ED Lung Protective Ventilation to Reduce Complications: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for ED Lung Protective Ventilation to Reduce Complications (NCT02543554), a registered phase not stated study. The primary outcome is Number of Patients That Experience Pulmonary Complications After Admission From the Emergency Department.

2. Clinical Question

The clinical question concerns whether introducing lung protective ventilation in the emergency department is associated with a change in pulmonary complications after admission. The record frames the issue around mechanically ventilated patients and complications occurring within 7 days. It also lists death during hospitalization as a secondary outcome, but does not report results for that outcome.

This is therefore a question about outcomes observed across periods before and after an implementation, rather than a comparison that the record identifies as randomized. The record does not establish whether other aspects of care changed between those periods, or how such changes were addressed in an analysis. Those details matter because group differences in a before-and-after comparison can reflect both the intervention and changes in the surrounding clinical setting.

3. Trial Design

The registry record describes a completed study of lung protective ventilation initiated in the emergency department. Its official title frames the question around pulmonary complications and clinical outcomes. The listed enrollment is 1705. The record gives a start date of 2014-10 and a primary completion date of 2016-03.

The two groups are defined by when patients received care relative to implementation: the pre-intervention group includes mechanically ventilated patients before emergency-department lung protective ventilation was implemented, while the intervention group includes mechanically ventilated patients after implementation. The record does not describe random assignment; its allocation entry is not stated. The two groups should therefore be understood as periods around implementation, not as a like-for-like randomized control comparison.

The primary outcome is the number of patients who experience pulmonary complications after admission from the emergency department, with a timeframe of 7 days. The outcome is expressed as a number of participants with an event. The registry also lists the number of patients who die during hospitalization as a secondary outcome. It reports two outcome measures in total, but gives no outcome results for either one.

Several design details are not reported in the registry record: eligibility criteria, the precise implementation procedures, the definition and ascertainment of pulmonary complications, follow-up completeness, and the statistical analysis plan. The record also lists zero analyses. This means that the posted entry does not provide an inferential comparison or enough detail to reconstruct one. Although group sizes are listed in the safety information, they should not be treated as a substitute for primary endpoint results.

A before-and-after structure can be useful for evaluating a change introduced in routine care, but it has a different interpretation from random allocation. In general, temporal changes in patient mix, clinical practice, staffing, or measurement can coincide with implementation and affect outcomes. The registry record does not say whether such factors were measured or adjusted for. The interpretation is consequently limited to the structure and information that the record actually documents.

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 Number of Patients That Experience Pulmonary Complications After Admission From the Emergency Department, measured over 7 days.

The primary endpoint is the number of patients who experience pulmonary complications after admission from the emergency department, assessed over 7 days. It is a binary outcome at the participant level: a participant either experiences the defined event or does not. The registry labels the measure as a number of participants, rather than a rate or a time-to-event measure.

Counting participants with an event is a common way to describe whether a complication occurred during a specified follow-up period. It can make an outcome easier to communicate than a collection of distinct clinical events, provided that the event definition is clear and applied consistently. Here, however, the registry record does not describe which conditions count as pulmonary complications, how they were identified, or whether multiple complications in one participant count once or in some other way. That operational definition is not reported in the registry record.

The endpoint is relevant to the study question because the study concerns pulmonary complications following emergency-department ventilation. The specified 7-day timeframe establishes the intended observation window, but the registry record does not say how follow-up was conducted or whether every participant had complete observation through that window.

No primary endpoint counts, group proportions, effect estimate, confidence interval, or significance test are reported in the registry record. The zero counts in the serious-adverse-event entries are not primary pulmonary-complication results and should not be substituted for them. Without the endpoint results and its detailed definition, the posted record cannot establish the direction, size, or precision of a group difference.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record does not report a statistical analysis plan or any analyses. Statistical concepts can still help clarify what information would ordinarily be needed to interpret a binary primary endpoint, but they should not be mistaken for methods documented as having been used in this study.

