Surgeon Infiltration QL Block Comparison: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Surgeon Infiltration QL Block Comparison (NCT03496610), a non-randomized phase 4 study. The primary outcome is Opioid Consumption in Oral Morphine Milliequivalents for the First 24 Hours After Surgery (Defined as 24 Hours After the Anesthesia End Time).

2. Clinical Question

The clinical question is comparative: it concerns opioid use after surgery under two different approaches to local anesthetic administration. The registry also describes secondary outcomes concerning self-reported Numeric Pain Scores on Postoperative Day Seven, worst bloating severity in the first postoperative week, and self-reported ability to walk for 15 minutes without any difficulty within the first postoperative week. Those measures address different aspects of recovery and are not interchangeable with opioid consumption. The record does not report their results either.

Because allocation was non-randomized and masking was absent, the groups should not be understood as a randomized, blinded comparison. Any observed difference could reflect the treatment approach, differences between the patients receiving each approach, or other factors. The registry record does not report enough information to determine how those potential influences were handled.

3. Trial Design

This was a Phase 4, parallel-group study sponsored by Duke University. The registry lists the study as completed, with enrollment of 44. It gives a start date of 2021-01-25 and a primary completion date of 2023-02-23. These details describe the registered study; they do not by themselves establish how many participants contributed data to each outcome.

The comparison was non-randomized, and the study was unmasked. In a parallel design, participants are assigned to a group and receive that group's approach rather than crossing between approaches. Here, the listed groups were Quadratus Lumborum (QL) Block and Surgical wound infiltration. Participants in the QL group were to receive a bilateral ultrasound-guided block from the anesthesia team. The wound-infiltration group was to receive 266 mg of liposomal bupivacaine mixed with 50 mg non-liposomal bupivacaine in the wound, administered by the surgeon.

Non-random allocation matters for interpreting a group comparison. Random assignment is one way to reduce systematic differences between groups at the outset. Without it, characteristics related to treatment selection may also be related to outcomes. The registry record does not report the allocation process or enough detail to assess whether the groups were similar on relevant baseline characteristics. It also does not report whether any statistical adjustment was planned or performed.

The record describes the primary endpoint as opioid consumption in oral morphine equivalents during the first 24 hours after surgery, summarized by the median and inter-quartile range. For this analysis, two subjects originally enrolled in the QL group were excluded: one voluntarily withdrew, and one was withdrawn by the PI for a surgical site infection. The record does not give group-specific analyzed sample sizes or explain how missing outcome values, if any, were handled beyond those exclusions.

The registry lists three secondary outcomes and states that there were four outcome measures and four analyses. Further details of the analysis plan, including prespecified models, covariates, and any adjustment for multiple testing, 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:

Analysis population for the primary outcome, as defined in the registry: This analysis excludes two subjects who were originally enrolled in the QL group--one subject who voluntarily withdrew and one who was withdrawn by the PI for a surgical site infection.

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: The number of participants in the QL group excludes two subjects-- one subject who voluntarily withdrew and one who was withdrawn by the PI for a surgical site infection.

6. Primary Endpoint

The registry lists the primary outcome as Opioid Consumption in Oral Morphine Milliequivalents for the First 24 Hours After Surgery (Defined as 24 Hours After the Anesthesia End Time), measured over 24 hours postoperatively.

The primary endpoint measures the amount of opioid medication consumed during the first 24 hours after surgery. The registry expresses consumption in oral morphine equivalents in milligrams and defines the observation window as 24 hours after the anesthesia end time. Expressing different opioid medications on a common scale can make total consumption more comparable when medications differ. This is a general explanation of the measure, not a claim about which medications were used in this study.

Opioid consumption is used as a postoperative outcome because it records medication use over a specified period. It complements patient-reported pain measures: reported pain and medication consumption describe related but distinct aspects of the postoperative experience. Consumption may also reflect clinical practice, medication availability, and patient or clinician decisions, so it should not be read as a direct measure of pain alone. This is a general consideration in interpreting such an endpoint.

