The Effect of Prophylactic FFP Administration on ECMO Circuit Longevity: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Effect of Prophylactic FFP Administration on ECMO Circuit Longevity (NCT01903863), a randomized na study. The primary outcome is ECMO Pump Longevity.

2. Clinical Question

The study asks whether a scheduled transfusion approach is associated with a different duration of ECMO circuit use than transfusion according to institutional practice. It also describes FFP use as a study interest. The registry record gives the intervention and comparator but does not report a primary outcome result for FFP use in the registry record for this analysis.

The question is specific to patients receiving ECMO and to the circuit-level outcome. It is not a comparison of FFP with no FFP: the control group could receive FFP according to institutional standard of care. The scheduled strategy was every 48 hours, while the control strategy was guided by specified clinical circumstances in the record. The study also lists secondary outcomes involving complications, blood products, laboratory measures, and time to therapeutic aPTT.

The registry describes the study as a randomized pilot study. The record does not report a broader target population beyond neonatal and pediatric ECMO patients in the named care settings, nor does it report a subgroup question that would narrow the primary comparison.

3. Trial Design

This was a prospective, randomized, parallel-group pilot study with no masking. The registry lists the phase as NA and the status as completed. Enrollment was 31. The study began in 2013-07, and primary completion was recorded as 2016-02-18. Duke University is listed as the sponsor.

Patients were assigned to scheduled FFP or control. In the scheduled group, patients received FFP every 48 hours. The control group received FFP per current institutional standard of care, including supplementation for clotting or bleeding diatheses, volume replacement, or after 3 red blood cell transfusions in a 24 hour period. Thus the comparison concerns two administration strategies, not FFP versus no FFP.

The primary outcome was ECMO pump longevity, measured in hours during the ECMO course. The record defines circuit life as the time from the start of a circuit to circuit change or decannulation from ECMO for each patient. The registry reports a median of 187.0 hours for scheduled FFP, with an interquartile range of 94.0 to 329.0, and a median of 131.0 hours for control, with an interquartile range of 73.0 to 251.0. The group counts reported with this outcome are 15 and 16, respectively.

The record lists secondary outcomes related to hemorrhagic and thrombotic complications, antithrombin levels, plasma free hemoglobin, red blood cell transfusion, time to therapeutic aPTT, platelet transfusion requirement, and FFP transfusion requirements. The specific analysis populations, randomization details, allocation concealment, and procedures for handling protocol deviations are not reported in the registry record.

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 ECMO Pump Longevity, measured over ECMO course (median 198 hours).

The primary endpoint, ECMO pump longevity, measures how long an ECMO circuit remains in use. The registry defines circuit life as the interval from the start of a circuit until a circuit change or decannulation from ECMO, and expresses the duration in hours. This makes the endpoint a measure of circuit duration during the patient’s ECMO course rather than a direct measure of transfusion volume or a patient-centered clinical outcome.

Circuit longevity is relevant to the study question because the proposed rationale for scheduled FFP concerned maintaining a balance in coagulation and potentially reducing the need for circuit changes. That rationale is described in the study summary; it should not be mistaken for a result. The endpoint records the duration of circuit use, but by itself does not establish why a circuit was changed or whether any observed duration difference was caused by the assigned FFP strategy.

The registry reports this outcome using the median and interquartile range. In general, the median gives the midpoint of ordered observations and is less affected by extreme values than the arithmetic mean. The interquartile range describes the middle portion of the observed distribution. These summaries can be useful when outcome durations are unevenly distributed, though the registry record does not state why this summary was selected or provide the underlying individual durations.

The specified timeframe is the ECMO course, described in the record as median 198 hours. That timeframe is distinct from the reported arm-specific medians for pump longevity. The record does not report an effect estimate with a confidence interval for the between-group difference.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary comparison as a Wilcoxon (Mann-Whitney) test. This is a rank-based method for comparing observations between two independent groups. Rather than comparing arithmetic means directly, it orders the observed values and evaluates how the ranks are distributed across groups. In general, this approach can be useful when an outcome is skewed or when a mean-based model’s assumptions are not suitable. The registry does not report whether distributional checks were performed or why this test was selected.

