Study of Exparel Versus Epidural for Pain Control After Thoracotomy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study of Exparel Versus Epidural for Pain Control After Thoracotomy (NCT02178553), a randomized phase 4 study. The primary outcome is Pain Scores With Cough on First Postoperative Day.

2. Clinical Question

3. Trial Design

The registry describes a randomized, parallel-group, unmasked phase 4 trial comparing epidural analgesia with intercostal bupivacaine after thoracotomy. Mayo Clinic is listed as the sponsor. The record reports enrollment of 102 participants, a start date of 2014-10-15, primary completion on 2018-10-09, and a completed status. These are registry entries and do not, by themselves, describe how participants were recruited or how the trial was conducted at each site.

The two groups are identified as Epidural and Intercostal Bupivicaine (Exparel). The registry’s arm descriptions refer to a thoracic epidural catheter in the epidural group and liposomal bupivacaine injected into intercostal spaces in the block group. Both descriptions end before the full procedures are specified. The exact treatment procedures beyond those fragments, including further details of administration and any co-interventions, are not reported in the registry record.

The endpoint results list 45 participants for epidural and 39 for intercostal bupivacaine. These are the group counts attached to the primary outcome, not a complete accounting of all enrolled participants. The registry record does not explain why these counts do not match the overall enrollment figure, nor does it identify the analysis population or give a participant flow account.

The official title identifies the study as a randomized non-inferiority trial of continuous thoracic epidural analgesia versus a single intercostal nerve block. The posted primary analysis is also categorized as non-inferiority. However, the registry record does not report the original sample-size justification, the non-inferiority margin rationale, or the full statistical analysis plan. The trial’s masking status is listed as none; the record does not describe whether outcome assessment was handled differently from treatment assignment.

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 Pain Scores With Cough on First Postoperative Day, measured over In the morning (8 am) on first postoperative day.

The primary endpoint is pain with cough, recorded using a numerical rating scale from 0 to 10 in the morning at 8 am on the first postoperative day. The registry reports the endpoint as a mean with standard deviation for each group. The posted group summaries are 6.1 with a standard deviation of 2.7 for epidural, among 45 participants, and 6.9 with a standard deviation of 2.4 for intercostal bupivacaine, among 39 participants. The posted comparison expresses the mean difference as 0.8, with the intercostal group listed as the comparison arm.

A cough-associated score captures pain in a specified activity rather than pain at rest. That makes it a distinct way to describe postoperative pain; it should not be treated as interchangeable with the separate resting-pain outcomes. The timing also matters: this is a measurement at one stated point on the first postoperative day, not a summary of pain across the whole recovery period.

In general, a mean summarizes the group’s average recorded score, while the standard deviation describes how spread out individual scores are around that mean. Neither gives the full distribution of responses. The registry record does not report the scale’s verbal anchors, a threshold for a meaningful difference, or how missing endpoint measurements were handled.

7. Results Posted in the Registry

• Intercostal Bupivicaine (Exparel): mean 6.90 versus 6.10 on control; difference 0.80 (95% CI -0.29 to 1.89), standardized effect d = 0.31; z-test p = 0.151.

8. Secondary Efficacy Endpoints

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

Pain Scores at Rest in the Morning on the First Postoperative Day

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Intercostal Bupivicaine (Exparel): mean 4.00 versus 2.90 on control; difference 1.10 (95% CI 0.20 to 2.00), standardized effect d = 0.53; z-test p = 0.017.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Intercostal Bupivicaine (Exparel) than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Pain Scores at Rest on the Second Postoperative Day

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Intercostal Bupivicaine (Exparel): mean 3.20 versus 2.80 on control; difference 0.40 (95% CI -0.35 to 1.15), standardized effect d = 0.23; z-test p = 0.295.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Intercostal Bupivicaine (Exparel) and the control. The interval gives the range of effects that remain compatible with the data.

The two posted secondary endpoints measure pain at rest on the first and second postoperative days. Their estimates show the same broad direction: the reported mean scores are higher in the intercostal bupivacaine group than in the epidural group. The strength of the evidence is not uniform across the two outcomes. One reported secondary analysis has an unadjusted p-value below 0.05, while the other does not. The estimates and intervals are shown in the tables and should be consulted for their individual magnitudes and uncertainty.

