Clinical Study of the Endotracheal Tube Used in Prone Position Ventilation Condition: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Clinical Study of the Endotracheal Tube Used in Prone Position Ventilation Condition (NCT02449356), a randomized na study. The primary outcome is Displacement of the Endotracheal Tube.

2. Clinical Question

The study rationale describes reducing or avoiding complications during perianesthesia and supporting respiratory therapy for critical patients in intensive care. Those statements explain the investigators’ motivation; they are not results. The registry record also lists prolapse of the endotracheal tube and looseness or dampness of the tape as secondary outcomes, but does not report their results.

3. Trial Design

This was a randomized, double-masked, parallel-group study, with the prone position endotracheal tube compared against a traditional endotracheal tube. The registry lists enrollment of 60 participants and marks the study as completed. The recorded start was 2015-09, and primary completion was 2016-09. The study phase is listed as NA.

The stated clinical context includes patients positioned prone during surgery and patients with acute respiratory distress syndrome in an intensive care unit. The primary outcome timeframe, however, is described specifically as follow-up for the duration of surgery, averaging 2 hours. The record does not clarify whether the enrolled participants came from both clinical settings or how the outcome timeframe applies to any intensive-care participants.

The two arms are described in terms of the tube used: one received the prone ventilation tube with a fixed device and fixed rope, and the other received the routine tube. Although the record labels the study double-masked, it does not report which people were masked or how masking was maintained. Details about random-sequence generation, allocation concealment, site count, eligibility criteria, and other aspects of study conduct are not reported in the registry record. The record also does not report the protocol, a sample-size justification, or a detailed statistical analysis plan.

The primary outcome is displacement, divided into severity categories. The registry record states that all patients in each group were analyzed, but it does not provide the category counts or a single group comparison. The record lists six outcome measures and two analyses; results for the listed secondary outcomes are not reported in the registry record. These gaps limit assessment of both the observed effect and the conduct of the analyses.

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: We finally enrolled 60 patients for our trail. Among the 80 candidates, 7 patients couldn't meet our inclusion criteria; the other 13 patients refused to participate in this trail at last.

Overall Study

Analysis population for the primary outcome, as defined in the registry: All patients in each group were analyzed

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: all participants in both groups were analyzed

6. Primary Endpoint

The registry lists the primary outcome as Displacement of the Endotracheal Tube, measured over Participants were followed for the duration of surgery, an average of 2 hours..

The primary endpoint is displacement of the endotracheal tube, measured as the number of participants and classified by the degree of displacement. Mild displacement is defined as a distance <0.5cm; moderate displacement is 0.5cm≤displacement distance<1.5cm; and severe displacement is 1.5cm≤displacement distance. Participants were followed for the duration of surgery, averaging 2 hours.

Tube displacement is relevant to the stated clinical purpose because the study focuses on airway devices used during prone ventilation and on potential complications in that setting. In general, classifying displacement by severity can distinguish smaller movement from more substantial movement rather than treating all movement as identical. That is a general reason such categories may be useful; it does not establish how the categories were analyzed in this trial.

The registry record gives no participant counts for the displacement categories and no single comparative result. It also does not report a threshold or combined endpoint that would reduce the categories to one event definition. Consequently, the endpoint’s direction and magnitude of difference between groups cannot be assessed from the posted results. The record’s statement that all patients in each group were analyzed does not fill in the missing category results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The design labels indicate a randomized, double-masked, parallel-group comparison. In general, random allocation is used to reduce systematic differences between groups at the point of assignment. Masking is intended to limit the influence of knowledge about treatment assignment on care, measurement, or assessment. These are general purposes, not confirmation that bias was avoided in this study. The registry record does not describe sequence generation, concealment of allocation, who was masked, or how masking was maintained.

What does the primary outcome represent?

The primary endpoint is recorded as a count of participants, with displacement classified as mild, moderate, or severe. The stated cutoffs are mild at a displacement distance <0.5cm, moderate at 0.5cm≤displacement distance<1.5cm, and severe at 1.5cm≤displacement distance. These levels have an order, but the registry record does not explain whether the analysis treated them as ordered categories, compared each category separately, or used another approach. Nor does it provide the numbers of participants in each category.

