Analgesia in Laparoscopic Cholecystectomy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Analgesia in Laparoscopic Cholecystectomy (NCT01388946), a randomized na study. The primary outcome is VAS Score Changes ( Cough) During 24 h Postoperatively.

2. Clinical Question

The clinical question is therefore specific to pain during coughing at a defined postoperative time. Pain at rest and pain at other times appear among the secondary outcomes, but they are not interchangeable with the primary measure: coughing can provoke pain differently from resting, and pain can change over postoperative time. The comparison estimates group averages, rather than the experience of every individual participant. The registry description does not report a threshold for a clinically important difference, so the magnitude of any contrast cannot be classified against such a threshold using the record alone.

3. Trial Design

The registry record identifies NCT01388946 as a completed, randomized, parallel-group trial sponsored by the University of Athens. Enrollment is listed as 110. The recorded start is 2010-05, and primary completion is listed as 2014-01. Phase is recorded as NA. These administrative details describe the registered study, but do not by themselves establish how participants were recruited or how the allocation sequence was generated.

The comparison was between continuous ropivacaine infusion and continuous normal saline infusion, each described at 2 ml/h for 24 hours. The ropivacaine intervention is specified as 7.5 mg/ml. The primary outcome description reports 50 analyzed patients in the ropivacaine group at 24 hours, and the posted primary results give group sizes of 50 and 52. The record does not explain the difference between enrollment and the outcome-analysis group sizes, or provide a complete participant-flow account.

The registry masking classification is TRIPLE, while the official title describes the trial as double-blind. The record does not say which roles were masked, how masking was maintained, or whether masking was assessed. It also does not report the randomization procedure, allocation concealment, or the trial's original statistical plan. These omissions limit what can be concluded about the conduct of the trial from the registry record alone.

The primary outcome is a continuous pain score during coughing at 24 hours. Secondary outcomes include pain ratings at rest at several postoperative times and pain during coughing at early times. The registry lists 14 outcome measures, with 13 secondary outcomes posted. The registered completion status is COMPLETED; that status should not be taken as evidence that every planned analysis or every outcome was reported.

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: Fifty patients in the Ropivacaine group were analyzed for the primary (VAS score at cough) and secondary outcomes 24 hours postoperatively. One patient presented ileus after the first 24 h and was not assessed for pain 48 h after surgery

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: To assess differences in patients' characteristics between the two groups, two-independent samples t-tests for normally distributed variables (age and duration of surgery) and Mann-Whitney tests for abnormally distributed variables (BMI and CO2 total volume consumed) were carried out.

6. Primary Endpoint

The registry lists the primary outcome as VAS Score Changes ( Cough) During 24 h Postoperatively, measured over 24 h.

The primary endpoint is the visual analogue scale score for pain during coughing over the 24 hours after surgery. The registry describes the measure in millimetres, with a total range from 0 to 100: 0 represents no pain and 100 represents the possible worst pain. The recorded summary is a mean with a standard deviation for each group.

A continuous pain scale retains more gradation than a simple category such as pain present or absent. A mean offers a concise description of the group's average score, while the standard deviation describes how spread out individual scores are around that average. Neither statistic gives the full distribution of scores, and a group mean does not imply that all participants had pain close to that value.

Coughing is a defined activity that can bring on pain, so this endpoint addresses pain under that condition rather than pain at rest. A common measurement condition and time point make a group comparison interpretable, while the chosen time point makes the estimate specific to the postoperative period measured. The registry's brief study description also mentions analgesic consumption as part of the investigators' hypothesis, but the posted primary endpoint is the pain score. The record does not report a threshold for a clinically important change in this scale, or details of how coughing and the score were standardized.

7. Results Posted in the Registry

• Normal Saline: mean 31.00 versus 32.00 on control; difference -1.00 (95% CI -10.90 to 8.90), standardized effect d = -0.04; z-test p = 0.843.

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.

Pain Scores in the Postoperative Care Unit (PACU) at Rest

• 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:
  • Normal Saline: mean 46.00 versus 36.00 on control; difference 10.00 (95% CI 1.02 to 18.98), standardized effect d = 0.43; z-test p = 0.029.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Normal Saline than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Pain Scores at Rest 2 h Postoperatively

• 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:
  • Normal Saline: mean 30.00 versus 26.00 on control; difference 4.00 (95% CI -4.54 to 12.54), standardized effect d = 0.18; z-test p = 0.359.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Normal Saline and the control. The interval gives the range of effects that remain compatible with the data.

