Anxiety Self-Management for ICU Patients Receiving Mechanical Ventilation: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Anxiety Self-Management for ICU Patients Receiving Mechanical Ventilation (NCT00440700), a randomized phase 2 study. The primary outcome is Sedative Exposure.

2. Clinical Question

The study therefore concerns a self-management approach that patients could use as desired, compared both with a sound-blocking option and with usual care. These comparisons address different possibilities: whether the music component is associated with a different pattern than usual care, and whether access to headphones without music has a different pattern. The registry record does not report a single prespecified contrast or a hierarchy among these pairwise questions. Its primary endpoint summaries should not be read as establishing whether any group difference is statistically distinguishable from chance.

3. Trial Design

This was a randomized, open-label, parallel-group phase 2 study sponsored by the University of Minnesota. The registry lists an enrollment of 364 and three behavioral intervention groups: patient-directed music, noise-cancelling headphones, and usual care. The study began in 2006-07, reached primary completion in 2011-06, and is listed as completed. Masking is listed as none, so the registry does not describe blinded treatment assignment or outcome assessment.

In the music group, participants chose music and could listen whenever they wished and for as long as they wished. In the headphones group, participants could use noise-cancelling headphones without music to block ICU noise. Usual care included ICU care and encouragement to self-initiate rest periods twice daily. The registry does not report the allocation ratio, the randomization procedure, concealment of assignment, or how adherence to the assigned approach was assessed.

The primary outcome was measured daily up to 30 days. Its analysis population was limited to participants with 2 or more days of study-enrollment data. The secondary outcomes listed were length of ICU stay, length of mechanical ventilatory support, and urinary cortisol. Their stated assessment periods differ, and the registry does not report a common analysis population across them. For the posted length-of-stay summaries, group counts are given separately for each endpoint.

The record does not report detailed eligibility criteria, the actual protocol, a sample-size justification, or whether interim analyses were planned or conducted. These omissions limit what can be said about the design choices and how closely the reported analyses followed a prespecified plan. The randomized parallel structure supports comparisons between assigned groups, but the absence of masking and the registry’s limited reporting of allocation and analysis details matter when interpreting the results.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Participants with 2 or more days of study enrollment data were included in the analysis for this aim.

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 Sedative Exposure, measured over Daily up to 30 days.

The primary endpoint, titled sedative exposure, was assessed daily up to 30 days and reported as a median with a full range. The registry describes two components: the number of sedative medication doses administered in a 4-hour period each day, and an aggregate sedation-intensity score based on sedative medications administered during a 4-hour period. The score was calculated for each study group on each protocol day. Participants who received no sedation had a score of zero for that day. Higher intensity scores indicate more sedative exposure.

These measures are intended to characterize sedative use over time in mechanically ventilated ICU patients. Dose frequency describes how often sedative doses were administered, while the intensity score summarizes medication exposure using the registry’s stated scoring approach. Daily measurement can describe changes across the study period, but it also raises analytic questions about how observations from the same participant are handled. The registry record does not report the statistical method used for that purpose.

A median gives the middle of the observed values and is less affected by extreme observations than a mean. A full range reports the lowest and highest observed values; it is not a confidence interval and does not quantify uncertainty in the estimated median. The posted primary summaries therefore show the distributions’ central values and endpoints, but do not by themselves establish the precision of a between-group difference. A primary-outcome comparison or confidence interval is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The study randomized participants to a parallel-group assignment, but the registry record does not describe the randomization sequence, allocation concealment, or masking beyond listing masking as none. These details affect the assessment of bias and the ability to evaluate whether group comparisons preserve the benefits of randomization. The record also does not report a prespecified statistical analysis plan. Accordingly, the methods explanation must distinguish the posted descriptive summaries, the sponsor-reported analysis, and simple unadjusted recalculations.

What does a median and full range convey?

For the primary endpoint, each arm is summarized by a median and full range. A median describes the central observation in an ordered set of values. The full range gives the observed minimum and maximum, but it does not show how values are distributed between those endpoints. Unlike a confidence interval, a range is not an estimate of uncertainty around the median. Because the primary endpoint is reported in this form, it should not be interpreted as a mean difference or as a treatment-effect estimate with known precision.

The primary endpoint description includes daily observations and a score calculated for each group on each protocol day. Repeated observations from a participant are generally correlated: values from the same person may be more alike than values from different people. General statistical practice accounts for this dependence when estimating uncertainty. The registry record does not report whether or how this issue was handled, and it does not report the model or test used for the primary outcome.

How should the secondary confidence intervals be read?

The posted recalculations for the continuous secondary outcomes use unadjusted mean differences and confidence intervals. A mean difference expresses the estimated difference between group means on the outcome’s original scale. A confidence interval gives a range of values compatible with the observed data under the method’s assumptions. If the interval includes zero, the data remain compatible with no mean difference as well as with differences in either direction. This does not prove equality between groups, and it does not establish that any possible difference is clinically important.

