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 Efficiency of the King Vision Video Laryngoscope (NCT02482870), a randomized na study. The primary outcome is Intubation Success Rate.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02482870 |
| Phase | NA |
| Condition | Respiratory Failure, Intubation |
| Allocation | Randomized |
| Design model | Sequential |
| Masking | Double |
| Enrollment | 388 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Recep Tayyip Erdogan University |
| Results posted | Yes |
2. Clinical Question
The clinical question is whether intubation outcomes differ according to which laryngoscope is used first: a Macintosh laryngoscope or a King Vision video laryngoscope. The registry describes adults scheduled for general anesthesia and lists intubation success rate as the primary outcome. Other outcomes include intubation time, glottic view time, Cormack-Lehane score, and airway complications.
Population
Adult patients scheduled for general anesthesia during the study period. The registry also lists respiratory failure and intubation as conditions, but does not give further detail about the analyzed population.
Intervention
King Vision video laryngoscope, used first in one sequence. The registry describes patients as subsequently intubated with the Macintosh laryngoscope.
Comparator
Macintosh laryngoscope, used first in the other sequence. The registry describes patients as subsequently intubated with the King Vision video laryngoscope.
Primary question
How does the recorded intubation success outcome compare across the two device sequences? A comparative estimate or result for this primary outcome is not reported in the registry record.
The sequence descriptions indicate that both devices were used, with their order differing between groups. This makes the order of device use central to interpreting any comparison: outcomes could reflect the device, the sequence, or the experience of having already undergone an intubation attempt. The registry record does not explain how those possibilities were handled in the analysis.
3. Trial Design
This was a randomized trial with a sequential model and double masking recorded in the registry. Enrollment was 388. The trial status is completed; its recorded start was 2014-01 and its primary completion was 2014-07. The sponsor was Recep Tayyip Erdogan University.
The two arm descriptions define the groups by order of device use. One group had the King Vision video laryngoscope first and the Macintosh laryngoscope afterward. The other had the Macintosh first and the King Vision afterward. Thus, the comparison is not simply between groups receiving only one device: the registry describes both devices being used in each sequence. It does not report the interval between attempts, how the order was generated, or whether the analysis accounted for paired observations and sequence effects.
Masking is listed as double, but the registry record does not identify who was masked or explain how masking was maintained while using visibly different devices. It also does not describe allocation concealment, protocol deviations, or whether the randomized sequence was analyzed as assigned. These details are important for judging potential bias, but should not be inferred from the masking and randomization labels alone.
The registry identifies five outcome measures and five analyses, but a single comparative result for the primary outcome is not reported in the registry record. The posted safety counts describe participants grouped by device sequence, but do not fill that gap. A protocol, statistical analysis plan, sample-size justification, and detailed participant flow 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.
Before assignment: None of the 388 patients enrolled between January 2014 and July 2014 were excluded from the trial.
Overall Study
| Stage | Macintosh First, Then King Vision | King Vision First, Then Macintosh |
|---|---|---|
| STARTED | 186 | 202 |
| COMPLETED | 186 | 202 |
| 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.
Population: Adult patients scheduled for general anesthesia with endotracheal intubation.
| Characteristic | Unit | All Study Participants |
|---|---|---|
| Participants analysed | 388 | |
| Age, Continuous | years | 48.5 (37 to 55) |
| Sex: Female, Male: Female | Participants | 158 |
| Sex: Female, Male: Male | Participants | 230 |
| Height, Continuous | cm | 171 (165 to 175) |
| Weight, Continuous | kg | 80 (70 to 88) |
| Body mass index, Continuous | kg/m^2 | 26.9 (24.3 to 30.9) |
| History of obstructive sleep apnea, Categorical: 0 - No history of obstructive sleep apnea | Participants | 292 |
| History of obstructive sleep apnea, Categorical: 1 - History of obstructive sleep apnea | Participants | 96 |
| History of snoring, Categorical: 0 - No history of snoring | Participants | 246 |
| History of snoring, Categorical: 1 - History of snoring | Participants | 142 |
| Mallampati class, Categorical: 0 - Ability to see any part of the epiglottis | Participants | 0 |
| Mallampati class, Categorical: 1 - Soft palate, fauces, uvula, pillars visible | Participants | 79 |
| Mallampati class, Categorical: 2 - Soft palate, fauces, uvula visible | Participants | 113 |
| Mallampati class, Categorical: 3 - Soft palate, base of uvula visible | Participants | 107 |
| Mallampati class, Categorical: 4 - Soft palate not visible at all | Participants | 89 |
| American Society of Anesthesiologists score, Categorical: 1 - A normal healthy patient | Participants | 192 |
| American Society of Anesthesiologists score, Categorical: 2 - A patient with mild systemic disease | Participants | 196 |
| Thyromental distance, Continuous | cm | 6.2 (5.3 to 7.3) |
| Sternomental distance, Continuous | cm | 10.9 (9.6 to 12.3) |
| Interincisor distance, Continuous | cm | 3.3 (2.7 to 4.1) |
6. Primary Endpoint
The registry lists the primary outcome as Intubation Success Rate, measured over less than 24 hours.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is named “Intubation Success Rate,” with a timeframe of less than 24 hours. The registry defines an intubation attempt as entrance of the endotracheal tube into the patient's mouth. A major change in laryngoscope alignment is defined as another attempt. Successful intubation is defined as the endotracheal cuff passing through the patient's vocal cords.