This pattern is related to, but does not resolve, the primary result. The primary endpoint concerns pain with cough on the first postoperative morning; the secondary measures concern pain at rest. Different activities and time points can yield different estimates. Agreement in direction across outcomes can be informative descriptively, but it does not convert the secondary outcomes into confirmation of the primary non-inferiority question.

The secondary analyses are unadjusted as posted. In general, when multiple outcomes are tested, the chance of at least one apparently noteworthy result can increase if no multiplicity procedure is used. A nominal p-value for one secondary outcome therefore carries less weight than a result interpreted under a prespecified plan that accounts for the number and hierarchy of tests. The registry record does not report whether a multiplicity adjustment or hierarchy was specified. The secondary results are best treated as supportive descriptions that need cautious interpretation, rather than as independent proof of a treatment difference.

The registry lists four outcome measures and four analyses, but only two secondary pain outcomes are posted. The remaining outcome details and any broader analysis plan are not reported in the registry record. That incomplete reporting makes it difficult to place the displayed secondary findings in the context of every planned comparison.

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

• Pain Scores at Rest in the Morning on the First Postoperative Day
• Pain Scores at Rest on the Second Postoperative Day

9. Statistical Interpretation

10. Statistical Methods Explained

The posted endpoint is continuous: each participant’s pain score is recorded on a numerical scale, and the registry summarizes the groups using means and standard deviations. A mean difference compares the group averages. Here, the comparison is listed as intercostal bupivacaine relative to epidural, and its estimate is 0.8. The standard deviations describe variation among individual scores within each group; they are not confidence intervals for the group means.

What does the confidence interval describe?

In general, a confidence interval is a range of values compatible with the observed data under the assumptions of the calculation. It communicates uncertainty around an estimate rather than the range of individual participants’ scores. A wider interval indicates less precision than a narrower one. The recalculated interval for the primary mean difference is -0.291 to 1.891. The sponsor’s reported analysis gives a 90% confidence interval from -0.1 to 1.8. These intervals come from differently described analyses in the registry; the posted record does not give enough methodological detail to attribute their difference to a particular choice.

What does the p-value say?

In general, a p-value describes how unusual data at least as discrepant as those observed would be under a specified null hypothesis and its assumptions. It is not the probability that a treatment has no effect, and it does not measure the size or clinical importance of a difference. The simple unadjusted comparison lists p=0.151. The sponsor’s listed test has p=0.142. The registry record labels the sponsor result as non-inferiority and identifies a two-sided t-test, but it does not fully describe the hypothesis, margin, or decision procedure behind that result. These p-values should therefore be read with the stated analysis labels and the posted estimates, not in isolation.

How is non-inferiority different from a test for equality?

General statistical context: a non-inferiority question asks whether an intervention is not worse than a comparator by more than a prespecified acceptable margin. It is not the same as asking whether the observed group difference is exactly zero. The margin and the direction of comparison are central to interpreting the result. Although the registry identifies this trial and its reported analysis as non-inferiority, the margin rationale and the full decision rule are not reported in the registry record. The value of 1 listed alongside the sponsor’s confidence interval is not explained sufficiently to treat it as a documented margin.

The registry’s analysis is identified as a two-sided t-test. In general, a t-test compares means while accounting for the amount of variability and the number of observations. Its validity depends on assumptions about the data and analysis. The registry record does not report diagnostics, transformations, covariate adjustment, or other details that would establish precisely how those assumptions were assessed. The recalculation is described as a simple, unadjusted calculation from posted summary statistics; it is not a replacement for a complete analysis of participant-level data.

Why do the group counts and variability matter?

Standard errors and intervals depend on both the variability of scores and the amount of information available. More variability or fewer observations generally makes an estimate less precise. The posted primary summaries include standard deviations of 2.7 and 2.4, and endpoint group counts of 45 and 39. The record does not provide participant-level values, so the analysis cannot be independently reconstructed in full or checked for unusual distributions and influential observations.

In general, over-dispersion means that observed variability is greater than a model or method expects. It can make standard errors too small if a method assumes less variability than the data contain. This endpoint is summarized as a continuous outcome with standard deviations, and the registry does not report an over-dispersion assessment or a model that addresses it. There is no basis in the posted record to claim that over-dispersion was present; the concept matters only as a general consideration when selecting and checking statistical methods.

