Pecto-Intercostal Fascial Plane Block Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Pecto-Intercostal Fascial Plane Block Study (NCT04928339), a randomized phase 4 study. The primary outcome is Total Opioid Consumption 72 Hours Post-operatively.

2. Clinical Question

The study is registered as a Phase 4 randomized, double-masked, parallel-group trial. Its stated purpose is to assess whether the intervention changes postoperative pain and opioid requirements relative to saline control. The primary endpoint addresses opioid use over the initial postoperative period; the registry also identifies pain outcomes and other postoperative measures as secondary outcomes.

The question is comparative: the relevant interpretation concerns the pattern of opioid consumption in the two randomized groups, not whether a value in one group is clinically acceptable in isolation. The posted primary summaries are medians with inter-quartile ranges. The registry record does not report a primary between-group test or an estimated treatment contrast with uncertainty, so the summaries alone do not establish the result of a formal comparison.

3. Trial Design

The registry describes a randomized, double-masked, parallel-group study sponsored by the University of Wisconsin, Madison. It is listed as Phase 4 and completed. The record gives a planned enrollment of 100 participants, and the posted primary results include 50 participants in each group. The start date is 2022-03-28, and the primary completion date is 2023-09-03.

Participants were assigned to bilateral PIFB with a mixture of standard and liposomal bupivacaine or to bilateral PIFB with saline only. The study summary characterizes the saline blocks as sham blocks. The record labels the trial double-masked, but does not report which groups of people were masked or how masking was maintained.

The primary endpoint is total opioid consumption during the initial 72 hours after surgery, measured in MME. The primary outcome is specified as a median with inter-quartile range. The record also lists secondary outcomes involving pain, opioid use at later time points, mechanical ventilation, bowel movement, and postoperative delirium. It reports 12 outcome measures and 11 posted secondary outcomes, but the numerical secondary results included in this record cover only delirium episodes and opioid use at 90 days.

The registry record does not report the randomization sequence method, allocation concealment, eligibility criteria, details of recruitment, participant flow, or the specific masking procedures. It also does not report a protocol-based sample-size justification, prespecified interim analyses, or a statistical analysis plan. These omissions limit what can be assessed about implementation and planned analysis beyond the design labels and outcome descriptions recorded in the registry.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Total Opioid Consumption 72 Hours Post-operatively, measured over up to 72 hours post-operatively.

The primary endpoint is total opioid consumption during the initial 72 hours after surgery, expressed in morphine milligram equivalents (MME). It is intended to represent cumulative postoperative opioid use over a defined period and directly addresses the study’s stated interest in opioid requirements after cardiac surgery. Pain scores and opioid consumption measure related but distinct aspects of postoperative experience, which is why the record includes pain outcomes separately.

The registry specifies a median and inter-quartile range for this endpoint. The posted median is 165.0 MME for the PIFB intervention group, with an inter-quartile range of 103.0 to 283.8. For the saline control group, the median is 205.1 MME, with an inter-quartile range of 144.9 to 280.8. These summaries describe the center and spread of observed values in each group; they do not, by themselves, quantify the uncertainty in a between-group effect.

A median can be useful when observations are unevenly distributed or include unusually high values, because it describes the midpoint rather than being pulled toward extremes in the same way as an arithmetic mean. The inter-quartile range describes the middle portion of the observed distribution. Those are general properties of these summaries, not evidence about the shape of this trial’s data beyond the reported values.

The registry does not report a primary comparison estimate, confidence interval, or p-value. It also does not report whether opioid consumption was analyzed with a model or adjusted for any other variables. Consequently, the endpoint summaries describe the two groups, but the registry record alone does not provide a formal estimate of the precision of their difference.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The endpoint is reported as a median with an inter-quartile range. A median is the central observation in an ordered set of values, while the inter-quartile range describes the spread of the middle part of that distribution. These summaries can convey the center and variability of opioid consumption without assuming that the distribution is symmetric. General statistical guidance is that medians and inter-quartile ranges are especially interpretable when distributions are skewed, but the registry does not report a distributional assessment for this endpoint.

