Kinetic Anesthesia Device Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Kinetic Anesthesia Device Study (NCT03344510), a randomized na study. The primary outcome is Pain of Lidocaine Injection, Measured by Visual Analog Scale..

2. Clinical Question

The registry describes a randomized split-body study. Each participant experienced both injection conditions, with the order randomized. This within-participant structure is relevant because pain ratings can vary considerably between people: comparing conditions within the same participant can account for some stable differences between participants. It does not, by itself, establish that the analysis accounted for the paired nature of the data.

The clinical context in the registry is discomfort from lidocaine injections. Its background describes prior use of vibrating devices in dentistry, pediatrics and dermatology, while noting the absence of studies at sites common to dermatologic surgery at the time described. The study question therefore concerns pain ratings under the two injection conditions in healthy volunteers, rather than treatment of a disease or a clinical outcome in patients undergoing surgery. Specific injection sites are not reported in the registry record.

The primary measure was pain marked on a visual analog scale immediately after each injection. A secondary outcome asked about participant preference after the second injection. These outcomes address related but distinct questions: pain ratings quantify a reported level of pain, while preference reflects a comparative judgment. Neither measure alone establishes how the device would perform in other populations, settings or injection procedures.

3. Trial Design

The registry classifies the study as randomized, unmasked and crossover, and describes it as a split-body study in healthy volunteers. Participants were assigned to an order of conditions: kinetic anesthesia device followed by no intervention, or no intervention followed by the device. Both conditions involved lidocaine injection. The registry reports enrollment of 47 participants and a completed study.

In a crossover design, participants receive each study condition in sequence. This permits a within-participant comparison, rather than relying only on comparisons between separate groups of people. Randomizing the sequence can help distribute order effects across sequences, but the registry record does not explain the sequence-generation method, allocation concealment, or whether any period or carryover effects were assessed. The term split-body is used in the registry; further details about injection locations and how those locations were assigned are not reported in the registry record.

The primary outcome was pain of lidocaine injection, measured on a visual analog scale in millimeters. The planned timing was immediately after each injection. The registry specifies the median and inter-quartile range as the summary measures. The secondary outcome was patient preference for injection with or without the device, collected immediately after the second injection.

The recorded study dates are 2017-01-23 for study start and 2018-01-27 for primary completion. The study phase is listed as not applicable, and the sponsor is the University of Pennsylvania. The registry lists two outcome measures, while it does not report an analysis count for the primary comparison. A statistical analysis plan, sample-size justification for the trial, and details of the analysis population are not reported in the registry record.

Because treatment order and participant responses can be linked in a crossover study, a complete account of the statistical method would ideally explain how within-participant dependence, sequence, period and any missing responses were handled. Those details are not reported in the registry record. The reported summaries can still be described, but they should not be treated as a substitute for a prespecified paired analysis or as evidence that such an analysis was conducted.

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: This was a split body study, so each participant functioned in both intervention and control arms.

First Injection (5 Minutes)

Wash Out (10 Minutes

Second Injection (5 Minutes)

Analysis population for the primary outcome, as defined in the registry: See above

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: This was a split body study, meaning that each participant was a part of both the "KAD" arm and the control arm.

6. Primary Endpoint

The registry lists the primary outcome as Pain of Lidocaine Injection, Measured by Visual Analog Scale., measured over This measurement will occur immediately after each injection.

The primary endpoint is pain from lidocaine injection, recorded immediately after each injection. Participants marked a 100mm visual analog scale, with the left end labelled no pain at all and the right end labelled worst pain imaginable. The distance from the zero point to the participant’s mark was measured in millimeters, over a possible range of 0 to 100 mm. Higher values represent more pain.

The registry specifies the median and inter-quartile range as the summaries for this endpoint. The median describes the central point of the observed ratings when ordered, while the inter-quartile range describes the spread of the central portion of those ratings. These summaries are useful when the distribution may be skewed or when extreme observations could make a mean less representative of a typical rating. They do not show the full distribution, and they do not quantify uncertainty in a comparison between conditions.

Visual analog scales are used to capture a participant’s own perception of acute pain as a position on a continuous line. This approach can reflect gradations in reported experience rather than forcing responses into a small set of categories. It remains a subjective measure: a rating is the participant’s report, not an objective measurement of tissue response. The registry’s endpoint description explains the scale, but does not report additional information about training, repeatability, or how marks were handled if they were unclear.

