Trans-incisional vs Laparoscopic Guided Rectus Sheath Block for Pediatric Single Incision Laparoscopic Cholecystectomy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Trans-incisional vs Laparoscopic Guided Rectus Sheath Block for Pediatric Single Incision Laparoscopic Cholecystectomy (NCT02494336), a randomized na study. The primary outcome is Post Operative Pain Rating.

2. Clinical Question

The clinical question is whether the method used to deliver a rectus sheath block is associated with a different postoperative pain rating for children and young people undergoing single-incision laparoscopic cholecystectomy. The comparison is between block delivery through the umbilical incision under direct visualization and delivery under direct laparoscopic visualization. The registry describes both methods as performed by the attending pediatric surgeon.

The posted group means are both 4.03. The recalculated unadjusted mean difference is 0.0, with a confidence interval that includes differences in either direction. That result describes the posted summaries; it does not establish that the methods are identical or that the difference is clinically unimportant. The registry record does not report a prespecified threshold for a meaningful pain-score difference.

3. Trial Design

The registry describes a prospective, randomized, parallel-group study. Allocation is listed as randomized, masking as triple, and the study status as completed. The record lists enrollment of 48 and reports 24 participants in each primary-outcome group. The study is listed as phase not applicable.

The comparison concerned two ways of delivering a rectus sheath block during pediatric single-incision laparoscopic cholecystectomy. In the trans-incisional group, the block was performed through the umbilical incision under direct visualization. In the laparoscopic-guided group, it was performed under direct laparoscopic visualization. Both were described as being performed by the attending pediatric surgeon. Ropivacaine is listed among the interventions, but further details about its administration are not reported in the registry record.

The study summary says that patients, their parents or guardians, select research team members, and post-anesthesia care unit staff were blinded to the method of analgesic administration. The registry labels masking as triple; it does not explain the exact meaning of that label or describe blinding procedures for every role. The summary describes preoperative screening and consent, followed by randomization to one of the block methods.

The study start is recorded as 2015-06, primary completion as 2018-10-01, and overall status as completed. These dates describe the registry record and do not establish when results were analyzed or posted. The registry record does not report the randomization sequence method, allocation concealment, the rationale for the enrollment target, or details of any protocol deviations. No formal analysis is listed among the reported analyses.

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 Post Operative Pain Rating, measured over 5 days.

The primary endpoint is postoperative pain rating, measured with the Wong-Baker FACES Pain Rating Scale. The description says participants choose the face that most closely represents their pain. The scale ranges from 0, “no hurt,” to 10, “Hurts Worst.” The reported summary is a mean score with standard deviation over a timeframe of 5 days.

Pain ratings are used to represent a participant’s reported pain experience in a form that can be summarized across a group. A mean allows a broad comparison of the average rating between randomized groups, while the standard deviation describes how spread out individual ratings are around each group mean. These summaries do not show the full distribution of individual scores or whether participants’ ratings changed during the timeframe.

The registry record does not specify how repeated ratings during the 5 days were collected or combined into the posted group mean. It also does not report the timing of each rating, the handling of missing ratings, or a threshold for a clinically important difference. Those details matter when interpreting a mean for a subjective measure: identical group means can coexist with different individual experiences, and a single summary does not show the pattern of ratings over time.

The posted primary means are 4.03 in both groups. This is a descriptive comparison of the recorded group summaries, not a claim that every participant had the same experience or that the two block methods are interchangeable.

7. Results Posted in the Registry

• Laparoscopic Guided Rectus Sheath Block: mean 4.03 versus 4.03 on control; difference 0.00 (95% CI -0.75 to 0.75), standardized effect d = 0.00; z-test p = 1.000.

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.

Operative Time

• 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:
  • Laparoscopic Guided Rectus Sheath Block: mean 60.00 versus 62.00 on control; difference -2.00 (95% CI -15.21 to 11.21), standardized effect d = -0.09; z-test p = 0.767.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Laparoscopic Guided Rectus Sheath Block and the control. The interval gives the range of effects that remain compatible with the data.

