Evaluation of a Powered Surgical Stapler in Video-Assisted Thoracoscopic Lung Resection Procedures in Korea: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of a Powered Surgical Stapler in Video-Assisted Thoracoscopic Lung Resection Procedures in Korea (NCT02196675), a registered phase not stated study. The primary outcome is Occurrence of Prolonged Air Leaks.

2. Clinical Question

The study was intended to collect real-world outcomes of video-assisted thoracoscopic lung cancer surgery in a Korean population using the study device. It included wedge resection, lobectomy, and combined wedge resection with lobectomy. The primary endpoint was a measure of prolonged air leaks, while secondary outcomes listed in the registry were postoperative air leaks, length of stay, estimated intra-operative blood loss, and time to chest tube removal.

The registry record reports enrollment of 105 participants, but it does not report the number included in the primary endpoint analysis or the observed primary endpoint result. It therefore does not establish what proportion had a prolonged air leak. Because the study has no control group, it also cannot provide a direct comparison of outcomes with another device or surgical approach. The question is descriptive: what outcomes were recorded among participants treated with the study device under the study’s clinical conditions?

3. Trial Design

This was a prospective, multicenter evaluation of a powered surgical stapler in video-assisted thoracoscopic lung resection procedures in Korea. The registry identifies a single arm, described as VATS wedge resection or lobectomy, with the device intervention listed as an Endocutter. The brief study description specifies collection of real-world outcomes in lung cancer surgery using the study devices.

The registry reports enrollment of 105 and a completed study. The recorded start was 2014-07 and primary completion was 2015-01. The sponsor was Ethicon Endo-Surgery. The listed condition was Non-small Cell Lung Cancer (NSCLC). The registry does not report the number of participating centers, the recruitment process, or details of how participants were selected.

The primary endpoint was occurrence of prolonged air leaks. Its timeframe covered the postoperative period through hospital discharge and follow-up at Day 30. The definition was a continuous air leak lasting longer than 5 days. Air leak was to be assessed quantitatively beginning on the evening after surgery and then twice daily during morning and evening rounds. Participants were instructed to perform standardized repeated forced expiratory maneuvers, including coughing and blowing.

The primary population definition included participants who consented, underwent wedge resection, lobectomy, or both, and were not converted to an open procedure. The registry does not say how many enrolled participants met this definition, how many completed follow-up, or how many were included in the endpoint analysis.

Because this was a single-arm study, its outcomes describe participants receiving the intervention rather than a comparative treatment effect. No randomization or allocation details are stated, and the registry record does not report a comparator group. The record lists four secondary outcomes in addition to the primary endpoint, but does not provide their results or analysis methods.

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: There was no assignment to treatment group given that this is a single arm study wherein the same device was used on all subjects. Results are presented for the overall cohort as well as by the individual procedure performed - lobectomy, wedge resection, or wedge resection with lobectomy.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: All subjects who consented to the study, had surgery for wedge resection, lobectomy, or wedge resection with lobectomy and were not converted to an open procedure

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 subjects who consented to the study, had surgery for wedge resection, lobectomy, or wedge resection with lobectomy and were not converted to an open procedure. Two enrolled subjects were converted to an open procedure and thus were not included in this summary. These subjects were followed for safety.

6. Primary Endpoint

The registry lists the primary outcome as Occurrence of Prolonged Air Leaks, measured over Post-operative period through hospital discharge and follow-up at Day 30.

The primary endpoint was the occurrence of prolonged air leaks, reported as a percentage of participants. A prolonged air leak was defined as an air leak lasting longer than 5 days continuously. The stated observation period extended from the postoperative period through hospital discharge and follow-up at Day 30.

Air leaks are relevant to lung resection because they concern air escaping from the lung after surgery. In general, measuring their occurrence can describe an aspect of postoperative recovery and provide a defined outcome for evaluating surgical procedures and devices. The registry’s protocol description sought to assess air leak quantitatively, starting on the evening after surgery and repeating the assessment twice daily during morning and evening rounds. It also describes standardized repeated forced expiratory maneuvers, including coughing and blowing.

The endpoint is a binary participant-level event in the registry’s analysis classification: a participant either met the prolonged-air-leak definition or did not. Reporting a percentage would convey the frequency among the endpoint population, while the stated 95% confidence interval would express uncertainty around that estimate. However, neither the percentage nor the confidence interval is reported in the registry record. The registry also does not report the analyzed denominator, so the endpoint frequency cannot be interpreted from the enrollment count alone.

