Vibrating, Cold Device for Pediatric Intravenous (IV) Cannulation Pain Relief: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Vibrating, Cold Device for Pediatric Intravenous (IV) Cannulation Pain Relief (NCT01394250), a randomized phase 2 study. The primary outcome is Change From Baseline in Faces Pain Scale Revised (FPS-R) at 30 Minutes After IV Cannulation.

2. Clinical Question

The trial asked whether Buzzy®, a reusable device that provides cold and vibration, could reduce pain associated with IV cannulation in children, and whether its performance was comparable to topical lidocaine cream. The primary endpoint was change from baseline in the child-reported Faces Pain Scale Revised (FPS-R) score at 30 minutes after cannulation. The registry record also lists a secondary comparison of immediate post-cannulation FLACC scores between groups.

The central statistical distinction is between describing change within each randomized group and estimating the difference between groups. The posted primary results give a mean change and confidence interval for each group. They do not give a direct estimate of the treatment-group contrast, so the group-specific results alone do not quantify how different the changes were from one another.

3. Trial Design

This was a phase 2, randomized, parallel-group trial with no masking. The registry record lists an enrollment of 240 and identifies Children's Hospital of Philadelphia as the sponsor. The study is marked completed; the recorded start was 2011-06 and primary completion was 2013-09.

Participants were assigned to Buzzy® or topical lidocaine 4% cream. The Buzzy device combined cold and vibration and was applied just before the IV cannulation procedure. The lidocaine cream was placed on at least two potential IV sites after consent, with IV placement no less than 30 minutes after application. These schedules are part of the interventions as described in the registry record; further details about implementation are not reported there.

Randomization is intended to create groups that are comparable, on average, with respect to both measured and unmeasured characteristics. In a parallel-group design, each participant is assigned to one group rather than receiving both interventions as part of the comparison. Randomization can support a causal comparison when the analysis and follow-up preserve the randomized groups, but it does not by itself guarantee that the reported analysis includes every randomized participant.

The trial was unmasked. Participants and clinical staff could therefore know which intervention was assigned. This matters when interpreting outcomes that involve a participant’s report or an observer’s rating: knowledge of assignment can potentially affect expectations, behavior, or assessment. The registry record does not describe masking of outcome assessors or other steps taken to limit assessment bias.

The primary analysis population was restricted to participants whose first IV cannulation attempt was successful. The posted group sizes for the primary outcome are 114.0 for Buzzy and 110.0 for topical lidocaine. The safety figures use a population of 134 in each group. These different reported populations should not be treated as interchangeable. The registry record does not explain the reasons for the difference between the primary-outcome and safety group sizes, or give a complete participant flow accounting.

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.

Before assignment: A total of 315 subjets signed informed consent forms. Of these 47 subjects were excluded prior to initiation of study procedures. Reasons included parent/child withdrawal of consent, change in clinical treatment plan including the decision to not place an IV for clinical reasons (study exclusion).

Randomization and IV Placement Attempt

Reasons for not completing this period:

Successful IV Placement & Follow-Up

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Analysis population includes only subjects whose first intravenous (IV) cannulation attempt was successful.

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.

Population: Baseline analysis population includes all subjects who were randomized and whose first attempt at IV access was successful (i.e., subjects in the "Successful IV Placement \& Follow-Up" group)

6. Primary Endpoint

The registry lists the primary outcome as Change From Baseline in Faces Pain Scale Revised (FPS-R) at 30 Minutes After IV Cannulation, measured over Baseline and 30 minutes.

The primary endpoint was change from baseline in the Faces Pain Scale Revised (FPS-R) score at 30 minutes after IV cannulation. The FPS-R is a numerical self-report measure of pain intensity developed for children. It uses six cartoon faces ranging from a neutral expression representing no pain, scored 0, to very much pain, scored 10. The recorded unit is units on a scale.

A change score describes how a participant’s measured value at follow-up differs from the baseline value. For a pain scale on which larger values represent more pain, a negative mean change indicates that the group’s average score was lower at follow-up than at baseline. The posted mean changes are negative in both groups. These are group averages; they do not show how every individual participant’s score changed.

