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 EZ-blocker Versus Left Sided Double Lumen Tube in Adult Patients for Thoracic Surgery (NCT03403192), a randomized na study. The primary outcome is Number of Double Lumen Tube (DLT) or Bronchial Blocker (BB) Replacements.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03403192 |
| Phase | NA |
| Condition | Thoracic Injuries |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 163 |
| Arms in the primary outcome | 4 |
| Lead sponsor | Wake Forest University Health Sciences |
| Results posted | Yes |
2. Clinical Question
Population
Adults undergoing thoracic surgery are the population named in the trial title and objectives. The registry lists thoracic injuries as the condition. The primary-outcome population is not specified in its description, and further eligibility details are not reported in the registry record.
Intervention
The intervention is an EZ-Blocker used to isolate a lung. The registry separates assignments by whether the device was placed for left- or right-lung surgery. The study objective was to examine positional stability and lung-isolation quality, alongside placement time and other clinical differences.
Comparator
The comparator is a double-lumen tube, also separated by left- or right-lung surgery. This creates four reported groups: EZ-Blocker in the left lung, EZ-Blocker in the right lung, DLT in the left lung and DLT in the right lung. The record describes a randomized, parallel-group design with single masking.
Primary question
The primary outcome asks how many times the DLT or bronchial blocker had to be replaced because it moved too deep or too shallow within the lung, measured at the end of the surgical procedure. This outcome addresses positional stability. The posted arm-level counts are available, but a two-arm primary comparison is not reported as estimable in the registry record.
3. Trial Design
This completed study is registered as NCT03403192, with the title “EZ-blocker Versus Left Sided Double Lumen Tube in Adult Patients for Thoracic Surgery.” The official title describes a comparison of positional stability between the EZ-Blocker and left-sided double-lumen tube in adults having thoracic surgery. The registry lists Wake Forest University Health Sciences as the sponsor.
The design is randomized, single-masked and parallel-group. Four arms are listed, distinguished by device and the side of lung isolation: EZ-Blocker in the left lung, EZ-Blocker in the right lung, DLT in the left lung and DLT in the right lung. The arm descriptions characterize each device as functioning as a bronchial blocker. The registry reports enrollment of 163. The phase is listed as NA.
The study began on 2018-01-26, reached primary completion on 2019-10-29 and is marked completed. The objective was to assess positional stability and quality of lung isolation for right- and left-sided thoracic surgery. Additional objectives concerned placement time, airway injury, postoperative sore throat and hoarseness, and whether preoperative high-resolution CT imaging might identify anatomical landmarks relevant to device choice.
The record lists four outcome measures, but the posted secondary outcomes include quality of lung isolation, placement time and device side effects. Numerical results are available for the quality score; numerical results for placement time and side effects are not reported in the registry record. Details of the randomization procedure, masking implementation, eligibility criteria, and analysis populations 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.
Overall Study
| Stage | EZ-Blocker in the Left Lung | EZ-Blocker in Right Lung | DLT in Left Lung | DLT in Right Lung |
|---|---|---|---|---|
| STARTED | 41 | 40 | 40 | 42 |
| COMPLETED | 37 | 36 | 37 | 36 |
| NOT COMPLETED | 4 | 4 | 3 | 6 |
Reasons for not completing this period:
| Reason | EZ-Blocker in the Left Lung | EZ-Blocker in Right Lung | DLT in Left Lung | DLT in Right Lung |
|---|---|---|---|---|
| Lost to Follow-up | 1 | 2 | 0 | 0 |
| Unable to respond | 0 | 1 | 0 | 0 |
| Incomplete | 3 | 1 | 3 | 6 |
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 | EZ-Blocker in the Left Lung | EZ-Blocker in Right Lung | Double Lumen Tube (DLT) in Left Lung | Double Lumen Tube (DLT) in Right Lung | Total |
|---|---|---|---|---|---|---|
| Participants analysed | 41 | 40 | 40 | 42 | 163 | |
| Age, Continuous | years | 62.1 (SD 10.5) | 65.3 (SD 12.4) | 66.2 (SD 12.9) | 60.6 (SD 11.7) | 63.5 (SD 12.02) |
| Sex: Female, Male: Female | Participants | 20 | 19 | 15 | 22 | 76 |
| Sex: Female, Male: Male | Participants | 21 | 21 | 25 | 20 | 87 |
| Race and Ethnicity Not Collected | Participants | — | — | — | — | 0 |
| Region of Enrollment: United States | Participants | 41 | 40 | 40 | 42 | 163 |
| Weight | kilograms | 81.0 (SD 17.1) | 77.0 (SD 17.7) | 82.9 (SD 16.4) | 82.0 (SD 20.0) | 80.7 (SD 17.8) |
| Body Mass Index (BMI) | kg/m^2 | 27.8 (SD 4.8) | 26.5 (SD 5.0) | 28.3 (SD 4.79) | 28.5 (SD 5.6) | 27.8 (SD 5.1) |
6. Primary Endpoint
The registry lists the primary outcome as Number of Double Lumen Tube (DLT) or Bronchial Blocker (BB) Replacements, measured over End of surgical procedure.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Number of replacements |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the number of DLT or bronchial-blocker replacements by the end of the surgical procedure. The stated reason for replacement is movement of the device too deep or too shallow, or proximally, within the lung. The measure is therefore intended to capture positional stability of lung isolation over the procedure.
