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 Can Virtual Reality Reduce Pain and Anxiety During Blood Draw (NCT04449341), a randomized na study. The primary outcome is Procedural Pain.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04449341 |
| Phase | NA |
| Condition | Procedural Anxiety, Procedural Pain |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 59 |
| Arms in the primary outcome | 2 |
| Lead sponsor | C.R.Darnall Army Medical Center |
| Results posted | Yes |
2. Clinical Question
The trial asked whether virtual reality used during a routine blood draw was associated with different patient-reported procedural pain, with procedural anxiety also identified as an outcome. Its planned population was adults aged 18–50 undergoing blood draw for routine laboratory evaluation. The registry record reports an enrollment of 59 and a completed trial.
Population
Adults aged 18–50 undergoing venipuncture for routine laboratory evaluation. The registry record does not report further eligibility details or the characteristics of participants whose outcomes were posted.
Intervention
Standard-care venipuncture while participants used an Oculus Go headset with the Ocean Rift virtual-reality application.
Comparator
Standard-care venipuncture while participants wore the Oculus Go headset with the device turned off.
Primary question
Did the recorded procedural pain scores differ between the virtual-reality and headset-off groups? Procedural anxiety was identified as a secondary outcome, but no anxiety results are posted.
The comparison concerns the experience of venipuncture under these two study conditions. Both groups underwent standard-care blood draw; the described difference was whether the headset played the virtual-reality application or remained off. The registry identifies pain as the primary outcome and anxiety as secondary. It describes pain as measured with a visual analog scale, with lower scores corresponding to less pain and higher scores to more pain.
3. Trial Design
The registry describes a randomized, single-masked, parallel-group trial. Participants were assigned to one of two conditions: venipuncture while interacting with the Ocean Rift application through an Oculus Go headset, or venipuncture while wearing the headset turned off. The trial is marked completed. Its sponsor is C.R.Darnall Army Medical Center.
The intended participants were adults aged 18–50 having a blood draw for routine laboratory evaluation. The registry reports an enrollment of 59. The primary outcome entries list 30 participants in the virtual-reality group and 28 in the headset-off group. The record does not explain how the enrollment count relates to the outcome counts, or whether the posted counts reflect everyone randomized, everyone assessed, or another analysis population.
“Single-masked” indicates that masking was used, but the registry record does not identify which participants or study personnel were masked, or how masking was maintained. The randomization sequence method, allocation concealment, and procedures for preventing participants from identifying their condition are not reported in the registry record. The parallel model means the record describes distinct groups assigned to the two conditions rather than a crossover comparison.
The primary endpoint is procedural pain, reported as a median with an interquartile range. Procedural anxiety is listed as a secondary outcome. Although the registry specifies two outcome measures, it posts results only for the pain endpoint in the record described. A statistical analysis plan, the method used to compare groups, and an explanation of the outcome analysis population are not reported in the registry record.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Virtual Reality | Control |
|---|---|---|
| STARTED | 31 | 28 |
| COMPLETED | 30 | 28 |
| NOT COMPLETED | 1 | 0 |
Reasons for not completing this period:
| Reason | Virtual Reality | Control |
|---|---|---|
| Protocol Violation | 1 | 0 |
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 | Standard Care Venipuncture With Additional of Virtual Reality | Standard Care Venipuncture Without Addition of Virtual Reality | Total |
|---|---|---|---|---|
| Participants analysed | 30 | 28 | 58 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 30 | 28 | 58 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 |
| Sex/Gender, Customized: Unknown | participants | 30 | 28 | 58 |
| Race and Ethnicity Not Collected | Participants | — | — | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Procedural Pain, measured over 2 months.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Inter-Quartile Range |
| Unit | score on a scale |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is procedural pain during venipuncture. The registry describes use of a visual analog scale, a linear scale running from 0 to 100 millimeters: 0 represents no pain and 100 represents maximum pain. The endpoint therefore captures participants’ reported perception of pain during the blood draw, rather than an objective measure of tissue injury or a later clinical outcome.
A patient-reported pain score is relevant to this question because the study concerns the experience of a procedure. The registry reports the endpoint as a median and an interquartile range. The median gives the midpoint of the ordered scores, while the interquartile range describes the spread of the middle portion of those scores. These summaries can be useful when scores are unevenly distributed or include extreme values, but they do not by themselves estimate the precision of a difference between groups.