What does a rank-based comparison test?

In general, the Wilcoxon-Mann-Whitney test evaluates whether values in one group tend to be higher or lower in rank than values in the other group. It is often described as a test of a difference in distributions. It should not automatically be interpreted as a test of medians alone: a median-focused interpretation requires additional assumptions about the shape of the distributions. The registry reports the test name but does not state a more detailed estimand or interpretation for the test.

The primary outcome is reported with medians and interquartile ranges. The median is a central summary, while the interquartile range reflects the spread of the middle part of the observations. Neither summary, on its own, shows the uncertainty in a between-group contrast. A confidence interval for an effect estimate would help communicate the range of effect sizes that are reasonably compatible with the data under the chosen method. The registry record does not report such an interval for the primary comparison.

How should the p-value be read?

The reported p-value is 0.39. In general, a p-value is calculated under a null hypothesis and the assumptions of a specified statistical test; it describes how unusual the observed data, or data more extreme, would be under that model. It is not the probability that the null hypothesis is true, and it does not quantify clinical importance. It also does not indicate whether the estimate is precise. The registry gives the p-value but does not report the test statistic, an effect estimate, or a confidence interval for the contrast.

The record describes randomized allocation and parallel groups. In general, randomization is intended to reduce systematic differences between groups at assignment, so a comparison can support an estimate of the effect of assignment when the analysis and follow-up preserve the randomized comparison. The registry does not report the randomization sequence method, allocation concealment, details of adherence, or the analysis population. Consequently, these design features cannot be assessed from the registry record.

Why does over-dispersion matter?

In general, over-dispersion means that outcome variation is greater than a model expects. It can make standard errors too small and confidence intervals too narrow if a model does not account for the extra variation. The primary analysis named in this record is a rank-based test, rather than a count model for an over-dispersed outcome. The registry does not report a diagnostic assessment of over-dispersion, and the record does not provide enough model details to assess whether it was relevant to any secondary analyses.

ECMO pump longevity is measured in hours and may be affected by the timing of circuit changes or decannulation. In general, time-to-event methods may be considered when events occur over follow-up and some observations are censored. The registry reports a Wilcoxon (Mann-Whitney) comparison and does not describe a time-to-event analysis, censoring rules, or an alternative method for handling patients whose circuit observation ended through decannulation. The recorded endpoint definition includes circuit change or decannulation as an end of circuit life, but the analysis handling of these events is not reported in the registry record.

The record lists 7 secondary outcomes and 10 analyses. When several outcomes or comparisons are examined, the chance of at least one apparently unusual result can increase unless the analysis plan addresses multiplicity. In general, multiplicity procedures may adjust interpretation or testing thresholds, depending on the goals of the study. The registry does not report whether any adjustment was planned or applied, how the listed analyses map to individual outcomes, or which outcomes were considered confirmatory versus exploratory.

Sample-size calculations are planning tools based on assumptions about an effect, variability, allocation, and error rates. They are not observed power calculations and cannot establish whether the completed study had adequate precision. The planning illustration described for this study uses the observed effect, two-sided significance level 0.05, equal allocation, and a normal approximation, with alternative target effects expressed as fractions of the observed effect. Those illustrations are assumptions for planning, not evidence that the study was designed around them. The registry does not report the trial’s own sample-size justification or statistical analysis plan.

10. Analyses Reported by the Sponsor

The registry reports the sponsor’s primary comparison as a Wilcoxon (Mann-Whitney) test, with p = 0.39. The arm-specific medians and interquartile ranges are also reported: 187.0 hours with an interquartile range of 94.0 to 329.0 for scheduled FFP, and 131.0 hours with an interquartile range of 73.0 to 251.0 for control. These values describe the posted group summaries; they are not a separate effect estimate with a confidence interval.

A recalculated comparison would be a simple unadjusted re-analysis of posted summary statistics, not a replacement for the sponsor’s analysis. The registry record does not report a recalculated effect estimate or recalculated test result for this primary comparison, so a numerical comparison between the sponsor’s analysis and a re-calculation cannot be made from the registry record. The sponsor’s reported p-value remains the available inferential result.