A replacement count is clinically interpretable as a tally of device repositioning events, but it is a count outcome rather than a continuous measurement or a proportion. Its interpretation depends on how events were defined and recorded, and on whether the groups were analyzed with an appropriate method for count data. Those details are not reported in the registry record. The record does not describe the outcome population or provide participant-level counts, distributions, or uncertainty estimates.
The registry posts arm-level values of 13.0, 14.0, 14.0 and 13.0 for the four groups, respectively. These are presented as the number of replacements, alongside group sizes. The registry record does not provide an estimable two-arm comparison for this endpoint, so the arm-level figures do not establish a comparative effect or its precision. The reason this comparison was not estimable is not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The primary outcome is directly aligned with the study’s stated interest in positional stability: it counts replacements attributed to movement too deep or too shallow. The registry posts 13.0 replacements for EZ-Blocker in the left lung, 14.0 for EZ-Blocker in the right lung, 14.0 for DLT in the left lung and 13.0 for DLT in the right lung. These are arm-level counts, not effect estimates. No two-arm primary comparison is reported as estimable, and no confidence interval or inferential result for the primary outcome is posted. Consequently, the record does not quantify the uncertainty around a difference between devices.
The outcome values should not be read as replacement rates: the registry reports counts, not a rate or participant-level probability. Nor does the posted information establish how replacement events were distributed among participants. Without those details, the counts cannot show whether events were concentrated in a small number of participants or spread across the groups. The registry’s stated measure is replacements, rather than the number of participants requiring at least one replacement.
The secondary lung-isolation-quality outcome is a score measured at the end of surgery. The reported mean for EZ-Blocker in the left lung is 2.76, with standard deviation 0.39. The posted comparison between this group and DLT in the left lung gives a mean difference of 0.16, with a confidence interval from 0.016 to 0.304 and an unadjusted p-value of 0.029. The score’s scale and direction are not described, so the difference cannot be interpreted as indicating better quality without that information. The comparison between EZ-Blocker in the left lung and EZ-Blocker in the right lung has a mean difference of -0.06 and an unadjusted p-value of 0.538; its confidence interval spans zero.
These secondary comparisons concern a score, not the primary replacement count. They do not resolve the missing inferential comparison for the primary endpoint. The p-values are unadjusted, and the registry does not report whether or how multiple comparisons were addressed. Accordingly, the posted results support a descriptive reading of each outcome and a cautious reading of the secondary estimates, rather than a definitive overall conclusion about the devices.
9. Statistical Methods Explained
The registry identifies the study as randomized, single-masked and parallel-group. Randomization is intended, in general, to create comparable groups at assignment, while a parallel-group design means participants are assigned to one group rather than crossing between interventions. The record does not describe the sequence-generation method, allocation concealment, or who was masked. Those implementation details are not reported in the registry record and should not be inferred from the design labels alone.
What does the primary count represent?
The primary endpoint is a count of device replacements by the end of surgery. Count outcomes are nonnegative event tallies, and statistical methods for them may need to account for the distribution of the counts. In general, a count analysis can be affected by over-dispersion: this occurs when the observed variability is greater than a chosen model expects. If over-dispersion is present and not accommodated, estimated uncertainty may be too small. The registry record does not report the distribution of individual counts, an analysis model, a dispersion estimate, or an adjusted treatment effect. It is therefore not possible to assess the primary endpoint’s inferential analysis from the posted information.
The four arm-level counts describe the total replacements reported for each group. A total count does not itself provide the number of participants with any replacement, the number of repeat replacements per participant, or a rate adjusted for exposure. Those quantities cannot be recovered from the registry’s arm-level summary. The registry also does not post a two-arm comparison for the primary endpoint; the values are marked as missing or not estimable for such a comparison. No reason or alternative analysis is reported.
How should a mean difference be read?
For the secondary quality score, the registry posts group means and standard deviations, as well as unadjusted mean differences and confidence intervals for two contrasts. A mean difference expresses the difference between group averages in the score’s units. Its sign depends on the order of groups used in the contrast; it does not by itself say which device is preferable. Interpretation also requires knowing the score’s scale and which direction represents better quality. That information is not reported in the registry record.
