Telemedicine Control Tower for the Post-Anesthesia Care Unit: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Telemedicine Control Tower for the Post-Anesthesia Care Unit (NCT04020887), a non-randomized na study. The primary outcome is Difference in Time to PACU Discharge Determination From Observation to Interaction Phase.

2. Clinical Question

This is a question about a change in workflow and the timing of a clinical determination, rather than a randomized test of patient outcomes. The registry also lists goals involving recognition of physiological derangements, symptoms requiring treatment, emergency situations, and discharge readiness. These goals describe the intended scope of the telemedicine evaluation; they do not establish that any particular improvement occurred. The posted results do not give the primary comparison’s magnitude, uncertainty, or statistical test, so the direction and precision of the endpoint result cannot be assessed from the registry record.

3. Trial Design

The registry describes a prospective, single-center, before-and-after proof-of-concept study evaluating a telemedicine center for the PACU. Its allocation is non-randomized and its model is sequential. The study was marked completed. The recorded start date is 2020-03-01, and the primary completion date is 2021-12-06. The recorded enrollment is 560.

The study proceeded in phases rather than assigning participants at random to concurrent groups. In the observation phase, described as the first three months, telemedicine-center clinicians monitored patients assigned to PACU bays. Both those clinicians and the nurses caring for patients in those bays independently recorded information on physiological derangements. In the interaction phase, described as the three months following the observation phase, telemedicine-center clinicians interacted with clinicians and patients in two designated PACU bays using audio-visual technology. They continued to document physiological derangements.

This structure is important to interpreting the comparison. Because the phases occurred sequentially, the observation phase is not a like-for-like randomized control group. Any difference between phases could reflect the interaction approach, but it could also reflect changes over time or differences in the patients and care circumstances in each phase. Such possibilities are general concerns with before-and-after comparisons; the record does not report analyses that would separate them.

The registry lists a device intervention called Alertwatch - Interaction and records the study phase as not applicable. It characterizes the study as observational in its official title and as a proof-of-concept evaluation in its summary. The record does not report the detailed eligibility criteria, the process for assigning patients to bays or phases, or the operational rules for starting or ending observation. It also does not describe a concurrent control group. The study’s design can inform feasibility and workflow questions, but the registry record alone does not establish a causal effect of telemedicine interaction.

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 Difference in Time to PACU Discharge Determination From Observation to Interaction Phase, measured over up to 1 day.

The primary endpoint is the difference in time to PACU discharge determination between the observation phase and the interaction phase. It concerns the time at which discharge readiness is determined, rather than the time a patient physically leaves the PACU. The unit is minutes, and the registry specifies that the measure is a median with an inter-quartile range. The stated timeframe is up to 1 day.

Time to a readiness determination can describe how quickly a care team reaches a decision in the PACU workflow. A median is a measure of the center of a distribution, while the inter-quartile range describes its middle spread. These summaries can be useful when times are unevenly distributed or include unusually long waits; they do not, by themselves, explain why the times differ. A comparison of medians also does not show whether every patient experienced a similar change.

The registry’s endpoint description says that discharge readiness time between the phases would be compared. It does not report the median for either phase, the inter-quartile range, the estimated difference, a confidence interval, or a test result. The direction, size, and precision of the observed comparison are therefore not available in the registry record. Nor does the endpoint alone measure patient experience, safety, or downstream outcomes.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical approach must be interpreted in light of what the registry record actually states. The primary endpoint is a comparison of time to PACU discharge determination between two sequential phases. It is summarized using a median and inter-quartile range, with minutes as the unit and a timeframe of up to 1 day. The record does not report the numerical summaries, the estimated phase difference, or the statistical test used for the primary comparison.

What do the median and inter-quartile range describe?

As a general statistical explanation, the median is the middle value after observations are ordered. It is less influenced by unusually high or low observations than the arithmetic mean. The inter-quartile range describes the spread of the central portion of the observations. Together, these summaries offer information about a typical time and its variability, but they do not reveal the entire distribution. They also do not indicate whether a difference is statistically distinguishable from chance. That assessment depends on the analysis and its uncertainty, neither of which is reported for the primary result in the registry record.

A difference between phase medians is not automatically the same as an adjusted or causal effect. It describes a contrast in summaries, and its meaning depends on how the observations were collected and compared. Because the phases were sequential and not randomized, time-related differences and other confounding factors may influence the contrast. This is a general limitation of before-and-after designs. The registry record does not report an adjustment strategy, a model for the endpoint, or details about handling possible confounding.

Why does the sequential design matter?