The endpoint population excluded participants converted to an open procedure and included those undergoing wedge resection, lobectomy, or both. This definition matters when interpreting any percentage: it specifies who would contribute to the primary endpoint, but does not tell how many participants actually did so.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a percentage endpoint and specifies a 95% confidence interval, but it does not provide an endpoint estimate, interval limits, or analysis method. The explanations below describe general statistical concepts; they should not be read as a claim about methods used in this study unless those methods are explicitly stated in the registry record.

What does a participant percentage represent?

For a binary endpoint, each participant in the analysis population is classified according to whether the event occurred. The event count divided by the relevant participant count gives a proportion, which can be expressed as a percentage. Here, the event definition is a continuous air leak lasting longer than 5 days. A valid interpretation requires knowing both the number of participants with the event and the number whose outcomes were assessed. The registry defines the intended primary population, but does not report its analyzed size or the number of events.

The enrollment count is not automatically the denominator for every endpoint. Participants may not meet a particular endpoint’s population definition, may not have a recorded outcome, or may not be included in an analysis. In this study, the primary population specifically excluded participants converted to an open procedure. The registry does not report how many participants were excluded for this reason or for any other reason.

What does a confidence interval communicate?

In general, a confidence interval gives a range of estimates compatible with the observed data under the assumptions of the statistical method. It communicates sampling uncertainty around an estimate; it does not guarantee that the true value lies within the calculated range, and it does not address every source of uncertainty, such as selection or measurement issues. For a participant percentage, the interval’s width is influenced by the number of observations and the event frequency. With a small number of events, uncertainty can remain substantial even if the point estimate appears clear.

The registry specifies a 95% confidence interval for the primary endpoint but reports neither the interval nor the estimate it would accompany. No particular interval formula or confidence-interval calculation method is stated. It is therefore not possible to assess the endpoint’s statistical precision from the registry record.

What can a single-arm design estimate?

A single-arm study can describe outcomes among participants who received the intervention. It does not directly estimate a treatment contrast against a concurrent control group. A comparison with an external or historical benchmark would require a stated benchmark and assumptions about whether populations, outcome definitions, and follow-up are sufficiently alike. No such comparison is described in the registry record.

The study is identified as single arm, and the record does not state an allocation method. Its surgical groups—wedge resection, lobectomy, and wedge resection with lobectomy—are procedure categories, not a stated like-for-like control comparison. Differences among those groups could reflect differing procedures or participant characteristics; the record does not report an adjusted comparison or a basis for causal interpretation.

How should the planning illustration be understood?

The registry’s planning description characterizes sample-size values as illustrations based on the observed effect, not as the trial’s own design justification. It states assumptions of a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect defined as a stated fraction of the observed effect. It further distinguishes participants per arm for ordinary outcomes from total events for time-to-event outcomes.

These are planning assumptions, not evidence that the study enrolled two randomized arms or used those methods for its actual analysis. The study is single arm, and the registry does not report its own sample-size justification or an observed primary endpoint effect. No planning values or effect fractions are included in the registry record summarized for this study. Such illustrations, when available, are prospective design calculations; they are not observed power and do not establish whether a result is statistically significant.

Why can event counts affect precision?

General statistical reasoning indicates that estimates based on fewer events tend to be less precise. A confidence interval can be wide when the event count is low, and percentage estimates can be sensitive to individual outcomes when the analysis population is small. That is one reason to read an event estimate together with its denominator and confidence interval rather than interpreting a percentage alone. The primary endpoint estimate and interval are not reported in the registry record, so this precision assessment cannot be made for prolonged air leaks.

For event data, over-dispersion generally means that observed variability exceeds what a simple statistical model assumes. It can affect standard errors and confidence intervals if a model is used. The registry does not describe a model for the primary endpoint or report a check for over-dispersion. No claim can therefore be made that this issue was assessed or that a particular adjustment was applied.

What does the absence of analysis details mean?

