This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Safety of Optimal PEEP in NSICU Patients (NCT03862027), a na na study. The primary outcome is Change in ICP Value.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03862027 |
| Phase | NA |
| Condition | Respiratory Failure, Intracranial Hypertension |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 1 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of North Carolina, Chapel Hill |
| Results posted | Yes |
2. Clinical Question
Population
Patients in neurocritical care with possible elevations of intracranial pressure and respiratory failure were the intended population. The registry record lists respiratory failure and intracranial hypertension as conditions. Enrollment was 1, so the recorded study experience is limited to one participant.
Intervention
The intervention was use of an esophageal balloon catheter in the context of transpulmonary-pressure-guided PEEP management. The study aim was to assess whether this approach was safe in patients with possible elevations of intracranial pressure. The registry description states that the catheter was inserted while the patient was upright; further procedural details are not reported in the registry record in a complete form.
Comparator
No separate comparator group is described. The registry lists a single-group model, and allocation is recorded as NA. The clinical question therefore is not framed as a randomized comparison between treatments or between concurrent groups.
Primary question
The primary endpoint was change in intracranial pressure (ICP), measured in mm Hg within 5 minutes of catheter placement. The stated criterion treated the post-intervention ICP as equivalent to the pre-intervention value if the 95% upper bound of the change was lower than the non-inferiority margin of 4 mm Hg. The registry record does not report an observed change or an analysis of that criterion.
The study’s stated purpose was to evaluate the safety of using transpulmonary pressure to guide PEEP management in neurocritical care patients. Its central statistical question was whether the measured change in ICP met the prespecified non-inferiority criterion over the short timeframe after catheter placement. That question requires an observed estimate of the change and an uncertainty interval around it. Neither is reported in the registry record.
The enrollment of 1 and absence of a comparator matter when interpreting the question. The record does not support a between-group treatment comparison, and it does not provide an analyzed estimate that could establish whether the endpoint criterion was met. The named secondary outcomes were change in cerebral perfusion pressure (CPP) and change in mean arterial pressure. Their results are not reported in the registry record either.
3. Trial Design
The registry identifies NCT03862027 as a single-group study titled “Safety of Optimal PEEP in NSICU Patients.” Its official title is “Evaluating Safety of Transpulmonary Pressure Guided PEEP Management in Neurocritical Care Patients.” The listed sponsor is University of North Carolina, Chapel Hill. Phase is recorded as NA, allocation is NA, and masking is none. The enrollment recorded in the registry is 1.
The study was intended to examine safety in neurocritical care patients with possible elevations of intracranial pressure. The registry lists respiratory failure and intracranial hypertension as conditions. The intervention is an esophageal balloon catheter, classified as a device. The arm description refers to catheter placement while upright and notes head-of-bed positioning, but the description is incomplete in the registry record. Additional procedural details should not be inferred from that incomplete text.
The primary outcome is change in ICP, with the timeframe specified as within 5 minutes of catheter placement. The registry describes the endpoint as a mean with standard deviation and gives a non-inferiority criterion based on the 95% upper bound of the change and a margin of 4 mm Hg. The named secondary outcomes are change in CPP and change in mean arterial pressure. Although the registry lists 3 outcome measures, it reports no analyses.
The recorded study start date is 2019-03-01, and the primary completion date is 2019-03-04. The status is terminated. The registry record does not report why the study was terminated, whether the planned enrollment was completed, or whether the termination affected collection or reporting of outcomes. It also does not report a comparator arm, a protocol-level sample-size justification, or the reason for the recorded enrollment.