The posted median was 6.5 in the virtual-reality group, with an interquartile range from 0.25 to 30.75. In the headset-off group, the median was 5.0, with an interquartile range from 1.0 to 24.25. The registry labels the endpoint timeframe as 2 months, while its description places the pain perception assessment during venipuncture. How the stated timeframe relates to the moment of measurement is not explained in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted pain summaries are medians and interquartile ranges for the two randomized groups. The median was 6.5 for participants using virtual reality and 5.0 for participants wearing the headset turned off. The corresponding interquartile ranges were 0.25 to 30.75 and 1.0 to 24.25. These are descriptive summaries of the posted scores, not a reported estimate of the treatment effect.
The scale runs from 0, meaning no pain, to 100, meaning maximum pain. The medians therefore describe the middle reported score in each group on that scale. They do not show how much individual participants’ scores changed, and the registry record does not provide a group-level estimate with a confidence interval. Interquartile ranges show variation among scores within each group; they are not confidence intervals for the medians or for a between-group contrast.
The registry record lists no analyses. It does not report a statistical test, a p-value, a confidence interval for the comparison, or an adjusted estimate. As a result, the posted summaries do not establish whether the groups differed beyond what could plausibly arise from sampling variation. Nor do they quantify the precision of any difference. The record also does not post procedural-anxiety results, despite listing anxiety as a secondary outcome.
The numerical direction of the medians should be read in context: the virtual-reality group’s posted median was 6.5, and the headset-off group’s was 5.0. These descriptive values alone do not support a conclusion about the effect of virtual reality. A sound comparison would require an analysis appropriate to the randomized design and outcome distribution, along with information about missing observations and the analysis population. Those details are not reported in the registry record.
The enrollment count is 59, while the primary outcome entries list 30 and 28 participants in the two groups. The record does not explain this difference. It is therefore not possible to determine from the registry alone whether the posted outcome summaries include all randomized participants or how any unavailable measurements were handled.
In short, the record gives a limited descriptive account of reported pain scores. It does not provide the inferential results needed to evaluate the uncertainty around a group comparison. No claim that virtual reality did or did not reduce pain follows from the posted medians alone.
9. Statistical Methods Explained
The trial is described as randomized and parallel-group. Random assignment is intended to make groups comparable, on average, with respect to measured and unmeasured characteristics. It does not guarantee that the groups will be identical in a particular trial. The registry record does not describe the randomization sequence, allocation concealment, or whether the analysis preserved the original assigned groups. Those details matter when judging how well the design and analysis protect a comparison from bias.
What does the reported median describe?
A median is the middle value after observations are ordered. It summarizes the location of the observed scores without being pulled as strongly by unusually high or low values as a mean can be. In this trial, the posted medians were 6.5 for the virtual-reality group and 5.0 for the headset-off group. These values describe the center of the recorded scores in each arm. They are not themselves a comparison estimate with a measure of uncertainty.
The registry identifies the dispersion measure as the interquartile range. An interquartile range describes the central spread of the observed scores, between the lower and upper quartiles. The posted ranges were 0.25 to 30.75 in the virtual-reality group and 1.0 to 24.25 in the headset-off group. This information helps readers see that scores varied within each group. It does not tell how precisely the difference between group summaries has been estimated.
Why is a confidence interval useful?
In general, a confidence interval expresses uncertainty around an estimate under the assumptions of a statistical method. For a randomized comparison, an interval around a between-group effect estimate would help show which effect sizes are compatible with the observed data and the method used. The registry record does not report such an interval for the pain comparison. The interquartile ranges cannot substitute for one: they describe score distributions within groups rather than uncertainty around the contrast between groups.
In general, a hypothesis test and a confidence interval address related but distinct questions. A test evaluates compatibility of data with a specified null hypothesis under a model, while an interval shows a range of estimates compatible with the data and method. Neither can be reconstructed responsibly from the posted medians and interquartile ranges alone. The registry record does not report a test, its assumptions, or a p-value.
How should the scale and outcome type be considered?
The pain outcome is described as a visual analog scale from 0 to 100 millimeters, anchored at no pain and maximum pain. The registry reports a median and interquartile range, suggesting a summary based on the ordered scores. In general, the choice of summary and comparison method should reflect how an outcome is measured and distributed. The record does not state the specific method used to compare the groups or whether the endpoint was analyzed as a continuous score, an ordinal measure, or another form.
In general, over-dispersion matters when a model assumes less variability than the data contain. If the variability is greater than the model allows, standard errors and uncertainty estimates can be misleading. This is a general consideration, not a reported finding about this trial: the registry record does not report a model, a dispersion assessment, or the assumptions used for any analysis.
