Serratus Plane Block for Postoperative Pain Control: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Serratus Plane Block for Postoperative Pain Control (NCT02865928), a randomized phase 4 study. The primary outcome is Postoperative Opioid Requirements.

2. Clinical Question

The clinical question concerns opioid consumption after outpatient breast surgery, with the saline injection serving as the placebo comparison. Opioid use was converted to a morphine-equivalent dose for analysis. The primary endpoint is reported as a mean with a standard deviation, and the registry gives the primary timeframe as 4 to 10 hours. The outcome description also says narcotic use would be recorded intraoperatively and through the postoperative day; that broader description should not be confused with the stated primary timeframe.

The record lists postoperative pain, nausea and vomiting, antiemetic use, recovery-unit length of stay, and patient experience among the secondary outcomes. These measures describe other aspects of recovery, but the posted results do not include an inferential analysis for every listed secondary outcome. The registry record does not report a more detailed definition of the population included in each outcome analysis, or a reason for the trial's terminated status.

3. Trial Design

The registry identifies this as a phase 4, randomized, parallel-group trial sponsored by Northwell Health. It lists quadruple masking. The brief summary describes the study as randomized, double-blinded, and placebo-controlled; the registry's design field and summary use different masking descriptions. The record does not explain that difference. Participants were assigned to a bupivacaine HCl serratus plane block or a normal saline placebo injection on the operated side, using the same technique. The brief summary says participants were to be stratified according to surgery type before randomization.

The registry lists an enrollment of 42 and a status of terminated. The brief summary describes a plan to enroll 90 subjects at presurgical testing. These figures describe the registry's enrollment and the planned enrollment stated in the summary, respectively; the record does not report why the trial was terminated or why enrollment did not reach the stated plan. The study start date is 2017-09-05, and the primary completion date is 2019-11-25.

Standard intraoperative anesthesia and standard postoperative pain control were described for both groups. Rescue medication was to be administered upon request according to standard of care, and narcotic consumption was to be converted to a morphine-equivalent dose. The primary outcome is postoperative opioid requirements during 4 to 10 hours. Secondary outcomes include pain and nausea or vomiting scores assessed at repeated intervals in the recovery unit, antiemetic use during the postoperative period, recovery-unit length of stay, and patient experience and satisfaction. The registry record does not report the trial's original sample-size justification, detailed analysis plan, or reasons for termination.

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.

Before assignment: * Any physical, mental or medical condition, makes study participation inadvisable. For example, chronic pain conditions, significant medical disease, laboratory abnormalities or condition(s) that could impact a subject's ability to communicate with the study staff, complete study activities such as provide pain scores, or would otherwise contradict study participation * Patients who are pregnant or nursing. * Patients may withdraw from this study at their discretion.

Overall Study

Reasons for not completing this period:

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: At pre-surgical testing, subjects screened will be recruited into the trial.

6. Primary Endpoint

The registry lists the primary outcome as Postoperative Opioid Requirements, measured over 4 to 10 hours.

The primary endpoint is postoperative opioid requirements, expressed in morphine milligram equivalents (MME), with the stated timeframe of 4 to 10 hours. It measures the amount of rescue opioid administered after surgery, converting oral and intravenous medications to a common morphine-equivalent scale. Using a common unit allows medication consumption to be summarized across the listed routes of administration.

The registry describes rescue medication as available to both groups upon request according to standard of care. It also says narcotic use would be recorded intraoperatively, during the recovery-unit and hospital stay, and through the end of postoperative day one. Those recording details cover a broader period than the primary endpoint's stated 4 to 10 hours, so the primary comparison should be read according to its specified timeframe.

Opioid consumption is used as a measure of postoperative medication use. It is not, by itself, a complete measure of pain, comfort, or recovery. The registry lists pain ratings, nausea and vomiting, antiemetic use, length of stay, and satisfaction as additional outcomes, reflecting different dimensions of the postoperative experience. The primary endpoint is reported as a group mean and standard deviation. A mean describes the central level of consumption, while the standard deviation describes how much individual observations vary around that mean. The registry record does not report additional details about the precise analysis population or handling of missing primary-endpoint observations.

7. Results Posted in the Registry

• Normal Saline: mean 17.50 versus 19.88 on control; difference -2.38 (95% CI -15.72 to 10.97), standardized effect d = -0.11; z-test p = 0.727.

