Mitigation of Postoperative Delirium in High-Risk Patients: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Mitigation of Postoperative Delirium in High-Risk Patients (NCT05777187), a randomized na study. The primary outcome is 4AT Delirium Score.

2. Clinical Question

The trial asks whether electronic health record clinical decision support changes postoperative delirium outcomes for adult surgical patients with cognitive impairment. The intervention combines a high-risk alert with perioperative best-practice recommendations for clinicians; the comparator is usual care without those decision-support alerts. The registry description also identifies provider adherence to best practices as an outcome of interest.

The primary outcome is a continuous score rather than a simple count of delirium cases. The registry describes the 4AT as a tool that identifies the presence or absence of postoperative delirium, while the recorded outcome is the mean score on that assessment. That distinction matters: a comparison of average scores does not, by itself, report how many participants met a particular threshold or how many were diagnosed with delirium.

The registry describes cognitive impairment as the risk context for the trial and postoperative delirium as the clinical concern. It does not report further eligibility details or a more specific definition of the target population in the primary outcome description.

3. Trial Design

This is a randomized, parallel-group trial with no masking reported. The intervention is clinical decision support; the control is standard of care. The registry identifies the trial as pragmatic and describes electronic health record data as the means of identifying patients at high risk for postoperative delirium. The alerts were directed toward anesthesiologists caring for patients with preexisting cognitive impairment.

The registry lists enrollment as 7412. The primary outcome summaries contain 644 participants in the clinical decision support group and 617 in the standard-of-care group. These outcome-specific counts are not the same as the overall enrollment figure. The registry record does not explain the difference, and the reasons participants may not appear in an outcome summary are not reported in the registry record.

The primary completion date is 2024-08-31, and the recorded study start date is 2023-06-20. The trial status is terminated. The reason for termination is not reported in the registry record, so the status alone does not establish whether termination was related to the intervention, recruitment, data availability, or another cause.

The registry lists three secondary outcomes: performance of perioperative best practices, mean arterial pressure above 65 mmHg, and age-adjusted minimum alveolar concentration. Numeric summaries are posted for the latter two continuous outcomes. A numeric result for the best-practice measure is not reported in the registry record. The registry does not report the original sample-size rationale or a detailed analysis plan, including the planned analysis population and handling of missing outcome data.

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.

Population: No baseline characteristics data on individual providers will be collected.

6. Primary Endpoint

The registry lists the primary outcome as 4AT Delirium Score, measured over Postoperative day 7.

The primary outcome is the mean 4AT delirium score recorded on postoperative day 7. The registry describes the 4AT as a four-part assessment covering alertness, the abbreviated mental test, attention, and acute change or fluctuating course. Its score ranges from 0 to 12, with higher scores indicating poorer health outcomes. The registry describes scores of 4 or above as possible delirium with or without cognitive impairment; scores of 1 to 3 as possible cognitive impairment; and a score of 0 as making delirium or severe cognitive impairment unlikely, while noting that delirium may still be possible when information is incomplete.

A continuous score allows the comparison to use the average recorded assessment across participants, rather than reporting only a threshold-based count. Such an average can be useful when the outcome is measured on a graded scale, but it does not show the distribution of scores or the number of participants at each 4AT threshold. Those details are not reported in the registry record.

The posted group summaries give the mean and standard deviation for each arm. The mean difference compares the clinical decision support group with standard of care. Because higher 4AT scores indicate poorer health outcomes, direction is important when interpreting that difference. The outcome is recorded at postoperative day 7; other follow-up times for the primary measure are not reported in the registry record.

7. Results Posted in the Registry

• Clinical Decision Support: mean 2.95 versus 2.76 on control; difference 0.19 (95% CI -0.23 to 0.61), standardized effect d = 0.05; z-test p = 0.375.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Mean Arterial Pressure >65 mmHg

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Clinical Decision Support: mean 0.05 versus 0.05 on control; difference -0.00 (95% CI -0.01 to 0.00), standardized effect d = -0.01; z-test p = 0.593.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Clinical Decision Support and the control. The interval gives the range of effects that remain compatible with the data.