The registry's description then expresses the success rate as “1 / [the number of attempts].” That wording is not a conventional definition of a participant-level success proportion, and the registry record does not clarify how this description was translated into the reported analysis. The endpoint is listed with participants as its unit and number as its parameter, but the primary outcome has several categories or time points and is not reduced to one comparison in the posted results.
Success and the number of attempts are relevant because they describe whether and how an intubation was completed. However, an endpoint needs a clearly specified analysis unit and summary to support a direct comparison. The registry record does not report the category-specific counts, an effect estimate, or uncertainty for this endpoint. Consequently, the clinical question cannot be resolved from the primary-outcome information recorded there.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes that the study randomized patients to different orders of Macintosh and King Vision video laryngoscope use, and it lists intubation success rate as the primary outcome. It does not provide a single comparative primary-outcome result. No effect estimate, confidence interval, or p-value for that comparison is reported in the registry record. Therefore, the size, direction, and precision of any difference in the primary endpoint cannot be interpreted from these entries.
The registry's decision not to reduce the primary outcome to one comparison matters. It indicates that the outcome has multiple categories or time points in the posted record, rather than one summary suitable for a straightforward two-group reading. Without category-level results and a clearly specified comparison, it is not possible to determine which outcome values were more frequent, or how those values related to the assigned device order.
Other listed outcomes include intubation time, glottic view time, Cormack-Lehane score, and airway complications. Their names indicate the topics studied, but do not establish what the observed results were. Comparative estimates and uncertainty for these measures are not reported in the registry record. It would be inappropriate to infer a benefit, harm, or lack of difference from the study title or outcome list.
The safety entries report zero serious events in each sequence group. They also report three other events in each group, with deaths listed as six and four, respectively. These are descriptive counts, not estimates of a causal effect. The registry does not provide event narratives, attribution, timing, or an analysis relating deaths to either device. The serious-event terms listed include situation of “can't intubate, can't ventilate,” laryngospasm/bronchospasm, and desaturation below 90%, each recorded as 0.0%. Those entries do not substitute for a complete safety assessment.
Overall, the posted information describes the design, endpoints, and selected safety counts, but does not supply the comparative efficacy results needed to answer the primary question. Missing estimates should not be interpreted as evidence of equivalence or as evidence that an outcome did not occur.
9. Statistical Methods Explained
Randomization assigns participants or sequences by a chance process, which is intended to make comparison groups less systematically different at baseline. The registry labels this study randomized. It does not report the randomization sequence method, allocation concealment, or whether the analysis followed assigned sequence. Those details are not reported in the registry record, so the label alone cannot establish how well allocation was implemented.
What does the sequence comparison involve?
The arm descriptions say that patients were intubated with both devices, with the order changing between groups. In a design where each participant experiences more than one condition, the observations may be related within a person. General statistical practice accounts for that dependence rather than treating all observations as independent. The registry gives the model as sequential, but does not report the analysis method or explain whether within-person dependence, order, or possible learning effects were addressed. It is therefore not possible to identify the statistical model used from the registry record.
How should a binary endpoint be interpreted?
A binary outcome classifies an observation into categories such as an event or no event. A useful comparison normally states the number of participants in each category and gives an effect estimate with an uncertainty interval. A confidence interval describes a range of values compatible with the data and the method's assumptions; a narrower interval indicates greater precision than a wider interval. General interpretation also depends on the exact analysis unit. The registry's primary endpoint description refers to success and attempts, but does not provide a single comparative estimate or clarify how its multiple categories or time points were handled.
A p-value, when reported, describes how incompatible the observed data are with a specified null model under the assumptions of the test. It does not measure the size or clinical importance of an effect, and a non-significant result does not establish equivalence. No primary-outcome p-value or confidence interval is reported in the registry record. No equivalence or non-inferiority margin is reported either.
What do the planning assumptions mean?
The record describes planning illustrations based on the observed effect, using a two-sided significance level of 0.05, equal allocation, and a normal approximation. The illustrations vary the effect to be detected as a stated share of the observed effect. For time-to-event outcomes, the record describes event totals using the Schoenfeld method; for other outcomes, the planning quantity is participants per arm. These are planning calculations, not the observed enrollment and not observed power. The numerical planning outputs and the observed effect used for them are not reported in the registry record.
