Perioperative Virtual Reality for Pediatric Anesthesia: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Perioperative Virtual Reality for Pediatric Anesthesia (NCT03583450), a randomized na study. The primary outcome is Perioperative Pediatric Anxiety (Change From Baseline).

2. Clinical Question

The statistical question is whether the posted change-from-baseline summaries differ between the headset group and the control group, and how precisely any difference can be estimated. The registry gives a median of 0.0 units for the headset group, with an inter-quartile range from 0.0 to 0.0, and a median of 5.0 units for control, with an inter-quartile range from 0.0 to 10.0. These are descriptive summaries, not a reported estimate of a randomized-group contrast. The record does not specify whether change was calculated as follow-up minus baseline or baseline minus follow-up. Because that convention determines how to read the direction of a change, the posted summaries alone do not establish whether anxiety increased or decreased in either group.

3. Trial Design

The registry describes a randomized, parallel-group trial with no masking. The intervention group received a perioperative virtual reality headset with a mobile app and routine anesthetic care; the control group received routine anesthetic care. The listed enrollment is 71. For the primary outcome, the posted group summaries give 33 participants in the headset group and 37 in control. The registry record does not explain the relationship between the enrollment figure and the group counts reported for this outcome.

The study is listed as completed. The registry gives a start date of 2018-08-29 and a primary completion date of 2019-03-27. Its phase is listed as not applicable. The sponsor is the University of California, San Francisco. The brief description places the study at UCSF Benioff Children's Hospital and describes pediatric patients undergoing elective surgery.

Random allocation is a design feature intended to support fair comparisons by assigning participants to groups by chance. In general, randomization does not ensure that groups will be identical, especially in a modest-sized study, and it does not by itself establish that a posted difference is precise. The record does not report the allocation sequence method, whether allocation was concealed, or details about implementation.

The trial was not masked. In general, lack of masking can matter when an outcome depends on observation or behavior, because expectations may influence how care is delivered or how an outcome is assessed. The primary outcome is described as an observational measure, but the registry does not report whether assessors were masked, how assessments were standardized, or whether any procedures were used to address possible observer expectations. It also does not report a statistical analysis plan, a sample-size justification, or interim analyses.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Perioperative Pediatric Anxiety (Change From Baseline), measured over (Day 0 + 15 minutes on average from initial baseline) On entering the OR.

The primary endpoint is perioperative pediatric anxiety, expressed as change from baseline on the Modified Yale Preoperative Anxiety Scale. The registry describes the measure as observational and says it covers activity, emotional expressivity, state of arousal, vocalization, and use of parents. Its total range is 0 to 100, with higher scores indicating greater anxiety. The endpoint is reported in units on a scale, using the median and inter-quartile range.

The stated assessment time is entering the OR on Day 0, an average of 15 minutes after the initial baseline. A change-from-baseline outcome is intended to describe how a measurement differs from a participant's initial measurement by a later assessment. In general, this can help frame an outcome in relation to starting values rather than reporting only a later score. The registry does not specify the arithmetic convention for the change, so the sign of a change cannot be interpreted from the record alone.

The scale is relevant to the stated study question because it measures observed anxiety-related behavior around induction of anesthesia. Its score range and direction help readers understand the underlying measurement: higher scale scores indicate greater anxiety. But that direction does not resolve the direction of a change score unless the subtraction convention is known. The registry also does not report details about the measure's administration, assessor training, or handling of incomplete assessments.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry reports descriptive summaries for the primary outcome but does not report the statistical method used to compare groups. The explanations below describe general statistical concepts and distinguish them from what can be established about this trial. A specific test, model, adjustment strategy, or analysis population is not reported in the registry record.

What does the median describe?

In general, the median is the central observation after values are ordered. It is less affected by unusually high or low values than the arithmetic mean. For the primary endpoint, the registry reports a median of 0.0 units for the headset group and 5.0 units for control. Those summaries are useful descriptions of the groups, but they are not themselves a direct estimate of the randomized treatment contrast. Comparing two medians descriptively does not show how much uncertainty surrounds the contrast or whether a formal statistical test was performed.

What does the inter-quartile range add?

In general, the inter-quartile range gives the lower and upper quartiles, marking the central half of the observations. It communicates some of the variability without relying on the most extreme values. The reported range is 0.0 to 0.0 for the headset group and 0.0 to 10.0 for control. These values describe the central portions of the observed distributions as recorded. They do not provide a confidence interval for a treatment effect, and they do not show every participant's score.

When a scale has repeated values or a bounded range, observations can cluster at particular scores. In general, that can make a median and inter-quartile range informative, while also limiting how much detail those summaries reveal about the shape of the distribution. The registry does not report the individual score distribution or describe any distributional checks.

Why does the change convention matter?

The endpoint is change from baseline, but the registry does not state how the change was calculated. In general, a change score can be defined as the later measurement minus the baseline measurement, or in the reverse order. Reversing the order reverses the sign while leaving the size of a nonzero change unchanged. Since higher scores on the Modified Yale Preoperative Anxiety Scale indicate greater anxiety, a reader needs both the scale direction and the change convention to interpret whether a positive change indicates more or less anxiety. The record states the former but not the latter.