Age Adjusted Minimum Alveolar Concentration (MAC)

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Clinical Decision Support: mean 16.50 versus 17.00 on control; difference -0.50 (95% CI -2.04 to 1.04), standardized effect d = -0.02; z-test p = 0.524.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Clinical Decision Support and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcome summaries give a broadly similar inferential picture to the primary comparison: the unadjusted mean differences are small relative to the uncertainty, and the recalculated confidence intervals include zero. The point estimates for the two posted continuous secondary measures are in the direction of lower means for clinical decision support, while the primary mean score is higher in that group. This mixed pattern does not establish a consistent direction of difference across the outcomes.

These measures address different aspects of perioperative care and are not interchangeable with the 4AT outcome. Mean arterial pressure above 65 mmHg and age-adjusted minimum alveolar concentration describe aspects of perioperative management, whereas the primary endpoint is a postoperative delirium assessment score. A secondary process measure concerning performance of perioperative best practices is also listed, but its numeric result is not reported in the registry record. The available secondary summaries therefore do not show whether the alerts changed adherence to the recommended practices.

Unadjusted secondary results carry less weight as a collection when multiple outcomes are examined. General statistical explanation: the more comparisons considered, the greater the opportunity for apparently notable results to occur by chance, unless the analysis plan addresses multiplicity. The registry record does not report a multiplicity strategy. The secondary findings should therefore be treated as descriptive and supportive rather than as independent confirmation of the primary result. They do not resolve the uncertainty around the primary 4AT comparison or substitute for a reported prespecified analysis.

The different participant counts across outcome summaries also matter when considering the pattern as a whole. The registry does not report why the denominators differ or how missing outcomes were handled. Without that information, it is not possible to determine whether the secondary summaries represent the same participant group as the primary outcome or to assess whether differences in availability could influence the apparent pattern.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Number of Participants Where Perioperative Best Practices for Intervention Was Performed
• Mean Arterial Pressure >65 mmHg
• Age Adjusted Minimum Alveolar Concentration (MAC)

9. Statistical Interpretation

10. Statistical Methods Explained

The primary result is a comparison of two group means for a continuous outcome. The reported mean difference is defined as the clinical decision support mean minus the standard-of-care mean. A positive estimate therefore indicates a higher average 4AT score in the intervention group; because higher scores are described as indicating poorer health outcomes, the sign has a clear descriptive direction. The comparison is unadjusted and recalculated from the posted summary statistics. The registry record lists no reported analyses, so this calculation should not be confused with a sponsor-reported adjusted analysis.

What does a mean difference represent?

A mean is the arithmetic average of observed values within a group. A mean difference expresses the distance between the two group averages in the outcome’s original units. Here, the outcome is a score on the 4AT assessment, so the difference is expressed in score units. The mean difference does not state how many participants crossed a clinical threshold, nor does it show whether individual participants improved or worsened. Those questions require information beyond the two means.

Each group’s standard deviation describes the spread of individual scores around that group’s mean. The posted standard deviations are 3.84 for clinical decision support and 3.77 for standard of care, which are substantially larger than the observed mean difference of 0.19. General statistical interpretation: a difference between averages must be considered alongside the variability in individual measurements and the uncertainty in the estimate. A small difference against a wide spread can be difficult to distinguish precisely, even when group averages can be calculated.

How should the confidence interval be read?

A confidence interval expresses uncertainty around an estimate under the statistical method used to construct it. In general, a wider interval indicates less precision than a narrower interval. For the primary comparison, the recalculated interval includes zero and extends to values on either side of no difference. Thus, the posted summary statistics are compatible with no mean difference as well as with differences in either direction. The interval does not prove that the true difference is zero. It also should not be read as a range containing every plausible individual participant score.

The registry does not report a sponsor analysis for the primary outcome. The interval and p-value discussed in this interpretation are unadjusted recalculations from group summaries, not a substitute for a prespecified model that might account for other variables or trial features. The registry record does not report whether such an analysis was planned or performed outside the posted results.

What does the p-value add?