General sample-size planning asks how much information would be needed to detect a prespecified effect under stated assumptions. It does not establish that a trial was adequately powered for every endpoint, especially when the actual outcome definition, analysis, or event frequency differs from the planning assumptions. The trial's own sample-size justification and the assumptions used in its protocol are not reported in the registry record.
Why does over-dispersion matter?
In general, over-dispersion occurs when outcome variability is greater than a model assumes. Standard errors can then be too small if the model does not account for that extra variation, making uncertainty appear lower than it is. This concept is most relevant for count outcomes modeled with assumptions about their variability. The primary outcome is listed as a participant count, but the record does not describe a fitted model or report enough outcome detail to assess over-dispersion. It should not be presumed that such an issue did or did not affect the analysis.
Finally, masking can reduce some forms of assessment or performance bias, but its meaning depends on who was masked and how. The registry records double masking without identifying the masked parties or the procedures. The different devices may also make practical masking difficult; the registry does not explain how this was handled. As a result, randomization and masking are design features to note, not substitutes for a transparent account of the analysis and results.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists several outcomes, including intubation success rate, intubation time, glottic view time, Cormack-Lehane score, and airway complications. Testing or analyzing multiple outcomes can raise multiplicity concerns: when many comparisons are made, the chance of at least one apparently unusual result may increase. General approaches include prespecifying a primary comparison, adjusting for multiple testing, or interpreting secondary findings as exploratory. Which approach was used in this trial is not reported in the registry record.
The record lists five outcome measures and five analyses, but does not provide a complete analysis plan, hierarchy among the outcomes, or multiplicity adjustment. The primary endpoint is described as having several categories or time points and is not reduced to one comparison. Without the analysis details, the meaning of any individual category or secondary result cannot be judged against an established testing strategy.
Missing-data handling is not reported in the registry record. The record also does not give participant flow, missing outcome counts, exclusions from analysis, or analysis-population definitions. It is therefore unclear whether every randomized participant contributed to every endpoint, or how incomplete measurements were treated.
These omissions do not show that the trial mishandled multiplicity or missing data. They limit the ability to assess whether the posted analyses followed a prespecified plan and whether results could be affected by selective availability of outcomes. A statistical analysis plan, definitions for analysis populations, and endpoint-level completeness information are not reported in the registry record.
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 |
|---|---|---|---|
| King Vision First, Then Macintosh | 0 | 202 | 0.0% |
| Macintosh First, Then King Vision | 0 | 186 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| King Vision First, Then Macintosh | 6 of 202 |
| Macintosh First, Then King Vision | 4 of 186 |
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 |
|---|---|
| King Vision First, Then Macintosh | 3 of 202 |
| Macintosh First, Then King Vision | 3 of 186 |
Most frequent serious adverse event terms
| Event term | Organ system | King Vision First, Then Macintosh | Macintosh First, Then King Vision |
|---|---|---|---|
| Situation of "can't intubate, can't ventilate" | Respiratory, thoracic and mediastinal disorders | 0 of 202 | 0 of 186 |
| Laryngospasm/Bronchospasm | Respiratory, thoracic and mediastinal disorders | 0 of 202 | 0 of 186 |
| Desaturation below 90% | Respiratory, thoracic and mediastinal disorders | 0 of 202 | 0 of 186 |
Most frequent non-serious adverse event terms
| Event term | Organ system | King Vision First, Then Macintosh | Macintosh First, Then King Vision |
|---|---|---|---|
| Cuts on lips | Skin and subcutaneous tissue disorders | 3 of 202 | 3 of 186 |
| Dental damage | Surgical and medical procedures | 0 of 202 | 0 of 186 |
| Sore throat | Skin and subcutaneous tissue disorders | 0 of 202 | 0 of 186 |
Serious events with the highest arm-level rate: situation of "can't intubate, can't ventilate" (0.0%), laryngospasm/bronchospasm (0.0%), desaturation below 90% (0.0%).
The safety record separates participants by device sequence. In the King Vision first, then Macintosh group, serious events affected 0 of 202 at risk, other events affected 3 of 202 at risk, and deaths were listed as 6. In the Macintosh first, then King Vision group, serious events affected 0 of 186 at risk, other events affected 3 of 186 at risk, and deaths were listed as 4. The registry also lists situation of “can't intubate, can't ventilate,” laryngospasm/bronchospasm, and desaturation below 90% among the leading serious-event terms, each at 0.0%.
These entries are counts recorded by group, not a causal comparison of device safety. The registry record does not explain whether the deaths were related to the procedures or devices, provide timing or circumstances, or clarify how the listed terms relate to the overall serious-event count. The identical count of other events does not establish equal risk, and zero recorded serious events does not establish that serious harm is impossible. No comparative safety estimate or uncertainty interval is reported in the registry record.
