Study of Sedative Medications in Patients With Severe Infection and Respiratory Failure: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study of Sedative Medications in Patients With Severe Infection and Respiratory Failure (NCT02203019), a randomized phase 4 study. The primary outcome is Duration of Mechanical Ventilation.

2. Clinical Question

The clinical question is about comparative sedation strategies in a specific intensive-care setting, not about either drug in isolation. The trial enrolled 36 participants, with 19 in the propofol group and 17 in the dexmedetomidine group. Its primary outcome is a duration measure, so the reported summaries describe the center and spread of observed ventilation times rather than an average difference. The registry lists a Wilcoxon (Mann-Whitney) analysis and gives a p value, but does not report a numerical estimate of the between-group difference or a confidence interval for it. That leaves the direction and possible magnitude of the group contrast less fully quantified than the group medians alone might suggest.

3. Trial Design

This was a Phase 4, randomized, parallel-group trial with no masking, listed as completed. The registry reports enrollment of 36 participants. The posted outcome groups include 19 participants assigned to propofol and 17 assigned to dexmedetomidine. The study was sponsored by Texas Tech University Health Sciences Center. The registry gives a study start of 2014-08 and a primary completion date of 2016-09-22.

The comparison concerns two sedatives used in mechanically ventilated patients with sepsis. The brief summary explains that mechanical ventilation requires a breathing tube, which can be uncomfortable, and describes sedation as part of routine care in this setting. It says the study aimed to determine whether one of the two drugs was associated with coming off the breathing machine faster. There was no placebo group, and the registry describes both drugs as approved medications rather than experimental drugs.

Random allocation supports a comparison between the assigned groups, but randomization does not guarantee that groups will be balanced on every characteristic, especially in a small trial. The registry does not report the allocation sequence method, allocation concealment, masking of outcome assessment, or further details of the randomization process. It also does not report the protocol's inclusion and exclusion criteria, the sedation targets, or the exact rules for starting, adjusting, or stopping study medication. These details matter when interpreting how consistently the assigned strategies were implemented.

The record lists fentanyl as an intervention as well as the two sedatives, but provides arm descriptions only for propofol and dexmedetomidine. The role of fentanyl in the study is not reported in the registry record. Further details about co-interventions, adherence to assigned sedation, and treatment switching are also not reported in the registry record. The design therefore establishes the intended comparison, but the available record leaves important implementation details unresolved.

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 Duration of Mechanical Ventilation, measured over Up to 28 days.

The primary endpoint is duration of mechanical ventilation, defined in the registry as the number of days a patient requires mechanical ventilation. The timeframe is up to 28 days. This outcome is relevant to the study question because the registry's stated aim is to compare whether patients assigned to one sedative come off the breathing machine faster than patients assigned to the other.

The posted results summarize duration using a median and an inter-quartile range. The median gives the middle of the observed distribution, while the inter-quartile range describes the span from the lower to the upper quartile. These summaries are often useful for duration data because the distribution may be uneven or contain some substantially longer stays. The record does not report the full outcome distribution, so readers cannot assess its shape directly from the summary values alone.

For propofol, the posted median is 5 days, with an inter-quartile range of 3 to 13 days. For dexmedetomidine, the median is 3 days, with an inter-quartile range of 2.75 to 5.75 days. The displayed group summaries are descriptive: they do not by themselves establish the size or precision of a treatment contrast. The registry reports a Wilcoxon (Mann-Whitney) test, but does not provide a confidence interval or an estimated difference for the primary comparison. The definition of how ventilation duration was handled for participants who died or remained ventilated at the end of the timeframe is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical methods help answer two different questions: how the groups' observed ventilation durations are summarized, and how the registry tested whether the outcome distributions differed. The results are based on a small randomized comparison, so interpretation should pay attention to both the kind of estimate reported and the uncertainty around it. A statistical test result alone is not a complete description of the clinical contrast.

Why report a median and inter-quartile range?

A median is the middle point of an ordered set of observations. Unlike a mean, it is not pulled as strongly by a small number of unusually long durations. An inter-quartile range describes the central portion of the distribution, extending from the lower quartile to the upper quartile. These summaries can be useful when duration values are skewed, as may occur when some patients have much longer ventilation than others.