A confidence interval describes the range of effect values compatible with the estimate and the method’s assumptions. In general, a narrower interval indicates greater precision, while an interval that spans zero is compatible with both a negative and a positive difference under that approach. It is not a guarantee that the true effect falls within the interval. The interval for the left-versus-left comparison excludes zero, whereas the interval for the EZ-Blocker side comparison spans zero. These are unadjusted comparisons; the record does not report a model accounting for other factors or a multiplicity adjustment.
What does an unadjusted p-value convey?
A p-value measures how unusual data at least as incompatible with a specified no-difference hypothesis would be under the statistical model and its assumptions. It is not the probability that the null hypothesis is true, nor does it measure the size or practical importance of an effect. The posted p-values for the quality-score contrasts are unadjusted. Their interpretation should therefore be considered alongside the estimates, intervals, endpoint definition, and the fact that the record contains multiple outcomes and contrasts. The registry does not report a prespecified multiplicity strategy or the sponsor’s detailed analysis plan.
What do the planning illustrations mean?
The sample-size illustrations are based on the observed quality-score effects, not on the trial’s design justification. The registry describes a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and scenarios targeting stated fractions of the observed effect. For example, planning for 75% of the observed effect in the left-lung quality comparison gives 121 participants per arm for 80% power and 162 participants per arm for 90% power. These are planning illustrations, not observed power and not evidence that the completed study was designed to detect those effects. The original sample-size assumptions and justification are not reported in the registry record.
In general, such calculations depend on the assumed effect, variability, allocation, statistical test and other design choices. They do not show the probability that the observed result is correct, and they do not replace an estimate with its confidence interval. Because the illustrations use observed effects, they can change substantially if the observed effect is imprecise or not representative. No power calculation for the primary replacement-count endpoint is reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists several outcomes and posts more than one comparison for lung-isolation quality. It does not report whether these outcomes and contrasts were prespecified in a statistical analysis plan, whether a hierarchy was used, or whether any adjustment for multiple testing was made. The quality-score p-values are explicitly unadjusted. In general, evaluating multiple hypotheses without adjustment can increase the chance of at least one false-positive finding. This is why unadjusted secondary results are usually interpreted cautiously, particularly when the full analysis plan is unavailable.
Missingness and analysis-population details are also limited. The primary endpoint’s population field is blank, and the record does not describe whether the analyses used all randomized participants, participants who received the assigned device, or another group. The number of participants contributing to each posted outcome and the handling of missing observations are not reported in the registry record. There is no account of exclusions, protocol deviations, or sensitivity analyses.
The registry posts the primary arm-level replacement counts but marks a two-arm comparison as missing or not estimable. It does not explain why. The absence of an estimate, confidence interval and test means that the comparative precision of the primary endpoint cannot be assessed from the record. It is not appropriate to fill this gap with a calculation from the arm-level summaries when the event-level distribution and analysis method are unavailable.
The record also does not report interim analyses, stopping rules, a detailed statistical analysis plan, or a sample-size justification. Those details should be treated as not reported in the registry record, rather than assumed to have been absent from the study’s conduct. The posted sample-size illustrations are planning scenarios based on observed secondary effects; they do not document the trial’s original design calculations.
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 |
|---|---|---|---|
| EZ-Blocker in the Left Lung | 0 | 41 | 0.0% |
| EZ-Blocker in Right Lung | 0 | 40 | 0.0% |
| DLT in Left Lung | 0 | 40 | 0.0% |
| DLT in Right Lung | 0 | 42 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| EZ-Blocker in the Left Lung | 0 of 41 |
| EZ-Blocker in Right Lung | 0 of 40 |
| DLT in Left Lung | 0 of 40 |
| DLT in Right Lung | 0 of 42 |
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 |
|---|---|
| EZ-Blocker in the Left Lung | 0 of 41 |
| EZ-Blocker in Right Lung | 0 of 40 |
| DLT in Left Lung | 0 of 40 |
| DLT in Right Lung | 0 of 42 |
The registry’s adverse-event summary reports zero serious adverse events, zero other adverse events and zero deaths in each of the four groups. The corresponding at-risk group sizes are listed as 41, 40, 40 and 42. These figures describe what was recorded in the registry’s safety summary; they do not establish that no adverse events occurred outside the definitions, observation period or reporting process used for the record.
Zero recorded events in a group should not be read as proof that an event is impossible or that the devices have identical safety profiles. When event counts are zero, the data provide limited information about uncommon harms, and the precision of any comparative safety conclusion cannot be evaluated without an analysis and appropriate uncertainty estimates. The registry does not post a safety comparison, event-specific details, or additional context about ascertainment and follow-up. The stated study objectives include airway injury, sore throat and hoarseness, but detailed numerical results for those outcomes are not reported in the registry record.
