Assessment of Patients Undergoing Cardiac Surgery and Admitted to the Intensive Care Unit: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Assessment of Patients Undergoing Cardiac Surgery and Admitted to the Intensive Care Unit (NCT06154473), a registered phase not stated study. The primary outcome is Mortality or Severe Postoperative Complications Within the First 3 Postoperative Days or Until ICU Discharge, Whichever Occurs First.

2. Clinical Question

The study is observational and prospective, so it follows clinical care rather than assigning a procedure. Its stated objective is to characterize patients undergoing cardiac surgery in the ICU, describe complications and mortality, and investigate factors associated with those outcomes. The primary endpoint combines death with a set of severe complications, while other objectives address additional perioperative events and ICU outcomes. The registry record does not report the observed primary endpoint count or an estimate of the association between any risk factor and outcome. The study therefore poses clinically relevant descriptive and associational questions, but the registered information alone does not answer how frequently the primary outcome occurred or which factors were associated with it.

3. Trial Design

This is an observational, prospective, multicenter study of patients undergoing cardiac surgery and admitted to the intensive care unit. The registry lists an enrollment of 528 and identifies Hospital Israelita Albert Einstein as the sponsor. The record gives a start date of 2023-09-01, a primary completion date of 2025-03-18, and a status of completed.

The study identifies two cohorts: open heart surgery and percutaneous cardiovascular surgery. The registry describes open heart surgery as an approach that accesses the heart by opening the chest wall. It describes percutaneous cardiovascular surgery as a catheter-based approach accessed through an incision in the skin. The registry does not state that patients were randomized or that assignment to these cohorts was controlled by the study. It specifically notes that allocation is not stated and that the arms are not a like-for-like control comparison.

The main objective is to investigate mortality and early postoperative complications, along with possible risk factors and the characteristics of patients, anesthesia, and procedures. The planned observation window for the primary outcome is within the first 3 postoperative days or until ICU discharge, whichever occurs first. Secondary objectives include descriptions of procedures and anesthesia, severe intraoperative complications, other postoperative complications, ICU length of stay, and mortality and its associated risk factors.

Details needed to reconstruct the study conduct, such as the full eligibility criteria, recruitment procedures, the number or identity of study centers, and the handling of differences between cohorts, are not reported in the registry record. The record also does not report a statistical analysis plan or the methods used to address confounding. Because the cohorts arise from clinical procedures rather than randomized assignment, comparisons should be read as observational descriptions unless further analysis information is reported.

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.

Before assignment: This was a prospective, multicenter observational cohort study. No randomization or intervention assignment occurred. All enrolled participants received standard-of-care management as determined by the treating clinical teams at each participating institution. Treatment decisions, including surgical approach, anesthetic technique, intraoperative management, and postoperative care, were not influenced by study participation. No participants were excluded after enrollment

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 Mortality or Severe Postoperative Complications Within the First 3 Postoperative Days or Until ICU Discharge, Whichever Occurs First, measured over Within the first 3 postoperative days or until ICU discharge, whichever occurs first, assessed up to 3 postoperative days.

The primary endpoint is the number of participants who experience mortality or a severe postoperative complication within the first 3 postoperative days or until ICU discharge, whichever occurs first. The registry says the endpoint is assessed up to 3 postoperative days and records its unit as participants. It is therefore a combined, participant-level outcome: a participant meeting any qualifying component counts as having the endpoint, rather than each event necessarily being counted separately.

The specified severe complications are stroke, septic shock, unscheduled urgent or emergency surgical reoperation, cardiovascular complications, hematological complications, pulmonary complications, and renal complications. Combining death with severe complications captures more than mortality alone and reflects the registry's stated focus on serious early outcomes after surgery. A composite endpoint can also make an overall outcome easier to describe when several important events are of interest. As a general statistical point, however, a composite needs careful interpretation: its overall count does not show which component occurred most often, and components may differ in clinical importance or frequency.

The registry record does not report the primary endpoint count by cohort, the number of participants meeting each component, or an uncertainty interval. The adverse-event figures listed separately are not a substitute for a reported primary endpoint result. Without the endpoint results and the analysis details, the frequency and precision of the primary outcome cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a prospective observational study. In general, prospective observation means that outcomes and relevant characteristics are collected as participants are followed over time, rather than relying solely on a retrospective review. Observational means that the study does not report assigning patients to the procedures being compared. Here, the two cohorts are defined by open heart surgery and percutaneous cardiovascular surgery, and allocation is not stated. The registry explicitly cautions that these are not like-for-like control arms.

What does a participant count represent?

The primary endpoint is recorded as a count of participants with an event. For a binary outcome, each participant is classified according to whether the event occurred during the specified window. This is different from counting every episode: one participant who experiences more than one qualifying event still contributes as a participant meeting the composite endpoint. The registry does not report the observed counts or the endpoint denominators by cohort, so no event frequency can be calculated from the stated endpoint definition alone.

As a general statistical explanation, a proportion or risk estimate for a binary outcome requires both the number of participants meeting the definition and the relevant denominator. A confidence interval describes the uncertainty around an estimate under the assumptions of the analysis; it does not guarantee that an estimate is free of bias. No primary endpoint estimate or confidence interval is reported in the registry record.