The unadjusted p-value is 0.375. General statistical explanation: a p-value measures how incompatible the observed data, or more extreme data, are with a specified null model, assuming that model and the calculation’s assumptions are appropriate. It is not the probability that the null hypothesis is true, the probability that the result arose by chance, or a measure of the size or clinical importance of a difference. A p-value does not replace the estimate and its confidence interval. The registry record does not report a planned significance threshold for the trial’s primary analysis.

Because no sponsor analysis is posted, the recalculated p-value should be read as a simple unadjusted comparison rather than as the trial’s definitive planned test. The absence of a discrepancy between the recalculation and sponsor analysis is not relevant as no sponsor analysis is listed. Any protocol-defined analysis could differ in its population, covariate adjustment, or treatment of missing data; those details are not reported in the registry record.

Why does variability matter?

General statistical explanation: greater variation among participant measurements makes an average difference harder to estimate precisely, all else being equal. The 4AT score can vary across participants, and the group standard deviations describe that variation in the posted outcome summaries. The pooled standard deviation used in the recalculated standardized effect is 3.806. A standardized effect expresses a mean difference relative to a standard deviation, which can help compare effects measured on different scales. It does not change the underlying clinical meaning of the 4AT score, and it should not be taken as a diagnosis or as a measure of benefit.

The calculated standardized effect is 0.050. This is a derived, unadjusted summary based on the reported means and variability. It should not be interpreted as the result of a fitted model or as an effect adjusted for baseline characteristics. Neither baseline outcome values nor an adjustment strategy are reported in the registry record.

What assumptions are not established?

General statistical explanation: simple mean comparisons usually rely on assumptions about the observations and the sampling distribution of the estimate. Relevant issues can include independence of observations, distribution of the outcome, and how missing scores are handled. The registry record does not report enough detail to assess these assumptions for the trial’s own analysis. The recalculation uses only the posted group summaries; it cannot check the participant-level score distribution, repeated observations, clustering, or the reason some enrolled participants may not appear in an outcome summary.

There are no reported analyses in the registry record, and the analysis population, missing-data method, covariate adjustment, interim analyses, and multiplicity plan are not reported. These omissions limit what can be inferred about the intended statistical procedure. The descriptive comparison remains useful for understanding the posted averages, but it cannot establish that it reproduces every feature of the trial’s planned analysis.

11. Confidence Intervals and Precision

The primary mean difference is 0.19 4AT score units, with the clinical decision support group having the higher mean. The recalculated confidence interval extends below and above zero. This means that the posted summary statistics do not pin the difference to one direction with high precision: values compatible with the data include no difference and differences in either direction.

Precision concerns the uncertainty in the estimated group difference, not whether the outcome is clinically important. The interval is wide enough to leave uncertainty about the direction and size of the underlying difference. The registry record does not report a threshold for a clinically meaningful change in 4AT score, so the interval cannot be classified against such a threshold. The group standard deviations, 3.84 and 3.77, also show that individual scores varied much more than the mean difference.

The p-value of 0.375 is consistent with the interval’s inclusion of zero, but the p-value alone does not convey the range of differences compatible with the data. Neither statistic establishes that the intervention has no effect. Conversely, the positive point estimate does not establish a difference in the population. The group-specific outcome counts are 644 and 617; the registry does not state how missing values were handled or why these counts differ from overall enrollment.

These are recalculated unadjusted precision measures from posted summary statistics. They are not reported sponsor-model estimates. If a prespecified analysis used additional information or a different analysis population, its estimate and interval could differ; that analysis is not reported in the registry record.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are illustrations based on the observed effect, not the trial’s original design calculation. For the primary outcome, they express participants per arm under each stated effect-size scenario. The listed scenarios use 100%, 75%, and 50% of the observed effect. At 100% of the observed effect, the illustration gives 6,299 participants per arm for 80% power and 8,433 participants per arm for 90% power. At 75%, the corresponding figures are 11,198 and 14,991 participants per arm; at 50%, they are 25,195 and 33,729 participants per arm.

The assumptions for these planning illustrations are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is the stated fraction of the observed effect. These are participants per arm, not total events. The event-count convention applies only to time-to-event planning figures; the primary outcome is continuous, so the figures are participants per arm.