12. What the Result Does, and Does Not, Mean
The posted results describe a randomized, parallel-group study comparing EZ-Blocker and DLT use for lung isolation in adult thoracic surgery. The primary measure is the number of device replacements attributed to positional movement by the end of surgery. The record gives arm-level counts, but no estimable two-arm comparison for that endpoint. It therefore does not provide a primary treatment-effect estimate or the uncertainty around one.
The quality-score results offer secondary information about end-of-procedure lung-isolation quality. The record provides group means, standard deviations and unadjusted comparisons, but does not define the score’s scale or direction. The findings can be read as reported differences in score, not as proof of which device produces better isolation. They also do not answer the primary question about replacement counts.
Zero adverse-event counts were posted for each group, but those figures do not establish absence of risk or resolve comparative safety. Numerical results for placement time and several stated side-effect objectives are not reported in the registry record. The available evidence is therefore incomplete across the outcomes described by the study objectives.
In general, a randomized design can support causal comparisons when allocation, follow-up, outcome measurement and analysis are appropriately implemented. The registry record does not provide enough detail to evaluate all of those elements, including analysis populations, missing data handling, or the primary endpoint analysis. The posted results should be understood as a limited registry summary, not as a full account of the trial’s methods or evidence. They do not establish a broad conclusion about comparative performance, and they should not be extended beyond the outcomes and groups described.
13. Why This Trial Matters Statistically
This trial illustrates why an endpoint’s definition and its analysis need to be considered together. The primary outcome is a count of replacements, chosen to represent positional stability. Yet the registry gives only arm-level totals and does not provide an estimable two-arm comparison. Without an effect estimate and uncertainty interval, the descriptive counts cannot answer how precisely the groups differ.
It also shows the distinction between an outcome that is clinically motivated and an outcome that is statistically interpretable from a registry summary. A count of replacement events may not convey how many participants experienced an event or how repeated events were distributed. Participant-level distributions and the analysis method matter, particularly for count data, where variability can be greater than a simple model assumes.
The quality score offers a different type of result: means, standard deviations and unadjusted contrasts. These can be useful for describing the posted data, but the score’s direction is not reported and the comparisons do not replace the primary analysis. The lack of a stated multiplicity plan also demonstrates why isolated secondary p-values should not carry the same weight as a prespecified primary result interpreted with its uncertainty.
Finally, the registry record highlights the limits of interpreting zero adverse-event counts and sample-size illustrations. Neither establishes absence of risk or observed power. Clear reporting of endpoint definitions, analysis populations, missing data, prespecified comparisons and uncertainty would make the evidence easier to assess. These are general statistical reporting considerations; the record does not indicate whether further details exist elsewhere.
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 are specific to the registry information for this trial. The primary endpoint is reported as arm-level replacement counts, but no two-arm comparison is estimable in the posted record. The reason is not reported, and there is no confidence interval or inferential result for the primary outcome. The totals also do not show how replacements were distributed among participants.
The group structure separates device and side, while the record does not provide a reported analysis that explains how those factors were handled together or whether comparisons were made within side, across device, or by another prespecified approach. The secondary quality-score contrasts do not cover every possible comparison among the four groups. The registry does not describe a full analysis plan, adjustment for other factors, or a multiplicity strategy.
For the quality score, the scale and the meaning of higher or lower values are not reported. This restricts interpretation of the observed mean differences. Numerical results for placement time and side effects are also unavailable in the registry record, despite their inclusion among the study objectives. The record does not provide detailed results for airway injury, sore throat or hoarseness.
Further limitations include unreported analysis populations, missing-data procedures, outcome-specific participant counts, allocation methods and masking procedures. The registry does not provide the count distributions or model details needed to evaluate the primary endpoint’s statistical treatment. The posted safety summary has no comparative estimates or uncertainty intervals. These limitations concern what is documented in the registry record; they do not establish that the study did not collect or analyze additional information.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: EZ-blocker Versus Left Sided Double Lumen Tube in Adult Patients for Thoracic Surgery — NCT03403192.
- Registry record last updated 2021-10-07; status last verified 2019-06.
- Results first posted 2021-10-07.
- 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
NCT03403192 is a completed randomized, single-masked, parallel-group study sponsored by Wake Forest University Health Sciences. It enrolled 163 adults for a comparison of EZ-Blocker and double-lumen tube use for lung isolation in thoracic surgery, with groups defined by device and lung side.
The primary outcome is the number of device replacements due to positional movement by the end of surgery. Arm-level counts are posted, but a two-arm comparison is not reported as estimable. Secondary quality-score results include unadjusted mean comparisons; numerical placement-time and side-effect results are not reported in the registry record. The safety summary records zero serious events, other events and deaths in each group.
Important details—including the primary analysis, analysis populations, missing-data handling, score direction and multiplicity plan—are not reported in the registry record. The posted information supports a descriptive account, but does not provide a precise comparative estimate for the primary endpoint.