A child self-report measure is relevant to a question about experienced pain because the person experiencing pain can report it directly. The 30-minute assessment provides a specified time point after cannulation, rather than an unspecified impression of pain. The registry record also lists immediate post-cannulation FLACC scores as a secondary outcome; that is an observer-rated measure rather than the primary self-report endpoint.

The primary analysis included only participants with a successful first cannulation attempt. The endpoint therefore describes change in that analysis population, not necessarily change among all enrolled participants. The registry record does not report a separate primary outcome for unsuccessful first attempts.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is continuous: it is measured on a numerical scale, and the registry record reports a mean change. A mean condenses the observed scores into an average, which is useful for describing the group’s central level of change. It does not convey the full distribution. Participants can have different scores and different changes even when the group mean is the same, so the average should not be read as an individual-level prediction.

What does a confidence interval express?

General statistical explanation: a confidence interval combines an estimate with information about its uncertainty under a specified method. A narrower interval indicates greater precision for the quantity being estimated; a wider interval indicates less precision. The FPS-R intervals in the registry record concern the mean change in each group. They do not describe the spread of individual scores and do not directly answer how far apart the two groups’ mean changes are.

In repeated use of a method under its assumptions, confidence intervals constructed at the stated level would cover the fixed quantity at that level over the long run. For an individual reported interval, the useful practical reading is that it conveys a range of values compatible with the data and method, not that there is a 95% probability that the fixed true mean lies inside that particular interval. This general interpretation does not establish whether the analysis assumptions were met in this trial; the registry record does not report diagnostic checks or the detailed interval calculation method.

Why is the between-group estimate important?

Randomization creates a basis for comparing assigned groups, but the statistical question about comparative performance is answered by a contrast between them. For a continuous change outcome, that contrast would describe how the average change in one group differs from the average change in the other, along with uncertainty around the contrast. The registry record gives separate group means and intervals but marks the two-arm continuous comparison as missing or not estimable. No contrast or corresponding uncertainty measure is posted. The group-specific estimates should therefore be interpreted as descriptive results, not as a completed test of comparative effectiveness.

General statistical explanation: a confidence interval for a contrast is the relevant measure of precision when the question concerns a difference. Looking at two separate intervals is not a substitute, because the uncertainty of the contrast depends on the variability and relationship of the estimates under the analysis. No new contrast can be reconstructed from the posted summary values without making additional assumptions, and no such recalculation is reported for this record.

What does the randomized design contribute?

Random assignment is designed to reduce systematic differences between groups at the point of assignment. It supports interpreting an appropriately analyzed between-group contrast as an effect of assignment, subject to issues such as adherence, missing outcomes, and the analysis population. Here, the primary analysis was limited to participants whose first IV cannulation attempt was successful. That restriction defines the reported population and may affect how well the result represents everyone randomized. The registry record does not report the full analysis plan or explain how the restricted population was selected beyond the successful-first-attempt criterion.

The trial was unmasked. General statistical explanation: when participants or observers know the assigned intervention, subjective measurements may be influenced by expectations or knowledge of assignment. The FPS-R is a child self-report, and the secondary FLACC measure involves ratings of behavior. This does not establish that bias occurred, but it is a design feature to consider when assessing the evidence. Whether outcome assessors were masked is not reported in the registry record.

What is not reported about the analysis?

The registry record does not report a detailed statistical analysis plan, a method for adjusting the primary comparison, a significance test for the between-group contrast, or a rationale for the sample size. It also does not report interim analyses. These items should not be inferred from the randomized design, the phase label, or the posted group summaries. The record lists one secondary outcome, the immediate post-cannulation FLACC score comparison, but does not post a corresponding analysis result.

The registry record includes a description of planning illustrations based on the observed effect, using a two-sided significance level of 0.05, equal allocation, and a normal approximation. Such illustrations are planning exercises under stated assumptions, not evidence about the trial’s original design rationale and not observed power. The registry record does not report the trial’s own sample-size justification. A sample-size calculation based on an observed effect can also be sensitive to that estimate; it should not be read as proof that the study had adequate or inadequate power.

