Laparoscopic TAP Block for Sleeve Gastrectomy: Does Timing Matter: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Laparoscopic TAP Block for Sleeve Gastrectomy: Does Timing Matter (NCT04787367), a randomized na study. The primary outcome is Pain Scores Between Early and Late Groups.

2. Clinical Question

The comparison is between two timing strategies rather than between a block and no block. That distinction matters when interpreting any contrast: the question is whether outcomes differ according to when the block is administered, not whether the block itself is better than no block. The registry summary describes the early timing as intended to provide superior analgesia to late timing, but this stated aim is not a finding.

Pain is recorded using a numerical assessment scale from 0 to 10. A score of 0 means no pain and is identified as the best outcome on the scale; 10 means the most pain and is identified as the worst outcome. The record specifies mean and standard deviation as the outcome parameter and dispersion. It does not report the observed scores, group means, mean differences, confidence intervals, or tests of the timing contrast.

Analgesic utilization is listed as a secondary outcome. Its measurement details and results are not reported in the registry record. The clinical question is therefore clear as a planned comparison, while the available record does not establish what the observed pain or analgesic-use results were.

3. Trial Design

The registry describes a randomized, parallel-group trial with single masking and enrollment of 200. The status is completed. The recorded start date is 2019-02-12, and the primary completion date is 2022-07-01. The phase is listed as NA. The sponsor is Arthur Carlin.

Participants were assigned to one of two groups, each receiving a TAP block during sleeve gastrectomy. In the early-operative group, the block was to be administered after placement of the camera port. In the late-operative group, it was to be administered at the completion of the case just before removal of the camera port. The registry summary states that a fixed amount of bupivacaine would be used, but the amount is not reported in the registry record.

Random allocation is intended to make treatment groups comparable, on average, with respect to factors that could influence outcomes. It does not guarantee identical groups, and it cannot replace reporting of participant characteristics, adherence, or outcome data. The registry does not describe the randomization sequence or allocation-concealment procedures, so those features cannot be assessed from this record.

Single masking is recorded, but the identity of the masked party and the procedures used to maintain masking are not reported in the registry record. This prevents a more specific assessment of how knowledge of group assignment might have influenced pain reporting, clinical care, or outcome assessment.

The main outcome is a continuous pain score summarized as a mean with standard deviation at specified post-operative times. Analgesic utilization is listed as a secondary outcome. The record lists 2 outcome measures and 0 analyses. Although the trial status is completed, completed status alone does not supply the results or establish how the planned comparison was analyzed.

4. Participant Flow and Accounting

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

Overall Study

5. Baseline Characteristics

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

6. Primary Endpoint

The registry lists the primary outcome as Pain Scores Between Early and Late Groups, measured over Post-operatively at 0 hours, 4 hours, 8 hours, 12 hours, 16 hours, 20 hours, and 24 hours.

The primary endpoint is pain measured with a patient-reported numerical assessment score. Participants choose a number from 0 through 10, with 0 defined as no pain and 10 as the most pain. The registry specifies that the outcome is to be represented by a mean and standard deviation. Measurements were planned post-operatively at 0 hours, 4 hours, 8 hours, 12 hours, 16 hours, 20 hours, and 24 hours.

Patient-reported pain is used because pain is a subjective experience; the participant’s own report directly records that experience on the stated scale. A mean describes the average score in a group, while a standard deviation describes how spread out individual scores are around that average. These are general interpretations of the specified summaries, not results from this trial.

The timing of measurement is central to the question. A comparison at one post-operative time may not convey the same pattern as comparisons across the full series of time points. Scores may differ in their averages or variability at different measurement times, so results at one time should not be treated as a substitute for the complete planned outcome profile.

