Observational Study of the LMA Protector: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Observational Study of the LMA Protector (NCT03664700), a registered phase not stated study. The primary outcome is First go Insertion Success Rate.

2. Clinical Question

The research question is descriptive: it concerns the observed performance of a device during clinical practice, rather than a randomized comparison of alternative airway devices. The registry description also identifies user friendliness as an interest, although a separate primary measure of user friendliness is not specified in the record.

The primary outcome is framed as a participant count: whether insertion on the first attempt was successful or not. The record lists other performance-related outcomes, including time to the first square capnography waveform, lowest oxygen saturation, airway-patency interventions, visible chest movement, adequate tidal volume at an attempt at ventilation, stable oxygen saturations, square capnography trace, and complications across insertion, anaesthesia, and device removal.

The registry lists 12 outcome measures in total, but outcome analyses are not reported in the registry record. Consequently, the record does not provide an observed first-go success count, an estimate of performance, or an uncertainty interval. It also does not identify a comparator group against which to interpret the device’s performance. These omissions limit the answer to the clinical question that can be drawn from the registry entry.

3. Trial Design

The registry describes ADEPT 1 as an observational study of the LMA Protector. Its stated purpose is to investigate user friendliness and performance, with the principal research question focused on overall performance. The investigators characterize their work as observation of device use during clinical practice. The listed intervention is the LMA Protector, and its arm description says that the device will be used.

The record lists enrollment of 112 and gives a status of terminated. The listed study start date is 2019-11-05, and the listed primary completion date is 2021-08-01. The reason for termination is not reported in the registry record. These registration details do not establish how many participants contributed data to the primary outcome or whether all planned observations were completed.

No randomized allocation or like-for-like control group is described. The allocation method is not stated. Without a stated comparator, the study’s primary question is best understood as a description of insertion success within the observed use of the device, not as an estimate of a difference between devices or care strategies. The record does not provide enough information to determine how participants were selected, how clinicians were trained, or what procedural criteria defined a successful insertion beyond the description that first-go insertion was successful or not.

The registry lists one primary outcome and additional secondary outcomes, but reports zero analyses. The statistical analysis plan, the sample-size justification, and any interim analyses are not reported in the registry record. The record’s planning assumptions describe a hypothetical two-arm calculation, but these assumptions are not evidence that the observational study used a two-arm design or that this was its own design plan.

As a result, the registered design provides context for the intended observations, while leaving important operational and analysis details unspecified. The enrollment figure and status should not be mistaken for a completed outcome analysis or a defined analysis population.

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

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.

6. Primary Endpoint

The registry lists the primary outcome as First go Insertion Success Rate, measured over Day 1.

The primary endpoint is the number of participants for whom LMA Protector insertion succeeds on the first go. The registry defines the measure as whether first-go insertion was successful or not and gives its timeframe as Day 1. It is therefore a binary participant-level outcome recorded as a count: each participant either has the defined event or does not.

First-attempt success is used as a direct measure of insertion performance. In general, a measure tied to an initial attempt can describe whether a device was placed successfully without requiring a later attempt. It does not, by itself, describe all aspects of airway management, the quality of ventilation over time, or the participant’s overall clinical course. Those questions require other outcomes and information about how observations were collected.

The registry also lists measures relevant to airway function and device use, such as capnography, oxygen saturation, interventions to maintain airway patency, ventilation, and complications. These may add context to the primary measure, but the registry record does not report their results or explain how they would be combined with first-go success.

No primary-outcome count, proportion, confidence interval, or statistical test is reported in the registry record. Thus, the endpoint’s definition is available, but its observed value and precision are not. The count of enrolled participants is not a substitute for the number with successful first-go insertion; the latter is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is binary at the participant level: first-go insertion either meets the recorded success definition or it does not. The registry expresses the measure as a count of participants, rather than reporting a mean or a time-to-event estimate. To interpret such an outcome, readers ordinarily need the number assessed and the number with the event. Neither primary-outcome count is reported in the registry record.

In general, a binary outcome may be summarized by its event count and the number of participants contributing data. A proportion can also describe the share with the event, while a confidence interval communicates uncertainty around that estimate. These summaries answer different questions: the count reports how many participants had the event, the proportion places that count in relation to those assessed, and the interval indicates how much statistical uncertainty remains. No such primary-outcome summaries are reported for this study, so no estimate or interval can be interpreted.

In general, statistical tests assess whether observed data are compatible with a specified null hypothesis under stated assumptions. A p-value is not a measure of the size or clinical importance of an effect, and it does not describe the probability that a hypothesis is true. The registry lists zero analyses, and no primary-outcome test or p-value is reported. The statistical analysis plan is not reported in the registry record, so the intended test, estimation method, and any adjustment strategy cannot be identified.