Use of Post-operative Intravenous/Oral Opioid and Non-opioid

• 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:
  • Laparoscopic Guided Rectus Sheath Block: mean 56.00 versus 0.49 on control; difference 55.51 (95% CI 55.30 to 55.72), standardized effect d = 148.68; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Laparoscopic Guided Rectus Sheath Block than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Time to First Rescue Analgesic

• 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:
  • Laparoscopic Guided Rectus Sheath Block: mean 17.90 versus 14.40 on control; difference 3.50 (95% CI -4.60 to 11.60), standardized effect d = 0.24; z-test p = 0.397.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Laparoscopic Guided Rectus Sheath Block and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes address several aspects of the procedure and postoperative course, rather than measuring the same construct as the primary pain rating. The listed outcomes include operative time, use of postoperative opioid and non-opioid medication, time to first rescue analgesic, side effects, and complications. Numerical summaries are posted for some continuous secondary outcomes; the registry record does not report numerical results for every listed secondary measure. This means the secondary record is not a complete quantitative account of all listed outcomes.

The broad pattern should be interpreted alongside the primary result, not as an independent confirmation of it. The primary comparison concerns average pain ratings over 5 days. Medication use, rescue timing, operative time, and safety events capture different features and can vary for reasons not represented by a pain score alone. Agreement or disagreement between endpoints would not by itself establish a single overall effect, particularly when the measurement details and analysis methods are not fully reported.

The opioid and non-opioid use summary deserves special caution: its posted group values are 0.49 and 56.0 MME/kg. That contrast is unusually large relative to the posted pooled standard deviation, and the registry record does not explain the discrepancy in scale or provide a reported analysis. The numbers should be read as recorded rather than silently corrected, but the record alone cannot establish whether the values reflect the intended measure and coding.

Secondary results generally carry less weight than a prespecified primary result because several comparisons create opportunities for chance findings. Unadjusted p-values, where listed, do not account for the number of outcomes examined. The registry record does not report a multiplicity plan, a hierarchy among secondary outcomes, or formal secondary analyses. These results can help describe the pattern of observations and suggest questions for further evaluation, but they should not be treated as definitive evidence on their own.

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

• Operative Time
• Use of Post-operative Intravenous/Oral Opioid and Non-opioid
• Time to First Rescue Analgesic
• Number of Participants With Side Effects
• Number of Participants With Complications
• Total Number of Complications

9. Statistical Interpretation

10. Statistical Methods Explained

The primary comparison is presented as a difference between group means. For a continuous outcome, a mean summarizes the central level of the recorded measurements, while a standard deviation describes their spread around that mean. In this study, the outcome is a pain-rating score, and the reported means and standard deviations allow a simple comparison of the two randomized groups. Such summaries are useful, but they do not preserve details such as skewness, clustering of scores, or changes over time.

What does the mean difference represent?

The comparison is oriented as laparoscopic-guided block relative to trans-incisional block. The posted means are 4.03 in both groups, and the recalculated unadjusted mean difference is 0.0. A difference of zero means the reported group averages are equal at the precision given. It does not mean that each participant had the same score across groups, or that all possible population differences have been ruled out.

An unadjusted comparison uses the group summaries without controlling for additional participant or procedural variables. Random allocation is intended to make groups comparable on average, but this registry record does not provide baseline characteristics or a model adjusted for them. The recalculation therefore should not be presented as an adjusted treatment effect or as the trial’s own formal analysis. No reported analyses are listed in the registry record.

How should the confidence interval be read?

A confidence interval describes the range of effect estimates reasonably compatible with the data and the method’s assumptions. For the primary mean difference, the interval is -0.746 to 0.746. Because it covers zero and extends in both directions, it is compatible with either group having a higher mean as well as with no difference. This does not prove equality. A narrow interval can indicate greater precision than a wide one, but whether an interval is sufficiently narrow for a practical decision depends on a prespecified meaningful-difference threshold, which is not reported in the registry record.

The interval is not an interval for individual pain scores. Nor should it be interpreted as the probability that the true difference lies inside its endpoints. Its repeated-sampling interpretation is general: if the same method were applied over repeated studies under its assumptions, the resulting intervals would cover the fixed target parameter at the method’s stated confidence level. The record does not state a confidence level alongside the posted interval, so no level should be inferred from the registry record alone.