In a randomized concurrent comparison, assignment is designed to make groups comparable on average. This study instead compares an observation phase with a later interaction phase. The phase structure is relevant because the telemedicine approach changed along with time. General changes in patient mix, clinical practice, staffing, or workload could coincide with the phase change. The record does not provide information to determine whether such changes occurred or how they were handled analytically. Accordingly, a phase difference would not, on its own, isolate the contribution of the interaction technology.

The design also affects how a reader should view the recorded group counts. They describe the study’s phases, not randomized arms. They should not be treated as evidence of a balanced control comparison. The record does not report the numbers contributing to the primary endpoint, whether all enrolled patients had an assessable endpoint, or whether the analysis used all eligible observations.

What can planning illustrations tell readers?

The stated planning illustration uses a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It is computed from the observed effect, with the effect to detect expressed as a stated fraction of that effect. For time-to-event tables, the stated approach gives the total number of events using Schoenfeld; other planning illustrations give participants per arm. These are planning assumptions, not results of the study’s own design process. They should not be interpreted as observed power, proof that the study had adequate power, or evidence that the primary comparison was significant. The registry record does not report the trial’s sample-size justification.

A planning illustration based on an observed effect is conditional on that effect estimate. General statistical reasoning cautions that an effect estimated in a study can be uncertain, and a planning calculation does not remove that uncertainty. In this record, the primary endpoint estimate itself is not reported, so the planning assumptions should not be used to infer the size or direction of the study result.

How should uncertainty and analysis details be assessed?

A confidence interval is, in general, a range of values compatible with the data under a specified statistical model and procedure. Its width helps readers assess precision; its interpretation also depends on the design and assumptions. No confidence interval for the primary endpoint is reported in the registry record. The primary analysis method, handling of skewed times, treatment of any censoring, and approach to repeated or clustered observations are also not reported in the registry record. These details would help determine how the endpoint comparison was estimated and how robust it may be.

The record lists six outcome measures and six analyses. It does not describe whether the primary comparison was adjusted, whether analyses were prespecified in a statistical analysis plan, or whether alternative analyses were conducted. The registry record also does not report interim analyses, a multiplicity procedure, or a method for handling missing endpoint data. These absences do not establish that a particular method was or was not used; they mean that the corresponding methods cannot be assessed from the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry records six outcome measures and six analyses, and lists secondary aims that include the potential ability of a remote PACU telemedicine center to assist with PACU functions, detection of physiological derangements, identification of symptoms requiring treatment, recognition of situations requiring emergency intervention, and determination of readiness for PACU discharge. The primary endpoint is time to discharge determination. The registry record does not explain how the primary endpoint relates to the analyses or how results across outcomes were interpreted together.

When multiple outcomes or analyses are considered, the chance of at least one apparently notable result can increase. As a general statistical principle, a prespecified multiplicity strategy can help control that risk, but no such strategy is reported in the registry record. The record does not report an analysis hierarchy, adjustments across outcomes, or which analyses were designated as confirmatory. It would therefore be inappropriate to assume that the listed results, if available elsewhere, have a particular multiplicity status.

The registry record does not report how missing endpoint observations were handled, whether any outcomes were unavailable, or which analysis population was used. It also does not define whether analyses followed an intention-to-treat, per-protocol, or other population principle. The primary outcome’s population field is blank. These omissions make it difficult to assess whether the reported phase summaries, if posted, represent all eligible observations or a selected subset.

Interim analyses and stopping rules are not reported in the registry record. A statistical analysis plan is also not reported. These details matter because analysis choices can affect estimates and their interpretation, particularly when several outcomes are assessed. Their absence from the record should be read as unavailable documentation, not as evidence that no such procedures existed.

11. 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 registry’s adverse-event entries list the observation phase with 304 at risk and the interaction phase with 256 at risk. For both phases, the recorded number of serious events is 0, the number of other events is 0, and deaths are 0. These are the counts recorded for each phase; they are not estimates of comparative risk.

Zero recorded events do not establish that the phases have identical safety, nor do they show that an event could not occur. General statistical reasoning recognizes that an observed count can be affected by the duration and completeness of follow-up, event definitions, and how events are collected. The registry record does not report those details, nor does it provide a comparative safety analysis or uncertainty intervals.

The phases were sequential and non-randomized, so the entries should not be interpreted as a randomized safety comparison. The record also does not report whether adverse-event ascertainment was independent of the clinical teams or whether all events were captured in the same way across phases. The entries are best read as descriptive registry counts, not as evidence that the telemedicine interaction caused, prevented, or had no effect on adverse events.