12. What the Result Does, and Does Not, Mean
The record shows a randomized study of two device-use sequences in adults scheduled for general anesthesia, with intubation success rate designated as the primary outcome. It also documents outcomes of interest and gives selected safety counts. Those details describe what the study set out to examine and what safety information was entered in the registry.
They do not establish whether either device sequence produced a higher intubation success rate, shorter times, a better glottic view, or fewer complications. The registry record does not report a single comparative primary-outcome result, and the listed secondary outcomes do not include comparative estimates in the registry record recorded. In the absence of estimates and measures of uncertainty, neither the magnitude nor precision of any difference can be judged.
Not reporting a comparison is different from reporting no difference. It is also different from demonstrating equivalence. The record does not provide an equivalence or non-inferiority framework, a margin, or a confidence interval that could support such a conclusion. Similarly, the presence of zero serious events in the group entries is a description of recorded counts, not proof that either device is free of serious risk.
The study's sequence design also warrants caution. Since both devices are described as used, the outcome for one may be influenced by what happened during the earlier attempt. Without a reported analysis that addresses within-person dependence and order, it is not possible to isolate a device-specific effect from a sequence effect. The registry record does not report whether these factors were modeled.
The defensible interpretation is therefore limited: the trial registered a randomized comparison of device order and recorded selected outcomes and safety counts, but the comparative primary result and supporting statistical details are not reported in the registry record. Conclusions about relative performance or safety would require information beyond these entries.
13. Why This Trial Matters Statistically
This trial is statistically notable because the registry describes two devices being used in different orders, rather than describing separate groups each receiving only one device. That structure raises questions about paired observations, order effects, and the possible influence of an earlier attempt on a later one. These are general design and analysis concerns for sequence comparisons; the registry record does not say how they were addressed.
The primary endpoint description also highlights why precise outcome definitions matter. It defines an attempt and a successful passage of the cuff through the vocal cords, then expresses the success rate as 1 divided by the number of attempts. The record does not explain how that description maps onto the primary outcome categories or the analysis. A clear definition helps readers understand what is counted, what constitutes success, and how a comparison should be interpreted.
Finally, the record illustrates the difference between trial registration details and results adequate for inference. Randomization, masking, enrollment, outcome names, and safety counts are informative, but they cannot replace an effect estimate and its precision. The absence of a single primary comparison prevents readers from assessing the direction or size of any observed difference. Reporting analysis methods, missing-data handling, and participant flow would also help readers evaluate the strength of the evidence.
The statistical importance is not a claim about which device is preferable. It is the need to align the design, endpoint definition, analysis, and reporting so that a reader can distinguish a device effect from sequence effects and can judge uncertainty rather than infer a conclusion from incomplete results.
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 single comparative primary-outcome estimate, its uncertainty, or a p-value. It also notes that the primary outcome has several categories or time points and is not reduced to one comparison. This is the central limitation for interpreting the trial's efficacy question.
The endpoint wording leaves uncertainty about its operational analysis. The record defines success by passage of the cuff through the vocal cords and defines an attempt, but describes the success rate as 1 divided by the number of attempts. How that wording was converted into categories or a participant-level comparison is not reported in the registry record.
The arm descriptions indicate that both devices were used in different orders. The statistical approach to repeated observations, order effects, and potential learning or carryover effects is not reported. The masking label is recorded as double, but the masked parties and masking procedures are not described. Randomization procedures and allocation concealment are also not reported.
For safety, the registry provides selected counts but not event descriptions, attribution, timing, or comparative uncertainty. The relationship between deaths and the devices or procedures is not reported. The record also does not provide participant flow, missing outcome information, analysis populations, or the handling of missing data. A protocol, statistical analysis plan, and trial-specific sample-size justification are not reported in the registry record. These limitations constrain assessment of both bias and precision, without establishing that any particular problem occurred.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Efficiency of the King Vision Video Laryngoscope — NCT02482870.
- Registry record last updated 2023-12-20; status last verified 2023-12.
- Results first posted 2018-02-22.
- 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
NCT02482870 is a completed randomized trial sponsored by Recep Tayyip Erdogan University. Enrollment was 388, and the recorded study period began in 2014-01, with primary completion in 2014-07. The registry lists double masking and a sequential model.
Adults scheduled for general anesthesia were assigned to sequences using the Macintosh and King Vision video laryngoscopes in different orders. The primary outcome is intubation success rate, with a timeframe of less than 24 hours. Other listed outcomes include intubation time, glottic view time, Cormack-Lehane score, and airway complications.
The record includes selected serious-event, other-event, and death counts by sequence group. It does not report a single comparative primary-outcome result, its precision, or a detailed account of the statistical analysis. Consequently, the comparative performance of the two device sequences cannot be determined from the registry record alone.