Because this is a single-group study, the design is not a like-for-like control comparison. The statistical interpretation depends on a within-participant before-and-after change, as described by the primary endpoint. However, the registry record does not provide the before-and-after values, the estimated change, or an uncertainty interval. Thus, the design and intended analysis question can be described, but the endpoint result cannot be evaluated from the registry record.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Esophageal Balloon Catheter |
|---|---|
| STARTED | 1 |
| COMPLETED | 1 |
| NOT COMPLETED | 0 |
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | Esophageal Balloon Catheter |
|---|---|---|
| Participants analysed | 1 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 1 |
| Age, Categorical: >=65 years | Participants | 0 |
| Sex: Female, Male: Female | Participants | 0 |
| Sex: Female, Male: Male | Participants | 1 |
| Race and Ethnicity Not Collected | Participants | — |
| Region of Enrollment: United States | Participants | 1 |
6. Primary Endpoint
The registry lists the primary outcome as Change in ICP Value, measured over Within 5 minutes of catheter placement.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | mm Hg |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is change in intracranial pressure (ICP), expressed in mm Hg and assessed within 5 minutes of catheter placement. The registry describes the summary measure as a mean with standard deviation. The clinical rationale in the record is to assess whether the intervention is safe in patients with possible elevations of intracranial pressure; ICP is the named measure used to address that concern.
The stated decision rule is a non-inferiority criterion. In general, a non-inferiority analysis asks whether an outcome change is sufficiently limited relative to a prespecified margin, rather than asking only whether a difference is exactly zero. Here, the registry states that the post-intervention ICP would be considered equivalent to the pre-intervention ICP if the 95% upper bound of the change were lower than the non-inferiority margin of 4 mm Hg. This interpretation depends on the direction and definition of the change being applied as specified in the analysis plan; additional details about those conventions are not reported in the registry record.
An estimate alone would not show how precisely the change was measured. The confidence bound is important because it expresses the range of values compatible with the data under the statistical model. The registry record does not report the observed mean change, its standard deviation, a confidence interval, or whether the criterion was met. It therefore identifies the intended endpoint and rule, but does not provide the information needed to assess the result.
Change in CPP and change in mean arterial pressure are named as secondary outcomes. Their measurement details, results, and analyses are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes the study’s intended question and design, but it does not provide analyzed outcome results. Enrollment is recorded as 1, the study is listed as terminated, and the number of analyses is 0. No observed change in ICP, standard deviation, confidence interval, or test result is reported in the registry record. Consequently, the primary non-inferiority criterion cannot be judged from the posted information.
The stated criterion focuses on whether the 95% upper bound of the change in ICP is lower than the margin of 4 mm Hg. A confidence bound is relevant because a non-inferiority conclusion depends not just on the point estimate but also on its uncertainty. If the estimate were close to the margin and imprecise, the bound could fail to satisfy the stated rule even if the point estimate appeared small. This is a general explanation of how non-inferiority criteria are interpreted; it is not a description of an observed result from this study.
There is no comparator group described. The record lists a single-group model and allocation as NA. Therefore, the study is not a randomized comparison of one group against another. Its primary question is described as a before-and-after change around catheter placement. Without outcome values and an analysis, it is not possible to determine the size, direction, or precision of that change.
The named secondary outcomes are change in CPP and change in mean arterial pressure. Although the registry lists 3 outcome measures in total, it does not report results for these secondary outcomes. The absence of reported analyses also means the record does not show how the primary and secondary outcomes were handled together, whether any adjustment for multiple testing was planned, or whether any outcome was designated for a particular analysis population.
The adverse-event figures record 1 participant at risk for serious adverse events and 0 affected, as well as 1 at risk for other adverse events and 0 affected; deaths are recorded as 0. These are the posted counts, not a precise estimate of event risk. With enrollment of 1, the counts describe a very small observed group and cannot establish that uncommon events would be absent in a larger population. The registry record does not list serious adverse-event terms.
The record also includes assumptions for planning illustrations: a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and effects expressed as fractions of an observed effect. These are described as planning assumptions rather than the trial’s own design. The illustration does not turn this single-group study into a two-arm trial, and its sample-size values should not be read as observed power. No numeric sample-size illustration is reported in the registry record summarized for this analysis.
Overall, the posted information supports a description of the intended endpoint, design, and recorded safety counts. It does not support a conclusion about whether the endpoint met its criterion or about the intervention’s safety beyond those limited counts. The study’s termination, enrollment, and lack of reported analyses are essential context for reading any apparent absence of outcome results.
