Clinical Effectiveness of the "PICU Up!" Multifaceted Early Mobility Intervention for Critically Ill Children: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Clinical Effectiveness of the "PICU Up!" Multifaceted Early Mobility Intervention for Critically Ill Children (NCT04989790), a randomized na study. The primary outcome is Days Alive and Ventilator-Free (AVF).

2. Clinical Question

The trial asks whether integrating PICU Up! into pediatric intensive care is associated with more days alive and free of invasive mechanical ventilation through Day 21 than usual PICU care. The primary outcome is days alive and ventilator-free, a continuous measure that combines survival and freedom from invasive ventilation over the stated period.

The clinical question concerns a care pathway rather than a single procedure or medication. PICU Up! is intended to support mobility by coordinating several aspects of daily care. The trial description explains the rationale for this approach: critically ill children may experience physical, cognitive, and psychological impairments, and immobility is one concern in intensive care. Those background statements do not establish whether the pathway changed the primary outcome in this trial.

The target population should not be assumed to consist exclusively of children receiving invasive ventilation at enrollment. The primary outcome concerns invasive ventilation, but detailed eligibility criteria and the analysis population are not reported in the registry record. The result therefore cannot be generalized from the record alone to a more narrowly defined patient group.

3. Trial Design

The study is identified as a pragmatic, stepped-wedge trial and as cluster randomized. Its registry model is listed as crossover. In general, a stepped-wedge cluster-randomized design introduces an intervention to groups of care units at different times, with units contributing information under usual care and after implementation. The record does not describe the clusters, the order or timing of implementation, or the unit of randomization in further detail, so those aspects cannot be reconstructed.

The intervention period is compared with baseline or pre-implementation usual PICU care. Because the intervention is integrated into routine practice, the comparison concerns implementation of a care pathway in a clinical setting rather than assignment of an isolated treatment to individual children. The registry record does not state how changes over calendar time, differences among units, or clustering of children within units were handled in the sponsor’s analysis.

The study is marked randomized and single masked. The identity of the masked party or parties is not reported in the registry record. In a care-pathway trial, the intervention is part of routine clinical practice; the masking label alone does not establish which assessments or analyses were masked.

Enrollment is recorded as 1470. The trial is listed as completed, with a start date of 2022-08-08 and a primary completion date of 2025-08-11. The sponsor is Johns Hopkins University. The phase is listed as not applicable. These administrative details describe the trial record, but they do not establish the number of children included in the primary analysis or the completeness of outcome follow-up.

The registry record lists secondary outcomes concerning days alive and delirium- and coma-free, days alive and coma-free, days alive, normal pediatric cerebral and overall performance categories at PICU discharge or Day 21, and functional status at patient discharge. The record does not provide statistical results for these outcomes. Since the design is cluster randomized, an individual-level recalculation that ignored the cluster structure would not be an appropriate substitute for the sponsor’s analysis.

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 Days Alive and Ventilator-Free (AVF), measured over Through Day 21.

The primary endpoint is mean days alive and ventilator-free through Day 21. It counts calendar days on which a participant is alive and free of invasive mechanical ventilation. A day qualifies when the endotracheal tube is absent for 24 continuous hours. For a participant with a tracheostomy, unassisted breathing counts as ventilator-free, whereas assisted ventilation does not.

This endpoint combines survival and respiratory support into a measure that can be summarized as a mean. It is used to describe the time participants spend alive without invasive ventilation during the stated follow-up window. A difference in the mean could reflect changes in survival, ventilation duration, or both; the endpoint alone does not distinguish those pathways. The registry record does not report additional rules for handling participants who die or for assigning their outcome values.

As general statistical context, a mean gives a concise summary of a continuous outcome, but it does not describe the full distribution. Participants can have different numbers of qualifying days, and the same mean can arise from different patterns of individual outcomes. A standard deviation describes how dispersed observations are around the mean; it is not a confidence interval and does not, by itself, express uncertainty about the estimated group mean.