The registry does not report actual pain scores, group summaries, or estimated between-group contrasts at any listed time. It also does not describe a single combined endpoint across the measurement times. Consequently, the endpoint definition can be explained, but the magnitude and precision of any observed difference cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a randomized, parallel-group design and a continuous primary outcome. The intended comparison is between pain scores after early-operative and late-operative TAP block. The record specifies means and standard deviations, but does not report an analysis method or any calculated outcome results. General statistical explanations below clarify how such information is ordinarily interpreted; they do not describe analyses confirmed for this trial.

What does randomization contribute?

Randomization assigns participants to study groups using a chance-based process. In general, this helps reduce systematic differences in baseline characteristics and supports a fair comparison of assigned strategies. It does not ensure that every prognostic characteristic is balanced in a particular trial, and it does not address problems such as incomplete follow-up or deviations from assigned treatment. The registry records random allocation, but the sequence-generation and allocation-concealment methods are not reported in the registry record.

The trial is described as parallel, meaning that the two strategies are assigned to separate groups rather than being described as a crossover comparison. The record marks the study as single-masked but does not say who was masked or how. Masking can matter for subjective outcomes because expectations or knowledge of assignment may affect reporting or assessment. Without the masking details, the extent to which this concern was addressed cannot be evaluated.

How should means and standard deviations be understood?

A mean is the arithmetic average of the recorded scores in a group. The standard deviation describes variation among those scores around the mean. A mean difference between groups would express the contrast in average pain score, with its sign depending on the order used for subtraction. The registry does not report either group’s means or standard deviations, nor does it report a difference. No direction or magnitude can therefore be inferred.

A confidence interval is a general way to express uncertainty around an estimated effect. A narrower interval indicates greater precision under the assumptions of the method; a wider interval indicates less precision. The interval is not reported for any pain-score comparison in this record. A p-value, if reported, would address compatibility between the data and a specified null model; it would not alone describe the size or practical meaning of an effect. No p-value is reported.

Why do the repeated time points matter?

Pain scores were planned at 0 hours, 4 hours, 8 hours, 12 hours, 16 hours, 20 hours, and 24 hours after surgery. Each measurement time can support a distinct comparison, and repeated scores from the same participant are generally related rather than independent. A method that analyzes repeated measures may account for that within-participant relationship. Alternatively, analyses may estimate contrasts at separate times, but doing so raises questions about how multiple comparisons are interpreted. The registry does not report which approach was used, or whether any overall time-course contrast was planned.

When several outcomes or time points are tested, the chance of at least one apparently unusual result can increase if each is treated as a separate test without adjustment. This is the general reason researchers consider multiplicity procedures or identify a primary comparison in advance. No multiplicity adjustment, hierarchy, or prespecified single time-point contrast is reported in the registry record. It is therefore not possible to determine how the listed time points were intended to contribute to a confirmatory conclusion.

What does the planning information mean?

The registry includes a description of a planning illustration based on an observed effect. It states assumptions of a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. These are planning assumptions, not a report of an observed treatment effect or a trial analysis. The numeric planning estimates are not reported in the registry record.

A sample-size illustration asks how much information might be needed under specified assumptions to detect a target effect. It is not observed power, and it does not show that an effect was present. In general, changing the target effect, variability, significance level, or allocation assumptions changes the planning result. Here, the record does not report the observed effect on which the illustration is said to be based, so the planning basis cannot be independently evaluated from the registry record.

What can be learned from the posted analysis information?

The registry lists 0 analyses, and no outcome estimates or inferential statistics are reported. It does not specify the analysis population, handling of missing scores, covariate adjustment, model assumptions, or treatment of deviations from assigned timing. Those details are important for understanding how an estimate was obtained and which participants contributed to it. In their absence, the design and endpoint can be described, but a trial-specific statistical conclusion cannot be reconstructed.

General statistical interpretation should separate the planned question, the observed data, and the method used to connect them. The registry identifies the planned contrast and measurement scale. It does not report the observed pain data or the method used to analyze them. No further estimate, test, or conclusion can be derived from the information recorded.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome is measured at several post-operative times: 0 hours, 4 hours, 8 hours, 12 hours, 16 hours, 20 hours, and 24 hours. The record does not state that these measurements were combined into one summary. It explicitly indicates that the primary outcome has several time points and is not reduced to one comparison. This leaves the intended role of each time-specific result unclear in the available record.