General statistical explanation: over-dispersion matters when observed variability is greater than a model assumes, because standard errors can then be too small and intervals too narrow if the model does not account for it. The registry record does not report evidence of over-dispersion or an analysis that addresses it. This is a general consideration rather than a finding about this trial.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists the primary FPS-R change outcome and one secondary outcome: comparison of FLACC scores immediately after IV cannulation between groups. It also reports two outcome measures overall. Reporting more than one outcome can raise multiplicity questions because repeated statistical testing can increase the chance of at least one apparently noteworthy result. Whether and how to adjust for multiple outcomes depends on the prespecified analysis strategy and the claims being made. An adjustment plan is not reported in the registry record, and no secondary-outcome analysis result is posted.

Missingness and analysis populations require separate consideration. The primary analysis included only participants whose first IV cannulation attempt was successful. The record reports 114.0 participants in the Buzzy primary outcome group and 110.0 in the lidocaine group, compared with 134 in each group for the adverse-event figures. These counts describe distinct reported populations, but the record does not explain the reasons for their difference or provide a participant flow account. The number of unsuccessful first attempts is not reported in the registry record.

The record also does not describe missing FPS-R measurements, how any missing values were handled, or whether all participants in the primary analysis had complete baseline and follow-up measurements. A restriction to successful first attempts is an eligibility rule for the stated analysis population; it should not be assumed to be a missing-data method. Without information on exclusions and missing outcomes, the potential effect of these features on the results cannot be assessed from the registry record.

The randomized groups may remain comparable for some purposes while an analysis restricted after assignment may differ from the full randomized comparison. The record does not report an analysis of all randomized participants or a sensitivity analysis for the successful-first-attempt restriction. These omissions limit assessment of how robust the posted group summaries are to the choice of analysis population.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry record reports serious adverse events in 0 of 134 participants in the Buzzy group and 0 of 134 participants in the topical lidocaine 4% cream group. It also reports other adverse events in 0 of 134 participants in each group. No serious adverse event terms are listed. The death counts are not reported in the registry record; a blank or unreported death value should not be interpreted as a reported zero.

These figures are counts within the recorded safety populations. They indicate that the registry record lists no serious or other adverse events for those participants during the reporting period, but the record does not provide further detail about how events were collected, the reporting period, or the definitions used. The safety group sizes differ from the primary-outcome group sizes, so the adverse-event counts should not be treated as applying to exactly the same analysis population as the FPS-R results.

General statistical explanation: observing zero events does not prove that an event is impossible or that there is no risk. A zero count is compatible with uncertainty about the event rate, especially when the population being monitored is limited. No event-rate estimate or confidence interval is reported in the registry record, and none should be inferred from the zero counts alone. The safety figures are descriptive registry reports, not a comprehensive assessment of safety.

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

The posted primary outcome results show that the average FPS-R score declined from baseline to 30 minutes in both reported groups among participants whose first IV cannulation attempt was successful. The Buzzy group mean change was -3.544 units, and the topical lidocaine 4% cream group mean change was -3.436 units. Each group’s 95% confidence interval is reported as an interval around its own mean change. Those values describe the groups separately.

The central comparative question is not resolved by these within-group summaries. A direct between-group estimate and its uncertainty are not reported in the registry record, and the record marks the two-arm continuous comparison as missing or not estimable. Therefore, these data as posted do not establish whether the mean changes differ, how large a difference might be, or whether a prespecified criterion for comparable effectiveness was met. The stated aim of comparing Buzzy with topical lidocaine is not itself evidence that equivalence or non-inferiority was tested.

The results also do not show that every child experienced a reduction in pain score. A mean describes an average and may coexist with varied individual responses. The registry record does not report participant-level score distributions or the proportion of participants whose scores increased, decreased, or stayed the same.

The primary analysis population was restricted to successful first attempts, so the results should not be generalized automatically to all enrolled participants or to unsuccessful first attempts. The trial was unmasked, which is relevant when interpreting self-reported pain and observer-rated outcomes. The registry record does not report the detailed analysis plan, missing-data handling, or the reasons that the primary-outcome group sizes differ from the safety populations.

The adverse-event record lists zero serious and zero other adverse events in each safety group, while deaths are not reported. These entries are descriptive and do not demonstrate that events cannot occur. Overall, the registry record provides group-level pain-change estimates and limited adverse-event counts, but does not provide the comparative primary analysis needed to answer the trial’s central between-group question.