The primary summary values are medians of 7.5 mm for injections using the kinetic anesthesia device and 26.0 mm for injections without it. Their inter-quartile ranges are 5.0 to 16.0 mm and 13.0 to 34.0 mm, respectively. The registry does not report a confidence interval or inferential test for the primary endpoint comparison.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

General: Statistical methods describe how observations are summarized and how uncertainty is evaluated. A numerical result can be descriptive, such as a median, or inferential, such as an estimate with a confidence interval and a test. A descriptive result tells what was observed in the recorded sample; an inferential result attempts to quantify how compatible the data are with a range of possible population effects, subject to assumptions about design and analysis.

Why does the crossover design matter?

In a crossover study, the same participant experiences more than one condition. Measurements from the same person are generally related, so the statistical analysis should preserve that pairing rather than treating the observations as independent. The paired structure can be informative because each participant serves as their own comparison. It can also make sequence, timing and carryover relevant: an experience in an earlier period could affect a later response. Randomizing order is a design feature, but it does not disclose which analysis was used or prove that period effects were ruled out.

The registry describes randomized sequences and reports summaries for each injection condition. It does not report the primary endpoint’s paired analysis, the statistical test, the model, or an adjustment for sequence or period. The primary summaries alone do not show the distribution of individual within-participant changes. A reader therefore cannot recover a paired effect or its uncertainty from the reported medians and inter-quartile ranges.

What do the median and inter-quartile range convey?

The median is the middle value in an ordered set of observations. The inter-quartile range spans the central half of the observations, with its lower and upper limits describing the spread around the median. These summaries are often useful for outcomes that are not symmetrically distributed or may include unusual values. They are not standard errors, confidence intervals, or ranges containing every observation. Overlap or non-overlap between inter-quartile ranges is not, by itself, a formal test of a difference.

For the primary endpoint, the registry reports the median and inter-quartile range separately for device and control injections. It does not report a confidence interval for the difference between conditions. A confidence interval for a contrast would express uncertainty around that contrast under the chosen statistical method. Without such an estimate, the observed separation between group summaries cannot be translated into a precise range of plausible paired effects.

How should the secondary confidence interval and p-value be read?

General: A confidence interval gives a range of estimates compatible with the data and the method used, under the method’s assumptions. It describes uncertainty in an estimate; it does not mean that a particular range contains the true value with a probability that can be assigned after the result is observed. The secondary outcome’s reported risk difference is 0.6, with a confidence interval from 0.437 to 0.763. This interval applies to the preference comparison, not to the primary pain score.

General: A p-value measures how unusual data at least as incompatible with a specified null hypothesis would be if that hypothesis and the test assumptions were correct. It is not the probability that the null hypothesis is true, and it does not measure clinical importance. The registry reports an unadjusted p-value of <0.001 for the secondary preference comparison. Because it is unadjusted, it does not account for the possibility of multiple outcome comparisons. The primary endpoint has no reported p-value in the registry record.

What does over-dispersion mean in general?

General: Over-dispersion occurs when observed variability is greater than a statistical model assumes. If it is ignored, uncertainty estimates can be too small and tests can appear more decisive than warranted. The registry does not report a model for the primary outcome or discuss over-dispersion. The concept is relevant when considering model-based analyses in general, but there is no basis in this record to say that over-dispersion was present or that a particular correction was needed.

How should the planning illustrations be understood?

The registry’s sample-size planning illustration is based on fractions of the observed secondary effect, with two-sided significance level 0.05, equal allocation between arms and a normal approximation. For planning for 100% of the observed effect, it gives 10 participants per arm for 80% power and 13 participants per arm for 90% power. For 75% of the observed effect, it gives 17 participants per arm for 80% power and 22 participants per arm for 90% power. For 50% of the observed effect, it gives 35 participants per arm for 80% power and 46 participants per arm for 90% power.

These are planning illustrations computed from the observed effect, not the trial’s own design justification. They are hypothetical sample-size calculations under stated assumptions. They are not observed power, do not establish that the study was adequately powered, and do not describe the analysis of the completed crossover trial. The record does not report a prospective sample-size calculation for the primary pain endpoint or a justification for the enrolled sample.

General: Power is a design-stage probability of detecting an effect of a specified size under a particular model and analysis plan. Retrospective calculations based on an observed effect do not tell whether a completed study had a high probability of detecting an unknown true effect. They can also be unstable because the observed effect is itself uncertain. The planning figures should therefore be read as illustrations of assumptions, not as evidence about the strength of the primary result.

