Feasibility of Laryngeal Mask Airway Gastro on Patients Undergoing Endoscopic Retrograde Cholangiopancreatography for Pancreas and Bile Duct Disorders: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Feasibility of Laryngeal Mask Airway Gastro on Patients Undergoing Endoscopic Retrograde Cholangiopancreatography for Pancreas and Bile Duct Disorders (NCT03775681), a na na study. The primary outcome is The Number of Participants With Overall Success of ERCP With LMA Gastro.

2. Clinical Question

The clinical question is therefore about feasibility in the setting of ERCP, rather than a randomized estimate of the difference between airway strategies. The registry describes a device-feasibility arm in which patients receive general anesthesia, undergo standard-of-care ERCP with LMA Gastro, and complete an interview afterward. The record does not specify a threshold for what proportion of procedures would constitute adequate feasibility, nor does it report a numerical success result. The count of participants meeting the primary outcome is not reported in the registry record. Consequently, the clinical question can be identified from the stated endpoint, but the posted record does not provide the result needed to quantify how often success occurred.

3. Trial Design

NCT03775681 is a completed, single-group study sponsored by M.D. Anderson Cancer Center. The registry lists enrollment of 33 and identifies the study as not applicable for phase. The start date is 2019-01-16 and the primary completion date is 2020-04-20. These registry entries describe the study's administrative record; they do not establish how many participants contributed data to each outcome.

The arm is titled Device feasibility (Laryngeal Mask Airway, ERCP). Participants receive general anesthesia and fall asleep before LMA Gastro is used during standard-of-care ERCP. The arm description includes a 5-minute interview after the procedure. ERCP, interview, and Laryngeal Mask Airway are listed as interventions, with the latter identified as a device.

Allocation is recorded as NA, masking is listed as none, and the model is single-group. The record therefore does not describe random assignment, masking, or a concurrent control arm. The official title asks whether LMA Gastro is a feasible alternative to a native airway, but that framing should not be confused with a controlled comparison: the registry record does not describe a native-airway arm for direct comparison.

The study is marked completed, and the primary outcome timeframe is up to 3 months. The record lists two outcome measures and zero analyses. It does not describe the recruitment approach, eligibility criteria, planned sample-size justification, protocol deviations, or the statistical analysis plan. Those omissions limit what can be inferred about how the study was conducted and how its findings were intended to be evaluated.

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

Reasons for not completing this period:

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: Race and Ethnicity was not the criteria for Inclusion in the study.

6. Primary Endpoint

The registry lists the primary outcome as The Number of Participants With Overall Success of ERCP With LMA Gastro, measured over Up to 3 months.

The primary endpoint is titled “The Number of Participants With Overall Success of ERCP With LMA Gastro.” It is a count of participants, and its description defines success as successful completion of ERCP with LMA Gastro. The stated timeframe is up to 3 months. The registry does not give a more detailed operational definition, such as criteria for deciding whether a procedure counts as successfully completed, or how a participant with an incomplete procedure would be classified.

A feasibility endpoint asks whether the planned approach can be carried out in the intended procedural setting. A completion count is relevant because it captures whether ERCP was completed while using the device, rather than describing a physiological measurement or a comparative treatment effect. It can help characterize procedural practicality, but interpretation depends on the definition of success, the population assessed, and the completeness of outcome recording.

The result for this endpoint is not reported in the registry record. No confidence interval or analysis result for the success count is described. The registry's enrollment figure is not a substitute for the number assessed for the endpoint, and it cannot establish how many participants had a successful procedure. Without the outcome count and its analysis population, the endpoint's observed frequency and precision cannot be evaluated from the record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record identifies a single-group study and a count-based primary endpoint. It does not report an analysis for that endpoint. The methods below explain general statistical ideas relevant to interpreting a feasibility count; they should not be read as a description of analyses performed in this trial unless the record explicitly says so.

What does a count endpoint represent?

A count records how many participants meet a defined outcome. For this study, the intended outcome is successful completion of ERCP with LMA Gastro. A count is most informative when it is read alongside the number of participants whose outcomes were assessed and a clear rule for classifying success. The registry provides the endpoint description and the enrollment figure, but it does not report the primary outcome count or its analysis denominator. Those quantities cannot be inferred from enrollment alone.

A count can be presented without a model, but statistical interpretation usually also considers uncertainty. A confidence interval is a range of estimates compatible with the observed data under a stated method and assumptions. It communicates how imprecisely the underlying event frequency is estimated; it does not guarantee that the true value lies within the interval. No confidence interval for the primary outcome is reported in the registry record. Without an observed count and denominator, an interval for that endpoint cannot be interpreted from the record.

