Continuous Interscalene Block Results in Superior Recovery Throughout the First Postoperative Week: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Continuous Interscalene Block Results in Superior Recovery Throughout the First Postoperative Week (NCT01881776), a randomized early/phase 1 study. The primary outcome is Patients With Pain: Numerical Rating Scale (NRS-11(0-10): 0:no Pain and 10:Severe/Worst Pain) ≥ 4.

2. Clinical Question

The trial addressed a comparative recovery question rather than a comparison of anesthesia combined with other techniques. The investigators described interest in postoperative pain and several aspects of recovery, including time to first pain, analgesic consumption, recovery-unit processes, discharge timing, sleep duration, and adverse effects. The primary endpoint focused specifically on participants reaching the stated pain threshold on postoperative days 1, 2, 3, and 7.

The registry record describes a prospective randomized trial and records 71 participants enrolled. It reports primary outcome counts for the three groups: 19 of 23 in SISB, 5 of 20 in CISB, and 11 of 20 in GA. These counts address the recorded binary endpoint: whether a participant had a pain rating at or above the threshold, not the average pain rating or the duration of pain. The results therefore speak to this particular threshold-based measure and the stated follow-up period. Other dimensions of recovery may provide relevant context, but they do not replace the primary question.

3. Trial Design

The registry record describes a prospective, randomized, single-masked, parallel-group trial. Participants were allocated to one of three anesthesia groups for outpatient arthroscopic rotator cuff repair: SISB, CISB, or GA. The arm descriptions identify single-injection interscalene block, continuous interscalene block, and general anesthesia, respectively. The brief summary says the techniques were used intraoperatively as sole anesthesia modalities. The masking details, including who was masked and how masking was maintained, are not reported in the registry record.

Enrollment is listed as 71. For the primary outcome, the recorded group sizes are 23 for SISB, 20 for CISB, and 20 for GA. Those are the denominators associated with the posted outcome counts; the registry record does not explain why the outcome denominators differ from the enrollment figure. Participant flow, exclusions after randomization, and the analysis population used for each outcome are not reported in the registry record.

The recorded study status is completed. The registry record gives the start as 2011-08 and primary completion as 2012-06. Its phase entry is EARLY PHASE1, and the listed intervention is a procedure, interscalene block. No rationale for the phase entry or further protocol detail is reported in the registry record. The listed sponsor is St. Luke's-Roosevelt Hospital Center.

The posted outcome comparisons use SISB as the reference group for both CISB and GA. The record contains primary outcome counts and two secondary outcomes, but no reported analyses for those secondary outcomes. The original statistical analysis plan, randomization procedure, allocation concealment, trial sample-size justification, and prespecified analysis populations are not reported in the registry record. Consequently, the registry entries support a description of the design and posted results, but not a complete reconstruction of the trial conduct or its original analysis plan.

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: One patient enrolled preferred to get SISB instead of GA and was therefore not randomized to treatment.

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.

6. Primary Endpoint

The registry lists the primary outcome as Patients With Pain: Numerical Rating Scale (NRS-11(0-10): 0:no Pain and 10:Severe/Worst Pain) ≥ 4, measured over throughout the first postoperative week on days 1, 2, 3, and 7.

The primary endpoint counts participants whose highest Numerical Rating Scale pain rating reached 4 or higher. The scale is described in the registry record as running from 0, no pain, to 10, severe or worst pain. The outcome is recorded as a number of participants, so it represents a threshold event rather than a group average pain score. The reported timeframe covers the first postoperative week, with assessments identified on days 1, 2, 3, and 7.

A threshold endpoint can make a result easier to interpret as the number of participants who crossed a predefined pain level. It also discards information about the exact rating for each participant: ratings below the threshold are grouped together, as are ratings at or above it. Thus, it does not describe the full distribution of pain scores or how far scores were from the cutoff. The registry record identifies the measure as the highest NRS pain rating, but does not provide a detailed rule for handling ratings across the listed assessment days or missing ratings.

