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 VL vs DL in Inexperienced Users: a Pediatric Manikin Study (NCT02991820), a randomized na study. The primary outcome is Time to Endotracheal Intubation.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02991820 |
| Phase | NA |
| Condition | Videolaryngoscopes (VL), Direct Laryngoscopy (DL), Inexperienced Users |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Not Stated |
| Enrollment | 43 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Joseph D. Tobias |
| Results posted | Yes |
2. Clinical Question
Population
Users performing intubation on a pediatric manikin. Inexperienced users include trainees—SRNAs, residents, fellows, and medical students—and nurses at NCH. Experienced users include faculty pediatric anesthesiologists and CRNAs. The registry reports enrollment of 43, but does not report the number in each experience group or other participant characteristics.
Intervention
The devices under study are the C-MAC and GlideScope videolaryngoscopes, along with Miller and Macintosh laryngoscopes used for direct laryngoscopy. The study concerns user performance with these devices during manikin intubation.
Comparator
The comparison is among the four named devices. The registry describes a randomized, parallel study, but the specific assignment scheme and which device comparisons were designated as primary are not reported in the registry record.
Primary question
How much time does it take to successfully intubate the manikin using each device? The primary outcome is time to endotracheal intubation, measured in seconds and described as a mean with standard deviation. The registry also lists successful intubation within 120 seconds as a secondary outcome.
The stated question is about performance in a simulated setting, not patient outcomes. The manikin provides a setting in which device use and time to successful intubation can be assessed without the endpoint being a clinical procedure on a child. The summary says the study assesses aspects of intubation by both experienced and inexperienced users, while the title emphasizes inexperienced users. The registry does not report separate outcome results by experience group, so it is not possible to determine from the record whether the device comparisons were intended to answer distinct questions for each group. Nor does the record provide a numerical estimate of the time differences among devices.
3. Trial Design
The registry classifies the study as randomized and parallel, with an enrollment of 43. The study is marked completed. Its listed start was 2016-06 and its primary completion was 2017-05. The phase is recorded as NA. The setting described in the summary is an intubating pediatric manikin, and the study compares performance using four laryngoscopes: Miller, Macintosh, C-MAC, and GlideScope.
The registry describes two user experience categories. Inexperienced users include trainees—SRNAs, residents, fellows, and medical students—and nurses at NCH. Experienced users include faculty pediatric anesthesiologists and CRNAs. Although the summary describes assessment of both groups, the title foregrounds inexperienced users. The number enrolled in each experience group, the numbers assigned to each device, and whether all user groups used all devices are not reported in the registry record.
Randomized allocation means assignment was described as random, and a parallel model means the trial was not registered as a crossover design. These labels do not reveal the sequence generation, concealment, allocation ratio, or the operational details of assignment. Those details are not reported in the registry record. The description also does not establish whether the same users tried multiple devices or how the study handled repeated attempts by a user. Such details matter when interpreting comparisons because observations from the same user may be related rather than independent.
The registry lists two outcome measures and zero analyses. It identifies time to endotracheal intubation as the primary outcome, but does not report device-specific means, standard deviations, participant counts for the outcome, or an inferential comparison. Successful intubation within 120 seconds is listed as a secondary outcome, without reported event counts or analysis. The record therefore establishes the broad design and intended measurements, but not the results or enough analytic detail to reconstruct the comparisons.
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 | Inexperienced Users | Experienced Users |
|---|---|---|
| STARTED | 12 | 31 |
| COMPLETED | 12 | 31 |
| NOT COMPLETED | 0 | 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 | Inexperienced Users | Experienced Users | Total |
|---|---|---|---|---|
| Participants analysed | 12 | 31 | 43 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 12 | 31 | 43 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 |
| Sex: Female, Male: Female | Participants | NA | NA | NA |
| Sex: Female, Male: Male | Participants | NA | NA | NA |
| Race and Ethnicity Not Collected | Participants | — | — | 0 |
| Region of Enrollment: United States | participants | 12 | 31 | 43 |
6. Primary Endpoint
The registry lists the primary outcome as Time to Endotracheal Intubation, measured over the same day (within seconds to minutes).