9. Statistical Methods Explained
The methods described in the registry record define a short-term, continuous primary endpoint in a single-group study. The endpoint is change in ICP within 5 minutes of catheter placement. A continuous measure can take a range of values rather than falling into only a small set of categories. The record specifies a mean and standard deviation as the summary approach, but it does not report the observed values or an analysis estimate.
What does a mean change represent?
In general, a mean change summarizes the average difference between measurements taken at two time points. For a before-and-after endpoint, the interpretation depends on how the change is defined, including which time point is subtracted from which. That direction affects how a positive or negative value is read. The registry record identifies change in ICP but does not report the exact calculation convention or the observed estimate. Therefore, no direction or magnitude of change can be described from the record.
A standard deviation describes the spread of individual measurements around a mean. It is not the same as the uncertainty in the estimated mean. Uncertainty in an estimate is commonly communicated with a confidence interval or confidence bound. The primary criterion specifically refers to a 95% upper bound, but the registry record does not report that bound or enough outcome data to reconstruct it.
How does the non-inferiority rule work?
In general, non-inferiority testing evaluates whether the data are compatible with an outcome change no worse than a prespecified margin. The margin marks the boundary used for that decision. The registry states a margin of 4 mm Hg and specifies that the post-intervention ICP would be considered equivalent to the pre-intervention value if the 95% upper bound of the change were lower than that margin. The bound incorporates both the estimated change and its uncertainty. A point estimate by itself would not be sufficient to apply the rule.
The registry uses the word equivalent when describing its criterion, but the stated statistical condition is a non-inferiority condition tied to a margin. In general, equivalence and non-inferiority are related but distinct frameworks: equivalence usually evaluates whether results fall within bounds on both sides, whereas non-inferiority focuses on whether an outcome does not cross a specified unfavorable boundary. The registry record gives the upper-bound rule, but does not report a lower bound or a complete protocol-level statistical analysis plan. The description should therefore remain tied to the condition that is actually recorded.
What does a confidence bound add?
In general, a confidence interval or one-sided bound conveys the precision of an estimate under a statistical model. A narrow interval indicates more precision than a wide interval, while either can be centered on a similar point estimate. For non-inferiority, the relevant question is whether the uncertainty bound remains on the acceptable side of the margin. A wide interval can leave the result inconclusive even when the point estimate is not beyond the margin. No confidence bound is reported for this study, so its precision and relationship to the criterion cannot be assessed.
The registry identifies a mean and standard deviation but does not state the inferential procedure used to calculate the 95% upper bound. Details such as the exact model, distributional assumptions for the outcome, and handling of repeated measurements are not reported in the registry record. No alternative method should be assumed.
What is the role of the secondary outcomes?
Change in CPP and change in mean arterial pressure are listed as secondary outcomes. In general, secondary outcomes can provide additional descriptions of effects or safety-related measures, but they do not replace the primary endpoint. Their interpretation depends on how they were defined, when they were measured, and how analyses were planned. The registry record does not report those details or the results for either outcome. It also does not report whether any multiplicity adjustment was planned across the outcomes.
What do the planning assumptions mean?
The registry describes sample-size calculations as planning illustrations, not as the trial’s own design. The stated assumptions include a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and effects set as fractions of an observed effect. For time-to-event tables, the stated convention is total events; for other calculations, it is participants per arm. The primary endpoint is continuous, not time-to-event.
These assumptions describe a hypothetical planning exercise. They do not establish that the actual study used two arms, because the registry describes a single-group model and gives allocation as NA. Nor do they establish an observed power calculation. Sample-size illustrations are planning quantities; they are not a measure of the probability that a completed study has detected an effect. The registry record reports no analyses, and no numeric illustration results are available in the record. The observed effect on which the illustration is said to be based is not reported in the registry record.
Why does over-dispersion matter in general?
For count outcomes, over-dispersion means that variability is greater than a simple model assumes. If a model underestimates variability, standard errors can be too small and confidence intervals too narrow. This is a general statistical issue, not a feature identified in the registry record. The primary endpoint in this study is described as a continuous change in ICP, and no count-outcome analysis is reported.