The 80% power column describes the planned chance of detecting the specified effect under the illustration’s assumptions if that effect were the true effect. The 90% column uses a higher target chance of detection and therefore requires more participants. For either target, smaller effects require more participants to detect than larger effects, which is why the illustrated requirements rise as the assumed fraction of the observed effect decreases. This is not observed power; it is a planning illustration based on the observed estimate.

The original trial’s sample-size justification and design assumptions are not reported in the registry record. These illustrations should therefore not be used to infer the trial’s original target, whether the trial met a planned target, or the likelihood that the trial would produce a statistically significant result.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 0.190; pooled standard deviation σ = 3.806.
2. n = 2 × (1.96 + 0.842)² × 3.806² / 0.190² = 6,298.7, rounded up to 6,299 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 0.19                      # observed difference in means
sigma <- 3.80591145894907                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(5777187)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 6,299 (80% power), 8,433 (90% power)
 75% of observed effect: n per arm = 11,198 (80% power), 14,991 (90% power)
 50% of observed effect: n per arm = 25,195 (80% power), 33,729 (90% power)
power.t.test: 6299.6 
Simulated power at n = 6,299 per arm: 0.796 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry record does not report a multiplicity plan. This is relevant because the record lists a primary outcome and several secondary outcomes, and multiple comparisons can increase the chance of at least one apparently unusual result. General statistical explanation: a prespecified strategy may define which outcome is primary, whether secondary tests are adjusted, and how confirmatory claims are controlled. Without a reported strategy, unadjusted secondary p-values should be interpreted cautiously and should not be treated as if each were the sole planned test.

The record lists no reported analyses. It does not report the planned analysis population, whether analyses were intended to follow assignment regardless of intervention use, or whether a per-protocol population was planned. These details can affect the meaning of a randomized comparison, particularly when an intervention is delivered through clinical workflows. The record also does not report how missing outcome values were handled, whether missingness was assessed by group, or whether sensitivity analyses were planned.

The difference between total enrollment and the numbers in the primary outcome summaries is visible in the record, but the reason is not stated. The secondary outcome counts differ as well. These differences might arise for various reasons, but their cause cannot be determined from the registry record. It would be inappropriate to assume that omitted observations were random, that every enrolled participant had an outcome measured, or that a particular analysis population was used.

Interim analyses and stopping rules are not reported in the registry record. Since the trial status is terminated, the missing information about termination and analysis plans limits interpretation of how the study ended and whether that status had statistical implications. No conclusion about those matters can be drawn from the status alone.

15. 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 lists zero serious adverse events and zero other adverse events for both groups. The recorded at-risk counts are 3634 for clinical decision support and 3678 for standard of care; deaths are listed as zero in each group. These are the figures recorded for the safety outcomes, not an estimate of comparative risk adjusted for follow-up time or participant characteristics.

The registry record does not report definitions for the adverse-event categories, the safety observation period, or details of ascertainment. It also does not explain how the safety denominators relate to the primary outcome counts or to overall enrollment. The recorded zeros should therefore be read as the registry’s reported counts, not as proof that no adverse events occurred outside the recorded scope or that the groups have identical safety profiles.

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

The posted primary result is a comparison of average 4AT scores on postoperative day 7 among participants represented in the two outcome summaries. The clinical decision support group mean was 2.95 and the standard-of-care group mean was 2.76. The recalculated unadjusted difference was 0.19 score units, with uncertainty spanning both sides of zero. The result does not establish a clear difference in average score, and it does not establish equivalence or absence of an effect.

The mean score is not the same as the number of participants who developed postoperative delirium. The registry describes thresholds for interpreting 4AT scores, but does not report the distribution of scores, the numbers meeting a threshold, or a separate diagnosis count for the primary endpoint. The result also does not directly show whether clinicians followed the perioperative recommendations. A best-practice performance measure is listed, but its numeric result is not reported in the registry record.

The trial’s intervention is a decision-support strategy in a clinical workflow, not a single treatment administered identically to every participant. The registry describes alerts and best-practice recommendations directed toward anesthesiologists. Without reported implementation, adherence, and missing-data details, the mean comparison cannot show how consistently the decision support was used or which parts of the strategy participants received in practice.