The p-value should be read alongside the group summaries and their uncertainty. The record does not provide a confidence interval for the primary between-group effect, so the precision of that contrast is not directly quantified. The sponsor’s test result does not establish equivalence, and the medians alone do not establish the size or clinical importance of an effect.

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 7 secondary outcomes and 10 analyses in addition to the primary outcome. The secondary outcomes include hemorrhagic and thrombotic complications, antithrombin levels, plasma free hemoglobin, red blood cell transfusion, time to therapeutic aPTT, platelet transfusion requirement, and FFP transfusion requirements. The record does not report how the listed analyses correspond to those outcomes, whether any outcome was designated as a key secondary outcome, or whether multiple comparisons were planned.

When a study examines several outcomes or contrasts, some results may appear notable by chance alone. In general, a prespecified hierarchy or multiplicity adjustment can help define how confirmatory claims should be interpreted. Whether such an approach was used is not reported in the registry record. No numerical results for the listed secondary outcomes are included in the registry record for this analysis, so they cannot be interpreted.

The registry record also does not report the amount or pattern of missing data for the primary or secondary outcomes. It does not describe imputation, sensitivity analyses, or how missing observations were handled. The analysis population is not reported in the registry record: it is not clear whether the primary analysis included all randomized participants, only participants with an observed circuit outcome, or another group. The record does not provide details on exclusions after randomization or protocol deviations.

These omissions matter because missing outcomes and post-randomization exclusions can affect the interpretation of a randomized comparison. They also limit assessment of whether the analysis followed an intention-to-treat approach. The registry record does not report the statistical analysis plan, so the prespecification of outcome definitions, analysis choices, or multiplicity handling cannot be verified from the available information.

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 5% reporting threshold.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: intracranial hemorrhage (33.3%).

The registry reports serious adverse events affecting 5 of 15 participants in the scheduled FFP group and 1 of 16 in the control group. It reports 0 other adverse events in each group. Deaths are listed separately as 6 in the scheduled FFP group and 8 in control. These are descriptive counts in the record; they do not, by themselves, establish that the assigned strategy caused or prevented an event.

The registry lists intracranial hemorrhage as a top serious adverse event term with 33.3%. The record does not specify in the registry record for this analysis the denominator or group attribution for that percentage. It should therefore be read as a registry-listed term and percentage, not converted into a participant count or assigned to a treatment group.

Safety comparisons require attention to the event definitions, observation period, exposure, and analysis population. Those details are not reported in the registry record. The counts also should not be combined or interpreted as mutually exclusive categories: the record does not state whether participants could experience multiple events or how serious events relate to the separately listed deaths. The small group counts make descriptive figures particularly unsuitable as stand-alone evidence of a difference in risk.

The serious adverse event figures are distinct from the primary endpoint of circuit longevity. The registry record does not report a formal comparative safety analysis or uncertainty intervals for these counts.

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

The posted results describe a randomized pilot comparison of scheduled FFP every 48 hours with FFP administered under institutional standard of care during neonatal-pediatric ECMO. The primary outcome was circuit longevity in hours. The reported median was 187.0 hours in the scheduled group and 131.0 hours in control, with the respective interquartile ranges of 94.0 to 329.0 and 73.0 to 251.0. The registry reports a Wilcoxon (Mann-Whitney) p-value of 0.39.

These results do not establish that scheduled FFP increases circuit longevity, nor do they establish that the two strategies have equivalent outcomes. A p-value does not quantify the magnitude or precision of a difference, and the registry does not report a confidence interval for the between-group effect. The posted medians are descriptive summaries, not a complete account of the distributions or an explanation for circuit duration.

The trial’s focus is circuit longevity. Its results should not be generalized automatically to all aspects of transfusion practice, other patient populations, or outcomes not measured in the record. The listed secondary outcomes cover several clinical and laboratory topics, but their numerical results are not reported in the registry record available for this analysis. The adverse event figures are descriptive and do not provide a formal estimate of comparative safety.