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | seconds |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is time to endotracheal intubation, measured in seconds. The registry defines it as the amount of time required to successfully intubate the manikin using each device, and identifies the summary measure as a mean with standard deviation. The timeframe is described as the same day, within seconds to minutes.
Time is a continuous measure: it can take a range of values rather than representing only a category such as success or failure. A mean describes the average recorded time, while a standard deviation describes how spread out individual times are around that average. Together, these measures can convey both typical timing and variability, although they do not show the full distribution or identify why times differ.
In general, timing can distinguish performance patterns that a simple success indicator may not capture. The registry also lists successful intubation within 120 seconds as a secondary outcome, which frames performance as a success status within a specified time limit. The two measures answer related but different questions: time to successful intubation describes duration, while the secondary measure classifies whether success occurred within the stated limit.
The record does not report the observed time values, device-specific means or standard deviations, or the number of successful intubations. It therefore does not establish which device had shorter recorded times or how precisely any device comparison was estimated.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record gives the study question, design labels, device names, population descriptions, and outcome definitions, but it does not report numerical results for either outcome. In particular, no mean time, standard deviation, device-specific sample size, confidence interval, or test result is reported in the registry record. There is consequently no posted estimate from which to describe the direction, magnitude, or precision of a device comparison.
The primary outcome is a continuous time measure. A comparison of means would describe differences in average time between devices, but the record does not provide the underlying summaries or an analysis. It is not possible to infer that any device was faster, slower, or similar to another. Lack of a reported comparison is not evidence that the devices performed identically; it means the registry record does not present enough results to assess their relative performance.
The secondary outcome, successful intubation within 120 seconds, is also defined, but no counts or percentages are reported. There is no basis in the record for assessing how often this outcome occurred, whether occurrence differed by device, or how uncertain such a comparison might be.
The registry reports enrollment of 43. That figure alone does not show how many observations contributed to the primary outcome, how participants were distributed among devices or experience groups, or whether all enrolled users completed the recorded assessment. The outcome-specific denominators and missing-data details are not reported in the registry record.
Interpretation is further constrained by the absence of reported analysis details. The registry lists zero analyses, and does not report the statistical model, any adjustment for user experience, or how dependence among observations from the same user was addressed. It also does not report whether the primary question was evaluated separately within user groups or across them. These omissions limit assessment of both the intended comparison and the reliability of any possible inference.
The study is described as a manikin assessment. Its endpoint therefore concerns timing in that simulated setting; the registry does not report patient-level outcomes. The posted information supports describing what the study set out to measure, but not drawing a conclusion about comparative performance or clinical effects.
9. Statistical Methods Explained
The registry identifies time to endotracheal intubation as a continuous outcome summarized by a mean and standard deviation. The following statistical explanations are general; they describe how such measures and comparisons are usually interpreted, not a claim about analyses performed in this study.
What does a mean describe?
A mean is the arithmetic average of observed values. For an intubation-time outcome, it would summarize the average recorded time among the observations included in a group. A mean can be useful for comparing groups, but it does not show whether most observations cluster near the average or whether a smaller number of unusually long or short times influence it. The registry does not report the device-specific means or the distribution of times.
What does a standard deviation describe?
A standard deviation summarizes the spread of individual values around their group mean. A smaller standard deviation indicates less dispersion around that mean, while a larger one indicates greater dispersion. It is not the same as the uncertainty of the estimated mean. The registry specifies standard deviation as the dispersion measure but does not report any values.
How would a mean difference be interpreted?
In general, a comparison of means expresses how far apart the average outcomes are in the groups being compared, in the outcome's original units. For this study, the unit is seconds. The interpretation would depend on which device groups were compared and how assignment and user experience were handled. The record does not report a mean difference, a confidence interval, or a statistical test, so no particular comparison can be interpreted.
