QL Block With Exparel in Colectomy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for QL Block With Exparel in Colectomy (NCT03827291), a non-randomized phase 4 study. The primary outcome is Cumulative Opioid Consumption Over 48 Hours.

2. Clinical Question

The study also lists pain while coughing, measured with the NRS-11, as a secondary outcome. Its stated purpose is to compare pain control and postoperative management between the block and epidural approaches. Those aims describe the clinical question, not a conclusion about either approach: the registry record does not report outcome results that would answer them.

3. Trial Design

This is a Phase 4, nonrandomized, parallel comparative study listed as completed. The registry record lists enrollment as 35. It gives a start date of 2019-10-31 and a primary completion date of 2022-12-02. These record details describe the study’s status and registration, not the results of the primary outcome.

The comparison is between a quadratus lumborum block and thoracic epidural analgesia. The block is described as bilateral administration on each side of a 30 ml aliquot containing 10 ml of liposomal bupivacaine (133 mg) and 20 ml of 0.25% bupivacaine (50 mg), in the fascial plane between the QL and psoas major muscles. The comparator is described as a historical cohort that received thoracic epidural analgesia.

The historical-cohort feature is important: the groups were not assigned through random allocation, and the registry explicitly cautions that they are not a like-for-like control comparison. Differences in outcomes, if reported, could reflect differences in the groups or their care as well as any difference associated with the analgesia approach. The record lists no masking.

The primary outcome is cumulative opioid consumption over 48 hours, expressed in morphine milligram equivalents and measured from arrival to PACU to 48 hours post-operatively. The registry also lists pain while coughing on the NRS-11 as a secondary outcome. It records 10 outcome measures but 0 analyses. Group summaries, comparative estimates, confidence intervals, and p-values are not reported in the registry record, so the design and endpoints can be described but comparative effects cannot be evaluated from this 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.

Before assignment: Historical Controls were not considered enrolled in this study.

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.

Population: Participants who completed the study.

6. Primary Endpoint

The registry lists the primary outcome as Cumulative Opioid Consumption Over 48 Hours, measured over From arrival to PACU to 48 hours post-operatively.

The primary endpoint is cumulative opioid consumption over the period from arrival to PACU to 48 hours post-operatively, measured in morphine milligram equivalents. It is summarized using the median and inter-quartile range. This endpoint captures opioid use accumulated over the specified postoperative period rather than a single measurement at a single time.

In general, opioid consumption can serve as a measure of analgesic use alongside measures of reported pain. It is not interchangeable with a pain score: use may reflect pain, prescribing and administration practices, patient preferences, and other aspects of care. Interpretation therefore depends on the study context and on what other outcomes and analyses are available.

The median describes the middle of the observed distribution, while the inter-quartile range describes the spread of its central portion. These summaries can be useful when observations are skewed or include unusually high values. They do not, by themselves, quantify uncertainty in a comparison or account for differences between groups.

The registry identifies this endpoint and its measurement window, but does not report the group medians, inter-quartile ranges, or an estimated comparison. As a result, the endpoint’s definition can be interpreted, but the recorded information does not establish the direction, size, or precision of any difference in opioid consumption.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a nonrandomized, parallel comparison, with a historical cohort receiving thoracic epidural analgesia. The distinction between the study’s structure and the statistical methods is important: a study can identify groups and outcomes without reporting the analysis used to compare them. Here, the record lists 0 analyses, and does not provide a primary-outcome estimate, interval, or p-value.

Why does nonrandomized allocation matter?

In general, random allocation helps make groups comparable in expectation with respect to both measured and unmeasured characteristics. Without it, treatment assignment may be related to factors that also influence the outcome. A historical comparator raises an additional concern: care practices, patient selection, or other conditions may differ across the periods represented by the cohorts. These possibilities are reasons to be cautious about attributing an observed difference to the intervention alone.

Statistical adjustment can sometimes address measured differences, but it cannot automatically remove bias from unmeasured or poorly measured factors. The registry record does not report whether an adjusted model was used, which covariates might have been included, or how the historical comparison was handled. It is therefore not possible to judge the adequacy of any adjustment from this record.

What do the median and inter-quartile range describe?

The primary endpoint is summarized by the median and inter-quartile range. In general, the median represents the center of an ordered distribution, and the inter-quartile range describes the spread of the central half of observations. These summaries are often useful for outcomes whose distributions are asymmetric or contain extreme observations. They are descriptive: comparing medians alone does not produce an adjusted treatment effect, a confidence interval, or a test of a hypothesis.

