The Prevention of Failure to Rescue Using Early Warning Scoring: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Prevention of Failure to Rescue Using Early Warning Scoring (NCT01197326), a registered phase not stated study. The primary outcome is Survival.

2. Clinical Question

The study asks whether an automated Early Warning System (EWS) resident in a spot-check patient monitor can help identify deteriorating patients, compared with standard paper-based systems. The device named in the record is the IntelliVue Patient Monitor MP5 Rel. G.1, and its intervention is described as use of the MP5 EWS patient monitor. The clinical focus is patients who triggered MET/RRT calls, with the primary outcome described as survival at the end of the response team call.

The registry record does not report a primary outcome result or an estimate comparing the groups. It therefore does not establish whether survival differed. Nor does the record provide enough information to assess whether the groups were otherwise comparable. The study's stated question is clinically relevant to recognition of deterioration and response to it, but interpretation depends on outcome results and study methods that are not reported in the registry record.

3. Trial Design

This is a completed study sponsored by Philips Healthcare. The registry lists an enrollment of 414 and dates the study start to 2009-08 and primary completion to 2010-05. The intervention is use of the MP5 EWS patient monitor. The two groups are described according to whether their MET/RRT calls occurred prior to or after use of the monitor.

The record explicitly indicates that this is not a randomized comparison. Allocation is not stated, and the arms are not a like-for-like control comparison. The before-use and after-use descriptions therefore identify a temporal contrast, but the record does not establish that the groups had the same patient mix, clinical circumstances, or care processes. This limits what can be concluded from any difference between them, even if an outcome estimate were reported.

The primary outcome is titled “Survival,” with a unit of percentage of participants and a timeframe listed as 6 months. Its description, however, defines survival at the end of the RRT call, when the RRT team left the patient, and says the average duration of calls was around 25 min. These are the registry's stated endpoint details; the record does not explain the relationship between the listed timeframe and the call-end description.

The record lists “Respiration Rate Impact on RRT Calls” as a secondary outcome and indicates two outcome measures. It lists zero analyses. Results, statistical methods, analysis populations, and details of allocation are not reported in the registry record. The study is marked completed, but completion status alone does not supply outcome estimates or establish that a comparison was conducted as a randomized trial.

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 Survival, measured over 6 months.

The primary endpoint is titled “Survival.” It is measured as a percentage of participants, and its description refers to survival at the end of an RRT call: the time when the RRT team left the patient. The record says average call duration was around 25 min and lists a timeframe of 6 months. It does not explain how that timeframe relates to the endpoint's description at the end of a call.

In general, a binary endpoint classifies each participant according to whether an event or status is present at a defined time. Reporting a percentage can make the frequency of that status interpretable within a group, but a group percentage alone does not establish a treatment effect. A comparison requires reported results for the relevant groups and an appropriate estimate of the contrast, with uncertainty described where available.

Survival at the end of an urgent response call is the outcome named by the record, and it is distinct from a longer-term survival endpoint unless the record specifies otherwise. The record does not report the number or percentage surviving at call end, a between-group estimate, or uncertainty around an estimate. It therefore does not show the observed primary outcome or how precisely any difference was estimated. No further endpoint definition, including the analysis population or handling of missing outcome data, is reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record does not report a statistical analysis plan or analysis results. The general concepts below explain how common methods would be interpreted; they should not be read as methods confirmed for this study. No particular model, adjustment strategy, or hypothesis test is identified in the record.

What does a percentage endpoint represent?

General: for a binary endpoint, each participant is classified into one of two outcome categories at the defined assessment point. A group percentage expresses the frequency in that group. To compare groups, analysts may report an absolute difference or another measure of association. The choice depends on the design, endpoint, and analysis plan. In this study, the registry defines the primary outcome as a percentage of participants but does not report the component counts or group percentages, so no such comparison can be interpreted.

What does a confidence interval add?

General: a confidence interval communicates uncertainty around an estimate. A relatively wide interval indicates that a broad range of values remains compatible with the data and model; a narrower interval indicates greater precision. The interval is not a guarantee that the true value lies within its endpoints, and it does not resolve biases from study design or measurement. No confidence interval for survival is reported in the registry record, so precision cannot be judged.

What does a p-value answer?