Why does the study structure matter?

A single-group design describes outcomes among participants receiving the study approach. It does not, by itself, separate the effect of that approach from other influences or show how outcomes would have differed under another airway strategy. Randomized comparisons can balance known and unknown factors on average through allocation, while a single-group design has no randomized concurrent comparison. Here, allocation is recorded as NA, masking as none, and the model as single-group. The official title's reference to an alternative does not create a comparator arm.

In a feasibility study, the goal may be to understand whether a procedure or device can be used in its intended context. The registry names successful ERCP completion with LMA Gastro as the primary measure, but does not state a target success threshold or a decision rule for proceeding to further study. The record also does not provide a detailed success definition. Those items are important to judging whether a count meets a prespecified feasibility criterion.

What can planning calculations tell a reader?

Planning calculations concern the size of a future study under specified assumptions; they are not observations from the completed study. The registry's planning description specifies a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect to detect expressed as a stated fraction of the observed effect. It describes time-to-event calculations as reporting total events using the Schoenfeld method, and other calculations as participants per arm.

These are planning assumptions, not evidence that this trial randomized participants between two arms. The registered study is single-group, and the planning assumptions do not replace its design description. Nor do planning illustrations establish observed power. Observed power is not a useful substitute for reporting the estimate and its uncertainty: it is driven by the observed effect and does not convey precision as directly as a confidence interval. No numerical planning results or observed primary effect are reported in the registry record, so the assumptions cannot be used to recover the primary result or assess the trial's actual precision.

Why can over-dispersion matter?

For count data, a statistical model may assume a particular relationship between the expected count and its variability. Over-dispersion means the data vary more than the model expects. If that occurs and the model does not account for it, uncertainty can be understated and inferential conclusions may appear more precise than warranted. This is a general consideration for count outcomes, not a claim that over-dispersion was present in this study. The primary outcome is a participant count with a binary meaning—participants with an event—rather than a repeated-event rate, and the registry does not describe a model, dispersion estimate, or analysis of the endpoint.

In a binary outcome analysis, the observed count is commonly interpreted relative to the number assessed, with uncertainty depending on both. If follow-up or outcome capture is incomplete, the analysis population and handling of missing outcomes also affect interpretation. The registry record does not report these details for the primary endpoint. Therefore, neither a modeled estimate nor a precise event frequency should be inferred from the information recorded.

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("LMA® Gastro™")
n      <- c(30)
events <- c(28)
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  LMA® Gastro™  30  28  93.3  77.9  99.2  78.7  98.2  78.6  98.0

11. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures, but the details of the other measure beyond the primary endpoint are not reported in the registry record. It lists zero analyses. No multiplicity strategy is described, such as whether one outcome was designated as the sole basis for a formal statistical claim or whether adjustment across outcomes was planned. When several outcomes are examined, multiplicity can increase the chance of finding an apparently notable result by chance; methods for addressing it depend on the questions and analysis plan. No such procedure can be attributed to this trial from the registry information.

The statistical analysis plan is not reported in the registry record. The record does not state which analysis population was intended for the primary endpoint, how participants with missing outcome information would be handled, or whether any sensitivity analyses were planned. It also does not report whether outcome assessment continued for every participant through the stated timeframe of up to 3 months. These are not minor technical details: missing outcomes can change the denominator and may affect how representative the observed count is of the enrolled group.

Enrollment of 33 and the adverse-event risk count of 30 refer to different reported quantities. The registry does not explain the relationship between them, and they should not be combined or treated as interchangeable. The primary endpoint's assessed population is not reported. Without that population, the outcome count, and a stated missing-data approach, the registry record does not permit evaluation of attrition, outcome completeness, or the impact of missing observations.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

For the LMA Gastro group, the registry reports 0 serious adverse events among 30 participants at risk, 0 other adverse events among 30 participants at risk, and 0 deaths among 30 participants at risk. These are separate categories in the safety summary. The record lists no top serious-event terms.

“At risk” is the denominator attached to each category in the registry summary; it is not the primary endpoint's reported analysis population. The record does not explain why this safety denominator differs from the enrollment figure of 33, and it does not report additional detail on event collection or follow-up for these counts. The timeframe for the primary outcome is up to 3 months, but the safety summary's specific observation period is not reported in the registry record.

Zero recorded events means that no events in the stated category are listed for the reported risk group. It does not establish that the risk is exactly zero, rule out unrecorded events, or show how safety compares with another airway strategy. With no comparator arm described, these counts are descriptive. They should be interpreted as the registry's reported observations, not as a comparative safety estimate or a guarantee about future use.

