Efficacy Of Quadratus Lumborum II Block For Laparoscopic Sleeve Gastrectomy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Efficacy Of Quadratus Lumborum II Block For Laparoscopic Sleeve Gastrectomy (NCT04073056), a randomized phase 4 study. The primary outcome is The Amount of Opioid Consumption During and After Procedure.

2. Clinical Question

The question is about a comparison between two postoperative pain-management approaches, not whether either approach is better than receiving no treatment. Both groups are described as receiving bupivacaine, but at different locations: the QL 2 group receives injections adjacent to the quadratus lumborum, while conventional therapy places the drug into incision sites. The registry identifies the primary outcome as opioid consumption and also lists pain scores and several other postoperative measures as secondary outcomes.

The registry describes the QL 2 block's proposed anatomical rationale, including posterior spread through fascia and a possible communication with the paravertebral space. That is background rationale, not a reported trial result. The central statistical question remains whether the observed outcome distributions differ between randomized groups at the specified times, and how precisely any estimated differences are measured. Numerical primary-outcome estimates are not reported in the registry record, so the direction and size of any group difference cannot be described.

3. Trial Design

This is a phase 4, randomized, triple-masked, parallel-group trial with an enrollment of 41. The registry lists the study status as completed, with a start date of 2018-08-01 and a primary completion date of 2021-02-23. Icahn School of Medicine at Mount Sinai is listed as the sponsor. The record concerns laparoscopic sleeve gastrectomy among people with morbid obesity or high BMI.

Participants were assigned to a quadratus lumborum II group or a conventional-therapy group. The QL 2 procedure is described as 15 mL of bupivacaine 0.25% on both sides, totaling 30 mL, administered under ultrasound guidance after surgery and before extubation. In the comparator group, the surgeon injects 30 mL of bupivacaine 0.25% directly into incision sites at the end of the procedure. Thus, the described contrast is principally the location and technique of administration.

Random allocation is intended, in general, to reduce systematic differences between groups at the point of assignment. A parallel design means that participants are assigned to one group rather than receiving both approaches in sequence. Masking can reduce the influence of expectations on care or assessment, but the registry record does not identify which people were masked or explain how masking was maintained. Details such as the allocation procedure, concealment, eligibility criteria, and site count are not reported in the registry record.

The recorded enrollment is 41, while the safety figures list 20 participants at risk in each group. The registry record does not explain this relationship or specify the number included in each primary-outcome analysis. It also does not report a target enrollment justification, a protocol-level statistical analysis plan, or interim-analysis procedures. The design label alone does not establish how those details were handled.

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

Analysis population for the primary outcome, as defined in the registry: Post Anesthesia Care Unity (PACU) hr 2 - one participant from each group was ready for discharge from the PACU prior to the 2nd hour. Postop Day (POD) 2 - two participants from each group could not be reached by phone.

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 The Amount of Opioid Consumption During and After Procedure, measured over Intraop, Postop 1hr, Postop 2hr, POD0, POD1, and POD2.

The primary outcome is the amount of opioid consumption during and after the procedure, expressed in mg IV morphine equivalents. The registry specifies a mean as the summary measure and standard deviation as the measure of dispersion. The listed assessment times are intraoperative, postoperative hour 1, postoperative hour 2, POD0, POD1, and POD2. The registry's description gives conversion references of 100mcg fentanyl= 10mg morphine and 1.5mg dilaudid=10mg morphine.

In general, opioid consumption is a quantitative measure of medication use. Expressing different opioid medications in morphine equivalents is intended to place amounts of different drugs on a common scale for comparison. A mean describes the average observed amount in a group; a standard deviation describes how much participant-level values vary around that average. Neither measure alone describes the precision of a between-group comparison.

The endpoint is relevant to the study question because the trial compares two approaches intended for pain management after surgery. However, the registry record does not report the group means, standard deviations, between-group estimates, confidence intervals, or test results for these time points. It therefore does not establish the size, direction, or precision of any difference in opioid consumption.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Several statistical ideas help frame the information in the registry record, while keeping the distinction clear between the design and the results. The record describes a randomized, triple-masked, parallel-group comparison and a continuous primary outcome summarized by a mean and standard deviation. It does not report the numerical outcome analyses or a detailed analysis plan.

What randomization contributes

In general, random assignment is used to create comparison groups without deliberately selecting which participants receive each approach. This can reduce the risk that known or unrecognized participant characteristics systematically determine group assignment. It does not guarantee that groups will be identical, especially in a modest-sized trial. Randomization also does not prevent missing measurements, ensure that an analysis follows the assignment, or substitute for reporting the allocation method. The registry gives the randomized design label but does not report the allocation sequence or concealment procedure.

What masking can and cannot tell readers

Masking, in general, is intended to limit the influence of knowledge about treatment assignment on behavior, care, or outcome assessment. The registry labels the trial triple-masked. It does not name the three masked roles or describe the practical steps used to preserve masking. Since the two procedures involve different injection locations, the label alone does not reveal how masking was implemented. It is therefore appropriate to report the recorded design label without assuming who was unaware of assignment.