Overall, the registry contains enough information to identify the endpoint and its stated decision rule, but not enough to reproduce or evaluate the analysis. The mean change, variability, confidence bound, analysis population, missing-data approach, and inferential procedure are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry names a primary outcome of change in ICP and secondary outcomes of change in CPP and change in mean arterial pressure. It does not report whether the analysis plan controlled the chance of false-positive findings across multiple outcomes, whether a hierarchy was used, or whether secondary analyses were considered exploratory. A multiplicity strategy is not reported in the registry record. Without that information, the intended interpretation of any collection of outcome tests cannot be established; in this case, no outcome analyses are reported.
The registry lists enrollment of 1 and reports 0 analyses. It does not describe an analysis population, such as whether all enrolled participants or only participants with complete measurements were intended for analysis. The record also does not report whether the participant received the intervention, whether the planned measurements were completed, or whether any data were excluded.
Missing-data procedures are not reported in the registry record. In general, missing-data methods matter because incomplete measurements can affect an estimated change and its uncertainty. The record does not describe imputation, a complete-case approach, or sensitivity analyses, so none should be presumed. The reason for termination and its relationship, if any, to outcome collection are also not reported.
These gaps limit statistical interpretation independently of the small recorded enrollment. There is no reported estimate for the primary endpoint, no reported precision measure, and no documented analysis population or missing-data approach. The record therefore cannot show how missingness or the set of outcomes might have influenced any result.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Esophageal Balloon Catheter | 0 | 1 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Esophageal Balloon Catheter | 0 of 1 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Esophageal Balloon Catheter | 0 of 1 |
The registry records 1 participant at risk for serious adverse events and 0 affected. It also records 1 participant at risk for other adverse events and 0 affected, with deaths recorded as 0. No serious adverse-event terms are listed. These counts describe what is entered in the registry; they do not provide a detailed event narrative or an estimate with a reported uncertainty interval.
With enrollment of 1, a count of 0 affected means that no affected participant is recorded among the one listed as at risk. It should not be read as proof that the intervention has no risk or that an event could not occur in a larger group. In general, a small observed group provides limited information about uncommon events, and a zero count can coexist with substantial uncertainty about the frequency of such events in a broader population.
The study is listed as terminated, but the reason for termination and its relationship to safety monitoring are not reported in the registry record. The record does not describe the duration or completeness of adverse-event follow-up. The posted figures should therefore be read narrowly as recorded counts, not as a comprehensive demonstration of safety.
12. What the Result Does, and Does Not, Mean
The result that can be described from the registry is primarily a set of design and reporting details: this was a single-group study with enrollment of 1, listed as terminated, and with 0 analyses. The primary outcome was intended to measure change in ICP within 5 minutes of catheter placement, with a stated non-inferiority criterion based on a 95% upper bound and a margin of 4 mm Hg. The registry record does not report the outcome estimate or whether the criterion was met.
Accordingly, the record does not establish the direction or size of any ICP change, how precisely it was estimated, or whether the stated endpoint rule was satisfied. It also does not report results for change in CPP or mean arterial pressure. The absence of reported analyses is not the same as a finding of no change, and it should not be interpreted as evidence that the endpoint showed no effect.
The safety counts record 0 serious adverse events among 1 at risk, 0 other adverse events among 1 at risk, and 0 deaths. These figures are limited to the registry entries and do not establish absence of risk beyond the recorded participant. No serious adverse-event terms are listed, and details of follow-up are not reported.
More broadly, a single-group design does not offer a concurrent comparison group. The study was not recorded as randomized, and the registry does not describe a like-for-like control comparison. Even if an outcome estimate had been reported, interpretation would need to account for the design and the short specified endpoint timeframe. Since no outcome analysis is posted, such an estimate cannot be evaluated.
The appropriate statistical reading is therefore restrained: the registry documents an intended safety question, a primary endpoint, a non-inferiority rule, a terminated status, and limited adverse-event counts. It does not provide analyzed evidence to determine whether the intended endpoint criterion was satisfied. No conclusion about broader safety or effectiveness follows from the reported information.