What can randomization support?

In general, randomization is used to make treatment assignment independent of participant characteristics in expectation, supporting a comparison between assigned groups. It does not guarantee that all measured or unmeasured characteristics will be balanced in a particular trial. Nor does randomization alone supply an estimate of effect or its precision. The registry identifies the study as randomized and parallel, but it does not report details of sequence generation, concealment, stratification, or the statistical method used for the comparison.

The study is listed as unmasked. In general, masking can reduce the influence of knowledge of assignment on care, reporting, or outcome assessment. This is relevant to an observational anxiety measure, but the record does not say whether the person scoring the measure knew the assignment. It therefore cannot establish the extent to which assessment was insulated from knowledge of the intervention.

How should uncertainty be assessed?

In general, a confidence interval gives a range of values compatible with the data and a specified statistical procedure. Its width conveys precision: a narrower interval generally indicates greater precision, while a wider interval indicates more uncertainty. The registry does not report a confidence interval for the primary between-group contrast. The inter-quartile ranges are not substitutes for that interval because they describe variability among observed scores rather than uncertainty in the estimated group contrast.

A p-value, in general, summarizes how unusual data at least as incompatible with a specified null model would be if that model and the test assumptions held. It is not a measure of the probability that a treatment works, nor a measure of effect size. No primary-outcome p-value or test is reported in the registry record. Consequently, significance cannot be assessed from the posted summaries, and no conclusion about a formal test should be inferred from them.

What are the planning calculations?

The planning illustration is based on the observed effect, uses a two-sided significance level of 0.05, assumes equal allocation between the two arms, and uses a normal approximation. The effect to detect is expressed as a stated fraction of the observed effect. In general, such calculations describe a hypothetical future design under the stated assumptions; they are not evidence about the probability that the completed trial detected an effect. The illustration is not the trial's own design justification, and its quantities should not be described as observed power. For non-time-to-event outcomes, planning quantities are participants per arm; time-to-event quantities are total events. The registry does not report the trial's own sample-size justification or power calculation.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 9 outcome measures. The named secondary outcomes are perioperative parental anxiety change from baseline, the Induction Compliance Checklist, and parental satisfaction. Numerical results for these secondary outcomes are not reported in the registry record. The record does not identify a hierarchy among outcomes or describe how multiple outcomes were handled statistically.

In general, assessing multiple outcomes can increase the chance of obtaining at least one apparently notable result by chance if each is tested separately. Researchers may use a prespecified hierarchy or adjustment methods to address that issue. The registry does not report whether such a strategy was planned or used, so no claim about multiplicity control is supported.

The record lists no analysis entries. It gives primary-outcome summaries but does not report the statistical analysis plan, a test of the primary comparison, or an analysis population such as intention-to-treat or per-protocol. The population field for the primary outcome is empty. It also does not report how missing observations were handled, whether participants with incomplete assessments were excluded, or whether any imputation was performed. The posted outcome counts therefore cannot be used to infer the reason for any difference from the enrollment figure.

In general, missing-data methods and analysis-population definitions can affect estimates and their interpretation. For this trial, the record does not describe the extent or pattern of missing data, so the possible influence of missingness cannot be assessed. The absence of those details is a reporting limitation; it does not establish that data were missing or that any particular method was used.

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 registry reports zero serious adverse events in the perioperative virtual reality headset group and zero in control. The listed numbers at risk for the serious-adverse-event summaries are 33 and 37, respectively. The record also reports zero other adverse events in each group and zero deaths in each group. No serious adverse-event terms are listed.

These entries describe what was recorded in the registry; they do not establish that no adverse events of any kind occurred outside the recorded categories or observation period. In general, an observed count of zero does not prove that an event is impossible or that the underlying risk is zero. Interpretation also depends on how events were defined, collected, and followed over time.

The registry record does not report event definitions, severity criteria, relatedness assessments, follow-up duration for safety, or methods for active safety surveillance. It also does not provide a statistical comparison of safety between groups. The zero entries should therefore be read as the posted counts, not as a precise estimate of comparative safety or as evidence that rare harms have been excluded.

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

The posted primary outcome summaries show a median change of 0.0 units in the perioperative virtual reality headset group and 5.0 units in control. The associated inter-quartile ranges are 0.0 to 0.0 and 0.0 to 10.0, respectively. They describe the reported central values and spread for each group. They do not quantify a formal between-group effect with uncertainty.

The record does not specify whether change was calculated by subtracting baseline from the later assessment or the later assessment from baseline. The scale's higher-score direction is reported, but without the change convention the direction of the change summaries cannot be translated reliably into a direction of anxiety change. This limits any plain-language claim that the summaries indicate greater or lesser anxiety in either group.