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.

Postoperative Pain With Numeric Rating Scale

• 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 0.75 versus 0.78 on control; difference -0.03 (95% CI -0.50 to 0.44), standardized effect d = -0.04; z-test p = 0.906.
• 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.

Postoperative Nausea and Vomiting With Verbal Rating Scale

• 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 0.34 versus 0.25 on control; difference 0.08 (95% CI -0.33 to 0.49), standardized effect d = 0.12; z-test p = 0.695.
• 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.

Number of Participants Who Required Antiemetics During the Postoperative Period.

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • Normal Saline: 25.0% (5/20) versus 27.3% (6/22) on control; risk difference -2.3 percentage points (95% CI -28.9 to 24.3), risk ratio 0.92 (0.33–2.54); unadjusted two-proportion z-test p = 0.867.
• 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 cover several different aspects of the postoperative period: pain and nausea or vomiting scores, use of antiemetics, length of stay in the recovery unit, and patient experience and satisfaction. Together, these measures broaden the clinical description beyond opioid consumption. They do not all measure the same construct, and a pattern across them should not be treated as if it were one unified endpoint.

The posted continuous-score summaries and the antiemetic comparison show modest estimated contrasts with intervals that include zero. The record does not provide reported inferential analyses for these secondary outcomes. The pain and nausea score comparisons and the antiemetic comparison are unadjusted recalculations; their uncertainty and exploratory status matter when interpreting any apparent pattern. Detailed results for recovery-unit length of stay and satisfaction are not reported in the registry record.

These outcomes relate to the primary result by describing other elements of recovery that could provide context for opioid consumption. However, agreement or disagreement among several measures would not by itself resolve uncertainty in the primary comparison. The outcomes have different scales, timeframes, and meanings, and the record does not describe a hierarchical testing strategy or specify which secondary comparisons were intended to support confirmatory conclusions.

When multiple outcomes are considered, the chance of finding an apparently notable result by chance can increase. Unadjusted secondary results therefore carry less weight than a prespecified primary analysis, especially when the analysis plan and multiplicity approach are not reported. The posted secondary information is useful for describing what was recorded, but it should be regarded as exploratory evidence rather than as independent confirmation of a treatment effect.

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

• Postoperative Pain With Numeric Rating Scale
• Postoperative Nausea and Vomiting With Verbal Rating Scale
• Number of Participants Who Required Antiemetics During the Postoperative Period.
• PACU Length of Stay
• Patient Experience and Satisfaction With a 5-point Categorial Scale

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is continuous: it is a measured quantity of opioid consumption expressed in MME. The registry reports the mean and standard deviation for each group. A mean gives the average level of the measured outcome within a group; a standard deviation describes variability among participants. Neither statistic alone describes the full distribution of individual observations. The record does not report additional distributional summaries for the primary outcome.

How to read the group comparison

The posted comparison is a mean difference for normal saline relative to bupivacaine HCl. Its estimate is -2.375 MME. A negative value indicates that the posted mean for the saline group is lower than the posted mean for the bupivacaine group, using that comparison's stated direction. The estimate is not an adjusted result. It is a simple unadjusted recalculation from the posted group summaries. The registry record does not report a sponsor-conducted inferential analysis for this primary comparison.

A confidence interval describes a range of values compatible with the data under the statistical procedure used. It communicates uncertainty around the estimate; it is not a range containing a known, fixed proportion of individual participants' outcomes. The primary interval, -15.72 to 10.97, includes zero. Thus the posted data do not distinguish clearly between a difference in one direction, little difference, or a difference in the other direction. Its width also signals that the estimate is imprecise.

The unadjusted p-value is 0.727. In general, a p-value measures how unusual data at least as inconsistent with a specified null hypothesis would be if that hypothesis and the test assumptions held. It is not the probability that the null hypothesis is true, and it does not measure the size or clinical importance of an effect. The registry record does not report the exact inferential procedure used by a sponsor; the p-value accompanying the recalculated comparison should be interpreted accordingly.

Why variability matters

The two primary-group standard deviations are 21.94 and 22.12, compared with group means of 19.88 and 17.5. These summaries show substantial variability in the measured outcome relative to the central values. In general, greater variability makes a group difference harder to estimate precisely when the amount of information is otherwise limited. That is one reason the interval around the mean difference is broad. The standard deviation does not indicate whether every participant's value is close to the mean, and the registry record does not provide individual observations.