Means, standard deviations, and comparisons

The outcome is continuous and is specified as a mean with a standard deviation. In general, the mean is an average, while the standard deviation describes dispersion among individual observations. A comparison between group means would estimate how far apart the group averages are on the morphine-equivalent scale. The standard deviations are not themselves confidence intervals: they describe variability among observations, whereas a confidence interval describes uncertainty in an estimate under a statistical model. The registry record reports neither group summary values nor a comparison estimate, so none can be interpreted.

Normal-approximation methods are among the general approaches that can be used for mean comparisons, but suitability depends on the data and analysis details. Opioid consumption may have a distribution that is not well represented by a simple normal model; for example, in general, a few large values can affect a mean. The record does not report the observed distributions, transformations, robust methods, or model diagnostics. No particular analysis method should therefore be attributed to the trial.

Why the time points matter

The primary measure is recorded across intraoperative, postoperative hour 1, postoperative hour 2, POD0, POD1, and POD2. In general, observations across time can be analyzed separately or with a method that accounts for their relationship within a participant. Repeated measures from the same person are not ordinarily independent. Choices about a primary time point, an overall measure, and how to handle correlation can affect both estimates and uncertainty. The registry says the outcome has several categories or time points and is not reduced to one comparison, but it does not report how the time-specific analyses were conducted or prioritized.

Precision and statistical evidence

A confidence interval is a general way to express the precision of an estimated difference. A narrower interval indicates less statistical uncertainty under the chosen method; a wider interval indicates more. Whether any interval includes values of practical importance is a separate interpretive question. A p-value, in general, describes how unusual data at least as incompatible with a specified null model would be if that model and the test assumptions held. It does not measure the probability that a treatment effect is real, nor does it show the size of an effect. No confidence intervals, p-values, or estimates for the primary outcome are reported in the registry record.

Planning illustrations are not trial results

The record describes sample-size planning illustrations based on a fraction of an observed effect, using a two-sided significance level of 0.05, equal allocation, and a normal approximation. It states that non-time-to-event illustrations are expressed as participants per arm. These illustrations are not the trial's original sample-size justification and are not observed power. The registry does not report a sample-size justification for the trial, and it does not provide primary-outcome effect estimates in the record used for this interpretation. A planning illustration cannot replace an analysis of the trial data or establish that a result is conclusive.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome is assessed at multiple time points, and the registry lists secondary measures including VAS pain scores, respiratory rate, heart rate, blood pressure, time to first dose of analgesic request, PACU length of stay, number of participants with pain, and number of participants with nausea. Testing multiple outcomes or time points can increase the chance of at least one apparently unusual result when each is examined separately. In general, a prespecified outcome hierarchy or multiplicity adjustment can help define how such evidence should be interpreted. The registry record does not report whether any adjustment, hierarchy, or prespecification strategy was used.

The registry identifies the primary outcome as spanning several times and says it is not reduced to one comparison. It reports no primary-outcome analysis. The analysis population, treatment of repeated observations, and any per-protocol or intention-to-treat approach are not reported in the registry record. The record also does not describe an analysis plan or interim analyses.

For postoperative hour 2, the registry notes that one participant from each group was ready for discharge from the PACU before the second hour. For POD2, two participants from each group could not be reached by phone. These are specific availability limitations; they do not establish how the data were classified or analyzed. The registry does not report imputation, sensitivity analyses, or the handling of other potentially unavailable observations. Therefore, the extent to which missingness could affect the estimates cannot be assessed.

The enrollment is 41, while the safety record lists 20 participants at risk in each group. The relationship between those counts and the analysis populations is not explained. This limits assessment of the denominators used for outcomes and the completeness of follow-up. No assumptions about those populations or about missing-data methods can be made from the 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.

The safety record lists 20 participants at risk in the Quadratus Lumborum II Group and 20 in Conventional Therapy. For each group, it records zero serious adverse events, zero other adverse events, and zero deaths. No serious adverse-event terms are listed.

These figures should be read as the event counts recorded for the listed groups, not as proof that no adverse events of any kind occurred during the trial. The registry does not describe the adverse-event collection window, definitions, ascertainment procedures, or whether all events were actively sought. It also does not provide detailed event narratives or estimates of uncertainty around the counts. The absence of listed serious-event terms means none are shown in this record; it does not establish that risks are identical between groups.

The arm-specific at-risk counts in the safety record do not match the total enrollment as stated, and the registry does not explain the difference. The safety counts should therefore be kept distinct from assumptions about how many participants contributed to each efficacy analysis. These data describe what is recorded for safety and do not answer the primary opioid-consumption question.