The registry specifies the median and inter-quartile range for summarizing the endpoint. 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 influential high values; that is a general statistical reason to use them. The registry record does not report the observed group medians or inter-quartile ranges, so the size, direction, and precision of the primary comparison cannot be assessed in the registry record.

The analysis population excludes two subjects initially enrolled in the QL group, for the reasons stated in the registry record. The record does not provide further information about endpoint collection or the handling of any other missing observations.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies opioid consumption as the primary endpoint and specifies a median with an inter-quartile range. It does not describe the full statistical analysis plan. The explanations below are general statistical context for reading the stated endpoint and design; they do not imply that any particular analysis was conducted beyond what the registry record says.

Why summarize with a median and inter-quartile range?

The median is the value at the center of an ordered set of observations. The inter-quartile range describes the interval containing the central portion of those observations. Together, these summaries give information about a typical value and the spread around it without requiring the distribution to be symmetric. This can be useful for consumption outcomes, which may have a skewed distribution. Whether the study's data were skewed is not reported in the registry record.

These summaries are descriptive. They do not, by themselves, show whether a group difference is statistically distinguishable from chance variation, nor do they quantify the uncertainty in a group contrast. That would require an inferential analysis and an uncertainty measure, such as a confidence interval. The registry record does not report the primary group summaries, a contrast, or a confidence interval.

What does non-random allocation mean?

In a randomized study, assignment by chance is intended to make groups comparable, on average, with respect to both measured and unmeasured characteristics. This is a general design principle. In this study, allocation is listed as non-randomized, so that protection cannot be assumed. If factors influencing which approach a patient received also relate to postoperative opioid use, a simple group contrast could mix treatment differences with those underlying differences.

Statistical adjustment can sometimes account for measured differences, but it cannot automatically address factors that were not measured or recorded. The registry record does not report the allocation procedure, baseline comparisons, adjustment variables, or a model used to estimate the primary comparison. It is therefore not possible to assess from the registry entries whether or how confounding was addressed.

What does the unmasked design imply?

The study is listed as having no masking. In general, knowledge of the treatment approach can influence care decisions, reporting, or outcome assessment. The primary endpoint is opioid consumption, which is a recorded quantity, but its measurement and the decisions that determine medication use may still depend on clinical practice. The registry record does not describe safeguards or standardized procedures that might limit such influences. This is a potential interpretation concern, not evidence that bias occurred.

How should the analysis exclusions be read?

The primary analysis excludes two subjects originally enrolled in the QL group: one who voluntarily withdrew and one withdrawn by the PI for a surgical site infection. An analysis that includes only participants with available outcome data can differ from an analysis that follows all enrolled participants. The consequences depend on why data are missing and how that relates to the outcome. The registry record does not specify whether the excluded subjects had primary endpoint data, how the exclusions were chosen for analysis, or whether alternative analyses were performed.

For a non-randomized study, changes in the analyzed population can further affect comparability between groups. The record does not provide group-specific numbers for the primary analysis or describe an intention-to-treat approach. Those features should not be inferred from the total enrollment.

How should planning calculations be interpreted?

The sample-size section is identified as a planning illustration computed from the observed effect, rather than the trial's own design. The stated assumptions are a two-sided significance level of 0.05, equal allocation between the groups, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. For time-to-event tables, the stated method gives a total number of events using Schoenfeld; other tables give participants per arm. These are planning assumptions, not proof that the study was designed or conducted using those conditions.

Such calculations illustrate how a planning target can change when the effect chosen for detection changes. They do not represent observed power and do not show how likely the result is to be correct. A planning illustration based on an observed effect also depends on that effect estimate, which can be uncertain. The registry record does not report the trial's own sample-size justification or a prospective calculation.

What remains unknown about inference?