The registry reports 0 analysis entries, but that is not evidence that investigators performed no analyses outside the posted record. It means the registry record does not contain posted analysis entries for the listed outcome measures. The analysis populations, missing-data handling, model specifications, confidence-interval procedure, and multiplicity strategy are not reported in the registry record. Without those details and the outcome estimates, readers cannot evaluate whether the analysis followed a prespecified plan or how sensitive results might be to alternative analytic choices.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Wedge Resection", "Lobectomy", "Wedge Resection With Lobectomy")
n      <- c(26, 69, 8)
events <- c(0, 4, 3)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Wedge Resection  26  0  0.0  0.0  13.2  0.0  12.9  0.1  12.8
ARM  Lobectomy  69  4  5.8  1.6  14.2  2.3  14.0  2.4  14.0
ARM  Wedge Resection With Lobectomy  8  3  37.5  8.5  75.5  13.7  69.4  13.7  70.1

11. Multiplicity, Missing Data and Analysis Populations

The registry lists five outcome measures: the primary endpoint of prolonged air leaks and four secondary outcomes covering postoperative air leaks, length of stay, estimated intra-operative blood loss, and time to chest tube removal. When several outcomes are examined, general statistical practice considers whether the chance of at least one false-positive finding is being controlled. Approaches can include prespecifying a hierarchy, adjusting significance thresholds, or treating secondary analyses as exploratory. The registry record does not report a multiplicity strategy, and it does not report results for the secondary outcomes.

Missing-data handling is also not reported in the registry record. The record does not state how participants with incomplete follow-up, unassessable air-leak status, or missing secondary outcome measurements were handled. It does not give outcome-specific denominators or describe imputation, exclusions, or sensitivity analyses. The primary population definition excludes participants converted to an open procedure, but the record does not report how many participants were excluded or how other departures from the intended assessment population were treated.

The registry defines the primary endpoint population as consenting participants undergoing wedge resection, lobectomy, or both, without conversion to an open procedure. It does not report the number analyzed within that population. It also does not identify an intention-to-treat or per-protocol analysis population. Accordingly, the enrollment of 105 should not be assumed to equal the denominator for the primary endpoint or each secondary outcome.

The registry record contains 0 posted analysis entries. This absence does not establish that analyses were not conducted; it means their results and methods are not available in the registry record. The analysis plan, handling of missing outcomes, and approach to multiple outcomes therefore cannot be assessed from the posted information.

12. 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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: pulmonary air leakage (37.5%), cardiac arrest (12.5%), abdominal pain (12.5%), pleural effusion (12.5%), constipation (1.4%).

The registry lists serious and other adverse events by surgical group. For serious events, it reports 0 of 27 participants in Wedge Resection, 9 of 70 in Lobectomy, and 3 of 8 in Wedge Resection With Lobectomy. For other events, it reports 17 of 27, 43 of 70, and 7 of 8, respectively. The record does not report death counts.

These are counts within groups, not comparative treatment effects. The groups represent different surgical procedures, and the study is single arm; the registry does not establish that the groups are comparable. The counts do not show that a difference between groups was caused by the device or by the procedure. The registry record also does not explain whether participants could contribute more than one event, how events were attributed, or the detailed observation period for these safety listings.

The registry names Pulmonary air leakage at 37.5%, Cardiac arrest at 12.5%, Abdominal pain at 12.5%, Pleural effusion at 12.5%, Constipation at 1.4%, and Pyrexia at 1.4% among the listed serious-event terms. The record does not explain the denominator or calculation behind these term percentages. They should therefore be read as registry-listed percentages, not converted into participant counts or interpreted as group-specific risks.

The registry does not report a complete narrative of adverse-event collection, severity grading, or relatedness assessments. These safety listings describe what is posted, but they do not by themselves establish the overall safety profile of the intervention.

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

The study addresses a clinically relevant descriptive question: what outcomes were recorded during video-assisted thoracoscopic lung resection for lung cancer using a powered stapler in a Korean population? Its prospective, multicenter evaluation and defined prolonged-air-leak endpoint provide context for understanding the intended observation. The registry also identifies the surgical procedures and lists selected safety counts.

However, the registry record does not report the primary endpoint estimate or its 95% confidence interval. It does not report outcome results for the four listed secondary measures, and it contains 0 posted analysis entries. The available information therefore cannot establish the observed frequency of prolonged air leaks, the precision of that frequency, or the results for the secondary outcomes.

The study’s single-arm design is important to interpretation. Without a control group, the record cannot provide a direct comparison with another device or approach. Any event frequency would describe participants in this study, not the effect of the device relative to an alternative. The listed surgical groups are not described as randomized or otherwise comparable, so differences among their safety counts should not be treated as causal comparisons.

The registry reports enrollment of 105, but not the primary analysis denominator or the number with complete outcome assessment. Its primary population definition excludes participants converted to an open procedure. Those details limit how much can be inferred about the representativeness and precision of any endpoint result, particularly when no endpoint estimate is posted.

