Audiovisual Aid Pilot Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Audiovisual Aid Pilot Study (NCT02506673), a randomized na study. The primary outcome is Skin Conductance Response.

2. Clinical Question

3. Trial Design

This completed pilot study is registered as a randomized, parallel-group trial with no masking. It enrolled 26 participants: 13 assigned to sedation alone and 13 assigned to sedation plus audiovisual aids. The setting described in the registry is ambulatory meniscectomy under spinal anesthesia. The study start date is 2016-01-14, and the primary completion date is 2017-05. The registry lists the phase as not applicable.

Both groups were intended to receive traditional sedation with 2 mg of midazolam on arrival in the operating room. The audiovisual group was also asked to wear Zeiss Cinema ProMED equipment in the holding area. Both groups were to wear a skin conductance monitor. The planned monitoring aimed to capture responses continuously from the holding area through discharge from the post-anesthesia care unit, with summaries at five-minute intervals and selected perioperative events.

The trial had a pilot purpose: the investigators hoped to estimate outcomes and gather data that might inform future study planning. This purpose is distinct from establishing a definitive treatment effect. The primary skin-conductance data could not be analyzed conclusively because of repeated technical difficulties with the device, and collection was stopped. The registry record does not report a sample-size justification for the trial, the planned statistical analysis in detail, or whether any interim analyses were conducted.

Results are posted for two secondary outcomes: the number of participants requesting additional sedation and scores on the Heidelberg Peri-anaesthetic Questionnaire. The registry lists 13 outcome measures overall and 12 secondary outcomes posted, but numerical results are not reported for every listed measure. The study's open-label design is relevant when interpreting participant-reported outcomes and requests for additional sedation, because participants and clinical staff were not masked to group assignment.

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

Analysis population for the primary outcome, as defined in the registry: We had planned to use the Med-Storm Stress detector to measure skin conductance throughout the procedure until discharge. However, due to repeated technical difficulties with the device and inconclusive data from an analysis of a small number of patients data collection was stopped. No data are presented here.

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 Skin Conductance Response, measured over Measured in 5 minute intervals, from holding area until PACU discharge..

The primary endpoint was skin conductance response, expressed as skin conductance responses per second; response amplitude was also part of the planned assessment. Skin conductance is used as a physiological measure related to sympathetic activity. As a general statistical and measurement concept, a continuously recorded physiological signal can describe short-term changes that may be difficult to capture with a later questionnaire. The registry describes the intended measure as a way to observe changes across perioperative events and over time.

Measurements were planned in five-minute intervals from the holding area until discharge from the post-anesthesia care unit, as well as around specified events. These included intravenous insertion, discussion with the surgeon and anesthesiologist, arrival in the operating room, monitor application, sedative administration, spinal insertion, incision, and recovery. This timing was intended to characterize stress responses in relation to the perioperative course rather than relying only on a retrospective report.

The registry states that repeated technical difficulties with the Med-Storm Stress detector, together with inconclusive data from a small number of patients, led to stopping data collection. The posted arm records have no primary endpoint means, standard deviations, or interval estimates. Thus, although the endpoint and its intended use are described, the primary outcome does not support a numerical comparison between the randomized groups in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registered design is a randomized parallel-group comparison. Randomization is intended, in general, to make assigned groups comparable on average with respect to both measured and unmeasured baseline factors. In a small pilot, random allocation does not guarantee that the realized groups are closely balanced, and the registry record does not report participant characteristics with which to assess balance. The design is open-label: masking is listed as none. This matters because awareness of assignment can influence behavior, reporting, and decisions made during care, particularly for outcomes such as a request for additional sedation or a patient-experience questionnaire.

The primary endpoint was a continuous physiological measure: skin conductance responses per second, with response amplitude also planned. The registry specifies a mean and standard deviation for the primary outcome. A mean describes the average value in a group; a standard deviation describes how much individual measurements vary around that average. The primary outcome records contain no means or standard deviations, so a group mean difference and its precision cannot be interpreted from the posted primary results. The reason given is repeated device difficulty and inconclusive data from a small number of patients, followed by cessation of data collection.

For the binary secondary outcome, the registry reports the number of participants requesting additional sedation and the number in each group. A risk difference expresses the difference between group event proportions, in the order of the comparison recorded. General explanation: a risk difference of zero corresponds to equal observed proportions, while a value on either side of zero indicates a difference in opposite directions. The posted estimate is -0.154. Its 95% confidence interval is -0.504 to 0.196. Because that interval crosses zero, it does not rule out no difference under the interval's assumptions, and its breadth conveys substantial uncertainty. The unadjusted p-value is 0.395. It is a test statistic summary under a null hypothesis and model assumptions, not a measure of the size or practical importance of an effect.