Multiplicity is a general statistical concern when several comparisons are considered. If each time point is tested separately, interpreting all tests as if there were only one can overstate the evidence from an isolated result. Researchers may address this by prespecifying a primary time point, using an adjustment, or analyzing an overall pattern. No such strategy is reported in the registry record, and no results are available to assess how multiple comparisons were handled.

The record does not describe whether pain scores were missing, how missing measurements were handled, or whether follow-up differed between groups. Missing outcome data can affect interpretation if the participants with recorded scores differ from those without them. No imputation method, sensitivity analysis, or completeness summary is reported in the registry record. The enrollment figure should not be taken to establish how many participants contributed scores at each time.

The registry does not state whether the analysis followed assigned groups regardless of treatment received, included only participants who followed the assigned timing, or used another analysis population. Nor does it describe how protocol deviations or incomplete treatment were handled. These issues matter because different analysis populations can answer different questions. Without the analysis plan and participant-level flow, the population represented by any outcome estimate cannot be identified; in any case, no estimate is reported.

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 separate adverse-event figures for the early-operative and late-operative TAP block groups. For the early group, 100 were at risk for serious adverse events and 0 were affected; 100 were at risk for other adverse events and 0 were affected; deaths were 0. The corresponding figures for the late group are 100 at risk for serious adverse events and 0 affected, 100 at risk for other adverse events and 0 affected, and 0 deaths.

These are the counts recorded in the registry, not an estimate of comparative risk. The record does not report event terms, severity details beyond the serious/other categories, timing, duration of surveillance, or the method used to collect events. The list of top serious-event terms is empty. It is therefore not possible to evaluate event types or ascertainment from this entry.

Zero events recorded does not establish that no events occurred outside the reporting process, or that the timing strategies have identical safety profiles. In general, safety interpretation depends on the completeness and duration of follow-up and on how events are defined and collected. Those details are not reported in the registry record. The figures should be read as posted counts, without converting them into percentages or treating them as a definitive comparison.

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

The record establishes a planned randomized comparison of two intraoperative TAP-block timings during sleeve gastrectomy. It identifies the early timing as after placement of the camera port and the late timing as at case completion just before removal of that port. It also identifies patient-reported numerical pain scores as the primary outcome and analgesic utilization as a secondary outcome.

What the record does not establish is whether pain scores differed between groups. It contains no group means, standard deviations, treatment-effect estimates, confidence intervals, or p-values for the primary outcome. The planned measurements span the post-operative period from 0 hours through 24 hours, but no results at those times are reported. The stated study objective must not be mistaken for a result.

Even if a difference were reported, statistical interpretation would depend on its size and precision, the measurement time, and the analysis plan. A confidence interval would help describe uncertainty around an estimate, while the scale anchors would support interpretation of the score direction. No trial-specific estimate or interval is available to assess. The record also does not report how repeated measurements or multiple comparisons were handled.

The completed status does not fill these gaps. It indicates the registry’s status entry, not whether outcome data were complete, analyzed, or posted. Similarly, a planning illustration based on an observed effect is a design aid under stated assumptions, not evidence that the effect occurred or that the trial had a particular observed power. Numeric planning estimates are not reported in the registry record.

The adverse-event entries record zero affected in the listed categories for both groups, but event definitions and ascertainment details are not reported. These counts cannot establish equivalence or rule out harms. Overall, the registry describes a clinically focused timing question and its planned outcome, while leaving the actual outcome findings and their statistical uncertainty unreported.

13. Why This Trial Matters Statistically

This trial addresses an important statistical distinction: comparing two timings of the same procedure is not the same as comparing a procedure with no procedure. Its randomized design is intended to support a comparison between early-operative and late-operative TAP block while reducing systematic differences between assigned groups. The registry does not provide enough methodological detail to assess how randomization and masking were implemented.