The trial's randomized design is relevant to evaluating an intervention, but the posted results do not include a confidence interval, p-value, or reported inferential analysis for the primary comparison. The registry also does not describe the primary analysis population, handling of missing data, or whether the assessor was masked. Those omissions limit assessment of precision, robustness, and potential sources of bias.

In general, a descriptive pattern is not the same as a demonstrated causal effect. To evaluate a treatment contrast, readers need an appropriately defined comparison, an estimate of its magnitude, and information about uncertainty and analysis choices. The posted medians and inter-quartile ranges are useful as group descriptions, but they do not supply all of that information. No conclusion about whether the intervention works or does not work follows from these summaries alone.

The safety entries are also limited to the reported counts: no serious adverse events, other adverse events, or deaths are recorded in either group. Such counts do not rule out events that were not captured, nor do they precisely characterize comparative safety. The registry's secondary outcomes are named, but numerical results are not reported. Overall, the record permits a descriptive reading of the primary outcome and safety counts, while leaving important inferential and reporting questions unanswered.

13. Why This Trial Matters Statistically

This trial raises statistical issues that are common in clinical research involving behavioral or observational outcomes. The primary endpoint is measured on a bounded scale, is described as a change from baseline, and is summarized using medians and inter-quartile ranges. Each feature shapes what can be inferred from the posted results.

First, reporting a change score requires a clear definition of its direction. The registry explains that higher scores on the underlying anxiety scale represent greater anxiety but does not state which score was subtracted from which. The missing convention prevents an unambiguous interpretation of positive or negative change. This is a basic reporting detail with direct consequences for readers trying to interpret results.

Second, a median and inter-quartile range describe observed data but do not quantify uncertainty in a treatment contrast. The primary summaries are not accompanied by a reported confidence interval, p-value, or statistical test. In general, readers need uncertainty estimates to judge how precisely a group difference has been estimated and how compatible the data are with a range of possible effects.

Third, the open-label design and observational endpoint make outcome assessment details important. The registry identifies the trial as unmasked and describes the primary measure as observational, but does not report whether assessors knew group assignment or what procedures standardized assessment. This does not establish bias; it identifies a question the registry record cannot resolve.

Finally, the record does not report the analysis population, missing-data methods, or approach to multiple outcomes. Those decisions can affect interpretation, especially when outcomes are assessed at a particular perioperative time. The trial is statistically instructive because its posted summaries are concrete, yet the information needed to judge precision, direction, and analysis choices is incomplete.

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 registry does not report the convention used to calculate change from baseline. Although the underlying scale is described as having higher scores for greater anxiety, the sign of the reported change cannot be interpreted without knowing the order of subtraction. This is a specific limitation for understanding the primary outcome.

The primary endpoint is summarized with group medians and inter-quartile ranges, but no formal group contrast, confidence interval, or p-value is reported. The registry record therefore does not indicate the estimated magnitude or precision of the comparison under a specified analysis. The displayed group summaries should not be treated as a substitute for that information.

The registry identifies the trial as randomized and unmasked, but does not report how the allocation sequence was generated or concealed. It also does not state whether the observer assessing the Modified Yale Preoperative Anxiety Scale was masked. Since the endpoint is described as observational, that assessment detail would help readers evaluate the risk of measurement bias, but its absence does not prove that bias occurred.

The record lists enrollment as 71 and gives primary-outcome group counts of 33 and 37. It does not explain how these figures relate or whether they reflect missing data, exclusions, or a defined analysis population. The primary outcome's population field is empty, and methods for handling missing observations are not reported.

Although the registry names secondary outcomes and lists 9 outcome measures, numerical results for the named secondary outcomes are not reported in the registry record. The record also does not describe multiplicity procedures, a statistical analysis plan, or a sample-size justification. The safety summaries give zero counts, but event definitions and safety follow-up details are not reported. These limitations restrict the conclusions that can be drawn from the registry record without establishing that any particular design or analysis choice was inappropriate.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Perioperative Virtual Reality for Pediatric Anesthesia — NCT03583450.
• Registry record last updated 2020-07-08; status last verified 2020-06.
• Results first posted 2020-07-08.
• 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

NCT03583450 is a completed, randomized, parallel-group, unmasked study sponsored by the University of California, San Francisco. It evaluates a perioperative virtual reality headset with a mobile app and routine anesthetic care against routine anesthetic care for pediatric patients undergoing elective surgery. The registry lists enrollment of 71.

The primary outcome is perioperative pediatric anxiety change from baseline on the Modified Yale Preoperative Anxiety Scale, reported at entering the OR on Day 0 and an average of 15 minutes after the initial baseline. The headset-group median is 0.0 units, with an inter-quartile range of 0.0 to 0.0; the control median is 5.0 units, with a range of 0.0 to 10.0. The change convention is not reported.

The registry does not report a formal primary comparison, confidence interval, p-value, analysis population, or missing-data method. The named secondary outcomes have no numerical results in the registry record. The adverse-event entries list zero serious adverse events, other adverse events, and deaths in both groups.