Random allocation is intended in general to reduce systematic differences between groups at the point of assignment. The registry says participants were randomized and that surgery type was a stratification factor in the brief summary. Randomization does not guarantee that every relevant characteristic is balanced in a small realized sample, and the record does not give a detailed balance table or explain whether any adjustment was planned. The record identifies a parallel-group design: participants were assigned to one of the two interventions rather than crossing between them.

Secondary outcomes and multiple comparisons

The secondary outcomes include continuous scores and a count of participants requiring antiemetics. A mean difference is used for the posted continuous comparisons; a risk difference is used for the antiemetic count. In general, a risk difference describes the difference between the proportions experiencing an event in two groups. Its confidence interval reflects uncertainty in that contrast. These outcome types answer different questions and should not be interpreted as interchangeable measures.

When many outcomes are examined, some comparisons may appear more notable by chance alone. Statistical methods can address this multiplicity, for example by adjusting inference across a defined family of tests. The registry record does not report a multiplicity strategy, a complete analysis plan, or reported inferential analyses for the listed secondary outcomes. The posted secondary comparisons are unadjusted recalculations, so they should be treated as exploratory rather than as a collection of confirmatory tests.

Planning illustrations

The sample-size illustrations use the observed effect as a reference and consider detecting the full observed effect, 75% of the observed effect, or 50% of the observed effect. The stated planning assumptions are a two-sided significance level of 0.05, equal allocation between groups, and a normal approximation. For the continuous outcomes, the figures are participants per arm. In general, the smaller the effect one aims to detect, the more participants are needed to distinguish it from random variation under the stated assumptions. These are planning illustrations, not the trial's own original design justification; that justification is not reported in the registry record.

General statistical explanations above describe common interpretations of means, standard deviations, confidence intervals, p-values, randomization, and multiplicity. They do not imply that the registry used a particular model, adjustment, or testing procedure beyond what is explicitly reported. The exact sponsor analysis methods, handling of missing observations, and analysis populations are not reported in the registry record.

11. Confidence Intervals and Precision

The primary mean difference is -2.375 MME, with a 95% confidence interval from -15.72 to 10.97. This interval is broad and includes zero. It therefore reflects substantial uncertainty about the size and direction of the difference represented by the posted summaries. The results are compatible with values that would favor either group, as well as with little or no difference. The interval should not be read as proof that the groups are the same.

Precision depends on the amount of information and the variability in the outcome. The primary comparison includes 22 participants in the bupivacaine HCl group and 20 in the normal saline group, and the reported standard deviations are 21.94 and 22.12. Those group sizes and the observed spread provide important context for the uncertainty. The terminated status and enrollment of 42, compared with the brief summary's planned enrollment of 90, are also relevant context; the record does not report the reason for termination.

Confidence intervals for secondary comparisons are also broad. For example, the pain-score comparison has a 95% confidence interval from -0.496 to 0.440, and the nausea-and-vomiting score comparison has a 95% confidence interval from -0.327 to 0.490. These intervals include zero as well. They are unadjusted recalculations, not a substitute for an analysis plan or a reported sponsor analysis.

In general, a confidence interval represents uncertainty in an estimated contrast under the method used to construct it. It does not account automatically for every limitation, such as possible missing data, selection of outcomes, or multiplicity. The registry record does not report enough methodological detail to assess those issues fully. The intervals are best read as measures of statistical precision for the posted comparisons, not as guarantees about future participants or 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 planning figures are participants per arm for the continuous and binary comparisons shown in the planning illustrations. They are not total numbers across both arms. No time-to-event outcome is presented in these illustrations, so the alternative convention of reporting a total number of events does not apply. The listed assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect used for planning is the stated fraction of the observed effect: 100%, 75%, or 50%.

The 80% power column describes the number of participants per arm estimated to give an 80% chance of detecting the specified effect under the stated assumptions, if that effect is the true effect and the planning model applies. The 90% power column gives the corresponding estimate for a 90% chance. In general, aiming for a higher chance of detecting an effect requires more participants. The illustrations also show that planning to detect a smaller effect requires more participants than planning to detect a larger one.