13. Why This Trial Matters Statistically

This trial illustrates why a clinical question about two interventions requires a direct comparison, not simply a separate result for each group. Mean change within each arm can describe what happened in that group, but the contrast between assigned groups is what addresses whether outcomes differed under the randomized comparison. Here, the registry record reports arm-specific FPS-R changes and confidence intervals, while the two-arm continuous comparison is not reported as estimable.

The example also highlights the importance of defining the analysis population. The primary endpoint applies only to participants whose first cannulation attempt was successful. That restriction is consequential for interpretation because the randomized enrollment and the primary-outcome populations are not presented as identical. The safety figures use another reported population size. Clear accounting of who was randomized, who was analyzed, and why is necessary for readers to understand how the estimates relate to the trial participants.

Unmasked assignment is another statistically relevant feature for outcomes that include self-report or behavioral assessment. It does not establish that the measures were biased, but it should be considered alongside the measurement method and the missing details about assessor masking. The record’s inclusion of both FPS-R and FLACC outcomes also makes it useful to distinguish participant-reported pain from an observer-rated measure rather than treating them as interchangeable endpoints.

Finally, this record demonstrates the limits of registry summaries. An enrollment figure, a randomized design, and precise-looking group intervals do not replace a reported analysis plan, a between-group estimate, missing-data details, or a sample-size rationale. Statistical interpretation depends on knowing both what the estimates describe and what analysis is absent. The posted results are therefore informative about the reported group means but incomplete for the comparative question that motivated the trial.

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 principal limitation for interpreting the primary result is that no between-group estimate or uncertainty interval is reported in the registry record. The posted mean changes and confidence intervals describe each group separately. They do not quantify the randomized contrast, and no statistical test or criterion for deciding whether Buzzy was as effective as topical lidocaine is reported.

The primary analysis included only participants whose first IV cannulation attempt was successful. The registry record does not report how many participants had unsuccessful first attempts, why the primary-outcome groups include 114.0 and 110.0 participants, or how those figures relate to the recorded enrollment of 240. The safety populations are listed as 134 in each group, but the record does not reconcile these counts. This limits assessment of participant flow and the extent to which the primary analysis represents all randomized participants.

The record does not report missing FPS-R data, how missing measurements were handled, or whether analyses were conducted in other populations. It also does not report the detailed statistical analysis plan, the method used to construct the confidence intervals, interim analyses, or the trial’s sample-size justification. A planning illustration based on an observed effect is not a substitute for that original rationale.

No masking was used. The registry record does not say whether outcome assessors were masked or identify procedures to reduce potential influence on self-reported or observer-rated outcomes. The secondary FLACC outcome is listed, but its result is not posted. Safety reporting is limited to the listed counts; the reporting period, event definitions, and death counts are not reported in the registry record. These limitations constrain both comparative interpretation and assessment of completeness.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Vibrating, Cold Device for Pediatric Intravenous (IV) Cannulation Pain Relief — NCT01394250.
• Registry record last updated 2016-09-16; status last verified 2016-07.
• Results first posted 2015-05-15.
• 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

NCT01394250 is a completed, randomized, unmasked, parallel-group phase 2 trial sponsored by Children's Hospital of Philadelphia. It recorded enrollment of 240 and compared Buzzy®, a device providing cold and vibration, with topical lidocaine 4% cream for pediatric IV cannulation pain. The recorded study start was 2011-06, and primary completion was 2013-09.

The primary endpoint was change from baseline in FPS-R score at 30 minutes after cannulation. The primary analysis included participants with a successful first cannulation attempt. The posted mean changes were -3.544 for Buzzy and -3.436 for lidocaine, with group-specific 95% confidence intervals. A between-group estimate is not reported in the registry record. One secondary outcome, immediate post-cannulation FLACC score, is listed without a posted analysis result.

The safety record lists zero serious and zero other adverse events among 134 participants in each group. Deaths are not reported in the registry record. The record does not report the detailed statistical plan, missing-data handling, participant flow, or the trial’s sample-size justification.