The registry lists four outcome measures and four analyses, but does not report the statistical methods for those analyses. It does not specify whether comparisons were adjusted for covariates, which inferential tests or models were used, whether confidence intervals were calculated, or how any distributional assumptions were assessed. It also does not report handling of multiplicity. These details matter when assessing the strength and precision of evidence, especially when several outcomes are considered. The tables and plots can display calculated information when available, but they do not replace a complete description of the analysis plan.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary outcome, three secondary outcomes, four outcome measures, and four analyses. It does not report how the four measures relate to the four analyses, whether any additional outcome is included, or which outcomes were prespecified for formal hypothesis testing. The multiplicity plan is not reported in the registry record.

Multiplicity is the general statistical issue that arises when several outcomes or comparisons are examined. Considering more tests can increase the chance of a finding that appears notable by chance. Methods such as adjusting significance thresholds or identifying a primary comparison in advance can address this issue, but the registry record does not say whether such methods were used. The listed primary endpoint gives readers a designated main measure, but does not establish how analyses of the secondary outcomes were handled.

For missing data, the record identifies two exclusions from the primary analysis among subjects originally enrolled in the QL group. One voluntarily withdrew; the other was withdrawn by the PI for a surgical site infection. The record does not state whether these subjects had endpoint measurements, how the missingness was classified, or whether any other outcome data were missing. It does not describe imputation, sensitivity analyses, or an analysis population definition beyond the stated exclusions.

These gaps make it difficult to judge whether the analyzed groups remained comparable or how robust any result would be to different assumptions about missing outcomes. Because the primary numerical results and analysis details are not reported in the registry record, the extent to which multiplicity and missingness affect interpretation cannot be determined.

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 5% reporting threshold.

The registry lists safety figures for the QL block group and the surgical wound infiltration group. For the QL group, 24 participants are listed as at risk for serious adverse events and 0 as affected; 24 are listed as at risk for other adverse events and 0 as affected; deaths are listed as 0. For surgical wound infiltration, 20 participants are listed as at risk for serious adverse events and 0 as affected; 20 are listed as at risk for other adverse events and 0 as affected; deaths are listed as 0.

These are registry counts, not a statistical comparison of safety between the approaches. Zero recorded events does not establish that an event is impossible or that the groups have equivalent safety. The at-risk counts also do not explain the duration or completeness of safety monitoring, event definitions, or whether events were assessed consistently. Those details are not reported in the registry record.

The primary analysis excludes two subjects originally enrolled in the QL group, whereas the safety figures list 24 as at risk in that group. The registry record does not explain the relationship between these populations. The figures should therefore be read as the posted safety summary and not assumed to use the primary endpoint analysis population. No serious adverse event terms are listed among the top serious terms.

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

This trial addresses a practical postoperative comparison: a bilateral ultrasound-guided QL block versus local anesthetic infiltrated into the surgical wound. Its primary question concerns opioid consumption in oral morphine equivalents during the first 24 hours after surgery. The registry also identifies patient-reported pain, bloating, and walking outcomes as secondary measures. These details establish what the study set out to examine.

The registry record does not report the numerical results for the primary endpoint or the secondary outcomes. It therefore does not support a description of which group had greater opioid consumption, whether the groups differed, or how precisely any difference was estimated. It also does not support a conclusion that the approaches had similar outcomes. Missing results are not evidence of no difference.

Even if a group difference were available, the study's non-randomized allocation and absence of masking would matter when interpreting it. Differences in patient characteristics or care may influence group outcomes, and the record does not describe adjustment or other steps to address those concerns. The two exclusions from the QL primary analysis also require consideration; the registry does not report analyses assessing their impact.

The safety summary records no serious adverse events, other adverse events, or deaths among the listed at-risk participants in either group. This describes the posted counts, not a guarantee of safety or a definitive comparison. The registry does not provide enough detail to establish the completeness of monitoring or the precision of safety estimates.