The posted counts are 19 of 23 participants in SISB, 5 of 20 in CISB, and 11 of 20 in GA. These counts form the primary comparison. They should be read as evidence about this specific binary pain measure and follow-up period, not as a complete measure of postoperative recovery.

7. Results Posted in the Registry

• Continuous ISB (CISB) Group: 25.0% (5/20) versus 82.6% (19/23) on control; risk difference -57.6 percentage points (95% CI -82.1 to -33.1), risk ratio 0.30 (0.14–0.66); unadjusted two-proportion z-test p = <0.001.
• General Anesthesia (GA) Group: 55.0% (11/20) versus 82.6% (19/23) on control; risk difference -27.6 percentage points (95% CI -54.4 to -0.9), risk ratio 0.67 (0.43–1.03); unadjusted two-proportion z-test p = 0.049.

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.

Time-to-first Pain

• 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:
  • Continuous ISB (CISB) Group: mean 26.00 versus 11.00 on control; difference 15.00 (95% CI 4.29 to 25.71), standardized effect d = 0.90; z-test p = 0.006.
  • General Anesthesia (GA) Group: mean 2.00 versus 11.00 on control; difference -9.00 (95% CI -11.43 to -6.57), standardized effect d = -2.15; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for Continuous ISB (CISB) Group than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for General Anesthesia (GA) Group than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The Number of Patients Consume ≥1 Dose of Analgesics

• 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:
  • Continuous ISB (CISB) Group: 60.0% (12/20) versus 69.6% (16/23) on control; risk difference -9.6 percentage points (95% CI -38.1 to 19.0), risk ratio 0.86 (0.55–1.35); unadjusted two-proportion z-test p = 0.512.
  • General Anesthesia (GA) Group: 65.0% (13/20) versus 69.6% (16/23) on control; risk difference -4.6 percentage points (95% CI -32.7 to 23.6), risk ratio 0.93 (0.61–1.42); unadjusted two-proportion z-test p = 0.750.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Continuous ISB (CISB) Group and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between General Anesthesia (GA) Group and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes add different dimensions to the recovery picture: time to first pain describes timing, while analgesic consumption records whether a participant took at least one dose. The posted summaries show a longer mean time to first pain in CISB than in SISB and a shorter mean in GA than in SISB. Analgesic consumption counts are closer across the groups than the pain-threshold counts. These measures are related to postoperative pain, but they are not interchangeable with the primary endpoint.

The time outcome and threshold outcome capture distinct features. A delay to first pain does not by itself establish how many participants later reached the threshold, and an analgesic-use count does not establish the severity or duration of pain. Participants may differ in how they use analgesics, and the registry record does not provide further details about medication type, dosing, or measurement procedures. The secondary summaries therefore provide context rather than a single unified measure of recovery.

The secondary comparisons are unadjusted recalculations, and the registry record contains no reported secondary analyses. Their p-values do not account for testing multiple outcomes and pairwise comparisons. In general, considering many results increases the chance that at least one may appear notable by chance, so unadjusted secondary findings carry less weight than a prespecified primary result analyzed according to a documented plan. The registry record does not report the multiplicity strategy or confirm which secondary analyses were prespecified.

Read together, the secondary results do not erase or independently confirm the primary finding. They show that the pattern depends on which aspect of recovery is measured, and that estimates for different outcomes have different levels of uncertainty. The registry summaries do not provide enough detail to assess whether the secondary endpoints were collected and analyzed consistently across participants. They are best treated as exploratory context for the primary endpoint rather than as separate definitive conclusions.

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

• Time-to-first Pain
• The Number of Patients Consume ≥1 Dose of Analgesics

9. Statistical Interpretation

10. Statistical Methods Explained

What does a risk difference represent?

In general, a risk difference subtracts the proportion with an event in one group from the proportion in a reference group. Here, the event is a participant having a highest NRS pain rating of 4 or higher. A negative risk difference for a comparison with SISB means the recorded event proportion was lower in the comparison group. The values reported for CISB and GA are simple, unadjusted recalculations from the posted counts. They do not account for other participant or study characteristics.