The registry contains a total enrollment figure and separate endpoint counts, but does not state whether the analysis followed an intention-to-treat, per-protocol, or another population definition. General non-inferiority practice often pays close attention to analysis populations and missing outcomes because different exclusions can affect the comparison. Here, the population rules, missing-data methods, and sensitivity analyses are not reported in the registry record. That limits how fully the formal analysis can be evaluated.

11. Confidence Intervals and Precision

The primary comparison’s point estimate is a mean difference of 0.8. The recalculated interval runs from -0.291 to 1.891, while the registry’s sponsor-reported analysis gives a 90% confidence interval from -0.1 to 1.8. The interval bounds describe uncertainty in the estimated difference, not the range of pain scores that individual participants experienced. The interval from the simple recalculation is not labelled with a confidence level in the registry data, so it should not be assigned one.

In general, an interval that includes zero is compatible with a range of possible group differences that includes no average difference, under the calculation’s assumptions. It is also compatible with differences in either direction within the interval. This is not proof of equality. For a non-inferiority assessment, the relevant question is whether the interval meets the prespecified margin criterion, not simply whether it crosses zero. The margin and its rationale are not reported in the registry record, so the sponsor’s interval cannot be fully judged against that criterion from the posted information.

The width of an interval reflects precision. The primary group summaries include standard deviations of 2.7 and 2.4, with endpoint counts of 45 and 39. The posted uncertainty should be considered in light of those group sizes and the variability, not just the point estimate. A confidence interval also does not account for all possible sources of uncertainty, such as bias from missing outcomes or limitations in trial conduct.

The sponsor’s analysis and the simple recalculation are distinct presentations. The sponsor reports a 90% interval, whereas the recalculated comparison displays its own bounds and an unadjusted p-value. The registry does not report all details required to reconcile their methods. The posted values are best read as complementary summaries, with the sponsor’s analysis representing the trial’s reported non-inferiority analysis and the recalculation serving as a summary-statistics check.

12. Planning a Similar Trial: Sample Size

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

The sample-size display is a planning illustration for the primary continuous outcome, not the trial’s original design calculation. Its figures are participants per arm, not total events. The stated assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is set as the stated fraction of the observed effect. The planning rows consider 100%, 75%, and 50% of the observed effect.

The 80% power column describes the planned number of participants per arm under those assumptions for a design with an 80% chance of detecting the specified effect, if that effect and the assumptions hold. The 90% power column gives the corresponding planning target for a design with a 90% chance under the same conditions. These are design probabilities for a hypothetical future study, not probabilities that the observed result is true.

The table illustrates that smaller effects need more participants. The planning target rises as the assumed fraction of the observed effect becomes smaller. That pattern is a general consequence of trying to distinguish a smaller signal from background variability. The table’s values depend on the observed effect used as the starting point and on the listed assumptions, so they should not be treated as a definitive recommendation for a new trial.

The original trial’s sample-size assumptions and justification are not reported in the registry record. The displayed figures are not observed power: they are planning illustrations based on the observed effect, not a retrospective measure of how much power this completed trial had.

13. How the Sample Size Is Derived

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

Formula

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

Worked calculation for this trial

1. Observed difference Δ = 0.800; pooled standard deviation σ = 2.565.
2. n = 2 × (1.96 + 0.842)² × 2.565² / 0.800² = 161.4, rounded up to 162 participants per arm for 80% power.

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

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 0.800000000000001                      # observed difference in means
sigma <- 2.56534122676811                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

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

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(2178553)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 162 (80% power), 217 (90% power)
 75% of observed effect: n per arm = 287 (80% power), 385 (90% power)
 50% of observed effect: n per arm = 646 (80% power), 865 (90% power)
power.t.test: 162.4 
Simulated power at n = 162 per arm: 0.800 (20000 replicates)

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

14. Analyses Reported by the Sponsor

The registry’s own primary analysis is categorized as non-inferiority. It reports a two-sided t-test, a 90% confidence interval from -0.1 to 1.8, and p=0.142. The registry also lists a value of 1 with that analysis, but does not explain its role or give a full account of the non-inferiority margin and decision rule. The sponsor analysis is therefore the relevant posted result when describing the trial’s formal analysis, while the missing context limits independent evaluation of its conclusion.