The endpoint’s interpretation depends on how it was analyzed, including how the cluster-randomized design was incorporated. The analysis method, group summaries, treatment contrast, and uncertainty interval are not reported in the registry record. Consequently, the record defines what the primary outcome measures but does not show the magnitude or precision of the comparison.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical interpretation of this trial depends on features of its outcome and design. The registry record identifies a continuous primary measure, mean days alive and ventilator-free through Day 21, and describes a cluster-randomized, stepped-wedge trial. It does not report the sponsor’s analysis, the primary outcome estimate, or its uncertainty. The points below are general statistical context, not a description of unreported methods used in this trial.

What does a mean summarize?

A mean represents the average value of a continuous outcome across observations included in an analysis. For this endpoint, each participant’s qualifying days are summarized into a value, and group means can be compared. The mean is easy to interpret in the outcome’s units, but it can conceal variation in individual experiences. A group average does not imply that every participant had an outcome close to that average.

A standard deviation describes variation among observations around the mean. It differs from a confidence interval, which describes uncertainty around an estimated quantity under the statistical model. A confidence interval is useful for assessing both the range of effects reasonably compatible with the data and the precision of the estimate. Neither a standard deviation nor a confidence interval for this trial’s primary outcome is reported in the registry record.

Why does the cluster design matter?

In a cluster-randomized trial, allocation is made to groups or care units rather than independently to each participant. Outcomes among participants in the same cluster can be correlated because they share care practices, staff, and setting. As general statistical context, that correlation means the information in the data is not equivalent to what would be available if every participant were independent. An analysis that ignores clustering can understate uncertainty.

A stepped-wedge design also has a time structure: clusters move from usual care to the intervention at different points. General analyses may need to account for both the cluster structure and time-related changes, because outcomes can change over the course of a study for reasons apart from the intervention. The registry record does not report the number or identity of clusters, the schedule of implementation, or the model used to account for these features. It is therefore not possible to describe the sponsor’s approach or verify its assumptions from the record.

What does a confidence interval contribute?

As general statistical context, an effect estimate describes the observed contrast between groups or periods, while its confidence interval expresses uncertainty around that estimate under the chosen model. A narrow interval indicates greater precision than a wide interval, but interpretation also depends on the outcome and the range of effects that would matter clinically. A p-value addresses compatibility with a specified null hypothesis under model assumptions; it does not report the probability that the null hypothesis is true, nor does it measure the size or importance of an effect.

For this trial, the registry record does not report a treatment contrast, confidence interval, or p-value for the primary endpoint. It also does not report whether the analysis used a particular scale or adjustment. These quantities should not be inferred from the design description or enrollment.

How should planning illustrations be read?

The record describes a planning illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. The effect to detect is expressed as a stated fraction of the observed effect. Such a calculation illustrates the participants per arm for 80% power under those assumptions, and may also include another power target. It is not evidence about the trial’s observed effect, and it is not observed power. A planning calculation cannot replace a treatment-effect estimate or its confidence interval.

The record describes participants per arm for non-time-to-event illustrations and a total number of events for time-to-event illustrations. Those are planning conventions, not observed trial counts. Because the trial is cluster randomized, a simple individual-level recalculation would be misleading; the sponsor’s own analysis should take precedence if results and recalculations conflict. The registry record does not report a primary outcome analysis to assess in that way.

What is needed to assess the analysis?

Interpreting the primary result would require the reported group summaries or treatment contrast, the uncertainty interval, and a description of the model’s treatment of clustering and time. Information about analysis populations, missing outcomes, and any adjustments would also help readers understand the estimate. These details are not reported in the registry record. General statistical principles explain why they matter, but they cannot fill in the missing trial-specific results.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Baseline/Pre-implementation", "Intervention/Post-implementation")
n   <- c(752, 718)
m   <- c(10.5, 10.7)
sp  <- c(5.5, 5.6)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Baseline/Pre-implementation  752  10.500  5.500  10.106  10.894
CARM  Intervention/Post-implementation  718  10.700  5.600  10.290  11.110

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists several secondary outcomes in addition to days alive and ventilator-free through Day 21. They concern delirium and coma, survival, performance categories, and functional status. Considering multiple outcomes raises a general issue of multiplicity: when many hypotheses are examined, the chance of at least one apparently notable result can increase. Statistical plans may address this through a prespecified hierarchy, adjustment, or a clearly exploratory interpretation. The registry record does not report a multiplicity strategy or identify a hierarchy among outcomes.