How should the confidence intervals be read?

In general, a confidence interval gives a range of estimates compatible with the observed data under a particular statistical method. A narrow interval indicates more precision than a wide interval, while an interval extending across zero for a risk difference includes values that would correspond to no group difference. The primary comparison intervals are presented with the estimates in the statistical results. They describe sampling uncertainty; they do not incorporate unreported sources of bias or variation in how the trial was conducted.

What does an unadjusted p-value say?

In general, a p-value describes how unusual data at least as extreme as those observed would be under a specified null hypothesis and analysis model. 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 primary comparison p-values are unadjusted. No multiplicity adjustment is reported in the registry record, so the values should not be read as accounting for the number of outcomes or comparisons considered.

How are the secondary summaries different?

The time-to-first-pain outcome is posted as a mean in hours with a standard deviation. The means are 11 hours for SISB, 26 hours for CISB, and 2 hours for GA; the corresponding standard deviations are 5, 24, and 3 hours. A mean describes the arithmetic average, while the standard deviation describes variability around that average. In general, means and standard deviations can be influenced by unusually high or low observations, and the registry record does not give the participant-level distribution needed to assess that possibility.

For that secondary outcome, the recalculated mean difference for CISB compared with SISB is 15.0 hours, with a 95% confidence interval from 4.285 to 25.71 and p = 0.006. For GA compared with SISB, the recalculated difference is -9.0 hours, with a 95% confidence interval from -11.43 to -6.57 and p < 0.001. These are unadjusted recalculations. The registry record reports no analyses for the secondary outcomes, so they should not be mistaken for sponsor-reported inferential analyses.

The other posted secondary endpoint counts participants consuming at least one dose of analgesics: 16 of 23 in SISB, 12 of 20 in CISB, and 13 of 20 in GA. Its recalculated risk differences are -0.096 for CISB and -0.046 for GA, each compared with SISB. The confidence intervals extend across zero, and the unadjusted p-values are 0.512 and 0.75, respectively. A count-based endpoint and a time-based mean answer different questions, so agreement or disagreement among them is not a direct replication of the primary endpoint.

Why can over-dispersion matter?

In general, over-dispersion occurs when observed variability is greater than a statistical model expects. It can make standard errors and confidence intervals too small if a model assumes less variation than the data contain. The registry record does not report a model-based analysis of the outcomes or an assessment of over-dispersion. For a mean with a large standard deviation, the spread of participant values is important to understand, but group summaries alone cannot show the shape of that distribution.

What analysis details remain unknown?

The registry record does not report the original statistical analysis plan, the method used to calculate sponsor-reported inferential results, any covariate adjustments, handling of missing observations, or analysis populations. It also records no reported analyses for the secondary outcomes. The risk differences, confidence intervals, and p-values discussed as recalculations are unadjusted comparisons derived from the posted summaries. They are useful for describing the data but do not recover undocumented features of the original analysis.

11. Confidence Intervals and Precision

The primary risk-difference interval for CISB compared with SISB runs from -0.821 to -0.331, around an estimate of -0.576. The interval is entirely below zero, indicating that the range of values compatible with this unadjusted calculation is in the direction of a lower recorded event proportion for CISB. The interval is still a range, not a single precise value. Its width reflects the uncertainty associated with the observed counts and group sizes.

For GA compared with SISB, the estimated risk difference is -0.276, with an interval from -0.544 to -0.009. This interval lies just below zero at its upper endpoint. The result is therefore less separated from the no-difference value than the CISB comparison, and its unadjusted p-value is 0.049. Neither the interval nor the p-value conveys the probability that the observed difference will recur in a future study.

In general, confidence intervals address sampling precision under their calculation method. They do not automatically account for selection bias, missing outcome data, measurement differences, or unreported analysis choices. The registry record does not provide participant-level data or a full analysis plan, so the intervals cannot be checked against alternative assumptions. The limited number of participants in each reported primary group also means the estimates should be considered in light of the uncertainty shown, rather than as exact underlying rates.