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

The registry record establishes that a randomized, triple-masked, parallel-group trial compared a QL 2 block with conventional incision-site bupivacaine therapy for laparoscopic sleeve gastrectomy. It also establishes the planned primary measure: opioid consumption in mg IV morphine equivalents at specified perioperative and postoperative times. The record gives enough detail to describe the contrast between the two procedures and to identify some follow-up availability issues.

It does not report numerical results for the primary outcome. No group means, standard deviations, effect estimates, confidence intervals, or test results are reported. As a result, the record does not show whether one group used more or less opioid medication, how large any difference was, or how precisely a difference was estimated. It also does not establish equivalence or absence of a meaningful difference. Such conclusions require results and an appropriate analysis, not only a randomized design and an outcome definition.

In general, statistical evidence and clinical importance are distinct. An estimate can be precise but small, or uncertain while including a range of potentially important values. Interpreting those possibilities requires outcome estimates, uncertainty measures, and context for what differences matter. Those numerical findings are not reported in the registry record.

The safety entries report zero serious adverse events, zero other adverse events, and zero deaths in each listed group. Those counts are useful as a description of the registry's recorded safety figures, but they do not demonstrate that risk is absent or equivalent. The record does not provide enough information to assess the completeness and duration of event collection.

Accordingly, the supported interpretation is limited: the record describes the trial design, interventions, outcome schedule, and recorded safety counts, but it does not provide the primary efficacy analyses needed to interpret comparative opioid consumption.

13. Why This Trial Matters Statistically

This trial is statistically notable for the way its primary outcome is defined: opioid consumption is measured on a common morphine-equivalent scale across several perioperative and postoperative times. In general, converting different opioid medications to a common scale allows quantities of distinct drugs to be described in a shared unit. The registry provides conversion references, as well as the times at which consumption was intended to be assessed.

The repeated time structure also makes the analysis question important. A set of time-specific comparisons and a single overall summary answer different questions. In general, repeated measurements from one participant may be related, and an analysis should account for that relationship if measurements are combined. The registry identifies several time points but does not report a single reduced comparison or explain the analysis method. That makes the analysis plan especially relevant to interpretation, yet it is not reported in the registry record.

The design includes randomization and triple masking, features intended in general to limit bias in group assignment and assessment. But design labels cannot replace transparent outcome reporting. Without group summaries and uncertainty estimates, readers cannot assess the size or precision of the primary comparison, regardless of the planned design.

The registry also records specific circumstances affecting outcome availability at postoperative hour 2 and POD2. These details matter statistically because the number and pattern of observed outcomes can influence an analysis. How those observations were handled is not reported. The record therefore illustrates why transparent reporting of analysis populations, missing-data handling, estimates, and uncertainty is essential when a trial measures outcomes repeatedly over time.

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 major limitation of the registry record is the absence of numerical primary-outcome results. It reports the outcome definition and time points but no means, standard deviations, comparisons, confidence intervals, or p-values. The efficacy question therefore cannot be answered from the recorded information. No primary-outcome analysis is listed.

The primary outcome covers multiple time points, but the record does not report how those measurements were analyzed or whether one time point had priority. It also does not state whether multiplicity was addressed, how within-participant correlation was handled, or which analysis population was used. These omissions prevent assessment of the statistical approach and the robustness of any intended conclusion.

Outcome availability is described as limited for some observations: one participant from each group was ready for PACU discharge before postoperative hour 2, and two participants from each group could not be reached by phone for POD2. The record does not explain how those observations were handled, whether other observations were missing, or whether sensitivity analyses were undertaken.

The registry reports enrollment of 41, whereas safety figures list 20 participants at risk in each group. It does not reconcile those counts or identify efficacy-analysis denominators. Other details, including the sample-size justification, eligibility criteria, allocation procedures, masking roles, and statistical analysis plan, are not reported in the registry record. These gaps limit appraisal of the trial's conduct and the interpretation of any unreported analysis.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Efficacy Of Quadratus Lumborum II Block For Laparoscopic Sleeve Gastrectomy — NCT04073056.
• Registry record last updated 2023-01-05; status last verified 2022-12.
• Results first posted 2023-01-05.
• 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

The registry record describes a completed phase 4, randomized, triple-masked, parallel-group trial sponsored by Icahn School of Medicine at Mount Sinai. It lists enrollment of 41 and a comparison between a bilateral QL 2 bupivacaine block and conventional bupivacaine injection into incision sites for laparoscopic sleeve gastrectomy.

The primary outcome is opioid consumption in mg IV morphine equivalents, assessed intraoperatively and at postoperative hour 1, postoperative hour 2, POD0, POD1, and POD2. The record also lists secondary outcomes related to pain, vital signs, analgesic request, PACU stay, pain, and nausea. Numerical primary-outcome analyses are not reported.

The safety record lists 20 participants at risk in each group and records zero serious adverse events, zero other adverse events, and zero deaths in both groups. Availability limitations are noted at postoperative hour 2 and POD2. The record does not explain the relationship between enrollment and the safety counts, or report the analysis populations and missing-data methods.