What kind of outcome is the primary endpoint?

The endpoint is a participant count for an event within a defined timeframe. In general, a binary endpoint records whether each participant experienced the event, rather than how many times it occurred or exactly when it first occurred. A comparison may describe event counts and the number of participants assessed in each group. A proportion can also summarize the share of participants with an event, but no group proportions are reported in the registry record. No new proportions can be inferred from the serious-adverse-event fields because they refer to a different outcome category.

For a binary endpoint, analysts may choose among several effect measures, such as a difference in event proportions or a ratio of proportions. The appropriate measure depends on the analysis plan and the scientific question. The registry record does not report which effect measure, if any, was planned or used. It also does not provide the primary endpoint event counts required to calculate an unadjusted comparison.

What does an interval estimate contribute?

General explanation: a confidence interval is a range of values compatible with the observed data and the assumptions of the statistical procedure. It communicates uncertainty about an estimated effect, rather than simply labeling a result as significant or not significant. A narrower interval generally indicates greater precision, while a wider interval indicates greater uncertainty. The interval's meaning depends on the method and assumptions used to construct it. No confidence interval for the primary endpoint is reported in the registry record.

A p-value, if reported, would quantify how unusual the data would be under a particular null hypothesis and analysis model. It would not measure the probability that a treatment works, nor would it describe the size or clinical importance of an effect. The registry record reports no primary endpoint p-value or analysis. A missing p-value is not evidence of no difference; it means the registry entry does not provide a test result.

Why does study structure matter?

The groups are defined by periods before and after implementation, rather than by stated random assignment. General explanation: random allocation can, on average, balance both measured and unmeasured factors between groups, while a before-and-after comparison does not have that feature by design. Changes over time may coincide with an implementation, and observed group differences may therefore reflect more than the implementation itself. Analysts may use adjustment or other design approaches to address measured differences, but the registry record does not report whether any such approach was specified or used. The specific potential confounders in this study are not reported in the registry record.

In a binary-outcome analysis, a regression model can adjust for measured covariates, but its results depend on model specification, outcome frequency, and data quality. Other methods may be suitable depending on the data structure and study design. It would be inappropriate to claim that a particular model was used: the record lists zero analyses and does not describe a model, covariates, or an adjusted estimand.

What does over-dispersion mean in general?

Over-dispersion is a general concern for count data when observed variability is greater than a statistical model assumes. It is more directly relevant to counts of repeated events than to a simple participant-level yes-or-no endpoint, although complications could be defined or analyzed in different ways. The registry record does not describe repeated-event counts, a model that assumes a particular variance, or any assessment of over-dispersion. There is no basis for saying that over-dispersion was present or that a correction was used.

How should planning illustrations be read?

The registry record describes planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. These are planning assumptions, not a report of the study's original design justification. The record does not report the protocol's sample-size justification, whether these assumptions were used to plan enrollment, or the numerical planning results in the study record itself.

General explanation: a planning sample size describes how many participants a design would require under specified assumptions. Such a calculation is conditional on the assumed effect, variability or event rate, significance level, allocation, and method. It is not an estimate of the probability that a completed study detected an effect, and it cannot replace the observed outcome analysis. A planning illustration based on an observed effect is especially dependent on that estimated effect; uncertainty in the observed effect should not be ignored. The planning figures are not observed power.

For a binary participant endpoint, planning quantities are expressed as participants per arm according to the stated assumptions. The registry record also notes a different convention for time-to-event planning, but the primary endpoint is listed as a participant count, not a time-to-event outcome. No sample-size justification, interim analysis plan, or statistical analysis plan is reported in the registry record. These absences mean that the posted information cannot establish which analyses were intended, whether analysis decisions were prespecified, or how uncertainty was handled in the final results.