The recalculated p-values are unadjusted. They assess compatibility with a null hypothesis under the specified calculation, but do not communicate the magnitude or practical importance of an effect. The registry separately reports a Kruskal-Wallis analysis for the patient-directed music and usual-care groups on mechanical ventilatory support. This is a rank-based method, rather than the mean-difference calculation used for the unadjusted recalculation. The methods and estimands differ, so the results should be kept distinct. The registry record does not provide further detail about the reported test, such as its analysis population or adjustments.

Why can over-dispersion matter?

General statistical explanation: over-dispersion occurs when observed variation is greater than a statistical model expects. It can make standard errors too small if the model assumes less variability than the data contain, which can make confidence intervals too narrow and p-values too small. This is a relevant general consideration for outcomes that are skewed, count-like, or measured repeatedly. The primary outcome combines daily medication-dose frequency and an intensity score, but the registry record does not report a model or diagnostic assessment, so it is not possible to determine whether over-dispersion was present or how it was addressed.

What do the planning illustrations mean?

The planning illustrations use observed secondary-outcome effects as inputs. They describe participants per arm for 80% power and participants per arm for 90% power under the stated assumptions: a two-sided significance level of 0.05, equal allocation, a normal approximation, and effects set to a stated fraction of the observed effect. These are planning illustrations, not observed power and not evidence that the trial was designed to detect those effects. They are also not the trial’s own sample-size justification; that justification is not reported in the registry record.

Planning calculations based on an observed effect are sensitive to the uncertainty and size of that estimate. A small or noisy observed effect can yield very large illustrative sample sizes, while an unstable estimate can make a planning target unreliable. The illustrations are best treated as conditional scenarios rather than as a statement about what sample size would guarantee a meaningful result. They also do not resolve the unreported choices about multiplicity, the primary endpoint analysis, or the analysis population.

How do multiple outcomes affect interpretation?

General statistical explanation: when many outcomes or group comparisons are examined, the chance of at least one apparently unusual result can increase. A multiplicity procedure can control that risk, but the registry record does not report a correction or a prespecified hierarchy for the listed outcomes and comparisons. Thus, secondary p-values should be treated as unadjusted findings and not as though they were the sole confirmatory test. This caution applies even when an individual result crosses a conventional threshold, because the full set of analyses informs how surprising that result is.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary outcome and several secondary outcomes, with analyses that include comparisons of each active group against usual care. It does not report a multiplicity adjustment, a prespecified order of testing, or a hierarchy that would identify which secondary comparisons were intended to be confirmatory. When multiple outcomes and contrasts are examined, the probability of at least one chance finding can rise. Without a stated adjustment or testing strategy, unadjusted secondary p-values should not be read as if they were the sole planned test.

The record reports an analysis population for the primary aim: participants with 2 or more days of study-enrollment data. It does not report how many randomized participants were excluded from that analysis, why any data were missing, or whether missingness differed by group. The detailed missing-data methods—including imputation, censoring rules where relevant, and sensitivity analyses—are not reported in the registry record. It is also not reported whether the secondary analyses used the same analysis population as the primary endpoint.

The registry does not state whether analyses followed intention-to-treat principles, whether participants were analyzed according to randomized assignment, or whether any per-protocol analyses were conducted. It does not report the handling of protocol deviations or incomplete follow-up. These omissions make it difficult to assess the potential effect of missing observations and exclusions on the results.

The primary outcome is described as daily through the stated assessment period, but the registry record does not specify a statistical model for those repeated measurements or whether all days contributed to the reported group summaries. The reported medians and ranges alone cannot show how incomplete daily records were handled. A full analysis plan and participant flow would be needed to evaluate these issues; they are not reported in the registry record.

11. 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 1% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: self-extubation (4.2%), seizure activity (0.8%), cardiac arrest (0.8%).

The registry reports serious adverse events for each group using the number at risk and the number affected. The serious-event counts are 5 among 122 for patient-directed music, 5 among 118 for headphones, and 7 among 124 for usual care. These figures describe the registry’s reported group counts; they do not, on their own, establish whether an event was caused by an intervention or whether groups differ statistically. The registry lists self-extubation at 4.2%, seizure activity at 0.8%, and cardiac arrest at 0.8% among the most frequent serious-event terms.

Other adverse events are reported as 0 among 122 for patient-directed music, 1 among 118 for headphones, and 1 among 124 for usual care. The registry record does not report deaths in the adverse-event data. These counts should be interpreted in light of the study’s clinical setting and the fact that the record does not provide event-level timing, severity details beyond the serious-event classification, or a causal assessment. The figures are descriptive safety reporting, not a comparison that establishes the relative safety of the groups.

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

The posted results describe a randomized comparison of patient-directed music, noise-cancelling headphones, and usual care among mechanically ventilated ICU patients. For the primary sedative-exposure outcome, the registry reports group medians and full ranges. These summaries show what was recorded in the primary analysis population, but the record does not provide an inferential comparison, confidence interval, or p-value for the primary endpoint. They therefore do not establish the precision of between-group differences.