What do the sample-size assumptions mean?
In general, a sample-size calculation is a planning exercise based on a target effect, an assumed variability, a significance level, and a desired power. It is not evidence that a trial was designed to detect the observed result. Planning illustrations based on an observed effect are distinct from a trial’s own prospective sample-size justification; they should not be interpreted as observed power. The registry record does not report the trial’s sample-size justification or the assumptions used to determine its enrollment.
The planning illustration framework associated with this record uses a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. These are planning assumptions, not reported features of the trial’s original design. The record does not report a prospective target effect or a design-based power calculation. For this endpoint type, a two-arm planning comparison is marked as not estimable from the available values, so no participant-per-arm estimate should be inferred from the posted summaries.
What remains unknown about the analysis?
The registry record does not identify the statistical test, any adjustment for covariates, the handling of missing outcomes, or the population included in the analysis. It also does not provide an analysis plan or results for the secondary anxiety outcome. These gaps prevent a detailed assessment of whether the method matched the randomized design, whether all planned outcomes were analyzed, and how uncertainty was quantified. The descriptive summaries remain interpretable as posted group-level results, but they do not replace those missing inferential details.
10. Multiplicity, Missing Data and Analysis Populations
The registry identifies procedural pain as the primary outcome and procedural anxiety as a secondary outcome. It reports two outcome measures, but only the pain results appear in the posted outcome entries. Anxiety is listed as a secondary outcome without a result. Whether anxiety was measured, analyzed, or omitted from the registry results is not explained in the registry record.
When a study evaluates more than one outcome or makes multiple statistical comparisons, the chance of a false-positive finding can rise if each is tested without an appropriate plan. In general, multiplicity procedures can control that risk, but the appropriate approach depends on the prespecified questions and analysis plan. The registry record does not report whether any multiplicity adjustment was planned or used. Because no inferential analyses are posted, there is no reported significance claim to assess for multiplicity.
The record lists enrollment of 59 and primary outcome group counts of 30 and 28. It does not account for the difference between those totals, describe missing outcome measurements, or state how participants with unavailable data were handled. The analysis population is also not reported in the registry record. It is therefore unclear whether the posted summaries reflect all randomized participants, participants with observed pain scores, or another defined group.
In general, missingness can affect a comparison if the availability of an outcome is related to a participant’s score or assigned condition. The registry record does not provide enough information to assess that possibility. It also does not report whether any sensitivity analyses were conducted. Without an analysis plan, outcome accounting, and anxiety results, readers cannot evaluate the completeness of the prespecified outcome reporting or the robustness of the pain summary.
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 |
|---|---|---|---|
| Standard Care Venipuncture With Additional of Virtual Reality | 0 | 30 | 0.0% |
| Standard Care Venipuncture Without Addition of Virtual Reality | 0 | 28 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Standard Care Venipuncture With Additional of Virtual Reality | 0 of 30 |
| Standard Care Venipuncture Without Addition of Virtual Reality | 0 of 28 |
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 |
|---|---|
| Standard Care Venipuncture With Additional of Virtual Reality | 0 of 30 |
| Standard Care Venipuncture Without Addition of Virtual Reality | 0 of 28 |
The registry reports zero serious adverse events and zero deaths in each group. The serious-event counts are recorded among 30 participants in the virtual-reality group and 28 in the headset-off group. The record also reports zero other adverse events in each group, among those same group counts.
These figures describe what was recorded in the registry, not proof that no adverse experiences occurred. The record does not explain how adverse events were defined, how actively they were collected, what period of follow-up they covered, or whether all participants were assessed for them. It also does not provide descriptions of non-serious events. The list of most frequent serious-event terms is empty, consistent with the posted count of zero serious events, but it does not add information about event monitoring or ascertainment.
In general, zero recorded events in a trial of this size do not establish that an event is impossible or that the conditions have equivalent safety. They indicate only that the registry reports no events in the stated categories for the listed participants. No statistical comparison of adverse-event risk is reported, and the registry record does not provide the detail needed to assess the completeness of safety reporting.
12. What the Result Does, and Does Not, Mean
The posted results establish that the registry contains descriptive pain summaries for two randomized venipuncture conditions. The virtual-reality group had a median score of 6.5, with an interquartile range of 0.25 to 30.75. The headset-off group had a median score of 5.0, with an interquartile range of 1.0 to 24.25. The score scale runs from 0 for no pain to 100 for maximum pain.
