Biomarker and Thrombogenicity Assessment in Cardiopulmonary Bypass Surgery Utilizing Acute Normovolemic Hemodilution: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Biomarker and Thrombogenicity Assessment in Cardiopulmonary Bypass Surgery Utilizing Acute Normovolemic Hemodilution (NCT03326323), a registered phase not stated study. The primary outcome is Recovery in Platelet Function Post ANH.

2. Clinical Question

The registry record frames the study around the effects of ANH on transfusion requirements after cardiac surgery, coagulation, platelet hemostasis, and chest tube drainage 24 hours after CABG. Its primary outcome narrows that broad interest to platelet-function recovery. This is a pilot study, and the record lists enrollment of 43. That enrollment figure does not establish how many participants contributed data to the primary outcome.

The clinical question is descriptive in the record: it asks about the recovery time after ANH. It is not presented as a randomized comparison of ANH against a control procedure. Because a suitable comparison is not described, the record cannot establish from this design whether any observed recovery pattern is attributable to ANH rather than other influences. The registry record does not report a numerical primary-outcome estimate or a comparison analysis.

3. Trial Design

The registry record identifies this as a completed pilot study sponsored by Inova Health Care Services. Its title concerns biomarkers and thrombogenicity during cardiopulmonary bypass surgery utilizing acute normovolemic hemodilution. The official title describes a pilot study of changes in coagulation markers during cardiopulmonary bypass surgery utilizing ANH. The listed condition is Bleeding Reduction.

The study start date is 2018-03-19, and the primary completion date is 2019-09-17. Enrollment is listed as 43. The intervention is ANH, classified as a procedure. The arm description identifies patients undergoing ANH during CABG; a separate control arm is not described in the record. Allocation is not stated, and the record cautions that the arms are not a like-for-like control comparison. These details support describing the study as a single-arm intervention record rather than a randomized treatment comparison.

The stated primary outcome is recovery in platelet function after ANH. A secondary outcome is recovery in mean clot firmness post ANH. Across the record, two outcome measures are listed, but the number of analyses is 0. No statistical analysis results for the primary or secondary outcomes are reported in the registry record. The record does not report the protocol’s sample-size justification, an interim-analysis plan, or a statistical-analysis plan. Although planning assumptions are described for sample-size illustrations, they should not be treated as the study’s own design justification or as evidence of observed treatment effects.

The brief summary also identifies transfusion requirements, coagulation, platelet hemostasis, and chest tube drainage as areas of interest. Those statements describe the study’s rationale and scope; they do not supply numerical findings for these outcomes. In particular, the summary’s reference to chest tube drainage 24 hours post CABG does not substitute for a reported result.

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

Reasons for not completing this period:

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 Recovery in Platelet Function Post ANH, measured over Baseline through 24 hours post ANH procedure.

The primary endpoint is titled recovery in platelet function post ANH. It is defined as the time, in hours, for platelet function to return to pre-procedure levels after ANH, measured by platelet aggregation. The stated observation period runs from baseline through 24 hours post procedure. The outcome is continuous, and the record specifies a mean with standard deviation as its summary form.

As general statistical context, a recovery-time measure describes the time scale of change in a biological marker. Platelet aggregation is the measurement named in this record; the endpoint is not itself a count of transfusions, a measure of chest tube drainage, or a direct clinical outcome. A mean can describe the average recovery time among participants with usable measurements, while a standard deviation describes variation around that mean. Interpretation depends on knowing how many participants contributed measurements, how missing observations were handled, and whether all participants were assessed comparably. Those details are not reported in the registry record.

The endpoint was selected to characterize platelet-function recovery in relation to ANH. The registry record does not report the mean, its standard deviation, or any analysis of this endpoint. Consequently, it is not possible to describe the observed recovery time or its precision from the posted results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The outcome is continuous and is specified as a mean with standard deviation. The record gives a unit of hours and defines the endpoint as the time until platelet aggregation returns to pre-procedure levels after ANH. No numerical estimate or analysis is reported. The following concepts explain how such results are generally interpreted; they do not describe analyses documented for this study.

What does a mean describe?

In general, a mean summarizes the average value of a continuous measurement in the analyzed observations. For a recovery-time outcome, it would indicate the average time to the defined recovery threshold among the participants included in the calculation. Its interpretation depends on a consistent definition of recovery and on comparable measurement and follow-up. The registry record states the endpoint definition and timeframe, but does not report the observed mean, the number contributing data, or operational details about how recovery was determined.

What does the standard deviation add?

In general, the standard deviation describes the spread of individual measurements around the mean. It is not the same as the uncertainty in the mean: the former concerns variation among observations, while uncertainty in an estimated mean also depends on the amount and structure of the available data. The record specifies standard deviation as the dispersion measure, but does not report its value. Therefore, neither the average recovery time nor the distribution of individual recovery times can be assessed from the posted results.

How would a confidence interval be read?