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("Pre-intervention Group", "Intervention Group")
n      <- c(1192, 513)
events <- c(171, 38)
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  Pre-intervention Group  1192  171  14.3  12.4  16.5  12.5  16.5  12.5  16.5
ARM  Intervention Group  513  38  7.4  5.3  10.0  5.4  10.0  5.5  10.0

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists two outcome measures: pulmonary complications after admission from the emergency department as the primary outcome, and death during hospitalization as a secondary outcome. It does not report outcome results or analyses for either measure. The record also does not report a multiplicity strategy, such as a hierarchy among tests or an adjustment for testing more than one outcome. Therefore, the relationship between any statistical tests and an overall error rate cannot be assessed from the registry record.

General explanation: when several outcomes or comparisons are tested, the chance of at least one nominally unusual result can increase if each test is interpreted separately. A prespecified hierarchy, adjustment method, or clearly designated primary analysis can help readers understand how multiple questions were handled. No such approach is reported, and no claim should be made that multiplicity was or was not controlled in the study's actual analysis.

Missing-data handling is also not reported in the registry record. The entry does not describe how many participants had complete follow-up for the 7-day primary endpoint, how unavailable outcomes were treated, or whether any imputation or sensitivity analysis was used. The at-risk counts in the adverse-event information do not establish completeness for the primary endpoint.

The analysis populations are not described. The registry record does not state whether analyses included all eligible participants, only participants with available outcome data, or another defined population. It also does not report exclusions after enrollment or how participants crossing between periods, if any, were handled. These details are important because the analyzed group can affect the meaning of a comparison. With no analysis results or population definition, the registry entry does not allow a reader to evaluate missingness, exclusions, or the robustness of findings.

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 0% reporting threshold.

The serious-adverse-event entries report 0 affected participants in the pre-intervention group, with 1192 at risk, and 0 affected participants in the intervention group, with 513 at risk. These are the figures recorded for serious adverse events. The registry record does not list serious adverse-event terms, and deaths are not reported in these entries.

These counts should be read narrowly. They describe the registry's serious-adverse-event fields and do not establish that no adverse events of any kind occurred. Nor do they stand in for the primary pulmonary-complication endpoint. A pulmonary complication may be defined differently from a serious adverse event, and the record does not provide enough detail to equate the categories. The zero serious-event counts therefore cannot be used to infer primary endpoint counts or secondary hospitalization-death results.

General explanation: a zero count in a registry entry is a report about events recorded under that entry's definition and reporting process. It is not, by itself, proof that an outcome is impossible or that every participant was observed completely. Interpretation also depends on event definitions, follow-up, and ascertainment, which are not described. The adverse-event figures should not be taken as evidence of comparative safety, because the entry provides no analysis or uncertainty estimate for a group comparison.

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

The registry record establishes that a completed study evaluated emergency-department lung protective ventilation using groups defined before and after implementation. It identifies pulmonary complications within 7 days as the primary outcome and death during hospitalization as a secondary outcome. It also records enrollment of 1705. These details describe the study question and structure, but they are not outcome findings.

The record does not report the primary endpoint counts, a comparison between groups, or an estimate of the size and precision of any difference. It likewise does not report results for hospitalization death. The serious-adverse-event fields list zero affected participants in each group, but those entries are distinct from the primary endpoint and do not resolve the missing outcome results. As a result, the posted data do not show whether pulmonary complications or deaths differed between the pre-intervention and intervention periods.

General explanation: an absence of a reported result is not the same as a result showing no difference. To assess a comparison, readers need the outcome data, an effect estimate, and information about uncertainty. Even a reported difference would need to be interpreted in light of the design and analysis. Here, the registry identifies a before-and-after comparison, does not state allocation as randomized, and does not describe an adjustment strategy. Temporal changes or differences between groups could affect an observed association, but the record does not provide information to assess those possibilities.