In general, a categorical endpoint can be presented as counts or proportions in each category. A comparison may focus on the distribution across categories, or on a prespecified threshold that defines an event. These approaches answer different questions. The record does not report a single comparison for the primary endpoint, and it does not report an analysis method for the categories. A method should therefore not be attributed to the investigators based on the outcome description alone.

How should a group comparison be read?

In general, an effect estimate describes the difference or relationship being assessed between groups, while a confidence interval describes the statistical uncertainty around an estimate under the method’s assumptions. A narrower interval indicates greater precision than a wider interval, but it does not by itself establish clinical importance. The registry record does not report a primary effect estimate or confidence interval for displacement, so neither the size nor the precision of a group difference can be evaluated.

For count or categorical outcomes, interpretation depends on the actual event counts, the denominator in each group, and the analysis selected. The outcome counts are not reported in the registry record. The description that all patients in each group were analyzed indicates an analysis population statement, but does not provide the counts needed to reproduce or assess a comparison.

What does the planning illustration mean?

The sample-size assumptions describe a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. The illustration is not the trial’s own design justification and is not observed power. In general, such planning calculations ask how many participants per arm might be needed to detect an effect under stated assumptions. They depend on the effect used, the chosen fraction of that effect, the outcome model, and the target power. The registry record does not report the trial’s own sample-size justification.

Because the primary outcome has several categories or time points and was not reduced to one comparison, a single effect for a planning calculation cannot be interpreted as a direct summary of the primary endpoint without further specification. Any planning values should be treated as illustrations under their assumptions, not as proof that the completed study had a particular probability of detecting an effect. They are not evidence that the intervention did or did not produce a difference.

Why can over-dispersion matter?

General statistical explanation: over-dispersion occurs when observed variability in count data exceeds what a model assumes. If present, standard errors from a model that assumes less variability may be too small, making intervals appear more precise than warranted. This concept matters when selecting or checking models for count outcomes. The registry record does not report a dispersion estimate or identify an analysis of over-dispersion, and it does not provide count results from which to assess it.

Overall, the design and endpoint descriptions provide context, but they do not reveal the statistical procedure used for the primary comparison. The analysis method, handling of the three displacement levels, effect estimate, uncertainty interval, and model checks are not reported in the registry record. These omissions prevent an independent statistical interpretation of the primary result.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists six outcome measures and two analyses. It does not report whether a primary analysis was selected in advance for each outcome, whether the analyses were prespecified, or whether any adjustment was made for examining multiple outcomes. In general, testing multiple outcomes can increase the chance of finding at least one apparently notable result by chance. Adjustment methods or a prespecified hierarchy can address that issue, but no such approach is reported in the registry record. Without analysis results or a stated multiplicity plan, the influence of multiple testing cannot be assessed.

The primary outcome is divided into mild, moderate, and severe displacement, but no category counts or combined comparison are reported. The record does not state whether missing displacement assessments occurred or how missing observations were handled. It therefore cannot be assumed that every enrolled participant had complete primary outcome data.

The record says that all patients in each group were analyzed. This describes the stated analysis population, but does not establish that the analysis followed an intention-to-treat approach: the record does not define the analyzed population, describe exclusions, or state how participants were handled if treatment assignment or outcome data were unavailable. The registry record also does not report sensitivity analyses or methods for handling missing data. These uncertainties matter because missingness and analysis-population choices can affect the interpretation of a randomized comparison.

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.

Most frequent non-serious adverse event terms

The registry record reports 0 serious adverse events among 30 participants at risk in the prone position endotracheal tube group and 0 among 30 at risk in the traditional endotracheal tube group. For other adverse events, it reports 1 affected among 30 at risk in each group. These are the event counts recorded for the study groups; they do not describe the displacement outcome.

The record does not provide further details about the other adverse events, their timing, severity, or relationship to the tube. It lists no serious adverse event terms, and death counts are not reported in the registry record. The posted counts should be read as descriptive entries, not as a complete account of all possible safety outcomes. With no event descriptions or uncertainty estimates, they do not establish whether the groups had comparable safety profiles or support a broader safety conclusion.

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

The record establishes that a randomized, double-masked, parallel-group study compared a prone position endotracheal tube with a traditional endotracheal tube. It identifies displacement as the primary outcome and describes three levels of displacement during surgery, with an average follow-up duration of 2 hours. The study context includes prone ventilation during surgery and acute respiratory distress syndrome in intensive care.