Overall, the record contains useful endpoint definitions and descriptive outcome summaries, as well as a secondary inferential result. It does not report enough of the statistical plan to determine how the primary paired comparison was analyzed. Interpretation should distinguish what is directly summarized from what would require an unreported model or test.

10. Multiplicity, Missing Data and Analysis Populations

Multiplicity arises when statistical testing covers more than one outcome, comparison, subgroup or analysis choice. If each is treated as a separate opportunity for a positive finding without an adjustment or prespecified hierarchy, the chance of at least one apparently unusual result can rise. The registry lists the primary pain endpoint and a secondary preference endpoint. It does not report a multiplicity strategy, a testing hierarchy, or an adjustment for the secondary result. The preference p-value is therefore reported as unadjusted and should be interpreted accordingly.

The registry does not report whether other analyses were planned or conducted, how outcomes were selected for reporting, or whether any interim analyses occurred. Those details are not reported in the registry record and should not be inferred from the posted outcome summaries. The record also does not report a statistical analysis plan that would clarify the prespecified estimand, analysis method, treatment of sequence effects, or rules for handling multiple comparisons.

Missing-data handling is also unclear. The primary endpoint summaries list 47 observations for each injection condition, while the secondary preference comparison lists 45 for each condition. The registry does not explain the difference in reported denominators, identify the reasons for any absent preference responses, or describe imputation or other missing-data methods. It does not report whether all randomized participants were included in each analysis or define an analysis population.

These are limitations in the record, not proof that missingness or multiplicity affected the results. Without information about why responses are absent, it is not possible to assess whether the observed preference responses represent the intended analysis population or whether missingness could be related to the outcome. Likewise, without a documented analysis plan, it is not possible to determine whether the secondary comparison was exploratory or part of a prespecified confirmatory strategy.

The registry’s reported summaries remain interpretable as posted observations. Their inferential weight is more limited because the analysis populations, missing-data procedures and multiplicity approach are not reported. The primary endpoint’s absent inferential comparison is a separate gap: even complete observations would not, on their own, provide the unreported paired estimate and uncertainty assessment.

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’s adverse-event summary lists the group as all participants. It reports 47 participants at risk for serious adverse events and 0 affected, and 47 at risk for other adverse events and 0 affected. Deaths are reported as 0. These figures are counts recorded in the registry; they should not be read as proof that the study conditions have no safety risks.

The record does not report the adverse-event collection period, event definitions, severity grading, relatedness assessments, or the method used to solicit and record events. It also does not provide serious adverse-event terms, consistent with the reported count of 0. Without those details, readers cannot determine the scope or sensitivity of event ascertainment. The figures describe the posted safety summary, not every possible event under every use condition.

The study enrolled healthy volunteers and evaluated injections in a specific study context. The adverse-event counts do not establish safety in other populations, procedures, or settings. They should be considered alongside the limited information about monitoring and follow-up in the registry record, which does not report further details.

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

The primary endpoint summaries describe lower median pain ratings for injections with the kinetic anesthesia device than for injections without it in this randomized crossover study of healthy volunteers. The ratings were collected immediately after each injection. This is a descriptive pattern in the posted data, not a reported estimate of the paired condition effect with its uncertainty. The registry does not report an inferential comparison for the primary endpoint, so the precision and statistical evidence for that comparison cannot be assessed from the record.

The secondary preference result offers a separate signal in a direction consistent with the primary descriptive pattern. It is accompanied by an unadjusted inferential comparison, but it does not replace a primary endpoint analysis. Its interpretation is limited by the absence of reported multiplicity procedures and by the lack of an explanation for all preference responses. The clinical meaning of a scale difference is also not established by the statistical summaries alone; the registry does not report a threshold for a meaningful change in pain rating.

The study design provides a within-participant comparison, which can be useful when people differ in their typical pain ratings. Yet the record does not report the paired analysis, the handling of order or period effects, or the allocation and analysis details needed to assess those features. The descriptive summaries do not reveal how individual participants’ ratings changed between conditions, and their inter-quartile ranges are not confidence intervals for a treatment effect.