Why can an observational comparison be difficult?

In a randomized study, random assignment is intended to make comparison groups similar on average with respect to measured and unmeasured characteristics. This registry describes an observational study and does not report randomization. Patients undergoing different procedures may differ in ways that also relate to outcomes. For that reason, an observed difference between cohorts would not, by itself, show that the procedure caused the difference. Statistical adjustment can sometimes address measured differences, but it cannot automatically remove unmeasured confounding. The registry record does not report whether adjustment was performed or which variables were considered.

The primary endpoint is a composite of death and several severe complications. As a general principle, combining events can provide an overall summary of outcomes, but the combined result may be driven by one component. Component-level counts and definitions are useful for understanding what contributes to the composite. The registry defines the severe-complication categories but does not report component counts or the primary endpoint result.

What does the record say about the analysis plan?

The registry lists nine outcome measures and zero analyses. The statistical analysis plan, model choices, covariate selection, missing-data procedures, and rules for defining analysis populations are not reported in the registry record. It is therefore not possible to determine from the record whether the investigators planned adjusted or unadjusted estimates, how they would address multiple outcomes, or how uncertainty would be quantified.

The sample-size assumptions described for planning illustrations are not the study’s own design justification. Those illustrations are described as based on the observed effect, with a two-sided significance level of 0.05, equal allocation between cohorts, and a normal approximation. They are planning illustrations, not evidence of the study’s observed power and not a substitute for an analysis of the enrolled participants. The registry does not report a sample-size justification for the study itself.

How should significance and precision be distinguished?

In general, a hypothesis test addresses how compatible data are with a specified null model, conditional on the model and its assumptions. A confidence interval gives a range of values that are compatible with the data under the interval procedure; a narrow interval indicates greater statistical precision than a wide interval, but neither resolves bias in study design or measurement. A p-value alone does not describe the magnitude or clinical importance of an association. No p-values, confidence intervals, or model estimates for the study outcomes are reported in the registry record.

The registry also identifies secondary questions about intraoperative and postoperative complications, fluid balance, ICU mortality, and length of stay. These outcomes may have different data structures and analytical requirements. For example, a binary outcome concerns whether an event occurred, whereas length of stay concerns duration. General methods should match the outcome definition and observation process, but the registry does not state which methods were used for these secondary outcomes.

Overall, the record provides outcome definitions and broad study aims rather than enough analysis detail to reproduce or evaluate statistical estimates. Conclusions about frequencies, associations, uncertainty, and adjusted cohort comparisons would require results and methods that are not reported in the registry record.

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("Open Heart Surgery", "Percutaneous Cardiovascular Surgery")
n      <- c(479, 49)
events <- c(163, 7)
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  Open Heart Surgery  479  163  34.0  29.8  38.5  29.9  38.4  29.9  38.4
ARM  Percutaneous Cardiovascular Surgery  49  7  14.3  5.9  27.2  7.1  26.7  7.2  26.7

11. Multiplicity, Missing Data and Analysis Populations

The registry lists nine outcome measures, including the primary composite endpoint and secondary outcomes covering patient characteristics, procedures, anesthesia, complications, fluid balance, ICU stay, and mortality. When a study evaluates multiple outcomes or several related hypotheses, the chance of at least one apparently notable finding can increase if each is tested separately. As a general statistical principle, multiplicity can be handled through prespecified prioritization, adjusted testing procedures, or interpretation that treats secondary analyses as exploratory. The registry record does not report a multiplicity strategy, a hierarchy among secondary questions, or a statistical analysis plan.

The record lists zero analyses and does not report outcome estimates or hypothesis tests. It is therefore not possible to determine which outcomes were analyzed, whether results were adjusted for multiple comparisons, or whether analyses were prespecified. The objectives alone do not establish that every listed outcome was analyzed.

Missing-data handling and analysis populations are also not reported in the registry record. The record does not say how incomplete follow-up, unavailable measurements, or participants without endpoint information were handled. It does not specify whether analyses included all enrolled participants, only those with complete outcome information, or another defined population. These details matter because missingness can affect both the estimated frequency of an outcome and the comparability of cohorts. Enrollment of 528 does not, by itself, establish how many participants contributed to any particular outcome analysis.

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 0% reporting threshold.

The registry’s adverse-event fields list zero serious adverse events and zero other adverse events in the open heart surgery cohort, with 479 at risk in each field. For the percutaneous cardiovascular surgery cohort, the fields likewise list zero serious adverse events and zero other adverse events, with 49 at risk in each field. These are the figures recorded under the registry’s adverse-event reporting fields.

The registry separately lists 14 deaths in the open heart surgery cohort and 1 death in the percutaneous cardiovascular surgery cohort. The death counts should be read separately from the serious and other adverse-event counts. The record does not explain how the death entries relate to the adverse-event classifications or to the primary endpoint’s assessment window. It also does not report primary endpoint results, component counts, or an analysis denominator for those outcomes.