The secondary results add context but are not a substitute for a primary-outcome analysis. The posted recalculations are unadjusted, and the registry does not report a multiplicity strategy. A separate sponsor-reported analysis for ventilatory-support duration uses a different method from the mean-difference recalculation. These distinctions matter: different statistical methods can target different features of the data, and their results should be described separately rather than treated as interchangeable.

The results do not establish that music, headphones, or usual care caused a particular outcome. Randomization supports group comparisons when analyzed appropriately, but the registry’s limited reporting on allocation, missing data, analysis populations, and statistical methods restricts the conclusions that can be drawn. Descriptive group differences are not proof of an effect, and an unadjusted p-value is not a measure of clinical importance.

The record also does not report numerical urinary-cortisol results, detailed participant characteristics, or a full account of missing observations. Those gaps prevent a complete evaluation of the outcomes and the population represented in each analysis. The evidence should therefore be understood as the results posted in the registry, with uncertainty and reporting limitations kept explicit, rather than as a definitive answer about the intervention’s effects.

13. Why This Trial Matters Statistically

This trial raises several statistical issues that are common in clinical research. The primary outcome is measured daily and summarized with medians and ranges, while the secondary outcomes include means, standard errors, and a separately reported rank-based analysis. Each summary has a different interpretation. Medians and ranges describe observed values, mean differences quantify contrasts on the original scale, and rank-based tests assess group distributions through ranks. Results from these methods should not be treated as if they estimate the same quantity.

The primary outcome’s repeated daily measurement makes the missing analysis method especially important. General statistical practice needs to account for the relationship between repeated observations from the same participant. The registry does not report how this was done, or whether the primary summary reflects all observed days or a particular aggregation. This highlights why reporting the estimand, analysis model, and handling of incomplete records is central to interpreting longitudinal outcomes.

The study also illustrates the distinction between a descriptive result and an inferential one. A difference between posted group medians can be described, but without an uncertainty estimate or test it cannot show how precisely the group contrast is known. The secondary analyses do include recalculated uncertainty estimates, yet these are unadjusted and sit alongside a different sponsor-reported test. Understanding which analyses were prespecified and how multiplicity was handled would help readers assess the strength of the evidence.

Finally, planning illustrations derived from observed effects are useful only as conditional scenarios. They are not observed power and do not reveal the original design rationale. The registry record does not report the study’s sample-size justification or full statistical plan. These reporting gaps make transparent analysis methods and complete outcome reporting particularly important for evaluating this study.

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.

Several limitations specific to this record affect interpretation. The primary endpoint has descriptive medians and full ranges, but no inferential comparison or confidence interval is reported. As a result, readers cannot assess the precision of differences among the groups from the primary results. The outcome combines a daily dose-frequency measure and an aggregate intensity score, while the posted arm summaries do not clarify how those components relate to the reported unit or how repeated daily observations were combined for comparison.

The registry does not report the randomization procedure, allocation concealment, participant flow, detailed eligibility criteria, or group characteristics. Masking is listed as none, and the behavioral interventions differ in whether participants received music, headphones alone, or usual care. The registry does not report adherence or exposure to the assigned approach, making it difficult to understand how closely the groups experienced their intended interventions.

Missing-data methods and analysis populations for the secondary outcomes are not reported. The primary population includes participants with 2 or more days of enrollment data, but the record does not describe exclusions, missingness, or sensitivity analyses. The statistical plan, sample-size justification, and any interim analyses are also not reported in the registry record.

Interpretation of secondary outcomes is limited by unadjusted recalculations, multiple outcomes and comparisons, and the presence of a separately reported analysis using a different method. Numerical urinary-cortisol results are not reported. Adverse-event counts are descriptive, with limited detail on timing and causal attribution. Together, these limitations mean the posted record supports cautious description rather than strong claims about comparative effects.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Anxiety Self-Management for ICU Patients Receiving Mechanical Ventilation — NCT00440700.
• Registry record last updated 2013-04-26; status last verified 2013-04.
• Results first posted 2013-04-26.
• 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.

18. Record Summary

The registry record identifies NCT00440700, titled “Anxiety Self-Management for ICU Patients Receiving Mechanical Ventilation,” with the official title “Reducing Sedative Exposure in Ventilated ICU Patients.” It is a completed, randomized, open-label, parallel-group phase 2 study sponsored by the University of Minnesota. The listed enrollment is 364; the study began in 2006-07 and reached primary completion in 2011-06.

The study compared patient-directed relaxing music, noise-cancelling headphones without music, and usual care. Its primary outcome was sedative exposure, measured daily up to 30 days and reported as medians and full ranges. Secondary outcomes were length of ICU stay, length of mechanical ventilatory support, and urinary cortisol. The primary inferential comparison, detailed missing-data methods, multiplicity strategy, and sample-size justification are not reported in the registry record. The posted evidence is therefore best interpreted with attention to the distinction between descriptive primary summaries, unadjusted secondary recalculations, and the separately reported sponsor analysis.