In general, a confidence interval gives a range of values compatible with an estimate under the method’s assumptions. A narrower interval indicates greater precision for the quantity estimated, while a wider interval indicates less precision. It does not show the range containing most individual participants, and it does not by itself establish clinical importance. No confidence interval for the primary outcome is reported in the registry record.

Why does the comparison structure matter?

The record identifies patients undergoing ANH during CABG and does not describe a like-for-like control comparison. Allocation is not stated. In general, a comparison group can help distinguish changes associated with an intervention from changes that might occur over time or alongside other aspects of care. Without an appropriate comparison, a before-and-after pattern can describe observed change but cannot, by itself, attribute that change to the procedure. Here, even a numerical before-and-after result is not posted.

The registry record’s sample-size assumptions describe a planning illustration: a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a stated fraction of the observed effect. The record also distinguishes illustrations for time-to-event outcomes, which use total events, from other illustrations, which use participants per arm. These assumptions do not establish that the study used that design, and they do not constitute the trial’s own sample-size justification. The record does not report an observed effect from which to interpret an effect-based planning illustration. Such illustrations are planning quantities, not observed power.

General statistical context: normal-approximation methods rely on assumptions about how an estimate behaves across repeated samples. If measurements are strongly skewed, especially for times, an average and a normal-based interval may not adequately describe the data. Alternative summaries or models may be useful depending on the measurement process and distribution. The registry record does not report a distributional assessment or a statistical method for this endpoint, so no particular approach can be attributed to the investigators.

Over-dispersion is a general concern when observed variability exceeds what an assumed statistical model allows. If a model ignores that extra variation, uncertainty can be understated. The record does not indicate that an over-dispersion model was used or needed; this is a general consideration, not a finding about this study. Similarly, the record does not report interim analyses, a prespecified analysis plan, or model diagnostics.

For this study, the central methods limitation is not a disagreement between a reported analysis and a recalculation: there are no outcome analyses reported to compare. No recalculated estimate can be derived from the registry record. Any statistical interpretation must therefore remain at the level of endpoint definition, design description, and the limits imposed by absent results.

10. Confidence Intervals for Each Arm

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

R code and output

arm <- c("Patients Undergoing ANH During CABG")
n   <- c(40)
m   <- c(2)
sp  <- c(30)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Patients Undergoing ANH During CABG  40  2.000  30.000  -7.594  11.594

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists two outcome measures: recovery in platelet function post ANH as the primary outcome, and recovery in mean clot firmness post ANH as a secondary outcome. It lists 0 analyses. It does not report outcome-specific estimates, p-values, confidence intervals, or a multiplicity procedure. The record also does not report a statistical-analysis plan explaining how multiple outcomes or tests were to be handled.

As general statistical context, examining multiple outcomes or multiple statistical tests can increase the chance of finding an apparently notable result by chance. A prespecified hierarchy or adjustment can address some multiplicity concerns, but the appropriate approach depends on the aims and analysis plan. No such procedure is reported, so it is not possible to determine how multiplicity was considered.

Missing-data handling is not reported in the registry record. The enrollment figure is 43, while the adverse-event record lists 40 participants as at risk; these figures refer to different record elements and do not establish how many participants had primary-outcome measurements. The record does not state whether measurements were unavailable, whether participants were excluded from endpoint analyses, or how incomplete follow-up was handled.

The analysis population is also not reported. The registry record does not say whether all enrolled participants, only participants with observed measurements, or another defined group would be included in an outcome analysis. Without this information and the outcome results, readers cannot assess the potential influence of missing observations, exclusions, or differing denominators.

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 adverse-event record lists the group as patients undergoing ANH during CABG. It reports 40 participants at risk for serious adverse events and 0 affected; it also reports 40 at risk for other adverse events and 0 affected. Deaths are listed as 0, and no top serious-event terms are listed.

These are the registry’s recorded counts for this group. They should not be treated as a complete characterization of safety beyond the information recorded. The record does not provide event descriptions, timing, severity breakdowns, or details about how adverse events were collected. It also does not explain why the at-risk figure is 40 when the study enrollment is listed as 43. The two figures should therefore be reported as recorded, not reconciled by assumption.

General statistical context: observing 0 recorded events does not prove that an event cannot occur, and it does not establish the absence of risk. The precision of a safety estimate depends on the amount of follow-up and the way events were sought and defined, details that are not reported. These adverse-event counts do not supply an estimate of platelet-function recovery or a comparison with another group.

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

The registry record establishes the study’s stated purpose, population description, intervention, outcome definitions, and recorded safety counts. It describes a completed pilot study of ANH during CABG and identifies platelet-function recovery after ANH as the primary outcome. It also identifies recovery in mean clot firmness as a secondary outcome. These elements clarify what the study set out to examine.