The simple recalculation uses the posted group summaries. It gives a mean difference of 0.8, an unadjusted p-value of 0.151, and an interval from -0.291 to 1.891. It is a straightforward unadjusted comparison, not a recreation of every feature of the sponsor’s analysis. The results are not identical, and the registry does not provide enough detail to explain the methodological reasons for the differences. The record does not flag a discrepancy between the posted result and the recalculation.

These analyses serve different purposes. The sponsor’s result is the analysis the registry records as non-inferiority; the recalculation is a transparent check based on group-level summaries. Neither should be interpreted without considering the endpoint counts, uncertainty, and incomplete reporting of the margin and analysis population. The recalculation does not override the sponsor’s analysis or establish the formal non-inferiority decision on its own.

15. Multiplicity, Missing Data and Analysis Populations

Multiplicity arises when several outcomes, time points, or statistical comparisons are examined. In general, if each test is judged separately without adjustment, the chance of at least one result appearing noteworthy can rise as more tests are considered. Approaches to address this include defining a primary outcome and a prespecified hierarchy, or adjusting the testing procedure. The registry identifies a primary endpoint and lists secondary pain outcomes, but whether a multiplicity strategy was prespecified or used is not reported in the registry record.

The record lists four outcome measures and four analyses, while two secondary measures are posted in addition to the primary results. It does not provide enough information to determine the relationship between every listed outcome measure and analysis, whether additional analyses were planned, or whether the displayed outcomes were selected from a larger set. Without that information, the secondary p-values should be considered unadjusted findings unless the record explicitly states otherwise.

Missing-data handling is also not reported in the registry record. The primary endpoint results include group counts of 45 and 39, whereas enrollment is listed as 102. The record does not explain the difference, give reasons for unavailable measurements, or describe imputation, exclusions, or sensitivity analyses. It is not appropriate to assume that all enrolled participants contributed data or to infer why some are not represented in the endpoint summaries.

The analysis populations are not identified. The registry does not say whether the primary analysis was intention-to-treat, per-protocol, or based on another definition. General statistical context: non-inferiority assessments can be sensitive to analysis-population choices, so reporting those definitions and sensitivity analyses helps readers judge robustness. The registry record does not report those details, nor does it give an interim-analysis plan, data-monitoring procedures, or the complete statistical analysis plan. These omissions limit assessment of multiplicity, missingness, and the formal non-inferiority interpretation.

16. 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.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: respiratory failure (8.7%), pulmonary complications (5.1%), prolonged hospital stay (2.6%), myocardial infarction (2.6%).

The registry reports serious adverse events among 46 participants at risk in the epidural group and 39 at risk in the intercostal bupivacaine group. Five participants in each group are listed as affected by serious adverse events. Other adverse events are reported for 3 participants in the epidural group and 0 in the intercostal group. The record also lists 1 death in the epidural group and 3 in the intercostal group.

These counts are descriptive. The registry record does not establish that an event or death was caused by the assigned intervention, and the figures should not be interpreted as causal comparisons. The group denominators and counts do not show the full clinical context, timing, duration, severity details, or individual event histories. The record’s leading serious-event terms include respiratory failure, pulmonary complications, prolonged hospital stay, and myocardial infarction, with percentages shown in the safety display. Those terms and percentages should be read as registry event reporting, not as evidence of attribution.

Differences in counts can be difficult to interpret without information about event definitions, follow-up, ascertainment, and participant characteristics. Those details are not reported in the registry record. These data are not a complete safety assessment and should be considered separately from the primary pain endpoint.

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

The posted results describe pain scores in two randomized groups after thoracotomy. For pain with cough on the first postoperative morning, the mean was 6.1 in the epidural group and 6.9 in the intercostal bupivacaine group. The simple unadjusted mean difference was 0.8, and the displayed interval indicates uncertainty around that estimate. The sponsor’s registry analysis is labelled non-inferiority and reports a 90% confidence interval from -0.1 to 1.8 with p=0.142.

Those figures do not, by themselves, establish that the approaches are equivalent, that one is superior, or that a non-inferiority criterion has been met. Non-inferiority depends on a prespecified margin and a decision rule. The margin rationale and full statistical plan are not reported in the registry record. A non-significant conventional comparison would not prove equivalence; likewise, a result labelled non-inferiority cannot be fully evaluated without its margin and analysis details.

The primary endpoint captures one type of pain at one stated time. It does not summarize pain across all activities or the full postoperative course. The resting-pain measures and safety counts offer additional descriptions, but they do not remove uncertainty around the primary endpoint or fill gaps in the trial’s reporting.