The outcome is cumulative opioid consumption in morphine milligram equivalents over the stated period. A distribution of cumulative use may not follow a symmetric, normal pattern. In general, a model that assumes a particular distribution should be checked for whether that assumption is reasonable. The registry does not specify a model, diagnostics, or an inferential method for this endpoint, so no claim about the suitability of a particular model can be made.

What would a confidence interval add?

In general, a confidence interval conveys uncertainty around an estimated effect under the assumptions of the analysis. Its width reflects precision, which can depend on factors such as sample size, outcome variability, and the analysis design. An interval also helps readers distinguish a precise estimate from one that remains compatible with a broad range of possible effects. No interval for the primary outcome is reported in the registry record.

A p-value is not a measure of effect size or clinical importance. In general, it describes how unusual data at least as incompatible with a specified null hypothesis would be under that hypothesis and the model assumptions. A p-value alone does not show whether groups were comparable, whether confounding was controlled, or whether the observed effect would matter clinically. No primary-outcome p-value is reported in the registry record.

How should planning illustrations be understood?

The record describes sample-size calculations as planning illustrations based on a fraction of the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. It specifies that non-time-to-event illustrations are expressed as participants per arm. Such illustrations are not observed results and are not observed power. The numerical planning values and the observed primary effect needed to interpret them are not reported in the registry record. The record also does not report the trial’s own sample-size justification, so the illustration should not be treated as evidence of the original design rationale.

In general, planning calculations depend on assumptions about the effect to detect, variability, allocation, and analysis. If the observed effect is used as the reference, the resulting illustration inherits uncertainty in that estimate. It cannot show that the study was adequately powered for the true effect, and it does not replace a reported estimate with uncertainty.

What remains unavailable?

The registry identifies 10 outcome measures, but does not report their comparative analyses. It does not specify the primary analysis population, missing-data methods, covariate adjustment, or model assumptions. These omissions prevent a detailed appraisal of the statistical analysis and limit what can be inferred from the record. General statistical concepts can clarify what such methods would address, but they cannot fill in methods or results that are not reported.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 10 outcome measures, including cumulative opioid consumption as the primary outcome and pain while coughing on the NRS-11 as a secondary outcome. It reports 0 analyses. No testing hierarchy, multiplicity adjustment, or strategy for interpreting results across outcomes is reported in the registry record.

In general, testing multiple outcomes can increase the chance that at least one result appears notable by chance. A prespecified hierarchy or adjustment can help clarify how results should be interpreted across a family of comparisons. Without a reported plan and analyses, it is not possible to determine how multiplicity was handled or whether any outcome result was selected for emphasis.

The record does not report how missing outcome data were defined or handled, whether participants were excluded from particular analyses, or which analysis population was used. It also does not provide the number of observations contributing to the primary outcome summaries. Missing-data methods matter because the pattern and reasons for missingness can affect both estimates and uncertainty; analysis-population definitions matter because they identify whose data contribute to each result.

These details are not merely procedural. In general, complete-case analyses, imputation approaches, and other methods rely on different assumptions. Without the registry’s methods and outcome-level data, those assumptions cannot be assessed. The absence of reported analysis details should not be interpreted as proof that a particular method was or was not used; the relevant information is not reported in the registry record.

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.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: extended hospital stay due to left lower extremity numbness (3.3%).

The registry reports serious adverse events for the quadratus lumborum block group as 1 event among 30 at risk, and for the thoracic epidural analgesia group as 0 among 30 at risk. It lists deaths as 0 in each group. These are descriptive figures; the registry does not report an inferential comparison or an adjusted safety analysis.

For other adverse events, the record reports 10 among 30 at risk in the quadratus lumborum block group and 19 among 30 at risk in the thoracic epidural analgesia group. These counts should be read as recorded events in their stated groups, not as proof that one approach caused more or fewer events. The record does not provide further detail about event definitions, ascertainment, timing, or whether multiple events could be associated with a participant.

The listed top serious-event term is “Extended hospital stay due to left lower extremity numbness,” reported as 3.3%. That entry does not provide a comparative estimate or establish a causal relationship. In general, safety counts are most informative when interpreted alongside definitions, follow-up, data collection procedures, and the study design. The historical comparison and lack of random allocation also limit causal interpretation of differences in these descriptive counts.

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

The registry record establishes that the study compared a quadratus lumborum block with thoracic epidural analgesia in patients undergoing laparoscopic colectomy, using a nonrandomized design and a historical cohort for the comparator. It identifies cumulative opioid consumption over 48 hours as the primary endpoint and pain while coughing as a secondary outcome. It also records selected adverse-event counts.

Those details explain what the investigators intended to compare, but they do not show the primary outcome result. The registry reports no group medians or inter-quartile ranges for opioid consumption, no estimated difference, no confidence interval, and no p-value. The secondary outcome results are likewise not reported. Therefore, the posted registry information does not establish the direction, magnitude, or precision of comparative effects on opioid consumption or pain.