A confidence interval, in general, gives a range of values compatible with the observed data under the statistical model and assumptions used. It describes uncertainty around an estimate; it is not a guarantee that the true value lies in the interval. A narrow interval indicates greater precision than a wide one, all else being equal. No confidence interval for a device comparison is reported in the registry record.
Why can the analysis structure matter?
Randomized allocation can support comparisons by reducing systematic differences between assigned groups, provided assignment and analysis are carried out appropriately. The registry label alone does not establish how randomization was implemented or whether the analysis preserved the intended comparison. The specific allocation procedures and analysis population are not reported in the registry record.
In general, observations from the same person may be correlated. For example, if one user contributed timing observations for more than one device, those observations would not necessarily be independent. A statistical model might need to account for that structure. The registry does not report whether users tried multiple devices, whether repeated observations were collected, or whether any analysis addressed within-user dependence. This is an uncertainty about the available description, not evidence that such dependence occurred or was ignored.
User experience is a feature of the stated study population. In general, it may be relevant to describe or account for experience when comparing device performance, because the study includes experienced and inexperienced users. The record does not state whether the principal comparison pooled the groups, adjusted for experience, or reported separate comparisons. No group-specific outcome results are reported.
What can the planning assumptions tell readers?
General sample-size illustrations can show how many participants per arm might be needed under specified assumptions; they are not observed trial results and do not establish the power achieved by a completed study. The registry describes a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It states that the effect to detect is a stated fraction of the observed effect. The available record does not report a trial-specific sample-size justification, and does not provide numerical planning outputs. Any such illustration should be read as planning information, not as observed power or evidence of a treatment effect.
In general, a significance test addresses compatibility of data with a specified null hypothesis under a model. A p-value is not the probability that the null hypothesis is true, and it does not measure the size or practical importance of an effect. The registry record reports no p-value or test result. The absence of a reported test does not establish either statistical significance or its absence.
The primary outcome is time to successful intubation, but the registry description does not give details about handling attempts that did not result in success or observations with no recorded time. Those rules can affect analysis of a timing endpoint. They are not reported in the registry record, so the statistical treatment of such cases cannot be assessed.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists two outcomes: time to endotracheal intubation as the primary outcome and successful intubation within 120 seconds as a secondary outcome. It does not report an analysis for either outcome. The statistical plan for handling multiple outcomes or multiple device comparisons is not reported in the registry record. It is therefore not possible to determine whether any multiplicity adjustment was planned or used, or which comparison was intended to carry the main inferential emphasis.
Multiplicity is a general issue when several hypotheses are tested. The more comparisons considered, the greater the chance that at least one result may appear notable by chance under a setting where all null hypotheses are true. Methods for controlling that risk can include prespecifying a primary contrast or adjusting the testing procedure. The registry does not describe such a procedure, so no claim can be made about how multiplicity was managed.
Missing-data handling is also not described. The record does not report whether any participants lacked a usable time measurement, how unsuccessful intubations were handled for the primary endpoint, or whether incomplete outcome observations occurred. It does not state whether analyses used all randomized users, only users with recorded outcomes, or another analysis population. These details are not reported in the registry record.
Such information matters because exclusions or missing measurements can change which users are represented in an estimate. The enrollment figure does not by itself establish the number analyzed for either outcome. With no reported outcome denominators, missingness description, or analysis-population definition, the completeness and representativeness of the analyzed data cannot be evaluated.
11. What the Result Does, and Does Not, Mean
The registry record describes a randomized comparison of four laryngoscopes in a pediatric-manikin study involving experienced and inexperienced users. It specifies time to successful intubation as the primary endpoint and successful intubation within 120 seconds as a secondary outcome. These details clarify the intended measurement and broad study question.
The record does not report outcome values or comparative analyses. It therefore does not show whether one device had a shorter average time, whether success within 120 seconds differed across devices, or how precise any such comparison was. It also does not support concluding that device performance was the same. Without estimates and uncertainty measures, the direction and size of any differences remain unknown from the registry record.