General: a p-value describes how unusual data at least as inconsistent with a specified null hypothesis would be, under the assumptions of the chosen statistical test. It does not give the probability that the null hypothesis is true, and it does not measure the size or importance of an effect. A p-value needs to be interpreted alongside an estimate, uncertainty, and design limitations. The registry record does not report a p-value or name a statistical test for the primary outcome.

Why does the study design matter?

General: random allocation can help make comparison groups similar in expectation with respect to measured and unmeasured factors. In a before-and-after comparison, group membership is linked to time, so changes in patients, practice, or other circumstances could accompany the change in monitoring. This is a general concern, not evidence that any particular change occurred in this study. The record says allocation is not stated and that the arms are not a like-for-like control comparison. It does not describe methods to address time-related differences, nor does it report adjusted analyses.

How should planning calculations be read?

The record describes sample-size assumptions for planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect, and that non-time-to-event calculations are expressed as participants per arm. These are planning illustrations, not observed power and not evidence of the study's original design or justification. The registry record does not report its own sample-size justification. Because it does not report the primary outcome effect, the planning assumptions do not supply an outcome result or establish the adequacy of the study for its question.

Overall, the methodological details needed to interpret a formal inferential analysis—including the test or model, confidence intervals, adjustment, and assumptions—are not reported in the registry record. General statistical principles can clarify what such information would mean, but cannot replace the missing study-specific results and methods.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Group 1", "Group 2")
n      <- c(205, 209)
events <- c(176, 192)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Group 1  205  176  85.9  80.3  90.3  80.4  90.0  80.4  90.0
ARM  Group 2  209  192  91.9  87.3  95.2  87.4  94.9  87.4  94.8

11. Multiplicity, Missing Data and Analysis Populations

The record lists two outcome measures and names “Respiration Rate Impact on RRT Calls” as a secondary outcome. It identifies “Survival” as the primary outcome. It does not report whether hypotheses were prespecified in a detailed analysis plan, how many comparisons were tested, or whether any procedure was used to address multiplicity. With multiple outcomes or analyses, the chance of at least one apparently notable result can increase; general methods to address this include prioritizing a primary outcome or adjusting inference. The registry record does not establish which, if any, approach was used.

Missing-data handling is not reported in the registry record. The record does not state how participants with missing endpoint measurements were handled, whether all enrolled participants were included in the primary analysis, or whether any imputation or sensitivity analysis was performed. Those details can matter because the interpretation of a percentage depends on its denominator and on how unavailable outcomes are treated.

Analysis populations are also not reported. The record does not specify whether the primary outcome analysis included all enrolled participants, only participants with a recorded RRT call outcome, or another defined group. It does not provide a participant flow or explain exclusions. The enrollment figure and adverse event risk counts do not fill this gap for the primary endpoint.

The registry lists zero analyses and contains no reported primary-outcome result. Therefore, there is no basis to evaluate multiplicity control, missing-data assumptions, or analysis-population choices in the outcome comparison. Their absence from the registry record should be treated as missing reporting, not evidence that a particular method was or was not used.

12. 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 0% reporting threshold.

The adverse event figures list zero serious events and zero other events in each of the two groups. The record lists 205 participants at risk in the group whose MET/RRT calls occurred prior to use of MP5 and 209 at risk in the group whose calls occurred after use. These figures describe the adverse event entries; they are not the primary survival outcome.

The registry record does not list serious adverse event terms, and it does not report death counts in these entries. A zero count in the posted adverse event categories means that no events are recorded in those categories in this record; it does not establish that no adverse events occurred outside the categories or reporting process represented. The record does not provide further detail about adverse event collection, definitions, ascertainment, or follow-up.

In general, event counts are most informative when read with their defined risk group, observation period, and collection rules. The registry record's adverse event information should not be used to infer the safety profile of the monitor or to draw conclusions about survival. It also does not resolve the limitations of the nonrandomized, before-and-after group comparison.

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

The registry record establishes that the study was completed and was designed to assess whether an automated EWS in a spot-check patient monitor could help identify deteriorating patients compared with standard paper-based systems. It identifies use of the MP5 EWS patient monitor as the intervention and describes groups whose MET/RRT calls occurred before or after its use. It names survival at the end of the RRT call as the primary outcome.

It does not report the primary outcome result, group survival percentages, a comparison estimate, or statistical uncertainty. Accordingly, the posted results do not establish whether the outcome differed between the groups, how large any difference was, or how precisely it could be estimated. The absence of a reported result is not evidence of no effect; nor is the study's stated purpose evidence that the intervention improved an outcome.