In general, a clinical trial's statistical interpretation depends on the estimated outcome, its uncertainty, the analysis population, and the design. Here, the record provides useful design and endpoint details, but not the outcome estimates needed for an efficacy comparison. The sample-size section is a planning illustration, not observed power and not a substitute for those results. The appropriate reading is consequently limited to what was registered and posted, without drawing a treatment-effect conclusion.

13. Why This Trial Matters Statistically

This study illustrates why design information is essential alongside outcome summaries. The comparison involves two approaches to local anesthetic administration, but the registry lists allocation as non-randomized and masking as absent. Those features shape what a group difference could mean: even a clearly described numerical contrast would need cautious interpretation because the groups may differ for reasons other than the approach received.

The endpoint also highlights the distinction between a descriptive summary and an inferential comparison. The median and inter-quartile range are appropriate ways to describe the distribution of opioid consumption when those summaries are used, but they do not by themselves show the size or precision of a between-group contrast. The registry record does not report the group summaries or an estimate with uncertainty, so readers cannot evaluate that central comparison from the information.

The stated exclusions matter statistically as well as clinically. Two subjects originally enrolled in the QL group were excluded from the primary analysis for specified reasons. Without a fuller account of missingness and analysis populations, it is difficult to assess how the exclusions might affect group comparability. This illustrates why transparent reporting should identify who was analyzed and how exclusions were handled.

Finally, the record lists several outcomes and analyses but does not report a multiplicity plan or detailed analysis methods. When a study examines several measures, readers need to know which comparisons were primary and how secondary analyses were interpreted. The registry's planning illustration is distinct from the trial's design justification and cannot supply missing results. These issues make the study a useful example of how design, endpoint definition, analysis transparency, and result reporting jointly determine the strength of a statistical interpretation.

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 registry record does not report the numerical primary outcome results, including group medians and inter-quartile ranges, an estimated contrast, a confidence interval, or a p-value. It also does not report results for the secondary outcomes. This prevents assessment of the direction, magnitude, or precision of the observed comparisons.

Allocation was non-randomized, and masking was absent. The registry record does not describe how participants came to receive each approach, whether important baseline characteristics differed, or whether the analysis adjusted for potential confounding. The posted comparison therefore cannot be treated as a randomized estimate of a causal effect.

The primary analysis excluded two subjects originally enrolled in the QL group, including a withdrawal by the PI for a surgical site infection. The record does not explain whether these subjects had endpoint data, whether additional data were missing, or whether sensitivity analyses examined the consequences of exclusion. It also does not report the primary-analysis group sizes.

Although the registry lists four outcome measures and four analyses, it does not detail the analysis methods, model assumptions, covariates, or multiplicity handling. The record also does not report a sample-size justification for the trial; the sample-size section is described as a planning illustration rather than the trial's own design.

The safety figures are limited to posted counts and at-risk totals. Monitoring duration, event definitions, and the relationship between the safety population and the primary analysis population are not reported in the registry record. Together, these limitations restrict both outcome interpretation and assessment of the robustness of any comparison.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Surgeon Infiltration QL Block Comparison — NCT03496610.
• Registry record last updated 2024-03-05; status last verified 2024-02.
• Results first posted 2024-03-05.
• 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

NCT03496610 is a completed Phase 4, parallel-group, non-randomized study sponsored by Duke University. It enrolled 44 participants and compares a bilateral ultrasound-guided QL block with surgical wound infiltration using 266 mg of liposomal bupivacaine mixed with 50 mg non-liposomal bupivacaine. The listed start date is 2021-01-25, and the primary completion date is 2023-02-23.

The primary endpoint is opioid consumption in oral morphine equivalents during the first 24 hours after surgery, summarized by the median and inter-quartile range. The primary analysis excludes two subjects originally enrolled in the QL group. Secondary outcomes concern postoperative pain scores, bloating, and walking ability.

The registry record does not report the primary or secondary outcome results or the detailed statistical analysis plan. Its safety summary lists zero serious adverse events, zero other adverse events, and zero deaths in both groups. The available record describes the study question and design but does not allow a numerical assessment of the primary comparison.