For this trial, the median and inter-quartile range are posted separately for the propofol and dexmedetomidine groups. They show the observed center and spread, but they do not directly quantify uncertainty in the difference between groups. Two group summaries can look different while the estimated treatment contrast remains imprecise. A confidence interval for a suitable between-group effect would help show the range of effects compatible with the data; one is not reported for the primary outcome.

What does the Wilcoxon (Mann-Whitney) test assess?

The registry identifies a Wilcoxon (Mann-Whitney) test for the primary outcome. In general, this is a rank-based method: observations from both groups are ordered, and the test assesses whether values from one group tend to rank higher or lower than those from the other. It does not automatically test only whether the medians are equal. Interpreting it as a test of a median difference requires additional assumptions about the shapes of the group distributions.

The test can be useful when a normal-distribution model for the raw values is not suitable. However, its p value does not express the size of a difference, and it does not provide an interval estimate unless an effect estimator and interval procedure are also reported. The registry does not provide the exact test statistic, the distribution of individual observations, or an interval estimate for this primary comparison.

How should the p value be read?

A p value summarizes how unusual the observed test result, or a more extreme result, would be under a specified null model and the assumptions of the test. It is not the probability that the treatments are the same, and it does not measure the clinical importance of an observed contrast. The primary p value is 0.107. That result does not cross a conventional 0.05 significance threshold, but it also does not establish equivalence or rule out a meaningful difference.

The registry labels the primary analysis as equivalence. In general, an equivalence analysis requires a prespecified range of differences considered acceptably small. The analysis then needs to show that the uncertainty around the treatment contrast is contained within that range. The equivalence margin, the confidence interval, and the statistical decision rule are not reported in the registry record. Without those details, the label alone is insufficient to establish an equivalence result.

Why is an effect estimate with an interval useful?

A confidence interval pairs an estimate with a range that reflects its statistical uncertainty under a specified method. It can help distinguish a precise estimate near no difference from an imprecise estimate that remains compatible with a broad range of effects. For this primary outcome, no treatment-effect estimate or confidence interval is posted. Readers therefore cannot use the primary result to assess the numerical precision of the between-group contrast directly.

The calculated tables and plots on this page display the posted values and analyses in accessible form. They do not recover unreported participant-level information or resolve missing analysis details. In particular, the group summaries should not be treated as if they were a confidence interval for the treatment effect.

What are the limits of a small trial?

With relatively few participants, estimates can be sensitive to the outcomes of individual participants, and chance differences between groups may remain despite randomization. Small samples often produce wide uncertainty, although the width of an interval depends on the outcome distribution and analysis method as well as sample size. The registry does not report a primary confidence interval with which to quantify that uncertainty.

Planning illustrations can show how much larger a future study might need to be under stated assumptions and for selected target effects. Such calculations are planning tools, not evidence that the current trial had a particular level of power, and not a measure of the probability that the observed result is correct. The sample-size illustrations on this page are based on an observed effect and should be interpreted only as planning scenarios. The trial's own sample-size justification and assumptions are not reported in the registry record.

What should be considered for duration outcomes?

Duration endpoints can be affected by events that change whether or how long an outcome is observed. Death, discharge, and reaching a study endpoint can complicate the interpretation of time spent on mechanical ventilation. In general, an analysis may need to define how such events are handled and whether the outcome is analyzed as a duration, a time-to-event measure, or another summary. The registry defines the primary measure as days requiring ventilation, but the handling of death and other events in the primary analysis is not reported in the registry record.

The record also does not report missing-data procedures, analysis populations, or whether the primary analysis followed randomized assignment regardless of treatment received. These omissions make it difficult to evaluate the robustness of the result or reproduce the analysis from the registry summary alone.

10. Analyses Reported by the Sponsor

The registry reports the sponsor's primary analysis as a Wilcoxon (Mann-Whitney) test, with p = 0.107. It does not provide a primary effect estimate or confidence interval. The displayed group medians and inter-quartile ranges are summaries, not recalculated estimates of the treatment contrast. Accordingly, there is no posted recalculated primary effect estimate to compare numerically with the sponsor's test result.

For the primary outcome, the registry labels the analysis as equivalence. That label should be read alongside the information actually reported: the equivalence margin, confidence interval, and decision rule are not reported in the registry record. Without those elements, the p value alone cannot demonstrate equivalence. It also cannot establish that the groups differ.