For the questionnaire outcome, the measure is continuous and the posted comparison is a difference in group means. The group means are 97.2 and 98.9, and the estimated mean difference is 1.7. The 95% confidence interval, -7.617 to 11.02, includes zero. As a general explanation, a confidence interval gives a range of estimates compatible with the observed data and the procedure's assumptions; it is not a guarantee that the true value lies within that particular interval. The unadjusted p-value is 0.721. Neither the interval nor the p-value establishes that the groups are equivalent. An equivalence conclusion would require a specified margin and a design and analysis aimed at testing equivalence; these are not reported in the registry record.

The record also gives standardized and relative summaries for the secondary comparisons. General explanation: standardized mean differences express a mean contrast relative to variation, while relative measures such as risk ratios or odds ratios compare event occurrence on a relative scale. Their interpretation depends on the outcome and calculation assumptions. The posted values for the additional sedation outcome include a risk ratio of 0.6 with interval 0.179 to 2.007, and an odds ratio of 0.48 with interval 0.087 to 2.645. For the questionnaire, the standardized mean difference is 0.141. These are unadjusted summaries, and they do not overcome the small amount of information or the uncertainty in the primary outcome.

The accompanying sample-size figures are planning illustrations based on the observed effect, not the trial's own design calculation. The stated assumptions are a two-sided significance level of 0.05, equal allocation, a normal approximation, and detection of a stated fraction of the observed effect. The figures describe participants per arm for 80% or 90% power under those assumptions. They are not observed power, and they should not be read as a guarantee that a future study of those sizes would detect an effect. The observed pilot estimates may be unstable, particularly when based on few participants. The registry record does not report its original sample-size justification or a prespecified target effect for a definitive trial.

Several statistical details that would help assess reproducibility are not reported in the registry record. These include the specific tests or models used for the posted secondary comparisons, handling of missing observations, the analysis population, covariate adjustment, and any multiplicity procedure. The calculations shown for the posted comparisons are unadjusted re-calculations from summary statistics. They should be distinguished from any sponsor analysis; no discrepancy is flagged in the record. General statistical principle: when over-dispersion is present, a model that assumes less variability than the data contain may understate uncertainty, while a suitable variance model can account for extra variability. The record does not describe over-dispersion analyses, and the primary skin-conductance data are unavailable for such assessment.

What does an unadjusted comparison tell us?

An unadjusted comparison describes the contrast without accounting for other variables or multiple testing. It can be a useful descriptive summary, but its interpretation depends on the randomized design, the observed data, and the analysis assumptions. Randomization supports a causal comparison in principle, but it does not fix missing outcome data or automatically address the effects of multiple outcomes. The secondary estimates should therefore be understood as exploratory descriptions, not definitive treatment effects.

Why does the missing primary outcome matter?

The endpoint that motivated continuous physiological monitoring cannot be compared using the posted results. The secondary outcomes address related but distinct questions: requests for additional sedation and experience scores are not substitutes for the planned skin-conductance measure. As a general principle, outcome-specific evidence should not be transferred from one measure to another. The missing primary results leave the main physiological question unresolved in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a broad set of outcomes, including physiological measures, vital signs, requests for additional sedation, pain ratings, narcotic consumption, anxiety questionnaires, and a peri-anesthetic experience questionnaire. It reports 13 outcome measures and 12 secondary outcomes posted, but numerical results are not available in the registry record for every listed outcome. The primary skin-conductance values are also absent after data collection was stopped because of device difficulties and inconclusive data.

The registry record does not report whether the investigators prespecified a hierarchy among outcomes, adjusted for multiple comparisons, or treated any secondary outcome as confirmatory. General statistical explanation: assessing many outcomes can increase the chance of a result that appears unusual even when no true group difference exists. Multiplicity procedures or a clearly defined primary analysis can help control that issue. Without a reported procedure, the posted secondary p-values should be treated as unadjusted and exploratory, not as a complete set of confirmatory tests.

The record does not explain how missing outcome values were handled, whether participants were analyzed according to randomized assignment, or which analysis population was used. The questionnaire result includes 13 participants in one group and 12 in the other; the reason for this difference is not reported in the registry record. Missingness can affect an estimate if the participants with observed outcomes differ systematically from those without them. No imputation or sensitivity analysis is reported.

These reporting gaps are particularly important for a pilot with a primary outcome that could not be collected to a conclusive standard. The registry does not report interim analyses, a detailed statistical plan, or a sample-size justification. It therefore is not possible to assess whether all analyses followed a prespecified plan or how missing outcomes and multiple comparisons were intended to be addressed. The limitations do not invalidate the posted descriptive figures, but they restrict the strength of conclusions that can be drawn from them.

11. 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 adverse-event record lists 13 participants at risk in each group. It reports zero serious adverse events, zero other adverse events, and zero deaths in each group. These are the counts recorded for this trial; they should not be interpreted as proof that no adverse events occurred in any broader population or that uncommon events are excluded.

The enrollment was small, and the registry record does not describe event definitions, collection procedures, severity grading, or the duration of safety follow-up. It also does not provide serious adverse event terms. With these limitations, the figures are best read as the registry's recorded counts for the enrolled groups, not as a precise estimate of safety risk. They do not resolve the primary efficacy question or establish a difference in safety between the groups.