The record does not provide results for the secondary outcomes, so their estimates and uncertainty cannot be interpreted. It also does not report whether analyses were prespecified, whether any were adjusted, or how any subgroup or sensitivity analyses were handled. Those details are not reported in the registry record.

Missing-data methods and analysis populations are also not reported in the registry record. The enrollment figure does not establish how many participants had primary outcome data, whether all randomized clusters or periods contributed, or how incomplete follow-up was addressed. As general statistical context, missing outcomes can affect both the number of observations informing an estimate and the assumptions required for interpretation. Readers need to know the extent and handling of missingness to assess possible bias.

The record’s completed status does not itself show that every participant had complete outcome data. Without an analysis population definition and missing-data description, the relationship between enrollment and the primary analysis remains unclear. The registry record therefore does not support a detailed assessment of multiplicity, missingness, or the population underlying any treatment estimate.

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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: accidental endotracheal tube dislodgement with hypoxic cardiac arrest (0.1%), accidental endotracheal tube dislodgement (0.1%).

The registry safety figures distinguish serious adverse events, other adverse events, and deaths by group. For usual PICU care, the record lists zero participants at risk and zero affected for serious and other adverse events, alongside 18 deaths. For PICU Up! post-implementation, it lists 718 participants at risk for each adverse-event category, 2 affected by serious adverse events, 39 affected by other adverse events, and 23 deaths.

The registry lists accidental endotracheal tube dislodgement with hypoxic cardiac arrest and accidental endotracheal tube dislodgement among the leading serious-event terms, each reported as 0.1%. These are registry-listed event terms; the record does not provide further detail about timing, relatedness, severity beyond the serious-event classification, or how events were attributed to the intervention.

Counts and percentages should not be treated as a causal comparison by themselves. The usual-care group’s recorded at-risk count is zero, so a direct comparison of event frequencies between the groups cannot be interpreted from these entries as if both groups had comparable reported denominators. The record also does not explain the zero at-risk count or provide a safety analysis method. Deaths are listed separately from adverse-event counts, and the registry does not state how those categories relate to one another.

These figures describe what the registry records; they do not establish that the intervention caused or prevented an event. A fuller safety assessment would require details on event definitions, follow-up, exposure, and the sponsor’s comparative analysis, which are not reported in the registry record.

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

The trial record defines a pragmatic comparison of usual PICU care with implementation of PICU Up!, a multifaceted pathway intended to support early and progressive mobility. It also specifies a primary outcome that combines survival and freedom from invasive mechanical ventilation through Day 21. These design details make the clinical question understandable, but they do not answer it.

The primary outcome result is not reported in the registry record. Without the group summaries or estimated contrast, it is not possible to state whether the observed mean was higher or lower during post-implementation care, how large any difference was, or how precisely it was estimated. A completed trial status and an enrollment of 1470 do not supply those missing results.

As general statistical context, evidence from a randomized design is interpreted through the estimated effect, its uncertainty, and the validity of the analysis for the design. In this trial, clustering and stepped-wedge timing are important features to account for. The record does not report the analysis model or its handling of these features. A simple recalculation that treats participants as independent would not be an appropriate replacement for the sponsor’s analysis.

The record’s safety entries also require caution. The two groups do not have comparable reported at-risk counts for adverse events, and the usual-care entry lists zero at risk. The listed event counts and terms therefore cannot by themselves establish a comparative safety effect or a causal relationship.

What can be said is limited to the trial’s stated purpose, design labels, endpoint definition, and recorded safety entries. What cannot be said from this registry record is whether PICU Up! increased or decreased days alive and ventilator-free, whether any effect was precise or statistically compatible with no difference, or whether a comparative safety difference occurred. Those conclusions require outcome analyses and context not reported in the registry record.