There is a distinction between statistical precision and clinical importance. A confidence interval can show how uncertain an estimated difference is, but the registry record does not state a threshold for what size of difference would be clinically meaningful. That judgment cannot be derived from statistical significance alone.

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 estimates are illustrations based on the observed effect sizes, not the trial’s original design calculation. For the binary primary outcome, and for the other non-time-to-event outcomes, the displayed planning quantities are participants per arm. The sample-size assumptions stated for these illustrations are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Each row considers detecting the stated fraction of the observed effect.

The 80% power column gives the estimated participants per arm for a design with an 80% chance of detecting the specified effect under those planning assumptions, if the effect and assumptions were correct. The 90% power column gives the corresponding per-arm estimate for a design with a 90% chance. These are planning targets, not outcome results. They are not observed power.

The rows for 100%, 75%, and 50% of the observed effect illustrate how the estimate changes when the target effect is smaller than the one observed. Smaller effects need more participants to distinguish them from no difference with the same planned power and significance level. For example, the primary CISB-versus-SISB planning estimates rise from 11 participants per arm at 80% power for 100% of the observed effect, to 19 for 75%, and 40 for 50%. The GA-versus-SISB values likewise increase across those effect assumptions.

The secondary time-to-first-pain planning values are also stated as participants per arm because the posted sample-size assumptions specify that all outcomes other than time-to-event tables use per-arm participants. No time-to-event planning table is present among the listed comparisons. These estimates are sensitive to the observed effect, which may be unstable in a small trial. The registry record does not report the assumptions or calculation used for the original enrollment target, so the illustrations should not be interpreted as the trial’s design justification.

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, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.826; treatment proportion p₁ = 0.250; average p̄ = 0.538.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.7051 = 1.3819.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.5755 = 0.4843.
4. n = (1.3819 + 0.4843)² / (-0.5761)² = 10.5, rounded up to 11 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
p0 <- 0.826086956521739                          # control proportion
p1 <- 0.25                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^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 (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(1881776)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 11 (80% power), 14 (90% power)
 75% of observed effect: n per arm = 19 (80% power), 25 (90% power)
 50% of observed effect: n per arm = 40 (80% power), 53 (90% power)
power.prop.test: 10.5 
Simulated power at n = 11 per arm: 0.837 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-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 record lists a primary endpoint and two secondary outcomes, with comparisons of CISB and GA against SISB. It reports unadjusted p-values for the displayed comparisons, and the record does not report a correction for testing multiple outcomes or comparisons. When multiple statistical tests are considered, the chance of at least one small p-value under a set of null effects can increase. In general, a multiplicity plan can specify which outcomes and contrasts are primary and whether the interpretation or threshold for secondary tests should be adjusted. Such a plan is not reported in the registry record.

The statistical analysis plan, including whether the primary outcome and contrasts were prespecified in the form analyzed, is not reported in the registry record. The record also does not report interim analyses or stopping rules. No inference should be drawn about whether these procedures were or were not used beyond the registry entries.

Missing-data handling and analysis populations are also not reported in the registry record. Enrollment is listed as 71, while the primary outcome denominators are 23 for SISB, 20 for CISB, and 20 for GA. The record does not explain the relationship between enrollment and these outcome denominators, whether any randomized participants were excluded from an analysis, or how missing outcome measurements were handled. It does not provide participant flow or a statement that all randomized participants were analyzed in their assigned groups.

These omissions matter because missing observations and exclusions can affect group comparisons, especially if the reasons for missingness differ across groups or relate to the outcome. In general, an intention-to-treat analysis includes participants in their assigned groups, while other analysis populations may use different inclusion rules. The registry record does not identify which population was used for the posted results. Consequently, the recalculated comparisons describe the posted counts and should not be assumed to establish the impact of missing data or the exact original analysis approach.

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.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: ponv (21.7%).