Pain Scores at Rest 4 h Postoperatively

• 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:
  • Normal Saline: mean 22.00 versus 16.00 on control; difference 6.00 (95% CI -1.38 to 13.38), standardized effect d = 0.32; z-test p = 0.111.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Normal Saline and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes extend the primary question across pain at rest and at different postoperative times, and include pain during coughing in the PACU and at an early postoperative time. Collectively, these measures can indicate whether the pattern of pain scores is similar across settings or whether any observed contrast appears confined to a particular condition or time. They should be treated as complementary outcomes rather than substitutes for the primary cough score at 24 hours.

The posted secondary results show a less uniform pattern than a single overall claim of consistent separation between groups would imply. The PACU-at-rest comparison stands out more than the other reported resting comparisons; at the later resting time points with posted numeric comparisons, the intervals include zero. This broad pattern does not establish that an effect changes over time, because the record does not report a formal test comparing effects across time points. Nor does it establish a consistent difference across all secondary outcomes.

The primary result remains the prespecified focus identified in the registry record, while secondary comparisons are exploratory context unless a plan says otherwise. The record lists 13 secondary outcomes, but does not report a multiplicity strategy. When many outcomes are examined, some may appear more notable by chance even if there is no underlying effect across outcomes. Unadjusted secondary results therefore carry less confirmatory weight than a primary comparison defined in advance.

The registry record has no reported analysis entries for these outcomes. It does not say whether all secondary outcomes were planned in their posted form, whether additional outcomes were measured but not reported, or whether a hierarchy was used. The displayed secondary findings can help describe the observed pattern, but they cannot establish a broad effect across postoperative pain conditions without a reported analysis plan and appropriate attention to multiple comparisons.

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

• Pain Scores in the Postoperative Care Unit (PACU) at Rest
• Pain Scores at Rest 2 h Postoperatively
• Pain Scores at Rest 4 h Postoperatively
• Pain Scores at Rest 8 h Postoperatively
• Pain Scores at Rest 24 h Postoperatively
• Pain Scores at Rest 48 h Postoperatively
• Pain Scores During Cough in the PACU
• Pain Scores During Cough 2 h Postoperatively

9. Statistical Interpretation

10. Statistical Methods Explained

The principal comparison concerns a continuous outcome: pain measured in millimetres on a visual analogue scale. Continuous outcomes can take a range of values, so the registry reports the mean and standard deviation for each group. The mean is the arithmetic average of the recorded scores. The standard deviation describes the typical spread of scores around that average; it is not the uncertainty in the mean and is not a confidence interval.

What does the mean difference represent?

A mean difference expresses the contrast between the two group means in the original measurement units. Here, the posted estimate is -1.0 mm, with the comparison ordered as normal saline relative to ropivacaine. Keeping the contrast in millimetres makes its scale directly interpretable against the 0-100 mm instrument range. The estimate is a group-level contrast and does not imply that each participant's score changed by that amount.

The calculation reported with the comparison is unadjusted. In general, an unadjusted comparison uses the group summary statistics without accounting for additional covariates or other features of the design. That may be a useful descriptive contrast, but it does not establish whether the trial's intended primary analysis used the same method. The registry record does not report the original statistical plan or an entry describing a sponsor-reported analysis.

How should the confidence interval be read?

A confidence interval gives a range of effect estimates compatible with the data and the method used to calculate the interval. Its width reflects uncertainty in the estimated contrast. The primary interval extends from -10.9 to 8.905 mm. Since it includes zero, the data do not clearly distinguish the observed group means from no mean difference under this comparison. The interval also includes contrasts in both directions, so it does not rule out every potentially meaningful difference. Whether its limits are clinically small or large cannot be judged without a clinical importance threshold, which is not reported in the registry record.

A confidence interval is not a range containing a fixed proportion of individual pain scores. It is also not a statement that a particular value inside the interval has a specific probability of being the true effect. Its practical value is that it presents the uncertainty and direction of plausible contrasts more fully than a single estimate or p-value.

What does the p-value contribute?