Those values do not establish that virtual reality reduced pain, increased pain, or made no difference. A median is a summary of a group’s observed scores, not a causal effect estimate. The registry record supplies no between-group estimate, confidence interval, p-value, or statistical test. It therefore does not quantify the uncertainty in the contrast or establish whether any observed separation is compatible with chance variation.
The results also do not answer the secondary question about procedural anxiety: anxiety is listed as an outcome, but no anxiety results are posted. The record does not explain the discrepancy between enrollment of 59 and the primary outcome counts of 30 and 28. It does not report how missing values were handled or define the analysis population. These omissions limit what can be concluded about the completeness and representativeness of the posted summaries.
In general, a trial result should be interpreted in light of its design, outcome definition, analysis method, uncertainty, and completeness of reporting. Here, the registry describes random assignment and the intervention conditions, but it does not report several analysis details needed to evaluate a between-group effect. No clinical recommendation follows from these descriptive data. The narrow interpretation is that the registry reports the listed pain scores and safety counts for the two study groups, while leaving the comparative statistical evidence unreported.
13. Why This Trial Matters Statistically
This trial presents a useful statistical distinction between describing group outcomes and estimating a comparative effect. Medians and interquartile ranges communicate the center and spread of recorded pain scores. They do not, on their own, show the uncertainty around a difference between randomized groups. Readers need an appropriate comparison estimate and its uncertainty to judge how much the observed data support a difference.
The registry also illustrates why outcome reporting should be complete. Procedural anxiety is identified as a secondary outcome, yet no anxiety result is posted. The record does not explain the relationship between the stated enrollment and the group counts for pain. Without outcome accounting and an analysis population, it is difficult to determine how fully the posted summaries represent the randomized participants.
For clinical researchers, these distinctions matter when interpreting small or descriptive trial records. A randomized design is relevant to causal inference, but randomization alone does not supply a statistical result or resolve missing analysis details. A clear report would also identify the analysis method, how missing outcomes were treated, and the uncertainty around the comparison. The registry record does not report those elements.
The trial’s question is focused on a patient-reported experience during a common procedure, and its design contrasts virtual reality with a headset-off condition while retaining standard-care venipuncture in both groups. Statistically, the posted results are best treated as descriptive rather than as evidence for or against a comparative effect. That distinction helps prevent over-reading numerical summaries when inferential results and reporting context are absent.
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 record does not report a statistical analysis plan, the method used to compare pain scores, or a confidence interval or test result. Without those details, the precision and statistical compatibility of a between-group effect cannot be assessed. The endpoint is reported with medians and interquartile ranges, but the record does not explain why that summary was selected or how the comparison was conducted.
Enrollment is reported as 59, while the pain outcome entries list 30 participants in the virtual-reality group and 28 in the headset-off group. The record does not reconcile those counts or describe missing measurements. It also does not identify the analysis population or say whether outcomes were analyzed according to randomized assignment.
The registry lists procedural anxiety as a secondary outcome but posts no anxiety result. It does not state whether anxiety was measured, whether its analysis was completed, or whether multiplicity was considered. The masking description is limited to “single”; which parties were masked and how masking was maintained are not reported. Details of sequence generation and allocation concealment are also absent.
The endpoint description places pain assessment during venipuncture, while the recorded timeframe is 2 months. The registry does not clarify how that timeframe relates to measurement. Further details about participant characteristics, the actual conduct of the trial, adverse-event monitoring, and the completeness of follow-up are not reported in the registry record. These omissions limit interpretation beyond the descriptive outcomes and safety counts that are posted.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Can Virtual Reality Reduce Pain and Anxiety During Blood Draw — NCT04449341.
- Registry record last updated 2021-07-13; status last verified 2021-07.
- Results first posted 2021-06-11.
- 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
The registry record describes a completed, randomized, single-masked, parallel-group trial of virtual reality during routine venipuncture. Adults aged 18–50 undergoing routine laboratory blood draw were assigned to standard-care venipuncture with an Oculus Go headset running Ocean Rift or standard-care venipuncture with the headset turned off. Enrollment was 59.
Procedural pain was the primary outcome, described using a visual analog scale from 0 to 100 millimeters and summarized by medians and interquartile ranges. The posted median was 6.5 for the virtual-reality group and 5.0 for the headset-off group. Procedural anxiety was listed as a secondary outcome, but no anxiety result is posted. The registry reports zero serious adverse events, zero other adverse events, and zero deaths in both groups.
No statistical analyses are listed. The registry record does not report an inferential comparison, missing-data handling, an analysis population, or the trial’s sample-size justification. The posted outcomes therefore support descriptive interpretation only.