before-and-after pattern in one group rather than a randomized contrast with a separate control group. A change across the two periods could coincide with the device’s use, but a single-group comparison by itself cannot distinguish the device’s contribution from other changes over time. This is a general limitation of sequential within-group comparisons, not a claim about what occurred among these residents. The record does not report information that would permit assessment of such alternative explanations.
Precision also cannot be judged from the enrollment figure alone. The registry does not report the variability of the endpoint, participant-level outcome data, the number of procedures contributing to the measure, or an uncertainty interval. Without these, a reader cannot determine whether an estimate, if available elsewhere, would be tightly or weakly determined. A general statistical principle is that an estimate’s uncertainty depends on both the amount and structure of the data, not merely on a single enrollment figure. Here, the measurement structure is not fully described.
The record lists five outcome measures and five analyses, but does not report how the results were analyzed or whether adjustment for multiple outcome testing was planned. That omission matters when interpreting a collection of results because the chance of at least one apparently notable finding can increase when many outcomes are tested. This is a general concern; it does not establish that any particular result is false or that an adjustment was required. The registry does not state the prespecified hierarchy or inferential approach.
Overall, the record supports a description of the study question and design, not a conclusion about whether posture changed or whether pain changed. No treatment benefit or lack of benefit can be inferred from the absence of reported results. The clinical interpretation remains undetermined in the registry record.
9. Statistical Methods Explained
The registry describes an outcome based on a cumulative percentage and a difference between two phases. The endpoint is not a comparison of separate randomized groups: it is the training-phase percentage minus the tracking-phase percentage in a single-group study. The study record does not provide enough information to identify the exact statistical model or test used. The concepts below explain general considerations for this type of outcome and should not be read as a description of an analysis that the registry confirms was performed.
What does the phase difference represent?
A difference between two measurements is a way to express change on the scale of the measurement. Here, the scale is percentage points of minutes spent upright during laparoscopic procedures. The definition gives the order of subtraction, which determines the direction of a difference. It does not by itself indicate whether the change is large, meaningful, or statistically distinguishable from random variation. Those judgments require an estimate and information about its uncertainty, neither of which is reported in the registry record.
Percentage points describe an absolute difference between two percentages. General statistical usage distinguishes this from a relative percent change, which would express a change in relation to a starting value. The registry explicitly defines the endpoint in percentage points of minutes and does not state a relative change measure. No conversion or alternate scale should be assumed.
Why does the data structure matter?
Posture measurements may be collected repeatedly within procedures and across residents, but the registry does not report the measurement-level structure. In general, observations from the same person or procedure can be correlated: one observation may tend to resemble another because they share a participant or context. Treating correlated observations as independent can make uncertainty estimates too small. A suitable analysis often needs to reflect the actual unit of observation and the clustering or repetition in the data. The record does not describe whether the analysis did this, or what unit was used.
A phase-level cumulative percentage could be calculated from underlying time observations in different ways. For example, combining all observed minutes before forming a percentage need not produce the same result as calculating participant-specific percentages and then summarizing those values. These approaches answer different weighting questions. The registry gives the endpoint’s cumulative definition but does not explain how measurements were aggregated across residents or procedures. It is therefore not possible to infer which participants or procedures contributed most to the endpoint.
Repeated measurements can also be analyzed by preserving the pairing between observations from the same participant. In general, a paired analysis can account for stable person-level differences when comparing phases, while an analysis that treats phase summaries as unrelated would use a different model of the data. The registry does not report whether participant-level pairing was available or retained. It would be inappropriate to assign a paired test or any other specific method based only on the study design description.
What does a confidence interval communicate?
In general, a confidence interval gives a range of values compatible with an estimate under the assumptions of the statistical procedure. It conveys uncertainty as well as the direction and scale of an estimated difference. A narrow interval indicates greater precision under that method; a wide interval indicates less precision. An interval that includes no difference does not prove that the true difference is exactly zero. Conversely, excluding no difference does not by itself establish clinical importance. The registry record does not report a confidence interval for the primary endpoint, so precision cannot be evaluated.
A p-value, in general, measures how unusual data at least as incompatible with a specified null model would be if that model and the analysis assumptions were correct. It is not the probability that the null hypothesis is true, and it does not quantify the size or practical importance of an effect. No p-value or null hypothesis for the primary endpoint is reported in the registry record. A statistical significance conclusion therefore cannot be drawn.
Why can over-dispersion matter?