In general, a registry record can clarify a study’s design and planned outcome definitions without providing enough results to support a quantitative conclusion. For this study, the record supports description of the intended primary question, the intervention setting, and selected event counts. It does not support a claim that the device improves or worsens outcomes, nor a definitive conclusion about the incidence of prolonged air leaks.

14. Why This Trial Matters Statistically

Statistically, this study illustrates why an outcome definition and a result are different kinds of information. The registry carefully characterizes prolonged air leaks as continuous leaks lasting longer than 5 days and describes repeated assessments through hospital discharge and follow-up at Day 30. That makes the intended event interpretable, but a definition alone cannot show how often the event occurred. The registry does not report the endpoint count, denominator, percentage, or confidence interval.

The distinction between enrollment and analysis population is also important. Although enrollment was 105, the primary endpoint population excludes participants converted to an open procedure and requires a qualifying surgery. The registry does not report how many participants met that definition or had usable endpoint data. A clear denominator is essential for interpreting a percentage and its precision.

The single-arm design clarifies the scope of inference. The study can be understood as an evaluation of outcomes in participants receiving the device in the stated setting. It does not create a direct comparison with a separate control intervention. The surgical procedure categories should not be mistaken for randomized treatment groups, and their event counts do not establish relative effects.

The record also distinguishes study planning from study results. Its sample-size description refers to an illustration based on an observed effect and specified assumptions, not the trial’s own design justification. Planning calculations are not observed power and do not substitute for outcome estimates. Here, the actual primary result and analysis details are not reported in the registry record.

These features make the study useful for understanding how registry descriptions define populations, endpoints, and safety reporting, while also showing the limits of interpretation when results and analytic details are absent. The appropriate statistical reading is consequently bounded: the record documents the evaluation’s aims and selected counts, but does not provide the estimates needed to assess the primary outcome’s frequency or precision.

15. 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 the primary endpoint result, its confidence interval, or the number of participants included in its analysis. Although enrollment was 105, the primary endpoint population excludes participants converted to an open procedure. The number excluded, the number with complete assessments, and the final analysis denominator are not reported. This prevents evaluation of both the event frequency and the precision that could be expected from the observed data.

The study is single arm, and the record does not identify a comparator or describe an allocation method. It therefore does not support a direct comparative estimate. The three listed surgical groups involve different procedures, and the registry does not establish that they are exchangeable or intended as control groups. Their adverse-event counts should not be interpreted as a controlled comparison.

The registry does not report the number of centers, participant selection details, baseline characteristics, or a full account of follow-up completion. The primary endpoint timeframe includes follow-up at Day 30, but the record does not state how many participants were assessed at that point or how incomplete follow-up was handled. It also does not report methods for missing data, endpoint analysis, or multiplicity across the five listed outcome measures.

The registry lists serious and other adverse-event counts, but the posted information does not explain event attribution, whether participants could contribute multiple events, or the denominators behind the percentages attached to serious-event terms. Death counts are not reported in the registry record. These limitations constrain interpretation of the safety listings as well as the efficacy-related outcomes.

Finally, the registry contains 0 posted analysis entries. This limits independent review of estimates and methods; it does not show that no analyses were performed. Overall, the posted record supports understanding the study’s design and definitions, but not a complete assessment of its outcomes.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Evaluation of a Powered Surgical Stapler in Video-Assisted Thoracoscopic Lung Resection Procedures in Korea — NCT02196675.
• Registry record last updated 2016-07-15; status last verified 2016-06.
• Results first posted 2015-12-18.
• 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.

19. Record Summary

The registry record describes a completed, prospective, multicenter, single-arm evaluation of a powered surgical stapler during video-assisted thoracoscopic lung resection in Korea. Enrollment was 105, and the listed condition was Non-small Cell Lung Cancer (NSCLC). The primary endpoint was prolonged air leaks, defined as continuous air leaks lasting longer than 5 days, assessed through hospital discharge and follow-up at Day 30.

The record lists four secondary outcomes and adverse-event counts by surgical group. It does not report the primary endpoint result, its confidence interval, secondary outcome results, or the primary analysis denominator. It contains 0 posted analysis entries. The listed safety counts are descriptive and do not constitute a controlled comparison. Consequently, the registry supports a description of the study’s intended evaluation and selected safety information, but does not provide the estimates needed to assess the primary endpoint’s frequency or precision.