The record does not report a sponsor analysis, a multiplicity plan, an analysis population, or a missing-data method. Those omissions mean the recalculated comparison should be understood as a straightforward summary-statistic analysis rather than a complete account of a prespecified statistical analysis. No medical advice or conclusion about treatment effectiveness follows from this result. It describes the posted data and their uncertainty, while leaving questions about implementation, individual outcome patterns, and the trial’s planned analysis unresolved.

17. Why This Trial Matters Statistically

This trial is statistically interesting because it evaluates a clinical decision-support intervention through a randomized comparison in a pragmatic care setting. The intervention is intended to place alerts and best-practice recommendations inside the electronic health record workflow, so the question involves both a clinical outcome and the delivery of care processes. The registry identifies postoperative delirium in patients with cognitive impairment as the motivating concern and identifies provider adherence as an outcome of interest.

The primary endpoint is a continuous assessment score, while the registry description also frames the tool as identifying the presence or absence of delirium. Those are related but distinct ways of describing outcomes. A mean score comparison can capture shifts across the score range, but it does not disclose threshold counts or individual score distributions. This makes clarity about the estimand and reporting of outcome distributions important for interpretation.

The record also illustrates why enrollment should not be mistaken for an outcome-specific analysis count. The enrolled total is 7412, while the primary outcome summaries contain 644 and 617 participants. The reasons for this difference are not reported. Transparent reporting of participant flow, analysis populations, missingness, and endpoint availability would help readers understand the precision and generalizability of the comparison.

Finally, the listed secondary outcomes span care processes and perioperative measures, but the record does not report a multiplicity strategy or all secondary numerical results. This limits the strength of conclusions drawn across outcomes. The trial therefore highlights the importance of reporting not only point estimates and uncertainty, but also how the planned analysis relates to workflow implementation, outcome availability, and multiple questions.

18. 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 does not report why the trial was terminated. That missing context prevents interpretation of whether the termination affected recruitment, follow-up, implementation, or analysis. The primary completion date is recorded, but the reason for the status and its statistical consequences are not reported.

The primary outcome counts are much smaller than overall enrollment, and the registry does not explain the difference. The record does not describe the flow of participants from enrollment to outcome measurement, the availability of postoperative day 7 assessments, or the handling of missing scores. The primary and secondary denominators also differ. These gaps prevent assessment of whether the analyzed participants were representative of those enrolled or whether outcome availability differed by group.

The primary result is an unadjusted recalculation from group summaries. No sponsor analysis is reported, and the registry does not state whether a covariate-adjusted analysis was planned. Participant-level data are not available in the registry summary, so the score distribution, outliers, baseline characteristics, and possible clustering cannot be assessed from these summaries. The original sample-size rationale and planned analysis assumptions are not reported.

The registry describes the intervention and intended best practices, but does not report numeric results for the best-practice performance outcome. This limits assessment of whether the decision-support strategy changed the care processes it was designed to influence. The record also does not report the multiplicity plan, missing-data method, interim analyses, or the analysis population. These are trial-specific reporting limitations; they do not determine the direction of the result, but they restrict how fully the posted comparisons can be interpreted.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Mitigation of Postoperative Delirium in High-Risk Patients — NCT05777187.
• Registry record last updated 2026-02-19; status last verified 2026-02.
• Results first posted 2026-02-19.
• 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.

22. Record Summary

NCT05777187, titled Mitigation of Postoperative Delirium in High-Risk Patients, is a randomized, parallel-group trial of electronic health record clinical decision support versus standard of care for surgical patients with cognitive impairment. The registry lists enrollment of 7412, a start date of 2023-06-20, a primary completion date of 2024-08-31, and a terminated status.

The primary outcome is mean 4AT delirium score on postoperative day 7. The posted means are 2.95 for clinical decision support and 2.76 for standard of care. The recalculated unadjusted mean difference is 0.19, with a confidence interval spanning zero and an unadjusted p-value of 0.375. The registry record lists no reported analyses and does not report the reason for termination, the original sample-size rationale, missing-data methods, or a multiplicity plan.