What does the p-value add?

The unadjusted p-value for the primary comparison is 1.0. In general, a p-value describes how compatible the observed result, or a result more extreme under a specified test, is with a null model. It is not the probability that the null is true, and it does not measure the size or importance of an effect. Here, the zero difference between the posted means corresponds to the reported p-value. It does not establish that any nonzero difference is impossible.

The adjective unadjusted matters because the record lists multiple outcome measures and does not report a multiplicity correction. Looking at many outcomes can increase the chance of at least one apparently unusual result even when no effect exists. An adjustment can address some of that issue, but the registry record does not report a planned adjustment or a prespecified hierarchy of outcomes. The primary endpoint is identified as primary, but the detailed statistical plan is not reported.

What can planning illustrations tell us?

Planning illustrations based on observed effects are included for some secondary continuous outcomes. They use a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the target effect set to a stated fraction of the observed effect. These are retrospective planning illustrations, not the trial’s original sample-size justification. The rationale used to select enrollment of 48 is not reported in the registry record.

Sample-size illustrations based on observed effects can be unstable, especially when an observed difference is small or unusually large. The illustrations depend on the observed effect and the variability estimates; changing the assumed effect changes the calculated requirement. They are not observed power, do not show the probability that the completed trial detected an effect, and do not establish that a future study would need the same number of participants. The calculation assumptions also do not account for all possible design features or missing data.

One secondary result reports values of 0.49 and 56.0 MME/kg, with a recalculated mean difference of 55.51 and pooled standard deviation of 0.373. The resulting standardized difference is unusually large relative to that pooled spread. The registry record does not explain this scale of contrast or provide a reported analysis to clarify it. It should be treated as a feature of the posted summaries requiring careful interpretation, rather than as evidence that the displayed magnitude is a reliable estimate of a broader effect.

Why do distribution and measurement details matter?

Methods based on means and standard deviations are most directly informative when the summary statistics represent comparable measurements and the analysis assumptions are reasonable. General statistical practice considers the outcome’s distribution, the presence of unusual values, whether observations are independent, and whether repeated observations require a model that accounts for their relationship. The registry record does not report diagnostic checks or a model for repeated pain ratings.

For event counts, over-dispersion is a general concern when observed variability exceeds what a simple count model expects. It can make uncertainty estimates too small if ignored. The posted secondary outcomes include event-related measures, but the registry record does not describe a model for them. This is a general reason to avoid assuming that every kind of endpoint can be analyzed with the same method used for a continuous mean.

11. Confidence Intervals and Precision

The primary mean difference is 0.0, with a confidence interval from -0.746 to 0.746. The interval communicates uncertainty around the estimated difference in group averages. Its inclusion of zero means the posted summaries do not distinguish a positive difference from a negative one at the level represented by the interval. The record does not report a threshold for a clinically important pain-score difference, so it is not possible to say whether the interval excludes effects that would matter in practice.

Precision is different from the point estimate. The point estimate is the single best estimate produced by the calculation, while the interval shows a range of values compatible with the data and its assumptions. Equal means and a zero point estimate do not make the uncertainty disappear. Conversely, a confidence interval is not a description of the range of individual responses: individual scores can vary around each group mean, as reflected by the standard deviations of 1.46 and 1.16.

The interval comes from an unadjusted recalculation of the posted summary statistics. It should not be mistaken for a sponsor-reported adjusted estimate or for a formal analysis documented in the registry record. The record does not report a confidence level, missing-data method, analysis population, or details about how the repeated pain ratings over 5 days were summarized. These omissions limit assessment of whether the interval captures all relevant uncertainty.

In general, precision can improve with more informative observations and less variability, but the observed group sizes alone do not establish that a study was designed to answer a particular clinically important question. The registry does not report the sample-size justification or a target precision. The interval therefore supports a restrained conclusion: the posted mean difference is zero, but the record does not show that all potentially meaningful differences have been excluded.