The study is observational and does not have a stated like-for-like control comparison. In general, an observational description can characterize outcomes in the people who were observed, but it does not by itself isolate the effect of a device from patient characteristics, clinician decisions, setting, or other aspects of care. A comparative causal interpretation would require an appropriate comparison and methods addressing the design and sources of bias. The registry record does not describe such a comparison or analysis.

The record lists a sample-size planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It describes the effect to detect as a stated fraction of the observed effect. Time-to-event illustrations use a total event count, while other illustrations use participants per arm. These are general planning assumptions, not reported features of the study’s own design. In particular, the record describes an observational study and does not state a two-arm allocation. It also reports no observed primary effect from which to assess the illustration. Such planning values, where displayed, must not be read as observed power or as evidence about the results.

In general, planning calculations depend on assumptions about the outcome, effect size, error rate, allocation, and analysis method. A planning illustration describes what a hypothetical design might require under those assumptions; it does not show that the study had that sample size, achieved a particular power, or found the assumed effect. The record’s sample-size justification for the trial itself is not reported in the registry record. The enrollment of 112 is not interchangeable with a planning target or with an analysis sample.

The registered secondary outcomes cover several types of data. Time to first square capnography waveform is a time-related measure; oxygen saturation and ventilation observations may be continuous or categorical depending on how they were recorded; airway interventions and complications may be counted as events or participants with events. The registry record names these outcomes but does not describe their data formats, assessment rules, or statistical methods. It would therefore be inappropriate to infer a specific model or summary measure for them.

For count outcomes, general statistical methods must account for what is being counted and the variation in counts. When counts vary more than a simple model assumes, over-dispersion can make standard errors too small and confidence intervals too narrow if it is ignored. That general concern cannot be tied to a particular analysis: the primary endpoint is described as a count of participants with a binary event, and no count model or analysis is reported.

Analysis populations are also important. In general, an analysis population specifies which participants are included and how missing or incomplete observations are handled. The registry record does not report a primary-outcome analysis population, exclusions, missing-data methods, or the number with available endpoint data. The listed enrollment alone cannot establish the denominator used in an analysis.

Finally, the study is marked terminated, while the reason for termination, interim analyses, and stopping procedures are not reported in the registry record. Termination status does not itself identify the amount of data collected or the reason the study ended. Without reported endpoint results, analysis details, and population definitions, readers cannot evaluate the precision, robustness, or completeness of a statistical estimate for first-go insertion success.

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 Protector")
n      <- c(111)
events <- c(100)
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 Protector  111  100  90.1  83.0  94.9  83.1  94.4  83.1  94.3

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 12 outcome measures, including a primary measure and outcomes concerning capnography, oxygen saturation, ventilation, airway-patency interventions, and complications. It reports zero analyses. The statistical plan for these outcomes, including any strategy for accounting for multiple comparisons, is not reported in the registry record.

In general, testing many outcomes can increase the chance that at least one result appears statistically notable by chance. Multiplicity methods can address that issue, but the appropriate approach depends on which outcomes were confirmatory, how they were ordered, and which analyses were planned. Those details are not reported, so no adjustment method or hierarchy of secondary outcomes can be inferred.

Missing-data handling and analysis populations are also not reported in the registry record. The record does not state how many participants had observed primary-outcome data, how incomplete observations were treated, or whether exclusions occurred. The enrollment of 112 therefore cannot be assumed to equal the primary analysis population.

The terminated status does not reveal whether termination affected data completeness or the planned analysis. Its reason is not reported in the registry record, and the record does not describe interim analyses or stopping rules. Without these details and without outcome analyses, the extent to which missingness, outcome selection, or multiple testing could affect interpretation cannot be assessed.

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 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: desaturation (0.9%).

The registry lists the LMA Protector group with 111 at risk for serious events and 1 serious event. It also lists 111 at risk for other events and 39 other events. Deaths are listed as 0. Desaturation appears among the top serious terms, with 0.9% recorded.

These are descriptive safety entries. They do not constitute a comparison with another device or group, because a like-for-like control comparison is not described. The figures should not be interpreted as proof that an event was caused by the device or as a complete account of all possible safety outcomes.

The record does not explain whether the event counts refer to distinct participants, repeated events, or a particular event-coding approach. It also does not report a statistical analysis or uncertainty interval for these safety figures. The at-risk counts in the serious and other event entries are both 111; they should be read as posted rather than treated as a basis for calculations not reported in the registry record.

The registry names complications during insertion, anaesthesia, and device removal as an outcome, but does not report analyses for that outcome. The safety figures therefore provide limited descriptive information and do not resolve the broader safety question.