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

The record identifies a clinically focused feasibility question: whether ERCP can be completed with LMA Gastro in the described procedural setting. It also states the intended primary measure, successful completion of ERCP with the device, and gives a timeframe of up to 3 months. These details clarify what the study set out to assess.

The primary success result itself is not reported in the registry record. Accordingly, readers cannot determine from this record how many participants met the success definition, what fraction of those assessed did so, or how precisely that frequency was estimated. The enrollment figure does not answer those questions. The record also does not describe the analysis population, missing-outcome handling, or a prespecified threshold for judging feasibility.

The study's single-group design means that its structure does not provide a randomized comparison with a native airway or another control. If a primary success count were available, it would describe the outcome in the LMA Gastro group, not establish the difference that would have occurred under another airway approach. The official title's wording about an alternative is the motivating question, not evidence of a comparative result.

The adverse-event summary documents zero reported serious adverse events, zero other adverse events, and zero deaths among 30 at risk for each category. These descriptive counts add safety information about the registry's reported group, but they do not establish comparative safety or eliminate uncertainty about uncommon or unrecorded events.

Thus, the posted information can be used to understand the design and intended endpoint, and to describe the recorded safety counts. It cannot support a conclusion that the primary feasibility objective was or was not met. That distinction is important: missing outcome reporting is not itself a result in either direction.

14. Why This Trial Matters Statistically

Feasibility questions are important because procedural innovations must be evaluated in the context in which they are intended to be used. ERCP is the procedure named in this registry, and the study tests LMA Gastro as an airway device in that setting. A count of successful procedures can be a direct, understandable measure of whether the planned procedure was completed with the device.

Statistically, the endpoint's usefulness depends on more than its label. A clear success definition, a known number assessed, complete outcome capture, and a measure of uncertainty allow readers to judge how stable the observed estimate may be. The registry describes success as completion of ERCP with LMA Gastro, but does not report the primary count, its denominator, or an interval estimate. That leaves the central quantitative feasibility question unanswered in the posted record.

The single-group structure also matters for how evidence should be framed. It can describe experience with the device in the study group, but it does not provide a randomized estimate of how outcomes compare with a native-airway strategy. The title's alternative framing should therefore be distinguished from a direct comparative design.

Finally, transparent reporting of analysis populations, missing outcomes, and the statistical plan supports reproducibility and helps readers understand uncertainty. Those details are not reported in the registry record. The study still illustrates why feasibility endpoints and study design need to be read together: the endpoint says what was to be counted, while the design determines which conclusions that count could support.

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.

Several trial-specific limitations follow from the information in the registry. Most importantly, the primary success count and its analysis denominator are not reported in the registry record. As a result, the central endpoint cannot be quantified, and its precision cannot be assessed. The enrollment figure is not a substitute for those missing outcome details.

The single-group design has no concurrent control described. It can address observed experience with LMA Gastro during ERCP, but it cannot by itself establish a comparative difference from native-airway management. Allocation is recorded as NA and masking as none, so the record does not describe randomization or masking that might otherwise shape the interpretation of comparative findings.

The registry's endpoint description does not give detailed success criteria or a threshold for deciding whether feasibility was adequate. Participant eligibility, demographic and clinical characteristics, and the analysis population are also not reported in the registry record. The record does not explain outcome completeness, missing-data handling, or how the two registered outcome measures were incorporated into the statistical plan.

The safety summary provides counts for the LMA Gastro group, but does not describe a comparison group or give further details on the safety observation period. Its risk denominator is 30, while enrollment is listed as 33; the registry does not explain this difference, and the figures should not be assumed to represent the same analysis set. These reporting gaps limit interpretation of both the primary endpoint and the adverse-event summary.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Feasibility of Laryngeal Mask Airway Gastro on Patients Undergoing Endoscopic Retrograde Cholangiopancreatography for Pancreas and Bile Duct Disorders — NCT03775681.
• Registry record last updated 2021-04-27; status last verified 2021-03.
• Results first posted 2021-04-27.
• 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

NCT03775681 is a completed, single-group feasibility study sponsored by M.D. Anderson Cancer Center. It lists enrollment of 33, phase NA, allocation NA, and no masking. The study evaluated LMA Gastro during ERCP for pancreas and bile duct disorders after general anesthesia; the arm description also includes a 5-minute post-procedure interview.

The primary outcome is the count of participants with successful ERCP completion using LMA Gastro, with a timeframe of up to 3 months. Its result is not reported in the registry record. The record lists two outcome measures and zero analyses. In the safety summary, the LMA Gastro group has 0 serious adverse events, 0 other adverse events, and 0 deaths, each among 30 at risk. The single-group design does not provide a concurrent comparison with a native airway.