The unadjusted p-value is 0.843. In general, a p-value measures how incompatible observed data are with a specified null model, assuming the model and analysis conditions are appropriate. It is not the probability that the null hypothesis is true, not the probability that the findings are due to chance, and not a measure of clinical importance. A large p-value does not prove the absence of an effect; it indicates that the observed data do not provide a strong statistical distinction from the null model under the analysis used.

The label unadjusted matters because the registry lists several secondary outcomes, and no multiplicity adjustment is reported. A p-value for an individual outcome does not account for the possibility of obtaining apparently notable results while examining many outcomes. No registry-reported entries appear under reported analyses, so the record does not describe a planned hierarchy, adjustment method, or confirmatory status for secondary comparisons.

Why do spread and sample size matter?

For a mean comparison, uncertainty depends on how variable the scores are and how much information is available in each group. Greater variability makes it harder to estimate a group mean precisely, all else being equal; more observations can generally improve precision. These are general statistical principles, not additional claims about how this trial was designed. The reported standard deviations show that there is substantial variation in participant scores around the group means, but they do not explain the causes of that variation.

In general, a statistical comparison also relies on assumptions about the data and the sampling process. For example, methods based on means need to produce reasonable uncertainty estimates for the observed distribution and design. The registry record does not report diagnostic checks, the exact test used, or adjustments for covariates. It is therefore more appropriate to describe the posted contrast as an unadjusted recalculation than to attribute a particular full analysis procedure to the investigators.

Over-dispersion is a concern for some count-data models when counts vary more than the model expects. It is not the central issue for this continuous mean endpoint. For this outcome, the directly relevant posted summaries are the mean, standard deviation, group size, mean difference, confidence interval, and p-value. General method explanations should not be mistaken for details of the trial's unreported analysis plan.

The posted recalculation uses the summary information in the record; it is not a reconstruction from participant-level data. Participant-level data could allow assessment of distributions, missingness, covariate adjustment, and other aspects that group summaries cannot show. The record does not report such data or explain whether any additional analysis was conducted. There is no stated discrepancy between the recalculation and a sponsor analysis, but the absence of a discrepancy does not supply missing methodological details.

11. Confidence Intervals and Precision

The primary mean difference is -1.0 mm, and its 95% confidence interval runs from -10.9 to 8.905 mm. The interval is wide enough to include both a negative and a positive contrast. This means the point estimate alone should not be read as a precise estimate of the direction or size of the underlying group difference. The interval gives a more informative account of uncertainty than the point estimate by itself.

The observed group means, 32.0 mm for ropivacaine and 31.0 mm for normal saline, are close together. Yet the individual scores vary substantially, as indicated by standard deviations of 26.0 mm and 25.0 mm. Variation among participants contributes to uncertainty about the group contrast. A small estimated difference and a broad interval can coexist: the estimate is near zero, but the data do not pin down the full range of plausible differences very narrowly.

The interval includes zero, so the posted comparison does not establish a statistically clear difference at conventional levels. That is not the same as demonstrating equivalence or ruling out an important effect. The record does not define a clinically meaningful margin, and therefore the interval cannot be judged against such a benchmark. It also does not report a minimally important change for the visual analogue scale.

Precision is specific to this outcome, contrast, and time point. It does not transfer automatically to pain at rest, other postoperative times, or analgesic consumption. Nor does the interval describe how individual participants respond. The registry record gives group summaries rather than a detailed account of participant-level variability or missing outcomes.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The sample-size figures are planning illustrations based on the observed effect, not the trial's original design calculation. The registry record does not report the original sample-size assumptions or justification. For these continuous outcomes, the displayed figures are participants per arm, not total participants. The underlying planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, a normal approximation, and an effect to detect set to the stated fraction of the observed effect.

The 80% power column describes the planned number of participants per arm for a hypothetical study that would have an 80% chance of detecting the specified effect under those assumptions, if that effect and the assumptions were correct. The 90% power column gives the corresponding planning target for a higher chance of detection. These are prospective planning concepts, not properties that can be read back as a probability that the completed trial found a real effect.

The rows for 100%, 75%, and 50% of the observed effect illustrate how the planned sample size changes when the effect targeted for detection is smaller than the observed estimate. Smaller effects need more participants to distinguish them from random variation at the same significance level and power target. This relationship is a general feature of statistical planning, not evidence that the observed effect is stable or that any smaller effect is clinically important.