General interpretation should also account for the endpoint counts, which are smaller than the overall enrollment, and the absence of reported reasons for that difference. The registry does not identify the analysis population or explain missing data. As a result, the posted summaries are useful for describing what was recorded, but they do not allow a full assessment of missing-outcome bias, robustness, or applicability beyond the trial population.

In short, this record contains randomized group summaries and a sponsor-reported non-inferiority analysis, alongside a simple recalculation. It does not contain all the methodological information needed to turn those results into a definitive claim about comparative effectiveness.

18. Why This Trial Matters Statistically

This trial is statistically interesting because it frames a pain-control comparison as a non-inferiority question, rather than only as a search for evidence of a difference. Those questions require different interpretations. A failure to detect a difference does not establish non-inferiority, and a non-inferiority conclusion depends on a margin that is clinically and statistically justified before the results are known. The registry record identifies the analysis as non-inferiority but does not report the margin rationale or full decision rule.

The endpoint is a continuous pain score, summarized with means and standard deviations. That makes the posted comparison accessible, while still leaving important questions about the distribution of scores, missing outcomes, and analysis populations unanswered. The displayed confidence intervals are essential because they show uncertainty that a single mean difference or p-value cannot convey.

The record also illustrates why registry results need to be read with attention to what is and is not posted. Enrollment is 102, but the primary endpoint group counts are 45 and 39, with no explanation of the accounting. The record lists more outcome measures and analyses than the two secondary pain outcomes posted. It does not describe multiplicity handling, missing-data methods, or the complete statistical plan. Each omission limits a different part of interpretation.

Finally, the simple recalculation and the sponsor’s reported result are not interchangeable. The recalculation is an unadjusted summary-statistics comparison; the sponsor’s result is the registry’s named non-inferiority analysis. Distinguishing these roles helps prevent an illustrative check from being mistaken for the trial’s complete inferential analysis.

19. Limitations

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

The registry record leaves several trial-specific uncertainties. The primary outcome group counts are 45 and 39, compared with enrollment of 102, but the record does not explain the difference or provide a participant flow description. It also does not report how missing pain scores were handled, the analysis population definition, or sensitivity analyses. These gaps make it difficult to assess whether the endpoint summaries represent all randomized participants or a selected subset.

The formal non-inferiority analysis is not fully specified in the posted record. Although the analysis is categorized as non-inferiority and includes a two-sided t-test, a 90% confidence interval, and a listed value of 1, the margin rationale and full decision rule are not reported. The original sample-size calculation and justification are also not reported. The planning illustration on this page is based on the observed effect and should not be mistaken for the trial’s original design assumptions.

The registry lists four outcome measures and four analyses, but only two secondary pain outcomes are posted. Multiplicity handling and the status of any other outcomes are not reported. The arm descriptions are incomplete, and the record does not provide a full account of treatment administration, co-interventions, or outcome-assessment procedures. Masking is listed as none, but the practical details of assessment are not described.

Safety results are counts without the full context needed to assess attribution or comparative risk. Event definitions, timing, follow-up details, and individual event histories are not reported in the registry record. These limitations do not negate the posted summaries; they define how far those summaries can be interpreted on their own.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Study of Exparel Versus Epidural for Pain Control After Thoracotomy — NCT02178553.
• Registry record last updated 2020-01-09; status last verified 2019-11.
• Results first posted 2020-01-09.
• 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.

23. Record Summary

The registry describes a completed, randomized, unmasked, parallel-group phase 4 trial sponsored by Mayo Clinic, comparing epidural analgesia with intercostal bupivacaine after thoracotomy. Enrollment is listed as 102. The primary endpoint is pain with cough on the first postoperative morning, measured using a numerical rating scale from 0 to 10. The posted group means are 6.1 for epidural and 6.9 for intercostal bupivacaine, with a recalculated unadjusted mean difference of 0.8.

The registry reports a two-sided t-test categorized as non-inferiority, with a 90% confidence interval from -0.1 to 1.8 and p=0.142. It does not report the margin rationale or enough of the analysis plan to fully assess the formal non-inferiority decision. Secondary resting-pain results and adverse event counts provide additional descriptions, but missing-data methods, analysis populations, and multiplicity procedures are not reported in the registry record.