Over-dispersion is a general issue when observed variability exceeds what a chosen statistical model expects. A model that understates variability can overstate precision and make inferential results appear stronger than warranted. The relevant variance structure depends on the outcome and its sampling process. The primary endpoint is expressed as a percentage, but the record does not report a model, variance estimate, or diagnostic assessment. There is no basis for claiming that over-dispersion occurred or that a particular correction was used. The general lesson is that the analysis should match the observed measurement process and variability.
How should planning illustrations be read?
The registry’s planning description characterizes its sample-size illustration as based on the observed effect, using 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. For non-time-to-event outcomes, the described quantity is participants per arm; for time-to-event outcomes, it is total events. These are planning assumptions, not a report of the trial’s actual design or observed power.
Those assumptions refer to two arms, while the registered study is described as single-group. The illustration should therefore not be interpreted as a description of the enrollment plan for this study. The numerical illustration and the observed effect are not reported in the registry record. Because its underlying effect is not available, its practical implications cannot be evaluated. In general, a sample-size calculation depends on assumptions about the target effect, variability, allocation, and statistical test; it does not establish that a study has a particular probability of finding a result after data collection.
Finally, a planning calculation is distinct from an analysis of collected outcomes. It does not supply an estimate, confidence interval, or test result. The registry does not report whether the planning assumptions were part of the protocol, whether they were revised, or whether any interim analyses were conducted. Such details should not be inferred from the planning description.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists five outcome measures and five analyses. The primary measure concerns change in the percentage of minutes spent upright during laparoscopic procedures. The listed secondary measures concern self-reported musculoskeletal pain, including a general score and CMDQ composite weighted scores for neck, right shoulder, and left wrist pain. No numerical results for these outcomes are reported in the registry record.
When several outcomes are analyzed, general statistical practice distinguishes the primary question from secondary or exploratory questions and considers how multiple testing will be handled. Testing many outcomes can increase the chance of at least one apparently notable finding under a collection of null effects. Methods such as prespecifying a hierarchy or adjusting inference can address particular multiplicity concerns, but the choice depends on the study’s aims and analysis plan. The registry record does not report a multiplicity procedure, an outcome hierarchy beyond identifying a primary measure, or whether the five analyses represent all planned analyses.
The registry does not report how missing posture measurements or missing pain responses were handled. It also does not state whether all enrolled participants were included in each analysis, what analysis populations were defined, or how incomplete follow-up was handled. These omissions prevent assessment of whether the analyzed data could differ systematically from the intended measurements. Missingness can affect both the estimate and its uncertainty, especially if the reason observations are unavailable is related to the outcome. This is a general concern, not evidence that missing data occurred in this study.
The record therefore does not support a judgment about multiplicity control, missing-data methods, or analysis populations. These details are not reported in the registry record and should not be posted by assumption.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Residents | 0 | 13 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Residents | 0 of 13 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Residents | 0 of 13 |
The adverse-event record lists Residents as the group. It reports 13 at risk for serious adverse events and zero affected, and 13 at risk for other adverse events and zero affected. Deaths are listed as 0. No top serious-event terms are listed. These are the registry’s reported counts; they are not evidence that no adverse events of any kind occurred outside the scope of what was recorded.
In general, an adverse-event count describes events captured and entered under the registry’s reporting definitions and observation procedures. It does not by itself show how actively events were sought, how long participants were monitored, or whether participants experienced symptoms that were not classified or reported as adverse events. The record does not provide those details. Nor does it report event severity beyond the serious-versus-other categories in this entry.
Zero reported events should therefore be read literally as zero events recorded in the listed categories, not as proof of zero risk. The record does not provide a comparison group, and the adverse-event figures cannot establish whether the device caused or prevented any event. These counts are separate from the listed self-reported musculoskeletal pain outcomes; those outcomes are not reported numerically in the registry record.
12. What the Result Does, and Does Not, Mean
The record establishes that a completed single-group study evaluated a posture biofeedback device among surgical residents. Its primary outcome was a defined phase-to-phase comparison of upright time during laparoscopic procedures. The registry also identifies musculoskeletal pain as a secondary outcome area. However, the record does not report numerical results for the primary endpoint or the secondary outcomes. It therefore does not show whether posture or self-reported pain changed.
The endpoint definition explains how a change would be calculated and interpreted directionally, but a definition is not an observed result. There is no reported estimate, interval, or test result from which to assess the amount of change or its precision. The registry status of COMPLETED indicates the recorded study status; it does not fill in missing outcome results. The adverse-event entry records zero serious events, zero other events, and zero deaths in the listed group, but that entry should not be expanded into a claim that no harms occurred.