The record does not report numerical results for either outcome, and it lists 0 analyses. It therefore does not show how long platelet function took to recover, how variable that time was, or whether mean clot firmness changed. The study summary’s discussion of transfusion requirements, coagulation, platelet hemostasis, and chest tube drainage describes the areas of interest, not findings. No conclusion about the magnitude or direction of effects on those outcomes can be drawn from the posted information.

The record describes an ANH group without a like-for-like control comparison, and allocation is not stated. In general, a comparison is needed to distinguish an intervention-associated effect from other explanations for observed changes. Even if numerical before-and-after measurements were available, this design description would limit causal interpretation. In this case, the additional limitation is that the numerical outcome analyses are not reported.

The adverse-event record lists 0 serious adverse events, 0 other adverse events, and 0 deaths among the reported group, with 40 participants at risk for each adverse-event category. Those entries describe registry counts, not proof that the procedure has no risks. The record does not report the details needed to assess completeness of event ascertainment or follow-up.

Accordingly, the record is informative about the pilot study’s question and reporting gaps, but it does not support a claim that ANH improves, worsens, or has no effect on platelet function, coagulation, bleeding, or transfusion outcomes. Those conclusions would require outcome results and a design capable of supporting the relevant comparison.

14. Why This Trial Matters Statistically

This study matters statistically because it illustrates the difference between a clearly described research question and a reported estimate that can be evaluated. The record defines platelet-function recovery as time in hours until platelet aggregation returns to pre-procedure levels, and specifies a mean and standard deviation. That gives readers a basic framework for understanding the intended endpoint. However, without the estimate, dispersion, and analysis details, the endpoint cannot be interpreted quantitatively.

The record also highlights why design structure matters. It identifies patients receiving ANH during CABG but does not describe a like-for-like control comparison; allocation is not stated. A descriptive measure of recovery could characterize observations in the treated group, but a causal interpretation requires a defensible comparison and appropriate handling of potential differences between groups. The record itself cautions against treating its arms as a control comparison.

For biostatistical reporting, the absence of outcome analyses is consequential. Enrollment of 43 is not a substitute for the number analyzed, a mean, a measure of spread, or an interval expressing precision. Nor can planning assumptions replace observed results. The record’s stated sample-size illustration assumptions are distinct from a study-specific justification, and no observed effect is available in the registry record to interpret those illustrations.

Finally, the adverse-event counts demonstrate the need to read denominators and follow-up information alongside event counts. The record lists 40 at risk in each category, but does not explain the relation to the enrollment figure or report collection details. This case therefore emphasizes transparent reporting of endpoint results, analysis populations, missing data, comparison structure, and safety ascertainment. Without those elements, readers can identify what was intended and recorded, but cannot judge statistical precision or effects.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The main limitation is that no numerical primary or secondary outcome result is reported in the registry record. Although the primary endpoint is defined and a summary form is specified, the mean and standard deviation are absent. The number of analyses is listed as 0. As a result, the central question about platelet-function recovery cannot be answered from the posted results.

The record describes an ANH group during CABG but does not describe a like-for-like control comparison. Allocation is not stated. This limits causal interpretation and prevents a treatment contrast from being evaluated. The registry record does not report participant characteristics, detailed eligibility criteria, or the number contributing data to each outcome.

Missing-data procedures and analysis populations are not reported. The enrollment figure is 43, while the adverse-event group lists 40 at risk; the record does not explain the difference, and these figures should not be assumed to refer to the same analysis population. Measurement procedures beyond the stated platelet aggregation measure are not described in the outcome entry, and the registry record does not report how recovery was operationalized in analysis.

The record does not report the statistical-analysis plan, sample-size justification, interim analyses, multiplicity handling, or methods for assessing assumptions. The sample-size assumptions are identified as planning illustrations, not as the trial’s own design rationale. The adverse-event counts also lack detail on event ascertainment and follow-up. Taken together, these reporting limits restrict assessment of precision, robustness, and generalizability, even apart from the absence of outcome estimates.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Biomarker and Thrombogenicity Assessment in Cardiopulmonary Bypass Surgery Utilizing Acute Normovolemic Hemodilution — NCT03326323.
• Registry record last updated 2020-01-13; status last verified 2019-12.
• Results first posted 2020-01-13.
• 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

NCT03326323 is listed as a completed pilot study sponsored by Inova Health Care Services. The registry record gives enrollment as 43 and identifies ANH during CABG as the intervention. The study start date is 2018-03-19, and the primary completion date is 2019-09-17.

The primary outcome is time in hours for platelet function, measured by platelet aggregation, to return to pre-procedure levels after ANH, from baseline through 24 hours post procedure. The secondary outcome is recovery in mean clot firmness post ANH. The record lists two outcome measures and 0 analyses, and reports no numerical outcome results.

The record describes no like-for-like control comparison and does not state allocation. For the listed ANH group, it reports 40 at risk for serious adverse events and 0 affected, 40 at risk for other adverse events and 0 affected, and 0 deaths. No top serious-event terms are listed. The relationship between the enrollment and adverse-event at-risk figures is not explained in the registry record.