These figures do not establish that no severe postoperative complications occurred. The primary endpoint includes death and specified complications, and its outcome count is not reported in the registry record. Nor do these figures support a direct risk comparison between the cohorts: allocation is not stated, and the registry notes that the arms are not a like-for-like control comparison. The adverse-event fields are a limited registry summary and should not be treated as a complete account of the study’s clinical outcomes.

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

The record identifies a prospective, multicenter observational study focused on patients undergoing cardiac surgery and admitted to an ICU. It defines a primary outcome combining death with severe postoperative complications during a short early postoperative window, and it sets out additional questions about complications, risk factors, fluid balance, and ICU outcomes. Those details show the scope of the investigation, but the registry record does not report the primary endpoint result or results for the listed secondary questions.

The record therefore does not establish the observed incidence of the primary composite, the frequency of its individual components, or the precision of any estimate. It also does not provide a reported statistical comparison between the surgical cohorts. The adverse-event entries, including the separately listed death counts, should not be substituted for the missing primary endpoint results.

Even if a cohort comparison were available, the observational design would limit causal interpretation. Patients were not reported as randomly assigned, and the registry cautions that the arms are not a like-for-like control comparison. An association between procedure cohort and outcome could reflect differences in the people receiving each procedure or other factors. The record does not report analysis methods that would address such differences.

These limitations do not negate the value of the study questions. They indicate what can and cannot be concluded from the information registered: the study’s aims, design type, cohorts, time window, and outcome definitions are described, while outcome estimates and statistical analyses are not reported in the registry record. Claims about benefit, harm, comparative performance, or risk factors cannot be drawn from the registered information alone.

14. Why This Trial Matters Statistically

This study is statistically relevant because it focuses on early outcomes after cardiac surgery in an ICU, where death and serious complications are important but distinct events. Its composite primary endpoint makes the outcome definition explicit and specifies a limited assessment window: within the first 3 postoperative days or until ICU discharge, whichever occurs first. Clear timing and event definitions are central to interpreting any future estimate.

The two cohorts also illustrate a common challenge in clinical data: procedure groups formed in routine care are not necessarily comparable. An observational design can describe outcomes and explore associations, but differences between cohorts may reflect patient and procedural characteristics as well as the procedure itself. The registry’s warning that the arms are not a like-for-like control comparison is important context for any potential comparison.

The study’s secondary aims span several kinds of outcomes, including complications, ICU mortality, fluid balance, and length of stay. Each raises different questions about outcome definition, follow-up, and analysis. Considering multiple outcomes also makes prespecification and transparent reporting important, yet the registry record does not report a statistical analysis plan or multiplicity approach.

The record’s value for statistical interpretation is therefore primarily in its description of the study questions and design. It does not provide the outcome results needed to estimate event frequency, quantify precision, or evaluate associations. Recognizing that distinction helps prevent the study’s objectives and adverse-event entries from being mistaken for evidence about the primary endpoint.

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 restrict interpretation of the registry record. Although the study is marked completed, the primary endpoint result and the results for the stated secondary outcomes are not reported. The record lists zero analyses, so it does not provide effect estimates, uncertainty intervals, or model outputs for assessing the study questions.

The two cohorts are observational and allocation is not stated. The registry explicitly says they are not a like-for-like control comparison. The record does not report participant characteristics by cohort, the extent of overlap between cohorts, or adjustment methods. As a result, a cohort contrast could not be interpreted as a causal effect from the registered information.

The registry gives an enrollment of 528 but does not report the number analyzed for the primary endpoint, cohort-specific endpoint denominators, or completeness of follow-up. It also does not report how missing outcome data were handled or define the analysis populations. This makes it difficult to assess whether any future reported outcome counts represent all enrolled participants or a subset.

The primary outcome combines death with multiple severe complications. While the definitions are listed, component-level results are not reported, limiting assessment of what would drive a composite result. The adverse-event fields are separate from the primary outcome reporting and do not resolve this limitation.

Further details—including eligibility criteria, center-level information, the study’s own sample-size justification, a statistical analysis plan, and a multiplicity strategy—are not reported in the registry record. These omissions limit assessment of representativeness, analytical choices, and the robustness of any conclusions based on results reported elsewhere.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Assessment of Patients Undergoing Cardiac Surgery and Admitted to the Intensive Care Unit — NCT06154473.
• Registry record last updated 2026-06-11; status last verified 2025-09.
• Results first posted 2026-06-11.
• 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 registry describes a completed, prospective, multicenter observational study sponsored by Hospital Israelita Albert Einstein. It lists an enrollment of 528 and a study start date of 2023-09-01, with primary completion on 2025-03-18. The cohorts are patients undergoing open heart surgery and percutaneous cardiovascular surgery; allocation is not stated, and the registry cautions that the arms are not a like-for-like control comparison.

The primary endpoint combines mortality or severe postoperative complications within the first 3 postoperative days or until ICU discharge, whichever occurs first. Nine outcome measures are listed, but zero analyses are listed. The primary endpoint result, statistical analysis plan, missing-data methods, and outcome estimates are not reported in the registry record. The adverse-event fields list zero serious and zero other adverse events in each cohort, with deaths listed separately as 14 and 1, respectively. These fields do not replace a reported primary endpoint analysis.