Even with numerical phase results, the single-group design would not by itself establish that the device caused a change. The two phases are sequential, and the registry does not report a concurrent control group or random allocation. General changes over time or differences in the procedures observed in each phase could also matter. This design limitation concerns causal interpretation; it does not show that any particular alternative explanation actually occurred.
The study can still be understood as an evaluation of a measurable posture outcome in a resident population, with pain outcomes also listed. Its statistical contribution in the available registry record is primarily the specification of the question and endpoint, not evidence for or against a treatment effect. No conclusion about clinical benefit, lack of benefit, or long-term musculoskeletal outcomes follows from the information recorded.
13. Why This Trial Matters Statistically
This study is statistically notable for asking a focused behavioral question in a population the registry’s rationale describes as less frequently studied in surgical ergonomics than attending surgeons. Its primary endpoint is expressed as a cumulative percentage of minutes spent upright, and it compares measurements from a tracking period with measurements from a training period. That makes the estimand—the quantity the study aims to describe—important: the record specifies a phase difference, not a randomized device-versus-control contrast.
The single-group structure illustrates why endpoint definition and design need to be read together. A clearly defined phase difference can describe change, but causal attribution requires more than a before-and-after contrast. Without a concurrent comparison group, the study cannot, from its design alone, separate the device’s contribution from other changes occurring across phases. This is a general interpretation issue and does not determine what the observed data would show.
The outcome also raises general questions about aggregation and repeated measurements. Posture can be measured during procedures and among residents, but the registry does not describe the observation-level data or its analysis. How repeated observations are combined and how their dependence is handled can affect both the estimate and its uncertainty. The record’s missing numerical results and analysis details mean these questions remain unresolved for this study.
Finally, the record lists a primary endpoint alongside pain outcomes, yet does not report results or multiplicity methods. This makes clear why a prespecified statistical plan and transparent outcome reporting matter: readers need to distinguish the main question from additional analyses and to assess precision, missing data, and the limits of inference. The registry record identifies the questions, but does not report the statistical evidence needed to answer them.
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 direct limitation for interpretation is that the registry record does not report the primary endpoint estimate or numerical results for the listed secondary outcomes. Without these, the magnitude, direction, and precision of changes cannot be assessed. The record also does not provide confidence intervals, p-values, or participant-level data.
The design is single-group, with the primary outcome comparing a tracking phase and a training phase. The registry does not report a concurrent control group or random allocation. Consequently, even a reported phase difference would not isolate the device’s effect from other time-related changes. Masking is listed as NONE, and the record does not describe any steps to reduce the influence of awareness of the intervention on measurement or reporting.
The endpoint is based on cumulative percentages during laparoscopic procedures, but the registry does not explain how the underlying measurements were aggregated, how repeated observations were handled, or how many procedures contributed data. It also does not report the variability of the outcome or the analysis model. These omissions limit evaluation of statistical precision and of whether the analysis reflected the measurement structure.
The registry does not report the sample-size justification for the study, a statistical analysis plan, interim analyses, missing-data methods, or analysis populations. The separate planning description assumes equal allocation between two arms, while the registered study is single-group; it should not be treated as the study’s own design calculation. The record also does not provide participant characteristics or detailed device-use procedures. These gaps constrain interpretation without establishing that any particular method or practice was deficient.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Resident Posture Biofeedback Study — NCT06564519.
- Registry record last updated 2026-11-05; status last verified 2025-11.
- Results first posted 2026-11-05.
- 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.
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18. Record Summary
NCT06564519 is the registry record for the Resident Posture Biofeedback Study, sponsored by Wake Forest University Health Sciences. It describes a completed, single-group study with an enrollment of 13 surgical residents. All resident participants use a posture biofeedback device. The allocation entry is NA, masking is listed as NONE, and phase is listed as NA.
The primary endpoint compares the cumulative percentage of minutes spent upright during laparoscopic procedures in the Tracking Phase (Days 1-14) with the Training Phase (Days 15-28), defined as training minus tracking. Listed secondary outcomes concern self-reported musculoskeletal pain, including neck, right shoulder, and left wrist scores. Numerical outcome results and statistical uncertainty are not reported in the registry record.
The study began on 2024-09-26, had primary completion on 2025-11-02, and is listed as COMPLETED. The adverse-event entry reports zero serious events, zero other events, and zero deaths in the Residents group. The record does not report the statistical analysis plan, missing-data approach, or multiplicity method.