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

The registry record establishes that a prospective, single-center proof-of-concept study compared an observation phase with a later phase in which remote telemedicine clinicians could interact with clinicians and patients in designated PACU bays. It identifies time to PACU discharge determination as the primary endpoint and specifies a median, an inter-quartile range, minutes, and a timeframe of up to 1 day. It does not report the primary endpoint values or the estimated comparison.

Consequently, the posted registry information does not show whether discharge readiness was determined sooner or later in either phase, how large any difference was, or how precise the comparison was. No conclusion about statistical significance can be drawn from the endpoint description alone. The missing result is not evidence of no difference; it means the primary result is not reported in the registry record.

Even if a phase difference were reported, the design would constrain what it could mean. The comparison is sequential and non-randomized, so a difference would be an association between phase and timing, not automatically a causal effect of telemedicine interaction. Other differences between the periods could contribute. The record does not report methods that would establish whether those factors were addressed.

The study’s proof-of-concept framing and its listed functional aims indicate an evaluation of workflow and telemedicine capability. Those aims do not demonstrate that the technology improved care, reduced delays, or changed patient outcomes. The recorded adverse-event counts are descriptive and likewise do not establish equivalence or a causal safety conclusion. The registry record supports an account of the study’s question, setting, and structure, but not a conclusion about whether the intervention achieved its intended effects.

13. Why This Trial Matters Statistically

This study raises a useful statistical question about how to evaluate a workflow intervention in a clinical setting. The endpoint, time to a discharge-readiness determination, concerns a process measure that may be relevant to PACU operations. The registry specifies a median and inter-quartile range, which can describe both a typical time and variation without assuming that times follow a symmetric distribution.

Its design also illustrates why the structure of a comparison matters as much as the endpoint. A sequential before-and-after study can be practical for an early proof-of-concept evaluation, but the phase contrast combines the change in telemedicine interaction with any other changes over time. Non-randomized phases cannot provide the same protection against confounding as a randomized concurrent comparison. Clear reporting of the analysis and its uncertainty would help readers judge what the observed data can support.

The registry record describes the clinical question and the planned type of endpoint, but does not report the primary result. That distinction is statistically important: a protocol-level endpoint description cannot answer the empirical question without the observed summaries and an analysis. Likewise, planning illustrations are not substitutes for results, and adverse-event counts alone do not establish comparative safety.

The record therefore offers a case study in the limits of interpreting registry information. It allows readers to recognize the design, the endpoint scale, and the non-randomized sequential structure. It does not allow assessment of the primary effect’s direction, magnitude, precision, or robustness. For clinical researchers, these boundaries are central to distinguishing a promising study question from evidence that answers it.

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 most immediate limitation for interpreting this registry record is that it does not report the primary endpoint result. The median time and inter-quartile range for either phase, the estimated difference, and uncertainty around that comparison are not reported in the registry record. Without these results, the main question cannot be answered from the record.

The comparison is non-randomized and sequential. The interaction phase followed the observation phase, so the phases may differ in ways other than telemedicine interaction. This limits causal interpretation. The registry record does not report whether patient characteristics, staffing, workflow, or other time-related factors were assessed or adjusted for. The record also does not provide enough information to determine how patients were assigned to phases or bays.

The study is single-center and described as proof-of-concept. Results from one center may not represent other PACU settings, and the registry does not report details that would allow assessment of how the intervention was implemented across sites. The record describes interaction in two designated PACU bays but does not provide further operational details about exposure or fidelity.

Important analysis information is not reported in the registry record, including the primary statistical method, the analysis population, missing-data handling, multiplicity procedures, and a statistical analysis plan. The outcome population field is blank. The adverse-event entries lack reported definitions and ascertainment details. These gaps do not show that the corresponding methods were absent; they limit what can be evaluated from the record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Telemedicine Control Tower for the Post-Anesthesia Care Unit — NCT04020887.
• Registry record last updated 2023-07-19; status last verified 2021-12.
• Results first posted 2023-07-19.
• 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

NCT04020887 is a completed, single-center prospective before-and-after proof-of-concept study of a telemedicine solution for the PACU. The registry records enrollment of 560 and a non-randomized, sequential design. It describes an observation phase followed by an interaction phase, when remote clinicians used audio-visual technology to interact with clinicians and patients in designated PACU bays.

The primary endpoint is the difference in time to PACU discharge determination between phases, summarized as a median and inter-quartile range in minutes over a timeframe of up to 1 day. The primary result is not reported in the registry record. The record lists six outcome measures and six analyses, and records zero serious events, zero other events, and zero deaths in each phase. The sequential design does not support treating the phases as randomized, like-for-like groups.