What the posted results do not establish is the comparative displacement experience. No counts are reported for mild, moderate, or severe displacement, and no single comparative result is reported. The secondary outcomes named in the record also have no reported results. Therefore, the stated study purpose cannot be treated as a finding that the special tube reduced complications, prevented displacement, or improved respiratory therapy.

The adverse-event entries show 0 serious adverse events in each group and 1 other adverse event in each group, with 30 at risk in each group for both entries. These limited counts are not a substitute for the primary outcome results and do not describe the nature or clinical significance of the reported other events. Death counts are not reported in the registry record.

In general, a well-described randomized comparison can help assess differences between assigned groups, but interpretation also depends on complete outcome reporting, clear analysis methods, and uncertainty estimates. Here, the record does not report the primary analysis method, category counts, confidence interval, missing-data handling, or multiplicity approach. The appropriate conclusion is limited: the registry describes the trial design and intended outcomes, but its posted results do not permit estimation of the primary comparative effect or a conclusion about the intervention’s impact.

13. Why This Trial Matters Statistically

This trial is statistically notable because its primary endpoint is not a single yes-or-no result in the registry description. Displacement is classified as mild, moderate, or severe, with stated distance thresholds. Such categories preserve distinctions in severity, but they also require a clear analysis plan: a comparison of the full distribution is not the same question as a comparison using a threshold or a selected category. The registry record does not report which approach was used or provide the category counts.

The randomized, double-masked, parallel design gives a framework for comparing the two tube groups, but design labels alone cannot answer the clinical question. The primary results and their uncertainty are necessary to assess the size and precision of any observed difference. Their absence means the comparison cannot be reconstructed from the posted registry results.

The trial also illustrates why safety counts and efficacy outcomes need separate interpretation. The adverse-event entries report few affected participants, but those figures do not answer the displacement question, and the record gives limited event detail. In general, a complete statistical account should connect the endpoint definition, analysis population, analysis method, effect estimate, and uncertainty. The registry record does not provide that chain for the primary endpoint.

For clinical researchers and statisticians, the key point is not that the design is inherently inadequate, but that the posted information is insufficient to evaluate the primary result. A clearly reported category distribution and a prespecified comparative method would be needed to understand what the study found and how precisely it found it.

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 interpretation is the absence of primary outcome counts. The registry record defines mild, moderate, and severe displacement but does not state how many participants experienced each level, or report a single group comparison. As a result, the primary effect cannot be estimated from the posted results.

Important details of the analysis and conduct are also not reported in the registry record. These include the method used to compare displacement categories, the identity of the people masked, randomization procedures, allocation concealment, the handling of missing data, and any adjustment for multiple outcomes. The statement that all patients in each group were analyzed does not resolve these questions or establish an intention-to-treat analysis.

The registry describes a broad intended context covering prone surgery and acute respiratory distress syndrome in intensive care, while the primary outcome timeframe refers to duration of surgery, averaging 2 hours. It does not clarify the enrolled population’s clinical setting or how the timeframe applies across settings. Eligibility criteria and further participant characteristics are not reported in the registry record, limiting assessment of how broadly the results might apply even if outcome results were available.

Secondary outcome results are not reported, and the adverse-event entries lack descriptions of the other events. The record does not provide death counts. These limitations constrain assessment of both comparative outcomes and safety; they do not establish that an outcome was absent or that the intervention had no effect.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Clinical Study of the Endotracheal Tube Used in Prone Position Ventilation Condition — NCT02449356.
• Registry record last updated 2017-06-15; status last verified 2017-03.
• Results first posted 2017-06-15.
• 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

The registry record describes NCT02449356, a completed randomized, double-masked, parallel-group study of a prone position endotracheal tube versus a traditional endotracheal tube. Enrollment is listed as 60. The study start is recorded as 2015-09, with primary completion in 2016-09; phase is listed as NA.

The primary outcome is endotracheal tube displacement, categorized as mild, moderate, or severe during surgery, with average follow-up of 2 hours. Prolapse and looseness or dampness of tape are listed as secondary outcomes. The registry record does not report primary outcome counts, a single primary comparison, or secondary outcome results. It reports 0 serious adverse events in each group and 1 other adverse event in each group, with 30 at risk per group for each entry. The record does not report enough outcome or analysis detail to determine the comparative primary effect.