14. Why This Trial Matters Statistically

This trial addresses a statistical challenge common to evaluations of care pathways: the intervention is delivered within routine clinical practice, while the outcome is measured for individual children. PICU Up! is an interprofessional approach that integrates mobility with elements such as sedation goals, delirium prevention, sleep promotion, and family engagement. Evaluating such a pathway requires attention not only to the outcome definition but also to how implementation is organized across care units.

The registry identifies a cluster-randomized, stepped-wedge design. As general statistical context, cluster allocation and changes over time affect the independence and comparability of observations. A suitable analysis needs to reflect the design rather than treating every child as independently randomized. This is why an individual-level recalculation that ignores clustering can be misleading and why the sponsor’s design-aware analysis matters.

The primary endpoint also illustrates a useful measurement trade-off. Days alive and ventilator-free has a direct interpretation in days and includes survival alongside invasive ventilation status. At the same time, a mean can conceal different participant-level patterns, and the endpoint’s interpretation depends on the rules for death, ventilation, and incomplete follow-up. The registry defines some ventilation rules but does not report the analysis details needed to assess the result.

The record lists a completed study and a substantial enrollment, but does not report the primary estimate or uncertainty. This is statistically important: design information alone cannot show the direction, magnitude, or precision of an effect. A transparent result would need to connect the outcome definition to an analysis that respects clustering and timing, while explaining the analysis population and missing data.

The case therefore underscores the difference between a trial being completed and its findings being available for interpretation in the registry. The stated question is clinically meaningful, but the registry record does not provide the statistical result needed to answer it.

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 principal limitation for interpreting this trial from the registry record is that the primary outcome results are not reported. There is no group mean, estimated contrast, confidence interval, or p-value for days alive and ventilator-free through Day 21. The direction, magnitude, and precision of the primary comparison are therefore unknown from this record.

Design information is incomplete. The study is described as cluster randomized and stepped wedge, and its model is listed as crossover, but the registry record does not explain the clusters, the implementation schedule, or the statistical model. It also does not identify who was masked. These omissions limit assessment of how the design was carried through to analysis.

The enrollment figure does not identify the primary analysis population or establish outcome completeness. Eligibility details, missing-data methods, and the handling of death in the primary endpoint are not reported in the registry record. The record also does not report the sponsor’s statistical plan, multiplicity approach, or results for the listed secondary outcomes.

Safety entries have a further interpretive limitation: the usual-care group is recorded with zero participants at risk for adverse-event categories, while the PICU Up! post-implementation group has 718 at risk. The record does not explain this difference or provide a comparative safety analysis. The serious-event terms and deaths should therefore be read as registry entries rather than evidence of a causal effect.

Finally, details of participating sites, care-unit characteristics, and the extent of implementation are not reported in the registry record. Without those details and the trial’s analysis, readers cannot assess how closely the intervention was delivered as intended or how broadly the findings might apply.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Clinical Effectiveness of the "PICU Up!" Multifaceted Early Mobility Intervention for Critically Ill Children — NCT04989790.
• Registry record last updated 2026-10-01; status last verified 2026-09.
• Results first posted 2026-10-01.
• 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.

19. Record Summary

NCT04989790 is a completed, pragmatic, stepped-wedge trial of PICU Up!, a multifaceted pathway for early and progressive mobility in critically ill children. The registry identifies the study as cluster randomized and lists a crossover model. Usual PICU care is the comparator.

The primary outcome is mean days alive and ventilator-free through Day 21, with specified rules for invasive ventilation and tracheostomy breathing. Enrollment is recorded as 1470. The sponsor is Johns Hopkins University; the recorded start date is 2022-08-08 and the primary completion date is 2025-08-11.

The registry lists secondary outcomes relating to delirium, coma, survival, performance categories, and functional status, along with adverse-event and death entries. It does not report the primary outcome estimate, the sponsor’s statistical analysis, or the analysis details needed to assess missing data and multiplicity. The direction and precision of the primary comparison are not reported in the registry record.