In general, even a reported difference in a nonrandomized comparison would need cautious interpretation. A historical cohort may differ from the intervention group in ways that influence outcomes. Without reported adjustment methods and sufficient analysis details, an observed association could not be attributed confidently to the intervention alone.

The safety counts are also descriptive. They show the figures recorded for each group, but do not establish that the intervention caused an event or that a difference between groups reflects a treatment effect. No inferential safety comparison is reported.

Accordingly, the registry entry is useful for identifying the clinical question, study structure, outcome definition, and recorded safety information. It is not a complete report of comparative effectiveness results. Conclusions about whether either analgesia approach produced better outcomes, or about the clinical importance of a possible difference, are not supported by the results reported in the registry record.

13. Why This Trial Matters Statistically

This study raises a clinically relevant statistical question: how to compare postoperative opioid consumption and pain outcomes across analgesia approaches when the comparison is nonrandomized. The registry’s description makes the design feature especially visible: the thoracic epidural group is a historical cohort, rather than a concurrently randomized control group. That structure affects how any eventual comparison should be interpreted.

In general, the statistical challenge is not limited to choosing a model. Researchers must consider whether the groups differ in patient characteristics, clinical context, or other factors that can influence both treatment choice and outcomes. Appropriate adjustment may help with measured differences, but its usefulness depends on the variables collected and the assumptions made. The registry record does not report an adjustment strategy, so readers cannot assess that part of the comparison.

The endpoint also illustrates why outcome summaries and uncertainty matter. Cumulative opioid consumption is summarized by a median and inter-quartile range, but descriptive summaries alone do not establish a comparative effect. An estimate with an interval, together with a transparent analysis plan, would help readers evaluate both the size and precision of a difference. Those primary-outcome results are not reported in the registry record.

The safety counts reinforce a separate statistical principle: event counts should be interpreted in context and should not be treated as causal evidence on their own. Definitions, ascertainment, follow-up, and study design all affect what a count can establish.

For biostatisticians and clinical researchers, the record is a useful example of the distinction between a clearly identified clinical question and a report that contains enough analysis to answer it. The design and endpoints are documented, but the comparative outcome analyses needed for statistical interpretation are not.

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.

The main trial-specific limitation for interpretation is the nonrandomized comparison with a historical thoracic epidural cohort. The registry itself cautions that the arms are not a like-for-like control comparison. As a result, differences between groups could reflect factors other than the analgesia approach. The record does not report an analysis that would allow readers to evaluate or adjust for such factors.

The registry does not report group-level results for the primary endpoint, an estimated comparison, or measures of uncertainty. It lists pain while coughing as a secondary outcome but does not report its results. Although 10 outcome measures are recorded, the entry lists 0 analyses. Thus, the documented outcomes cannot be used to assess comparative effectiveness from this record.

Information needed to appraise the analyses is also not reported: the primary analysis population, missing-data methods, model specification, covariates, and multiplicity strategy. The enrollment entry is 35, while the adverse-event figures list 30 at risk in each group; the registry record does not explain this difference in the reported figures, so no reconciliation should be assumed.

The safety information is limited to the recorded counts and a listed serious-event term. Definitions, ascertainment procedures, and an inferential safety comparison are not reported. The sample-size information describes planning illustrations, but their numerical values and the observed effect used as a reference are not reported in the registry record. These limitations restrict conclusions to a description of the study question, design, and posted safety counts.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: QL Block With Exparel in Colectomy — NCT03827291.
• Registry record last updated 2025-10-16; status last verified 2025-09.
• Results first posted 2025-10-16.
• 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

NCT03827291 is a completed Phase 4, nonrandomized, parallel comparative study sponsored by Duke University. The registry lists enrollment as 35, a start date of 2019-10-31, and a primary completion date of 2022-12-02. It compares a quadratus lumborum block using liposomal bupivacaine and bupivacaine with thoracic epidural analgesia received by a historical cohort.

The primary endpoint is cumulative opioid consumption in morphine milligram equivalents from arrival to PACU to 48 hours post-operatively, summarized by median and inter-quartile range. Pain while coughing on the NRS-11 is listed as a secondary outcome. Although 10 outcome measures are recorded, the registry lists 0 analyses and does not report primary or secondary comparative results.

Adverse-event counts are recorded for both groups, including the serious-event term “Extended hospital stay due to left lower extremity numbness,” reported as 3.3%. Given the nonrandomized historical comparison and the absence of reported outcome analyses, the registry record does not establish comparative effectiveness or a causal safety difference.