The group comparison also has important design limits. The record says the study is not randomized, allocation is not stated, and the arms are not a like-for-like control comparison. A temporal comparison can be affected by factors that change along with the intervention. The registry does not report an analysis that addresses such factors, so causal attribution cannot be assessed.

Any sample-size calculations described as planning illustrations should be read as prospective design scenarios based on the observed effect and stated assumptions, not as observed power. They do not replace outcome estimates or show that the study detected a clinically meaningful difference. The registry record does not report the trial's own design justification or its statistical analysis results.

In short, this record provides context about the question, device, groups, and endpoint, but not the evidence needed to judge the observed primary outcome. Conclusions about effectiveness, lack of effect, or clinical importance are not supported by the registry information reported.

14. Why This Trial Matters Statistically

This study raises a useful statistical question about evaluating a monitoring approach in the setting of MET/RRT calls: how should outcomes be compared when groups are defined by periods before and after device use? The issue is important because a temporal contrast can coincide with changes in care or patient characteristics. Without random allocation or a reported strategy to address such differences, observed group contrasts would not necessarily isolate the contribution of the monitor.

The endpoint also illustrates why clear definitions matter. The registry calls the primary measure “Survival,” describes it at the end of the RRT call, and lists a timeframe of 6 months. It does not explain the relationship between these descriptions. A reader needs a precise assessment time and definition to understand what a percentage measures and whether it is comparable across groups.

Finally, the record demonstrates the difference between a completed study and a fully interpretable result. It identifies the study's purpose and primary outcome but lists zero analyses and reports no primary outcome estimates. Without counts, percentages, uncertainty, and methods, readers cannot assess effect size, precision, or the role of chance. This is a reporting limitation, not a finding that the intervention had no effect.

For biostatistical interpretation, the record is therefore most informative about the design and reporting questions it leaves open: comparability of groups, endpoint timing, analysis populations, missing data, and statistical methods. Those issues shape what can be learned from any eventual comparison and what claims would be justified.

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.

Several trial-specific limitations follow directly from the registry record. The comparison is not randomized; allocation is not stated; and the record characterizes the arms as not a like-for-like control comparison. The groups are distinguished by whether their MET/RRT calls occurred before or after use of the MP5 EWS patient monitor. This makes it difficult to separate the device's contribution from other differences between periods using the information reported.

The primary endpoint description has an unresolved timing detail: the timeframe is listed as 6 months, while the description refers to survival at the end of the RRT call. The record does not explain how these statements fit together. It also does not report the primary outcome values, an estimate comparing groups, or uncertainty. That prevents assessment of the result's magnitude and precision.

The registry record does not report analysis methods, analysis populations, missing-data handling, participant flow, or the trial's sample-size justification. It lists two outcome measures, but only names a secondary outcome concerning respiration rate and RRT calls, and it lists zero analyses. Multiplicity procedures and the handling of multiple outcomes are not reported. These omissions limit reproducibility and make it impossible to judge whether the posted outcome reporting covers the intended analyses.

Finally, the adverse event figures do not supply primary survival results, and the record does not describe adverse event ascertainment or follow-up in detail. These limits concern what is documented in the registry record; they should not be converted into assumptions about procedures that may or may not have occurred.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: The Prevention of Failure to Rescue Using Early Warning Scoring — NCT01197326.
• Registry record last updated 2016-05-05; status last verified 2016-04.
• Results first posted 2014-11-20.
• 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 record describes a completed study sponsored by Philips Healthcare, with enrollment of 414 and a study start of 2009-08 and primary completion of 2010-05. It evaluates use of the IntelliVue Patient Monitor MP5 Rel. G.1 with an automated Early Warning System. Its stated purpose is to assess identification of deteriorating patients compared with standard paper-based systems.

The primary outcome is survival at the end of the RRT call, measured as a percentage of participants; the listed timeframe is 6 months. The groups are defined by MET/RRT calls before and after MP5 use. The record says the comparison is not randomized, allocation is not stated, and the arms are not like-for-like controls.

The registry lists a secondary outcome concerning respiration rate and RRT calls, two outcome measures, and zero analyses. It does not report primary outcome results, statistical estimates, or analysis methods. The adverse event entries record zero serious and zero other events in each group. These entries do not resolve the missing primary outcome information.