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

The registry record documents a randomized pilot comparing traditional sedation with the same sedation plus audiovisual equipment during ambulatory meniscectomy under spinal anesthesia. The main planned physiological outcome was skin conductance response, intended to be measured repeatedly across the perioperative period. Technical problems with the monitoring device and inconclusive data led investigators to stop collection. Because no primary outcome values are posted, the study does not provide a numerical estimate of whether the randomized groups differed on the primary stress measure.

Two secondary outcomes have posted numerical comparisons. Both are imprecise, and their confidence intervals include no difference. These estimates describe the observed pilot data; they neither establish a benefit nor prove that the approaches are equivalent. The registry does not report a clinically meaningful threshold for the questionnaire score or a detailed analysis plan for the secondary outcomes. The other listed outcomes do not have numerical results in the record, so no conclusion about their group comparisons can be drawn from this information.

The trial's pilot status matters. Pilot estimates can help describe feasibility and identify measurement challenges, but small studies often yield uncertain estimates of comparative effects. Here, the technical difficulties are themselves an important result about the feasibility of the planned primary measurement in this study. They do not establish that the device would fail in every setting, nor do they answer the clinical question about audiovisual aids and stress response.

In general, a randomized design can support causal inference when outcomes are measured and analyzed appropriately. In this record, randomization does not compensate for the missing primary data, incomplete numerical reporting across the listed outcomes, or the absence of reported detail about missing-data and multiplicity handling. The evidence should therefore be read as a limited and exploratory account of a small completed pilot, rather than as a definitive assessment of the audiovisual intervention.

13. Why This Trial Matters Statistically

This trial is statistically informative because it shows how a measurement problem can prevent a randomized study from answering its primary question. Skin conductance was selected to capture rapid physiological responses continuously, including responses around specific perioperative events. The registry's account of repeated technical difficulties and inconclusive observations led to stopping data collection. As a result, the primary endpoint is described in detail but has no posted group estimates. A clear endpoint definition is not enough when the measurement process does not yield analyzable data.

The pilot also illustrates the distinction between feasibility and comparative-effectiveness evidence. The study planned to generate outcome estimates and information for future power analyses. Its small enrollment and uncertain secondary comparisons provide descriptive information, but they do not establish a precise treatment effect. The posted planning illustrations are based on observed effects and assumptions; they are not observed power and are not the study's original sample-size justification.

Finally, the record highlights the importance of complete outcome and analysis reporting. Many secondary outcomes are named, while numerical results are posted for only two. The analysis populations, missing-data handling, multiplicity approach, and detailed statistical plan are not reported in the registry record. Those omissions limit the ability to assess how broadly the findings apply or how much confidence to place in exploratory comparisons. Statistically, the clearest lesson is that the primary result remains unavailable, while the secondary results are too uncertain and limited in scope to resolve that gap.

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.

Important limitations specific to this trial include the failure to obtain conclusive primary skin-conductance data. The registry attributes this to repeated technical difficulties with the monitor and inconclusive findings from a small number of patients, after which data collection stopped. Consequently, there is no posted estimate for the primary outcome and no way to assess its variability or compare groups on that endpoint.

The study enrolled 26 participants in total, so the posted secondary estimates are based on small groups. Their confidence intervals are broad and include the null value. The record does not report participant characteristics, detailed eligibility criteria, or the reason that the questionnaire outcome has 12 participants in one arm and 13 in the other. The extent or pattern of missing data for other outcomes is also not reported in the registry record.

The open-label design is another consideration. Participants and clinical staff were not masked, and some secondary measures involve behavior or reported experience. Expectations or awareness of assignment could influence such outcomes. The record does not report a detailed statistical plan, adjustment for covariates, analysis populations, missing-data methods, multiplicity control, or interim analyses. Numerical results are absent for many listed outcomes.

The study's setting and population are described as ambulatory meniscectomy under spinal anesthesia, but the record does not give information to assess how readily findings would generalize beyond that setting. These constraints mean that the study's available numerical findings are exploratory, while its primary physiological question remains unanswered in the posted results.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Audiovisual Aid Pilot Study — NCT02506673.
• Registry record last updated 2024-12-27; status last verified 2024-04.
• Results first posted 2020-02-10.
• 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

NCT02506673 is a completed, randomized, open-label, parallel-group pilot study sponsored by Hospital for Special Surgery, New York. It enrolled 26 participants undergoing ambulatory meniscectomy under spinal anesthesia. The comparison was traditional sedation with 2 mg of midazolam versus the same sedation plus audiovisual equipment; both groups were intended to wear a skin conductance monitor.

The primary endpoint was skin conductance response, measured repeatedly during the perioperative period. Device difficulties and inconclusive data led to stopping collection, and primary outcome values are not reported in the registry record. Numerical results are posted for requests for additional sedation and the Heidelberg Peri-anaesthetic Questionnaire, but both comparisons are unadjusted and uncertain. Numerical results for many other listed outcomes are not reported in the registry record. The adverse-event record lists no serious events, other events, or deaths in either group.