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

The registry record establishes that investigators planned an observational assessment of LMA Protector use in clinical practice, with first-go insertion success as the primary outcome. It also identifies other performance and complication outcomes. This defines the questions of interest, but it does not answer them quantitatively.

No primary outcome result or analysis is reported. Consequently, there is no posted estimate of first-go insertion success, no confidence interval describing its precision, and no comparative estimate against another device. The absence of a result should not be interpreted as evidence for or against successful performance.

The record lists enrollment of 112, but does not identify the primary analysis population or the number with observed endpoint data. It is not possible to use enrollment as though it were the denominator for the primary outcome. The record is marked terminated, but does not report why the study ended or how termination affected completion of data collection and analysis.

The posted safety figures describe events in the LMA Protector group, including one serious event among 111 at risk, 39 other events among 111 at risk, and zero deaths. They do not provide a comparative safety estimate or a complete account of how events were defined, counted, and assessed. Desaturation is listed as a top serious term at 0.9%, but the registry does not report an analysis of this term.

In general, observational findings describe what was recorded in a particular setting and population. Without a suitable comparator and methods addressing differences in participants and care, they cannot isolate a causal effect. In this case, the absence of reported outcome analyses further limits interpretation: even a descriptive estimate for the primary endpoint is unavailable.

The record is therefore informative about the intended clinical question and the outcomes the investigators listed, but not about the observed primary performance result. Any conclusion about the magnitude, precision, or comparative meaning of first-go insertion success would go beyond the results reported in the registry record.

14. Why This Trial Matters Statistically

This study raises a practical statistical question: how should device performance be described when use is observed in clinical practice rather than assigned within a randomized comparison? The answer begins with clear outcome definitions, transparent participant counts, and a precise account of who contributed data. The registry identifies first-go insertion success as the primary measure, but does not report its result or the number assessed.

The distinction between enrollment and analysis is particularly important. The record lists 112 participants, yet does not report the primary-outcome analysis population. Readers cannot determine from enrollment alone how many observations informed the endpoint, whether data were incomplete, or how exclusions were handled. Those details affect the interpretation and precision of any estimate.

The record also illustrates why outcome registration and outcome reporting are separate. Twelve measures are listed, spanning insertion, ventilation, oxygenation, and complications, but the registry reports zero analyses. Naming an outcome does not establish that it was measured or analyzed, and it does not supply the result needed to answer the research question.

Finally, the study’s observational description and lack of a stated comparator shape the conclusions that would be possible even if results were available. Descriptive performance estimates can be useful, but they do not by themselves show how results would differ under another device or approach. The record is most valuable statistically as an example of why estimates, uncertainty, analysis populations, and comparison structure all matter when interpreting a clinical study.

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 primary limitation is that the registry record reports no outcome analyses. The first-go insertion success result is not reported, so the central performance question cannot be answered from the posted information. The same absence applies to the listed secondary outcomes.

The record gives enrollment as 112 but does not report the number of participants assessed for the primary endpoint or define an analysis population. It does not describe missing observations, exclusions, or how success was determined in practice beyond the binary description of whether first-go insertion was successful. These gaps prevent assessment of completeness and outcome ascertainment.

The study is described as observational, and no like-for-like control comparison is identified. Allocation is not stated. The record therefore does not establish a basis for a comparative estimate, and it does not provide details about participant selection, clinical settings, operator experience, or other factors that could influence observed performance.

The status is terminated, but the reason for termination is not reported in the registry record. It is also not reported whether termination affected data collection, outcome availability, or the planned analysis. No sample-size justification for the study, statistical analysis plan, interim analyses, or missing-data strategy is described.

The safety entries provide limited descriptive counts, but event definitions, assessment procedures, and whether counts represent distinct participants are not explained. Taken together, these limitations mean the record describes the study’s intent and selected registration details more clearly than its analyzed findings.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Observational Study of the LMA Protector — NCT03664700.
• Registry record last updated 2025-01-14; status last verified 2025-01.
• Results first posted 2025-01-14.
• 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 ADEPT 1, an observational study of the LMA Protector focused on user friendliness and overall device performance during clinical practice. It lists enrollment of 112, a terminated status, a start date of 2019-11-05, and a primary completion date of 2021-08-01. The reason for termination is not reported in the registry record.

The primary outcome is first-go insertion success, recorded as a participant count with a Day 1 timeframe. The registry also lists measures concerning capnography, oxygen saturation, ventilation, airway-patency interventions, and complications. It reports zero analyses, so the primary result and secondary outcome results are not reported in the registry record.

Safety entries list 1 serious event among 111 at risk, 39 other events among 111 at risk, and 0 deaths. Desaturation is listed as a top serious term at 0.9%. No like-for-like control comparison or primary analysis population is described.