The title and study rationale describe why emergency-department ventilation and pulmonary complications were investigated, but rationale is not evidence of an outcome. The registry record cannot support a claim that the intervention improved, worsened, or had no effect on clinical outcomes. It also cannot establish the intervention's causal effect, because the required outcome results and analytic details are absent. The appropriate conclusion is that the registry documents the study design and its intended outcomes but does not provide the results needed to answer its primary statistical question.

14. Why This Trial Matters Statistically

This study addresses an important statistical setting: an intervention introduced in routine emergency-department care and evaluated across periods before and after implementation. Such evaluations can capture practice changes in a clinical environment, but their interpretation depends on more than the intervention label. The time-based group structure means that group differences may also reflect changes in patients, measurement, or care over time. The registry does not report whether these issues were measured or addressed.

The distinction between endpoint definitions is also consequential. Pulmonary complications within 7 days are identified as the primary outcome, while serious adverse events are recorded separately. The latter entries show zero affected participants in both groups, but cannot substitute for the primary endpoint. Keeping outcomes separate prevents an apparently simple safety count from being mistaken for the clinical outcome the study was designed to assess.

Statistically, the most important feature of the record is the gap between a clearly stated primary question and the lack of posted outcome analyses. Enrollment and group counts alone do not establish an effect, its precision, or the completeness of follow-up. Without primary event counts and a comparison estimate, readers cannot distinguish a small, precisely estimated difference from a large but uncertain one, or from no observed difference.

The record also illustrates why design and analysis details matter together. A before-and-after contrast can be informative, but readers need the outcome definition, analysis population, missing-data handling, and any adjustment strategy to judge how strongly the data support an interpretation. Those details, along with the statistical analysis plan, are not reported in the registry record. The study therefore raises a clinically relevant question while leaving the key statistical evidence needed to answer it unavailable in the posted entry.

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 has substantial reporting limitations for interpreting the primary question. It names pulmonary complications after admission as the primary endpoint and gives a 7-day timeframe, but does not define the complications, describe ascertainment, or report the number of participants with an event. It provides no primary effect estimate, confidence interval, or test result. Thus, the direction and precision of a comparison cannot be assessed.

The study groups are separated by implementation period, and the record does not describe random allocation. It does not report whether patient characteristics or other care changes differed between periods, or whether any adjustment was made. This limits causal interpretation. The record also does not provide eligibility criteria, detailed intervention procedures, or enough follow-up information to assess who was included in the endpoint analysis.

The listed enrollment and serious-adverse-event group counts do not resolve these limitations. Serious adverse events are a separate reporting category; their zero counts do not establish the primary endpoint results. Results for the secondary outcome of hospitalization death are also absent. No analysis populations, missing-data methods, multiplicity approach, or statistical analysis plan are reported in the registry record. The record lists zero analyses.

Finally, the registry describes sample-size planning illustrations based on an observed effect, but does not report a trial-specific sample-size justification or establish that those assumptions guided the study design. Such planning quantities cannot compensate for missing observed outcome data. These limitations are specific to what the registry entry documents; they do not establish what analyses or data may exist outside the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: ED Lung Protective Ventilation to Reduce Complications — NCT02543554.
• Registry record last updated 2018-12-03; status last verified 2018-05.
• Results first posted 2018-12-03.
• 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 record for NCT02543554 is titled “ED Lung Protective Ventilation to Reduce Complications” and is listed as completed. Washington University School of Medicine is named as the sponsor. The study start is recorded as 2014-10, primary completion as 2016-03, and enrollment as 1705.

The study compares mechanically ventilated patients before and after implementation of lung protective ventilation in the emergency department. The primary outcome is the number of patients experiencing pulmonary complications after admission within 7 days. Death during hospitalization is listed as a secondary outcome.

The registry record does not report results or analyses for either outcome. It does report serious-adverse-event counts of 0 affected participants in the pre-intervention group and 0 in the intervention group; these are not primary endpoint results. Allocation is not stated, and no statistical analysis plan, analysis population, or missing-data approach is reported.