The findings concern healthy volunteers receiving lidocaine injections under the study conditions. The registry does not report enough detail to establish whether the same pattern would apply to patients, particular injection sites, other procedures, or routine clinical practice. It also does not provide a trial-specific sample-size justification or a primary analysis plan. These limitations constrain what can be concluded about generalizability and statistical certainty.

Accordingly, the posted data show a descriptive difference in pain-rating summaries and a secondary preference result, but they do not document a formal inferential conclusion for the primary outcome. They neither establish a clinical benefit nor establish an absence of one. The distinction is between the observed summaries and the broader claims that would require a reported primary analysis, clearer methods and evidence in the intended clinical settings.

13. Why This Trial Matters Statistically

This trial illustrates why design and analysis must be read together. Randomized crossover allocation creates a within-participant comparison, but the statistical method needs to reflect that dependency. Separate condition summaries can show the broad pattern in ratings, yet they cannot reveal the distribution of paired changes or quantify uncertainty in the paired contrast. Reporting medians and inter-quartile ranges is informative about the observed ratings, but it does not complete the inferential analysis of a crossover primary endpoint.

The record also shows why outcomes should not be treated as interchangeable. Pain rating is the primary outcome and directly captures reported pain after each injection. Preference is a secondary outcome collected after the second injection. A favorable preference comparison can complement the primary description, but its unadjusted p-value does not answer the primary statistical question. Keeping endpoint roles distinct protects against overinterpreting a result simply because it is accompanied by a confidence interval or a small p-value.

Planning calculations require similar care. The registry’s illustrations use fractions of an observed secondary effect and stated assumptions. Such calculations can help show how assumptions affect planning, but they are not evidence of observed power and do not reveal the rationale for the actual enrollment. No trial-specific sample-size justification for the primary endpoint is reported in the registry record.

Finally, transparent reporting of analysis populations, missing responses, multiplicity, and paired methods is essential for readers to judge precision and robustness. The record contains useful descriptive outcome information but leaves these aspects unreported. This case therefore emphasizes a general statistical principle: a visible pattern in endpoint summaries and a formal estimate of an effect answer different questions, and both design-aware analysis and complete reporting are needed to connect them.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

Several limitations specific to this study constrain interpretation. The participants were healthy volunteers, so the posted summaries do not directly describe patients receiving injections during dermatologic surgery or other clinical care. The registry’s background identifies injection sites common to dermatologic surgery as the motivation for the study, but the specific sites used in the study are not reported in the registry record. Details of injection technique, dose, operator procedures and the device protocol are also not reported there.

The design is crossover and randomized, but the registry does not describe the randomization method, concealment, sequence balance, or analysis of order and period effects. The order of the two conditions could matter if the experience of the first injection influenced the second response. The record does not report whether a washout or other measure was used, or how the split-body description relates to injection locations. No assumption about these procedures should be made from the design label alone.

The primary results are presented as medians and inter-quartile ranges without a reported paired contrast, confidence interval or p-value. This limits assessment of the magnitude and precision of the within-participant comparison. Participant-level paired ratings are not reported, so the distribution of individual changes cannot be evaluated from the record. The secondary outcome has an unadjusted result, but the registry does not explain the preference responses not represented by the two reported categories or describe missing-data handling.

Further limitations include the absence of a reported multiplicity plan, analysis population, statistical analysis plan, and trial-specific sample-size justification. Adverse-event collection details and follow-up are also not reported. These omissions do not establish that the study was conducted improperly; they limit what readers can verify and how confidently the reported summaries can be generalized or interpreted.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Kinetic Anesthesia Device Study — NCT03344510.
• Registry record last updated 2019-04-02; status last verified 2019-03.
• Results first posted 2019-04-02.
• 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

The registry describes a completed randomized, unmasked, split-body crossover study of a kinetic anesthesia device during lidocaine injection in healthy volunteers. Enrollment was 47. The primary endpoint was immediate pain rating on a visual analog scale, summarized by median and inter-quartile range. The median was 7.5 mm for injections with the device and 26.0 mm for injections without it; no inferential primary comparison is reported in the registry record.

The secondary endpoint was participant preference after the second injection. The registry reports a risk difference of 0.6, a confidence interval from 0.437 to 0.763, and an unadjusted p-value of <0.001. Missing-response handling, multiplicity procedures, and the analysis population are not reported. Safety counts list 0 serious adverse events, 0 other adverse events and 0 deaths. The record does not report a trial-specific sample-size justification or sufficient analysis details to establish the precision of the primary comparison.