These figures are not observed power. They are hypothetical sample-size calculations, and their values depend on the assumptions stated above. They should not be interpreted as the trial's actual enrollment target, because the registry record does not report the original design calculation. The planning results also do not replace examination of the observed estimate and its confidence interval: the latter describe the uncertainty in the posted outcome comparison.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = -1.000; pooled standard deviation σ = 25.495.
2. n = 2 × (1.96 + 0.842)² × 25.495² / -1.000² = 10,203.4, rounded up to 10,204 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- -1                      # observed difference in means
sigma <- 25.4949014510745                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(1388946)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 10,204 (80% power), 13,660 (90% power)
 75% of observed effect: n per arm = 18,140 (80% power), 24,284 (90% power)
 50% of observed effect: n per arm = 40,814 (80% power), 54,638 (90% power)
power.t.test: 10204.3 
Simulated power at n = 10,204 per arm: 0.799 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry lists 14 outcome measures, including 13 secondary outcomes. Examining multiple outcomes creates a multiplicity concern: even when each individual comparison is interpreted using its own unadjusted significance test, the chance of at least one apparently notable finding across a collection of tests can increase. This is a general statistical issue and does not show that any particular secondary finding is false. It does mean that an isolated secondary result should be interpreted cautiously unless it was supported by a prespecified analysis plan.

No multiplicity adjustment is reported in the registry record. The record also contains no reported analysis entries, so it does not describe a testing hierarchy, a family of outcomes, or a method for controlling the error rate across comparisons. Without those details, the secondary p-values are best viewed as unadjusted evidence for individual comparisons rather than as a coordinated set of confirmatory tests.

Information about missing data is limited. The primary outcome description says that 50 patients in the ropivacaine group were analyzed at 24 hours, and the posted comparison reports 50 and 52 participants for the two groups. It notes that one patient presented with ileus after the first 24 hours and was not assessed for pain at 48 hours. That note concerns the 48-hour assessment; it does not explain missingness at the primary time point. The record does not give a participant-flow account, reasons for other missing measurements, or a missing-data method.

The analysis population is also not fully described. The record does not specify whether the primary comparison followed intention-to-treat principles, whether any participants were excluded after randomization, or how deviations from the assigned infusion were handled. Such details matter because analyses restricted to participants with observed outcomes can differ from analyses that preserve the randomized groups. The registered sample sizes and outcome summaries are not enough to resolve these questions.

The masking classification is recorded as triple, while the official title describes the trial as double-blind. The record does not define the masked roles or describe the procedure. These omissions, together with the absence of a statistical plan and analysis-population detail, limit assessment of how outcomes and analyses were selected and conducted.

15. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The adverse-event record lists 55 participants at risk in each group for serious adverse events and other adverse events. It records 0 serious adverse events and 0 other adverse events in the ropivacaine group, and the same counts in the normal saline group. These are the event figures recorded in the registry; they do not establish that no symptoms or events occurred outside the registry's definitions or reporting process.

The record does not provide serious adverse-event terms, and no top serious-event terms are listed. Death counts are not reported in the registry record. The displayed at-risk counts are safety denominators and should not be confused with the group sizes reported for the primary outcome. The record does not explain the safety monitoring period, event-collection procedures, or whether the event categories were defined in a particular way.

Zero recorded events in these categories means that the registry reports no events in the listed categories for the stated at-risk groups. It does not prove the absence of risk, and it does not by itself establish comparative safety. Interpretation depends on event definitions, follow-up, ascertainment, and the amount of information available; those details are not reported in the registry record.

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

The posted primary outcome describes mean pain during coughing at 24 hours after laparoscopic cholecystectomy. The group means were close, and the unadjusted mean difference was -1.0 mm. The confidence interval includes zero and extends in both directions. Taken together, these results do not provide a clear statistical separation between the group averages at this endpoint, but they also do not establish that the groups are equivalent.

The distinction matters because failure to demonstrate a clear difference is not proof that there is no difference. To support an equivalence conclusion, the study would need an appropriate design and a prespecified margin for an acceptable difference. The registry record does not report such a margin. It also does not identify a clinically important threshold for interpreting the visual analogue scale, so the clinical importance of the interval's possible contrasts cannot be determined from the record alone.