For mortality, the registry reports a Chi-squared analysis with p = 0.739. The posted unadjusted recalculation has p = 0.516. These are distinct reported and recalculated analyses; the record does not explain the difference in their results or provide enough detail to identify its cause. The discrepancy flag is not set for this record, but that does not make the two p values interchangeable. The reported sponsor analysis and the unadjusted recalculation should be kept distinct, with their methods and scope understood rather than treated as if they were the same calculation.

More generally, recalculations from posted summary statistics cannot reproduce analyses that depend on participant-level data, covariate adjustment, or details not present in the registry. For the mortality comparison, the recalculation is explicitly unadjusted. For the primary outcome, no recalculated treatment-effect estimate is available in the posted results.

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary outcome and several secondary outcomes, but does not report how the inferential questions were prioritized or whether a multiplicity strategy was used. When a study examines multiple outcomes, tests, or time points, the chance of at least one apparently unusual result can increase even if there is no underlying effect. In general, prespecifying a primary question, ordering secondary questions, or adjusting inference can help control how strongly results are interpreted. Whether any such approach was used is not reported in the registry record.

The record gives a timeframe of up to 28 days for the primary ventilation outcome and mortality. Details about other time points, interim analyses, or any repeated looks at accumulating data are not reported in the registry record. Interim analyses and stopping rules should not be inferred from the fact that the study is completed.

Missing-data methods are also not reported in the registry record. The available summaries do not state whether all randomized participants contributed to each outcome, how unavailable outcome values were handled, or whether any imputation was used. The record does not describe an intention-to-treat, per-protocol, or other analysis population. These are important details because exclusions or missing outcome information can affect what a comparison represents.

For a duration outcome, the registry does not explain how deaths, withdrawal, discharge, or ongoing ventilation at the end of the timeframe were handled in the primary analysis. Such events can affect the interpretation of ventilation duration, and different analysis choices can answer different questions. The mortality outcome is reported separately, but that does not reveal how mortality was incorporated into the ventilation analysis.

The record also does not provide the protocol's sample-size justification, the planned effect size, or the assumptions used in the original design. The planning illustrations elsewhere on this page are not a substitute for that information. They use an observed effect for illustrative planning scenarios and should not be read as observed power or as evidence of the original design's rationale.

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.

The safety summary reports zero serious adverse events and zero other adverse events in both posted groups. It also reports 8 deaths in the propofol group and 9 in the dexmedetomidine group. These are separate registry summaries: the death counts should not be treated as counts of serious adverse events unless the record says they are, and the record does not provide that link.

These figures are descriptive counts in groups of 19 and 17 participants. With a small study, the absence of reported adverse events does not establish that an event cannot occur, and the counts alone do not provide a precise comparison of safety. The registry does not provide details about how adverse events were defined, collected, graded, or attributed to treatment, nor does it report a safety analysis plan in the information.

The death counts are important to note as part of the clinical context, but the registry's summary does not explain causes of death, timing, or how deaths were handled in the primary ventilation analysis. Those details are not reported in the registry record. These safety figures should therefore be read as posted event counts, not as evidence that either sedation strategy is safer or less safe.

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

The results describe a randomized comparison of propofol and dexmedetomidine for sedation in mechanically ventilated patients with sepsis. The posted primary summaries show different observed medians for duration of mechanical ventilation, and the registry reports a Wilcoxon (Mann-Whitney) p value of 0.107. Taken together, these results do not establish that one sedative leads to a shorter ventilation duration, and they do not establish equivalence.

Those statements are not the same as concluding that the treatments have no difference. A nonsignificant p value can arise when a true difference is small, when the data are variable, or when a study cannot estimate the contrast precisely. The registry does not provide a confidence interval for the primary contrast, so readers cannot assess the range of treatment effects compatible with that analysis. The equivalence label does not solve this problem because the margin and corresponding interval are not reported.

The sample consisted of 36 participants, and the posted groups were small. Randomization is valuable for reducing systematic differences at assignment, but a small randomized study can still leave substantial uncertainty. The trial also provides limited information in the registry about eligibility criteria, treatment implementation, missing data, and analysis populations. These gaps constrain how confidently the results can be generalized or independently evaluated.

The mortality result is a secondary finding and should be interpreted separately from ventilation duration. The record also names duration of MICU stay and duration of vasopressor support, but detailed results for those outcomes are not reported in the registry record. The available data therefore do not provide a complete account of all intended secondary outcomes.