13. Why This Trial Matters Statistically
This study is statistically notable because it states a non-inferiority-style decision rule for a continuous physiological endpoint while reporting no outcome analysis. The distinction between an endpoint definition and an analyzed result is important. A protocol-level threshold alone cannot show whether the observed data met that threshold; the estimate and its uncertainty are needed.
The record also illustrates why a confidence bound matters in non-inferiority reasoning. In general, conclusions depend on the uncertainty around an estimate relative to the chosen margin, not just on whether a point estimate appears small. The registry specifies a 95% upper-bound criterion and a margin of 4 mm Hg, but provides no bound to evaluate. The statistical question is therefore identifiable, while the answer is not reported.
The single-group design and enrollment of 1 further constrain interpretation. A single-group before-and-after question differs from a controlled comparison, and a very small recorded enrollment cannot provide broad evidence about the distribution of outcomes or uncommon safety events. The posted adverse-event counts are descriptive entries rather than precise risk estimates.
Finally, the registry describes planning illustrations based on two-arm assumptions, while the trial itself is listed as single-group. That contrast is a useful reminder that hypothetical sample-size planning is not the same as the implemented design, and that a planning calculation is not observed power. Here, the numeric illustration outputs and the underlying observed effect are not reported in the registry record.
The statistical importance of the record lies in making these distinctions clear: planned criterion versus observed result, planning assumptions versus actual design, and recorded zero events versus evidence about broader risk. Those distinctions prevent missing analyses from being mistaken for a negative finding.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The principal limitation for interpreting this specific study is the absence of reported outcome analyses. The registry records 0 analyses and provides no observed mean change in ICP, standard deviation, confidence bound, or test result. Therefore, the stated primary endpoint criterion cannot be assessed. Results for the named secondary outcomes are also not reported in the registry record.
Enrollment is recorded as 1, and the study is listed as terminated. The reason for termination, whether the intended enrollment was achieved, and whether data collection was complete are not reported in the registry record. The available information does not establish why the study ended or whether termination affected outcome reporting.
The single-group model and allocation recorded as NA mean the study is not described as a randomized comparison. There is no separate comparator group in the registry record. The primary endpoint is specified over a short timeframe, within 5 minutes of catheter placement, so the record does not describe longer-term outcome measurement for that endpoint.
The arm description is incomplete, and the registry does not report a full statistical analysis plan, including the precise change convention, inferential procedure, analysis population, or missing-data approach. The record also does not explain how the primary and secondary outcomes would be handled for multiplicity. These omissions prevent detailed assessment of the intended analysis.
The adverse-event counts are based on 1 participant at risk, with 0 affected for serious and other adverse events and 0 deaths. The record does not provide event follow-up details or serious-event terms. These limited counts should not be generalized as a precise estimate of safety. The planning illustrations are described using two-arm assumptions, which do not match the registry’s single-group design; their numeric outputs are not reported in the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Safety of Optimal PEEP in NSICU Patients — NCT03862027.
- Registry record last updated 2021-04-27; status last verified 2020-09.
- Results first posted 2021-04-01.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
NCT03862027 is a terminated, single-group study titled “Safety of Optimal PEEP in NSICU Patients,” sponsored by University of North Carolina, Chapel Hill. The registry records enrollment of 1, allocation as NA, and no masking. The listed conditions are respiratory failure and intracranial hypertension.
The intervention was an esophageal balloon catheter. The primary outcome was change in ICP in mm Hg within 5 minutes of catheter placement. The registry states a non-inferiority criterion using a 95% upper bound and a margin of 4 mm Hg. Secondary outcomes were change in CPP and change in mean arterial pressure.
The registry reports 0 analyses and no outcome estimates. It records 0 serious adverse events among 1 at risk, 0 other adverse events among 1 at risk, and 0 deaths. The reason for termination, missing-data methods, analysis population, and outcome results are not reported in the registry record.