The result is limited to pain during coughing at the specified postoperative time. It does not answer every question about pain at rest, pain at other times, or analgesic consumption. The investigators' brief description mentions analgesic consumption as part of the hypothesis, but the posted primary result is the pain score. The secondary results offer additional context, but multiple unadjusted comparisons and the lack of a reported analysis plan make them less decisive.

The outcome summaries also do not establish individual benefit or harm. Group means and standard deviations describe distributions at an aggregate level, and the registry record does not provide participant-level results, detailed missing-data information, or the full analysis population. Safety entries report zero serious and other adverse events in the listed groups, but deaths are not reported and the safety ascertainment details are absent. Accordingly, the record supports a cautious description of the measured results, not a general claim about effects or safety beyond the reported outcomes and follow-up.

17. Why This Trial Matters Statistically

This trial illustrates why an estimated difference should be read together with its uncertainty. The primary mean difference is near zero, but the confidence interval still spans contrasts in both directions. Reporting only the group means or the p-value would conceal part of that uncertainty. The interval makes clear that the data do not sharply determine the size or direction of the underlying contrast.

It also highlights the difference between a null finding and evidence of equivalence. A non-significant comparison does not show that two approaches are the same. That conclusion requires a design and interpretation based on a clinically justified equivalence margin, which is not reported in the registry record. This distinction is particularly important when the interval remains compatible with a range of effects.

The several secondary measures add clinical context but also introduce multiplicity. A result that looks more notable at one time or condition should not automatically be treated as proof of a consistent pattern. With no reported adjustment or analysis hierarchy, those outcomes are less conclusive than a single primary question defined in advance.

The record further shows why registration details and analysis details are not interchangeable. Randomization and masking are recorded, but important information about sequence generation, allocation concealment, missing data, the statistical plan, and the analysis population is not reported in the registry record. Those details affect how confidently a reader can assess bias and interpret the posted comparisons. Statistical interpretation depends not only on the numerical estimate, but also on how the outcome was collected, which participants were included, and which comparisons were planned.

18. 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 original sample-size justification, randomization sequence method, or allocation concealment. It also does not provide the original statistical plan, the planned analysis population, or details of any covariate adjustment. These omissions make it difficult to determine whether the posted recalculations match the trial's intended analysis.

There is limited information about outcome availability. The primary result reports analyzed group sizes, but the record does not provide a full participant-flow account or explain missing observations at the primary time point. The note about one patient with ileus concerns assessment at 48 hours, not the 24-hour primary measure. The relationship between enrollment and the outcome-analysis groups is not explained.

The primary outcome is a single pain rating during coughing at 24 hours. The registry does not report how coughing was standardized, how the visual analogue scale was administered, or whether assessors were masked in practice. The official title says double-blind, while the registry masking classification says triple; the record does not clarify which participants or study personnel were masked.

The confidence interval includes zero, and no clinical importance threshold or equivalence margin is reported. This limits interpretation of whether the range of compatible contrasts is practically small or important. Several secondary outcomes are listed, but no multiplicity strategy or reported analyses are described. The safety record lists zero events in its categories, but does not report deaths, detailed event definitions, or safety follow-up procedures. These limitations call for restraint when extending the observed summaries beyond the specific outcomes and groups recorded.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Analgesia in Laparoscopic Cholecystectomy — NCT01388946.
• Registry record last updated 2016-07-06; status last verified 2016-07.
• Results first posted 2016-07-06.
• 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.

22. Record Summary

NCT01388946 is a completed randomized parallel-group trial sponsored by the University of Athens, with enrollment listed as 110. It compares continuous perioperative ropivacaine infusion with continuous normal saline infusion in laparoscopic cholecystectomy. The primary endpoint is mean pain during coughing at 24 hours, measured in millimetres on a 0-100 visual analogue scale.

The posted group means are 32.0 mm for ropivacaine and 31.0 mm for normal saline. The unadjusted mean difference is -1.0 mm, with a 95% confidence interval from -10.9 to 8.905 and an unadjusted p-value of 0.843. This does not show a clear difference in group means, but it does not establish equivalence.

The record lists 13 secondary outcomes, with no reported analysis entries or multiplicity method. It reports zero serious and other adverse events in both listed safety groups; deaths are not reported in the registry record. Details of the original statistical plan, missing data, and analysis population are also not reported in the registry record.