In general, a trial result is most informative when it includes an effect estimate, a measure of uncertainty, clear outcome definitions, and transparent analysis methods. Here, the posted primary summaries and test provide some information about observed ventilation durations, but not a precise estimate of the treatment contrast. The evidence is limited to this small trial and should not be stretched into a broader statement about all patients, care settings, or sedation strategies.

14. Why This Trial Matters Statistically

This trial illustrates why statistical interpretation should go beyond comparing two medians or deciding whether a p value crosses a familiar threshold. The posted group medians differ, but the registry does not report a primary effect estimate with a confidence interval. Without that estimate and its uncertainty, readers cannot tell how large a treatment contrast is compatible with the primary analysis or how precisely it is measured.

It also highlights an important distinction between a test that fails to show a difference and a formal finding of equivalence. Equivalence requires a defined margin and an analysis that rules out differences larger than that margin. The registry labels the primary analysis as equivalence, yet the margin and interval needed to evaluate that claim are not reported. This is a useful reminder that a label or p value should be interpreted in the context of the complete analysis plan.

Duration outcomes raise additional design and analysis questions. In general, the meaning of ventilation duration depends on how events such as death or continued ventilation at the end of follow-up are handled. Those rules are not reported in the registry record. Transparent definitions are essential for understanding what a duration comparison represents.

The trial also demonstrates the limits of small studies and of registry summaries. Randomization helps structure a fair comparison, but small groups can yield uncertain estimates. Detailed protocols, participant-level data, and complete reporting of analysis populations and missing-data procedures would be needed to assess robustness more fully. The secondary results also show why multiplicity matters: findings across several outcomes need to be interpreted in light of whether questions were prioritized or adjusted.

For researchers, this record is a case study in reading results with discipline: separate descriptive summaries from treatment-effect estimates, distinguish nonsignificance from equivalence, and treat secondary tests as supplementary when multiplicity handling is unclear. The key statistical lesson is not a claim for either sedative, but the importance of reporting effect sizes, uncertainty, and analysis decisions clearly.

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 several limitations for interpreting this specific trial. It reports group medians and inter-quartile ranges for the primary endpoint but does not provide a numerical between-group effect estimate or confidence interval. The primary p value is available, but it does not quantify the size or precision of the contrast.

The primary analysis is labeled as equivalence, yet the equivalence margin, confidence interval, and decision rule are not reported in the registry record. This prevents an independent assessment of whether the analysis supports equivalence. The record also does not report the protocol's sample-size justification, planned treatment effect, or original design assumptions.

Important details about trial conduct are not reported in the registry record, including eligibility criteria, the randomization procedure, allocation concealment, outcome-assessment masking, sedation targets, treatment adherence, and the role of fentanyl. The record states that the study was unmasked, but does not specify whether outcome assessors were masked. Without these details, readers cannot fully assess implementation or potential sources of bias.

Analysis populations and missing-data procedures are not reported in the registry record. Nor does the primary outcome description explain how deaths, withdrawals, or participants still receiving ventilation at the end of the timeframe were handled. These omissions matter for interpreting a duration endpoint. The record does not provide the individual outcome distribution or enough information to reproduce the primary analysis.

For secondary outcomes, the registry names duration of MICU stay and duration of vasopressor support, but their detailed results are not reported in the registry record. The multiplicity plan is also not reported. The death and adverse-event summaries are counts without additional definitions, timing, or attribution details. Finally, the small enrollment limits the amount of information available, and the registry summaries alone cannot establish how generalizable the findings are beyond this study population.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Study of Sedative Medications in Patients With Severe Infection and Respiratory Failure — NCT02203019.
• Registry record last updated 2020-03-02; status last verified 2020-02.
• Results first posted 2020-03-02.
• 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 describes a completed, Phase 4 randomized parallel-group trial without masking, comparing propofol and dexmedetomidine for sedation in mechanically ventilated patients with sepsis. Enrollment was 36, with 19 participants in the propofol group and 17 in the dexmedetomidine group. The primary outcome was duration of mechanical ventilation, measured in days over a timeframe of up to 28 days.

The posted primary summaries report a median of 5 days for propofol and 3 days for dexmedetomidine, with a Wilcoxon (Mann-Whitney) p value of 0.107. The registry labels the analysis as equivalence, but does not report the margin or a confidence interval. The result therefore does not establish equivalence or a definitive treatment difference.

The record also lists secondary outcomes and posts mortality and adverse-event summaries. Further details on the analysis plan, missing data, and the other named secondary outcomes are not reported in the registry record.