12. Multiplicity, Missing Data and Analysis Populations

The registry identifies postoperative pain rating as the primary outcome and lists multiple secondary outcomes. It does not report how the family of outcomes was handled statistically. No multiplicity adjustment, testing hierarchy, or rule for interpreting secondary p-values is reported in the registry record. When multiple comparisons are considered, the chance of at least one apparently notable result can rise; this is a general statistical concern, not proof that any particular result is false.

The registry record lists no reported analyses. The estimates described in the statistical interpretation are recalculated from the posted summary statistics and are unadjusted. There is no documented analysis plan against which to assess whether these calculations match the prespecified approach, whether covariate adjustment was intended, or whether any outcome transformations or alternative analyses were planned. The record also does not report interim analyses or stopping rules; their absence from the record should not be taken as evidence about what occurred outside the record.

Missing-data handling is not reported. The record gives group sizes for posted outcomes but does not explain whether all randomized participants contributed to each measure, whether observations were missing, how missing values were treated, or whether any sensitivity analysis was performed. A stated group size does not by itself establish that all randomized participants were included in the analysis or that the analysis followed intention-to-treat principles.

The analysis population is likewise not reported. The registry record does not identify an intention-to-treat, per-protocol, or safety population, nor does it describe exclusions after randomization. This limits evaluation of how randomization was preserved in the analysis and whether participants were analyzed according to assigned group.

These gaps matter for interpretation because analysis choices can affect both estimates and uncertainty. The primary result remains a description of the posted group summaries, but the record does not permit a full assessment of the statistical plan, missingness, analysis population, or multiplicity control.

13. 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.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: readmission (4.2%), attempted suicide (4.2%).

The safety record reports serious adverse events among participants at risk in both groups. The trans-incisional group has 2 serious adverse events among 24 at risk, and the laparoscopic-guided group has 1 among 24 at risk. Other adverse events are recorded as 0 in each group, and deaths are recorded as 0 in each group. These are counts in the registry record; they do not identify cause, timing, severity beyond the serious classification, or relation to the block method.

The record also lists readmission and attempted suicide among the serious-event terms, each with a reported frequency of 4.2%. The registry record does not provide enough detail in these summaries to assign those terms to a particular group or to establish whether they describe separate events or participants. They should not be attributed to a treatment method on the basis of this information alone.

Safety counts are descriptive and do not establish that an event was caused by an intervention. With the available summaries, differences between groups should not be treated as reliable evidence of a difference in risk. The registry record does not report a formal comparative safety analysis, definitions used for each event category, or details needed to assess event timing and attribution.

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

The primary result means that the posted average pain rating was 4.03 in each randomized group. The unadjusted recalculation gives a mean difference of 0.0, with an interval from -0.746 to 0.746. This is a description of the recorded group summaries and their statistical uncertainty. It does not establish that the two procedures produce exactly equal pain ratings in all patients or in every setting.

The result also does not show that either method is superior, inferior, or interchangeable. The confidence interval includes differences in either direction, and the registry record does not state a threshold for a difference that would matter clinically. A conclusion about practical equivalence would require an appropriate design and a prespecified margin, neither of which is reported.

The trial concerns a defined setting: pediatric single-incision laparoscopic cholecystectomy and two approaches to rectus sheath block. Its findings should not automatically be extended to other procedures, age groups, block techniques, or clinical settings. The registry record does not provide enough information about participant characteristics, surgical details, or outcome collection to assess how closely the enrolled population represents other settings.

The result is also limited to the outcome as summarized. A mean pain score over 5 days does not reveal the full distribution of ratings, the course of pain at individual time points, or the experience of each participant. The record does not explain how the repeated ratings were combined or how missing observations were handled.

Finally, the secondary and safety summaries provide additional descriptive context but do not resolve these limitations. Some listed outcomes lack posted numerical results, and no formal analyses or multiplicity strategy are reported. The unusually large posted contrast for medication use requires particular care rather than a confident substantive interpretation. Overall, the registry supports a narrow reading of the primary summary, not a broad claim about treatment effectiveness or safety.