The PIFB group’s median is 165.0 MME and its inter-quartile range is 103.0 to 283.8. The saline control group’s median is 205.1 MME and its inter-quartile range is 144.9 to 280.8. The inter-quartile ranges describe spread within each group; they are not confidence intervals for the difference between groups. Overlap or non-overlap of group summaries is not a substitute for a direct comparison with uncertainty.

A treatment contrast would summarize the difference between groups using a prespecified scale and analysis. A confidence interval for that contrast would show a range of values compatible with the data and the analysis assumptions. The registry record does not report such an interval or a primary test for total opioid consumption. Nor does it identify a model, transformation, covariate adjustment, or method for handling unusual observations. Those details are not reported in the registry record, so the posted primary summaries should remain descriptive.

The two secondary comparisons use binary outcomes: whether participants experienced postoperative delirium episodes and whether they were using opioids at 90 days. A risk difference expresses the difference between the observed proportions in the groups, with the direction determined by the comparison order. For delirium, the point estimate is -0.06 for PIFB relative to saline; for opioid use at 90 days, it is 0.02. The point estimates are recalculations from the posted group counts and are unadjusted.

A confidence interval communicates uncertainty in an estimate, conditional on the method used to construct it. For the delirium comparison, the reported interval is -0.191 to 0.071; for opioid use at 90 days, it is -0.047 to 0.087. Both intervals span zero, meaning that the intervals include differences in either direction as well as no difference. The widths indicate that the estimates do not pin down a narrow range of plausible risk differences. This is particularly important when the observed event counts are small.

The p-values for these unadjusted secondary comparisons are 0.372 for delirium and 0.558 for opioid use at 90 days. A p-value measures how unusual data at least as incompatible with a stated null model would be, if that model and the analysis assumptions held. It is not the probability that the null hypothesis is true, and it does not measure clinical importance. In these results, the p-values do not provide strong evidence against a no-difference null model. They do not prove equivalence or absence of an effect, either.

The recalculated secondary comparisons are not sponsor-reported analyses. The registry lists no reported analyses for either result, and the recorded discrepancy indicator is false. Therefore, the recalculations are best treated as simple unadjusted readings of the posted counts rather than as the trial’s full prespecified analysis. No adjustment for baseline characteristics or other variables is shown in the registry record.

The record includes planning illustrations for the two binary secondary comparisons. These use a two-sided significance level 0.05, equal allocation, and a normal approximation, with the effect set to a stated fraction of the observed effect. For delirium, the illustration gives 492 participants per arm for 80% power and 659 participants per arm for 90% power when planning for 100% of the observed effect; at 75% of the observed effect, it gives 919 and 1,229 participants per arm; at 50%, 2,162 and 2,893. For opioid use at 90 days, the corresponding figures are 1,141 and 1,527 for 100% of the observed effect, 1,865 and 2,496 for 75%, and 3,826 and 5,121 for 50%.

These are planning illustrations, not observed power and not evidence about the original trial’s design. They are derived from the observed secondary effects and stated assumptions; the registry does not report that these assumptions were used to plan the study. In general, planning for a smaller effect requires more participants to achieve a specified power under otherwise unchanged assumptions. The illustrations should not be mistaken for a sample-size justification for the primary opioid-consumption endpoint.

Over-dispersion is a general statistical concern when count or binary outcomes vary more than an assumed model allows. If present, a model that understates variability can produce uncertainty estimates that are too narrow. The registry record does not report a model for the secondary outcomes or a check for over-dispersion, and the comparisons listed are unadjusted calculations from summary counts. No claim about whether over-dispersion occurred in this trial can be made from the recorded results.

10. Multiplicity, Missing Data and Analysis Populations

The registry record does not report a statistical analysis plan describing how multiplicity was handled across the primary and secondary outcomes. It also does not report whether the secondary outcomes were arranged in a prespecified testing hierarchy or whether any adjustment to account for multiple comparisons was planned. With several outcomes listed, unadjusted secondary p-values require caution: the more comparisons considered, the greater the possibility that an apparently notable result arises by chance. The record does not quantify that possibility or give an adjusted analysis.