The primary outcome is subjective and measured repeatedly. A numerical pain scale creates a quantitative outcome that can be summarized by means and standard deviations, but its interpretation still depends on who reported scores, when they were collected, and how missing observations were handled. The registry specifies the scale anchors and time points, yet does not report the actual measurements or analysis methods.

Repeated measurements raise a broader design issue: a study may ask whether groups differ at particular times, whether their patterns across time differ, or whether one summary captures the overall course. Those questions are not interchangeable. The record does not specify a single comparison or explain how the several time points would be interpreted together. That absence limits statistical interpretation even before considering the lack of results.

The registry also illustrates why trial status, planning information, and findings should be kept separate. A completed status is not an outcome report. A planning illustration based on an observed effect is not a result, and is not observed power. Without outcome estimates and uncertainty measures, readers cannot judge the size or precision of the timing contrast.

For biostatistical interpretation, the key contribution of the record is therefore the definition of a randomized timing question and its measurement schedule. Its key limitation is that the planned comparison cannot be evaluated empirically from the outcomes recorded. Clear reporting of the analysis population, missing data, multiplicity approach, and estimates with uncertainty would be needed to assess the study’s statistical findings.

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 provides limited detail about the trial population. It lists obesity and postoperative pain as conditions and names sleeve gastrectomy in the study title, but eligibility criteria, baseline characteristics, and the characteristics of participants enrolled are not reported in the registry record. This prevents assessment of how closely the enrolled group matches any particular clinical population.

The intervention descriptions specify timing but do not report the amount of bupivacaine, other procedural details, adherence to assigned timing, or deviations from the planned procedure. The record identifies single masking but does not say who was masked or how masking was maintained. The randomization sequence and allocation-concealment procedures are also not reported.

The primary outcome is defined at multiple time points, but no method for combining or comparing those measurements is reported. No analysis model, multiplicity strategy, covariate adjustment, or analysis population is specified. The registry lists 0 analyses and does not provide pain scores, group summaries, treatment-effect estimates, or confidence intervals. This is the principal limitation for interpreting efficacy: the recorded design does not come with reported primary outcome findings.

Participant flow, the number with scores available at each time, missing-data handling, and sensitivity analyses are not reported in the registry record. Analgesic utilization is named as a secondary outcome, but its definition and results are not given. Adverse-event counts are listed without event terms or detail about collection and follow-up. These gaps restrict assessment of both outcome completeness and safety reporting.

The enrollment is recorded as 200, but that figure does not establish how many participants contributed to each outcome. The planning description gives assumptions for a sample-size illustration but no numeric planning estimates, and does not supply enough information to evaluate the effect basis. Together, these limitations mean the record supports description of the intended comparison, not a conclusion about its results.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Laparoscopic TAP Block for Sleeve Gastrectomy: Does Timing Matter — NCT04787367.
• Registry record last updated 2026-07-02; status last verified 2026-06.
• Results first posted 2026-07-02.
• 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 describes NCT04787367, titled “Laparoscopic TAP Block for Sleeve Gastrectomy: Does Timing Matter.” It is recorded as a completed, randomized, parallel-group, single-masked trial with enrollment of 200. The phase is listed as NA. The recorded study start date is 2019-02-12, and primary completion is recorded as 2022-07-01.

The trial compares early-operative TAP block after placement of the camera port with late-operative TAP block at case completion just before removal of the camera port. The primary outcome is patient-reported pain on a scale from 0 to 10, planned at 0 hours, 4 hours, 8 hours, 12 hours, 16 hours, 20 hours, and 24 hours post-operatively. Analgesic utilization is listed as a secondary outcome.

No primary outcome estimates or analyses are reported in the registry record. The listed adverse-event figures show 0 serious events affected, 0 other events affected, and 0 deaths in each group, without further event detail. The record defines the planned timing comparison but does not report findings that would establish the magnitude or precision of an outcome difference.