These figures are planning illustrations based on the observed effect in this trial, not the original justification for its planned enrollment. The registry record does not report the trial's original sample-size assumptions or justification. The values do not tell how likely the trial was to detect an effect after it was conducted, and they are not observed power.

The observed estimates come from small groups and are imprecise. Planning directly from an observed effect can produce unstable illustrations because the observed effect itself is uncertain. The figures should therefore be read as conditional examples under the stated assumptions, not as recommended enrollment targets or as evidence that a particular sample size would guarantee a result.

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 = -2.375; pooled standard deviation σ = 22.026.
2. n = 2 × (1.96 + 0.842)² × 22.026² / -2.375² = 1,350.2, rounded up to 1,351 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 <- -2.375                      # observed difference in means
sigma <- 22.0260667194935                     # 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(2865928)
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 = 1,351 (80% power), 1,808 (90% power)
 75% of observed effect: n per arm = 2,401 (80% power), 3,214 (90% power)
 50% of observed effect: n per arm = 5,401 (80% power), 7,230 (90% power)
power.t.test: 1351.1 
Simulated power at n = 1,351 per arm: 0.798 (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 a primary endpoint and several secondary outcomes, including repeated postoperative ratings and measures of medication use, recovery-unit stay, and patient satisfaction. Examining multiple outcomes can increase the chance of observing an apparently unusual result by chance. A statistical analysis plan may define which outcomes are primary, how repeated measurements are handled, and whether any adjustment is made for multiple comparisons. Those details are not reported in the registry record.

The posted secondary comparisons are unadjusted recalculations. The registry record reports no inferential analyses for the secondary outcomes. Without a reported multiplicity strategy, the secondary p-values and intervals should not be interpreted as a family of confirmatory tests. The record also does not report whether the repeated pain and nausea assessments were analyzed at individual time points, combined, or summarized in another way for any sponsor analysis.

Missing-data handling is not reported in the registry record. The posted group sizes give the number represented in the outcome summaries, but the record does not explain whether all randomized participants contributed data, how missing outcome values were treated, or whether any sensitivity analyses were conducted. An analysis population, such as an intention-to-treat or per-protocol population, is not specified in the posted results.

The registry record does not report a detailed statistical analysis plan, adjustment covariates, interim analyses, or stopping rules. It states that the trial was terminated, but the reason is not reported in the registry record. These omissions limit assessment of whether the posted comparisons follow prespecified methods and how robust they might be to missing observations or analytic choices. They do not establish that any particular method was or was not used outside the posted record.

15. 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 registry lists 20 participants at risk in each group for the serious-event and other-event summaries. It records zero participants affected in the serious adverse event category and zero in the other adverse event category in both groups, and it records zero deaths. These are the posted counts for the safety summaries, not estimates that establish the absence of risk.

Safety counts should be interpreted in light of the number of participants recorded and the amount of follow-up represented. The record does not provide a detailed event listing, event definitions, exposure-adjusted rates, or further information about safety follow-up. It also does not explain why the safety population is listed as 20 per group while the primary outcome summaries include 22 and 20 participants.

Zero recorded events in a limited trial population does not demonstrate that an event cannot occur, and the counts alone do not support a broad comparison of safety. The registry record reports the figures but does not provide enough detail to assess completeness of event ascertainment or the duration of safety observation.

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

The results describe postoperative opioid consumption in the enrolled groups and an unadjusted estimate of the difference between their means. The estimate is imprecise: its confidence interval includes zero and extends in both directions. The registry's posted data therefore do not determine a clear direction or size for the difference. They should not be interpreted as demonstrating equivalence or as establishing that either intervention changes opioid use.

The primary result is one measure within a broader set of postoperative outcomes. Opioid consumption does not fully represent pain, nausea, recovery time, satisfaction, or other aspects of a participant's experience. The registry lists these as secondary outcomes, but does not report a complete set of sponsor analyses for them. Their unadjusted summaries can add descriptive context, but they do not resolve the uncertainty around the primary comparison.

The trial's recorded enrollment was 42, and its status is terminated. The brief summary describes planned enrollment of 90, while the reason for termination is not reported in the registry record. The limited enrollment and observed variability are relevant to the width of the confidence interval. They do not reveal why enrollment ended or predict what a larger study would find.