The primary endpoint is specified, but the registry does not report its analysis method, a primary comparison estimate, a confidence interval, or a p-value. The record reports no analyses. The two secondary comparison estimates are unadjusted recalculations from posted counts, and no sponsor-reported analyses are listed for them. The registry also does not state whether these calculations follow the trial’s prespecified analysis approach.

Missing-data procedures are not reported in the registry record. There is no posted account of missing observations for the primary endpoint, missingness in secondary outcomes, reasons for missing data, or an imputation or sensitivity-analysis strategy. The posted arm counts for the primary and two numerical secondary outcomes are 50 participants each, but those counts alone do not establish whether all randomized participants contributed to every outcome or how missing measurements were handled.

Analysis populations are also not reported in the registry record. The record does not specify whether results were based on all randomized participants, participants who received their assigned intervention, or another population definition. It does not report exclusions after randomization or departures from assigned treatment. These details matter because analysis population choices can affect the interpretation of randomized comparisons.

Interim analyses, stopping rules, and the handling of protocol deviations are not reported in the registry record. Their absence from the record should not be taken as evidence that they did or did not occur. Without these details, the posted results cannot be fully evaluated against a prespecified analysis plan, and the secondary findings should be regarded as limited, unadjusted evidence.

11. 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.

For both groups, the registry reports 50 participants at risk for serious adverse events, 0 participants with a serious adverse event, 50 at risk for other adverse events, and 0 participants with an other adverse event. Deaths are recorded as 0 in each group. No top serious adverse event terms are listed.

These figures describe the adverse-event counts recorded for the groups in this registry entry. They do not establish that no adverse events of any kind occurred beyond the categories and definitions reflected in the registry record. The entry does not provide event descriptions, event severity criteria, collection methods, exposure-adjusted rates, or a narrative safety analysis. The absence of listed serious-event terms is not an estimate of the risk of an event outside this study or under other circumstances.

Zero observed events in a group is not the same as proof that an event is impossible. Safety estimates are most informative when considered with the number of participants observed, the period of observation, and the completeness of event reporting. The study summary says participants could expect to be on study for 100 days, while the adverse-event figures alone do not specify the relevant event-collection window. The posted counts therefore provide a concise record of reported events, not a comprehensive safety conclusion.

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

The results describe a randomized comparison of bilateral PIFB using bupivacaine formulations with saline-only blocks in cardiac surgery patients. For the primary endpoint, the posted median opioid consumption is 165.0 MME in the PIFB group and 205.1 MME in the saline control group during up to 72 hours after surgery. The inter-quartile ranges describe the spread within each group. These summaries establish what was recorded for the groups, but they are not a formal estimate of the difference between them.

The registry does not report a primary inferential analysis. Without a primary contrast and its uncertainty, the difference between the posted medians cannot be interpreted as a statistically established effect. The summaries also do not determine whether any observed separation is clinically important. The secondary numerical comparisons are unadjusted, have uncertainty intervals that span zero, and do not provide a conclusive result. They measure different outcomes and time points from the primary endpoint.

The findings do not establish that PIFB reduces opioid use or pain, nor do they establish that it has no effect. A lack of a reported primary test is not evidence of equivalence. Similarly, the unadjusted secondary p-values do not demonstrate that the groups are the same; they reflect uncertainty in the comparisons available in the registry record.

The safety counts record no serious adverse events, other adverse events, or deaths in either group. Those counts should not be generalized beyond the participants and event reporting described in the record. The registry does not supply event definitions, detailed safety follow-up, or a broader safety analysis.

Interpretation is also limited by unreported information about missing data, analysis populations, masking procedures, and the planned analysis. These are important to judging whether the randomized comparison was preserved in the analysis and whether the reported results match the original analysis plan. The registry record supports a cautious description of observed summaries and limited secondary estimates, not a definitive statement about efficacy, lack of efficacy, or overall safety.

13. Why This Trial Matters Statistically

This trial is statistically interesting because its primary question is framed around an outcome that can be summarized in more than one way. The registry specifies total opioid consumption in MME, reported as a median with an inter-quartile range. That choice emphasizes the center and spread of the observed distributions, but an arm-by-arm summary is not itself a treatment-effect estimate. A complete inferential account would also identify the comparison scale, method, and uncertainty for the contrast.