The record identifies the study as a pilot and reports enrollment of 31. It does not report the trial’s sample-size justification, analysis population, missing-data handling, or complete statistical analysis plan. Those gaps restrict assessment of precision and of how fully the reported analysis preserves the randomized comparison. Overall, the registry provides a primary outcome summary and a test result, but not enough information to make a definitive claim about the size, precision, or broader clinical implications of a difference between strategies.

14. Why This Trial Matters Statistically

This study illustrates why a trial result should be read through both its design and its statistical reporting. The clinical question concerns a scheduled transfusion strategy compared with usual institutional practice, not a treatment compared with no treatment. That distinction matters when interpreting the contrast: both groups could receive FFP, but the timing and indications differed.

The outcome is a duration measured in hours, reported as a median and interquartile range. These summaries make the central tendency and spread more visible than a single number would, but they do not directly quantify uncertainty in the between-group effect. The reported Wilcoxon comparison supplies a test result, while the absence of an effect confidence interval limits interpretation of precision. A p-value should not be used as a substitute for an effect estimate or its uncertainty.

The record also demonstrates the importance of separating a primary outcome from secondary outcomes and safety descriptions. Multiple outcomes can raise multiplicity questions, while adverse event counts require information about definitions, follow-up, and participant-level overlap. Here, the registry lists several secondary outcomes but does not report their numerical results or the approach to multiplicity.

Finally, pilot studies can contribute useful information about feasibility and outcome measurement, but their results require careful interpretation. The record does not report a formal sample-size justification or the analysis population. Without those details and an effect estimate with its uncertainty, the primary comparison is informative as a posted result but limited as a precise estimate of the contrast between strategies.

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 registry provides arm-level medians and interquartile ranges for the primary outcome, along with a Wilcoxon (Mann-Whitney) p-value, but does not report a between-group effect estimate with a confidence interval. This limits direct assessment of both the magnitude and precision of the comparison. The individual outcome data and full distributions are not reported in the registry record.

The outcome definition includes circuit change or decannulation as the end of circuit life, but the record does not report how these circumstances were represented in the analysis or whether any observations were censored. It also does not give reasons for circuit changes. The reported ECMO-course timeframe is median 198 hours, but details about follow-up and the handling of different ECMO course lengths are not reported in the registry record.

Further trial-analysis details are not reported in the registry record, including the randomization sequence method, allocation concealment, analysis population, adherence, protocol deviations, missing-data handling, and statistical analysis plan. The registry does not report the trial’s sample-size justification. Therefore, the planning illustrations based on the observed effect should not be mistaken for the original design rationale or for observed power.

The record lists 7 secondary outcomes and 10 analyses but does not describe multiplicity handling or provide numerical results for the secondary outcomes in the registry record for this analysis. Safety figures are descriptive; event definitions, observation details, group attribution for the listed intracranial hemorrhage percentage, and a formal comparative safety analysis are not reported in the registry record. These limitations constrain conclusions about secondary outcomes and safety as well as the primary endpoint.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: The Effect of Prophylactic FFP Administration on ECMO Circuit Longevity — NCT01903863.
• Registry record last updated 2017-06-27; status last verified 2017-05.
• Results first posted 2017-06-27.
• 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

NCT01903863 is a completed prospective, randomized, unmasked, parallel-group pilot study sponsored by Duke University. It enrolled 31 neonatal and pediatric patients requiring ECMO support. The comparison was scheduled FFP every 48 hours versus FFP administered per current institutional standard of care.

The primary outcome was ECMO pump longevity, measured in hours from circuit start to circuit change or decannulation. The reported medians were 187.0 hours for scheduled FFP and 131.0 hours for control. The registry reports a Wilcoxon (Mann-Whitney) comparison with p = 0.39. A confidence interval for the primary between-group effect is not reported in the registry record.

The record also lists secondary outcomes and descriptive adverse event figures. The statistical analysis plan, missing-data handling, analysis population, and multiplicity approach are not reported in the registry record.