The posted results also do not provide a detailed analysis plan, missing-data methods, analysis populations, or a multiplicity strategy. Consequently, the recalculated comparisons should be understood as unadjusted descriptions of the posted summaries. They are not a substitute for a prespecified sponsor analysis. The results concern the studied outpatient breast-surgery setting and the specified intervention and placebo; the registry information does not establish how they would apply in other settings or populations.

In general, statistical uncertainty is distinct from clinical importance. A confidence interval can be compatible with a range of possible effects without indicating which values would matter clinically. The registry record does not report a threshold for a clinically important difference in MME or the secondary measures. No medical recommendation follows from these summaries alone.

17. Why This Trial Matters Statistically

This trial illustrates the difference between an estimated effect and the precision of that estimate. A single mean difference gives a direction and scale for the observed contrast, while its confidence interval shows how uncertain that contrast is. Here, the primary interval is broad and includes zero, so the estimate alone cannot support a confident conclusion about the direction or magnitude of the difference.

It also demonstrates why variability matters in planning and interpretation. The primary outcome is variable across participants, while the enrolled groups are limited in size. An observed contrast may be small relative to that variability, making its estimate imprecise. The planning illustrations make the relationship between target effect size and required enrollment explicit under stated assumptions, but they are not a record of the original design rationale.

The registry's planned enrollment and recorded enrollment provide an additional lesson in distinguishing a design target from the analyzed data. The brief summary describes a plan for 90 participants, whereas recorded enrollment is 42 and the status is terminated. The reason is not reported. These registry entries are important context, but they do not explain the trial's course or establish how its results would change with additional enrollment.

Finally, the study shows why a list of secondary outcomes does not automatically create confirmatory evidence. Multiple measures can describe different parts of recovery, but interpretation depends on prespecified priorities, analysis methods, and multiplicity handling. Those methods are not reported in the registry record. Statistical reporting is strongest when the estimate, its uncertainty, the analysis population, and the planned inferential framework can all be interpreted together.

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.

Several limitations specific to this trial affect interpretation. The registry records enrollment of 42, while its brief summary describes planned enrollment of 90. The status is terminated, and the reason for termination is not reported in the registry record. This leaves uncertainty about the circumstances of completion and limits the context available for judging the results.

The primary comparison is based on group summaries and is an unadjusted recalculation. The registry record does not report a sponsor-conducted inferential analysis, a detailed statistical analysis plan, the analysis population, or handling of missing data. It also does not report whether the observed primary comparison was adjusted for any factors, including surgery type, which the brief summary says was used for stratification.

The primary endpoint description refers to recording opioid use across a broad postoperative period, while the primary timeframe is stated as 4 to 10 hours. The record does not give further detail about how the primary-window measure was assembled or how observations within that period were handled. The record also lists 20 participants per group for safety summaries, while the primary outcome summaries include 22 and 20; an explanation for this difference is not reported.

The secondary outcome list is broader than the detailed results posted. The registry does not report results for every listed measure, nor does it report a strategy for handling multiple comparisons or repeated ratings. The safety summary provides counts but little detail on event definitions or follow-up. These limitations leave the posted results useful for a narrow description of the recorded data, but insufficient for a complete assessment of the analysis and trial conduct.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Serratus Plane Block for Postoperative Pain Control — NCT02865928.
• Registry record last updated 2024-02-22; status last verified 2024-02.
• Results first posted 2024-02-22.
• 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

The registry describes a phase 4 randomized parallel-group trial of an ultrasound-guided serratus plane block with bupivacaine HCl versus a normal saline placebo injection for outpatient breast surgery. The listed sponsor is Northwell Health. The record gives enrollment as 42, status as terminated, and identifies the primary outcome as postoperative opioid requirements in MME during 4 to 10 hours.

The primary group summaries are 19.88 MME for 22 participants in the bupivacaine HCl group and 17.5 MME for 20 participants in the saline group. The unadjusted recalculated mean difference is -2.375, with a 95% confidence interval from -15.72 to 10.97. The interval is broad and includes zero. The brief summary describes planned enrollment of 90; the reason for termination is not reported in the registry record.

The record lists additional postoperative outcomes, but does not report a full inferential analysis or detailed analysis plan. The posted results are best read as limited, imprecise descriptions of the recorded groups rather than as definitive evidence of a treatment effect.