15. Why This Trial Matters Statistically

This trial is statistically informative because it compares two procedural approaches using random allocation and reports a continuous patient-reported endpoint. The equal posted primary means make the distinction between a point estimate and its uncertainty especially clear. A zero estimated difference is not the same as proof that the underlying effects are identical; the confidence interval shows the range of differences still compatible with the summaries and assumptions.

The record also illustrates why precision and practical importance are separate questions. To judge whether uncertainty is small enough to exclude a meaningful difference, readers need a meaningful-difference threshold or a design framed around equivalence or non-inferiority. The registry record does not report such a threshold or design objective. The interval can be described, but its practical adequacy cannot be determined from the record alone.

The secondary outcomes show another statistical lesson: endpoints can represent different concepts and should not be collapsed into one general conclusion. A pain rating, medication-use measure, procedure time, and adverse-event count have different measurement properties. The unusually large medication-use contrast further illustrates how posted summaries should be checked for context and interpreted cautiously when scale or coding details are unclear.

Finally, the record demonstrates the value of a complete analysis report. Details about the analysis population, missing data, multiplicity, and the handling of repeated pain ratings would help readers assess how the estimates were produced and how broadly they apply. In their absence, readers can distinguish the observed summaries from the questions the registry record leaves unanswered.

16. 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.

Several trial-specific limitations arise from the registry record’s level of detail. The primary endpoint is summarized as a mean over 5 days, but the record does not state when pain ratings were collected, how many ratings were obtained, or how they were combined. It is therefore unclear whether the mean represents one summary per participant, an aggregation of repeated observations, or another approach.

The record does not report missing-data methods, the analysis population, or participant flow by randomized assignment. Although 24 participants are reported in each primary group, that information alone does not establish whether all randomized participants contributed data or whether exclusions occurred. No baseline characteristics are reported in the registry record, so comparability on measured participant factors cannot be assessed.

Masking is listed as triple, and the summary names some blinded roles, but the registry does not explain how masking was maintained or whether it was assessed. The surgeon performing the block is described, but the record does not detail who rated outcomes or whether all outcome assessors were blinded. For a subjective pain measure, the process of collecting ratings is relevant to interpretation.

There is no reported analysis plan, multiplicity approach, interim-analysis information, or original sample-size justification. The sample-size illustrations based on observed secondary effects do not fill these gaps and are not evidence of the trial’s original planning. The registry also does not provide numerical findings for every listed secondary outcome.

The medication-use values are particularly difficult to interpret because the posted 0.49 and 56.0 MME/kg summaries produce an unusually large contrast relative to the stated pooled variability. The registry record does not explain this pattern. These limitations counsel against treating any single secondary comparison as a definitive finding or extending the primary result beyond the recorded setting.

17. Related Tutorials

18. Related Statistical Calculators

19. Sources

• ClinicalTrials.gov: Trans-incisional vs Laparoscopic Guided Rectus Sheath Block for Pediatric Single Incision Laparoscopic Cholecystectomy — NCT02494336.
• Registry record last updated 2021-01-22; status last verified 2021-01.
• Results first posted 2020-04-13.
• 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.

20. Record Summary

NCT02494336 is a completed, prospective randomized parallel-group study comparing trans-incisional and laparoscopic-guided rectus sheath block for pediatric single-incision laparoscopic cholecystectomy. The registry lists triple masking and enrollment of 48. The study start is 2015-06, and primary completion is recorded as 2018-10-01.

The primary outcome is mean Wong-Baker FACES Pain Rating Scale score over 5 days. The posted mean is 4.03 in each group, with standard deviations of 1.46 and 1.16. The recalculated unadjusted mean difference is 0.0, with a confidence interval from -0.746 to 0.746 and an unadjusted p-value of 1.0.

The record lists several secondary outcomes and serious adverse-event counts. It does not report formal analyses, an analysis population, missing-data handling, or a multiplicity plan. A secondary medication-use contrast is unusually large relative to its posted pooled variability and is not explained in the registry record. The evidence therefore supports a cautious description of the posted summaries, rather than a claim of equivalence or a broad conclusion about treatment effects.