The posted primary summaries differ in their medians, while their inter-quartile ranges overlap. Neither observation alone determines the result of a formal comparison. This is a useful example of why statistical interpretation should distinguish descriptive summaries from inferential estimates. A direct effect estimate with an uncertainty interval would make the size and precision of the group contrast easier to evaluate, but it is not reported in the registry record.

The secondary comparisons illustrate another important issue: sparse binary outcomes can yield uncertain estimates. The delirium and 90-day opioid-use comparisons are based on small counts, and their confidence intervals span zero. The point estimates give a direction, but the uncertainty intervals show that a range of directions remains compatible with the data under the stated calculation. Reporting counts alongside estimates helps readers see the scale of the underlying information.

The registry also lists many secondary outcomes without numerical results in this statistical record. Multiple outcomes can be useful for describing different aspects of recovery, but they complicate interpretation when no multiplicity strategy or testing hierarchy is reported. A result on a secondary measure should not be treated as independent confirmation of the primary question without considering this context.

Finally, the planning illustrations demonstrate why sample-size calculations depend on the effect size chosen for planning. They are based on observed secondary effects and stated assumptions, not on the trial’s reported design justification. Separating those planning illustrations from observed evidence avoids confusing a hypothetical future-study calculation with the strength of evidence in the completed trial.

14. 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.

A central limitation is the absence of a reported primary analysis. The registry provides group medians and inter-quartile ranges for total opioid consumption, but not a primary treatment contrast, confidence interval, or p-value. This prevents a direct assessment of the estimated primary effect’s precision and makes it inappropriate to infer a formal result from the descriptive summaries alone.

The available secondary numerical results are limited to two outcomes, and both are simple unadjusted recalculations from posted counts. Their confidence intervals are wide and span zero. Numerical results for the other listed secondary outcomes are not reported in the registry record, so a broader view of pain, opioid consumption, and recovery cannot be formed from these results.

Several details needed to assess the trial’s conduct and analysis are not reported in the registry record. These include eligibility criteria, the randomization method, allocation concealment, masking procedures, analysis populations, missing-data methods, protocol deviations, and the statistical analysis plan. The record also does not report interim analyses or multiplicity procedures. These omissions limit evaluation of bias, precision, and whether the analyses followed prespecified methods.

The primary endpoint is total opioid consumption over up to 72 hours, while the later opioid-use outcome records participants using opioids at 90 days. These outcomes are not interchangeable: one summarizes cumulative use over an early period, while the other is a participant count at later follow-up. The secondary comparisons therefore cannot substitute for a missing primary inferential result.

The record reports no adverse events in the posted categories, but does not provide detailed event definitions or a narrative safety analysis. Those counts are limited to what was entered in the registry. Finally, the planning illustrations are based on observed secondary effects and do not document the original study’s sample-size justification. The rationale for the planned enrollment is not reported in the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Pecto-Intercostal Fascial Plane Block Study — NCT04928339.
• Registry record last updated 2024-11-19; status last verified 2024-11.
• Results first posted 2024-11-19.
• 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.

18. Record Summary

NCT04928339, titled “Pecto-Intercostal Fascial Plane Block Study,” is a completed Phase 4 randomized, double-masked, parallel-group trial sponsored by the University of Wisconsin, Madison. The registry lists planned enrollment of 100, a start date of 2022-03-28, and a primary completion date of 2023-09-03. The posted primary results include 50 participants in each group.

The primary outcome is total opioid consumption in MME up to 72 hours after surgery, reported as a median and inter-quartile range. The PIFB group median is 165.0 MME (103.0 to 283.8), and the saline control median is 205.1 MME (144.9 to 280.8). A primary comparison analysis is not reported in the registry record.

Two numerical secondary comparisons are included: postoperative delirium episodes and opioid use at 90 days. Their unadjusted estimates are uncertain, with confidence intervals spanning zero. The registry reports 0 serious adverse events, 0 other adverse events, and 0 deaths in each group. Details of the analysis plan, missing-data methods, and analysis populations are not reported in the registry record.