Even if outcome comparisons were available, a manikin endpoint would describe performance in the stated simulated setting. The registry does not report patient outcomes, so the time measure should not be treated as evidence about clinical outcomes in children. The description also does not establish whether results differ by user experience, because group-specific results are not reported.
The enrollment of 43 describes the registered study enrollment, not the number necessarily analyzed for each endpoint. Outcome-specific participant counts and handling of missing or unsuccessful attempts are not reported. Those omissions limit assessment of how much information supports any potential comparison.
Accordingly, the record is informative about the intended design and outcomes, but not about comparative results. A statistical interpretation of relative performance would require the posted outcome estimates, uncertainty, and analysis details, none of which are reported in the registry record.
12. Why This Trial Matters Statistically
Statistically, this study raises questions about how performance should be summarized when multiple devices and different user experience groups are involved. The primary endpoint, time to successful intubation, is continuous, while successful intubation within 120 seconds is a threshold-based outcome. These outcomes can describe different aspects of performance, so clear prespecification of the primary comparison and analysis is important in general.
The registry’s randomized, parallel classification gives readers a broad description of the design, and the enrollment is recorded as 43. Yet interpretation of a randomized comparison also depends on assignment details, outcome denominators, and the analysis plan. Those details are not reported in the registry record. Their absence means that readers cannot assess how comparisons were structured or whether all relevant observations were represented.
Including experienced and inexperienced users makes the target population description more specific, but it also makes it important to know whether experience was considered in the analysis. Device comparisons could be described overall, by experience group, or using a model that includes experience; the registry does not say which approach was taken. No subgroup results are reported.
The study also illustrates the distinction between defining outcomes and reporting results. The endpoint definitions identify what the investigators intended to measure, but they do not reveal the observed performance or the uncertainty around comparisons. With no reported analyses, the record does not allow readers to evaluate effect size, precision, or multiplicity handling. This is a limitation of what can be interpreted from the registry record, rather than a conclusion about the conduct or findings of the study.
13. 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 contains limited information for evaluating the study’s results. It reports enrollment and broad design labels, but no outcome estimates, confidence intervals, p-values, or analysis details. The number of participants in each user group and device group is not reported. The registry also lists zero analyses, leaving no reported statistical comparison to interpret.
The description does not specify the randomization procedure, allocation ratio, concealment, or the sequence in which users encountered devices. It does not state whether users performed assessments with more than one device or how repeated observations, if any, were handled. The record also does not explain whether user experience was incorporated into the analysis or whether results were reported separately by experience group.
For the primary outcome, the registry defines the time measure and its summary as a mean with standard deviation, but does not explain how unsuccessful intubations, incomplete measurements, or any missing observations were handled. It does not provide endpoint-specific denominators. The record gives no numerical counts for successful intubation within 120 seconds.
The study uses a pediatric manikin, as described in the registry. The registered outcome is therefore a measure of performance in that setting; patient-level outcomes are not reported. Finally, the statistical plan for multiple outcomes and device comparisons is not reported in the registry record. These limitations restrict assessment of the analysis and findings, but do not establish that any particular method was or was not used.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: VL vs DL in Inexperienced Users: a Pediatric Manikin Study — NCT02991820.
- Registry record last updated 2018-07-18; status last verified 2018-07.
- Results first posted 2018-07-18.
- 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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17. Record Summary
The registry record describes a completed randomized, parallel pediatric-manikin study with enrollment of 43. It compares Miller and Macintosh direct laryngoscopes with the C-MAC and GlideScope videolaryngoscopes. The population description includes inexperienced users—trainees and nurses at NCH—and experienced users, including faculty pediatric anesthesiologists and CRNAs. The listed primary outcome is time to endotracheal intubation, measured in seconds and summarized as a mean with standard deviation. Successful intubation within 120 seconds is listed as a secondary outcome.
The registry does not report device-specific outcome values, analysis results, outcome denominators, or statistical methods. Consequently, the record defines the study question but does not provide enough reported evidence to interpret comparative performance or its precision.