The registry record lists serious adverse events for 5 participants in SISB, 0 in CISB, and 2 in GA. The corresponding numbers at risk are 23, 20, and 20. It lists 0 other, non-serious adverse events in each group, with the same group denominators. The record also lists PONV as a serious adverse event term at 21.7%, but does not provide further context for that entry in the available safety summary.

These are counts within the recorded groups. They do not, on their own, establish that an anesthesia approach caused or prevented an event. The small group sizes and the absence of further event details limit interpretation. The registry record does not report the definitions used for serious events, event timing, severity breakdowns, attribution assessments, or a statistical comparison of safety outcomes.

Deaths are not reported in the registry record. A blank death entry should not be interpreted as a reported zero. The safety entries are descriptive and should be considered separately from the efficacy endpoints; they do not establish a comprehensive safety profile.

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

The primary outcome results describe how many participants in each group reached a specified pain-rating threshold during the first postoperative week. In the recorded counts, fewer CISB participants than SISB participants met the threshold, and the recalculated unadjusted risk-difference interval for that contrast lies below zero. The GA-versus-SISB interval also lies below zero, but its upper endpoint is close to zero. Those statistical summaries describe the observed data and their uncertainty under the recalculation method.

They do not establish that one approach is generally superior, that any difference is important to patients, or that the same results would occur in other settings. The trial involved a particular outpatient surgical context, and the registry record does not report enough detail about participant characteristics or conduct to determine how broadly the findings apply. It also does not establish effects on outcomes beyond those posted.

The primary endpoint is a threshold count, not a complete account of pain experience. It does not show the full distribution of NRS scores, the degree by which a participant crossed the threshold, or every aspect of postoperative recovery. The secondary outcomes address other specific measures, but their analyses are unadjusted and the registry record does not report a multiplicity plan. Their results should therefore be interpreted cautiously and as distinct from the primary endpoint.

The statistical evidence is not a treatment recommendation. Decisions about anesthesia require clinical context and assessment beyond these registry results. The posted data can inform a discussion of the measured outcomes, but they do not provide all the information needed to judge benefits, harms, or suitability for an individual. In particular, safety counts are descriptive, the original analysis plan is not reported, and the reason for the difference between enrollment and outcome denominators is not given.

The title’s wording about superior recovery is a stated framing of the study, not a substitute for evaluating the estimates, uncertainty, endpoint definitions, and limitations. Statistical significance alone does not prove clinical importance, while a non-significant result does not establish equivalence. No equivalence or noninferiority margin is reported in the registry record.

17. Why This Trial Matters Statistically

This trial illustrates how a randomized comparison can produce results that differ depending on the outcome chosen. The primary endpoint counts participants reaching a pain threshold, while the secondary endpoints describe time to first pain and analgesic use. These outcomes relate to postoperative recovery but measure distinct things. A clear statistical interpretation keeps the meaning of each endpoint separate rather than treating all outcomes as interchangeable evidence for a single claim.

The study also highlights the value of reporting uncertainty alongside group counts. Risk differences and confidence intervals make the direction and precision of the primary comparisons more explicit than counts alone. The CISB-versus-SISB interval is separated from zero, while the GA-versus-SISB interval approaches zero at its upper endpoint. The contrast in precision and the relatively small reported group sizes help explain why point estimates should not be read as exact effects.

Another statistical lesson is the distinction between a trial’s original design and retrospective planning illustrations. Planning calculations based on observed effects can show how required sample sizes change as a target effect becomes smaller, but they do not explain how the trial’s enrollment target was chosen. The original sample-size justification is not reported in the registry record.

Finally, the record demonstrates why analysis transparency matters. Missing details about multiplicity, missing data, participant flow, and analysis populations constrain interpretation, even when outcome counts and comparisons are available. These are not merely technical footnotes: they affect how confidently readers can connect the posted estimates to the randomized design and judge the reliability and scope of the findings.

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 leaves several trial-specific limitations unresolved. It does not report participant characteristics, the randomization sequence method, allocation concealment, or who was masked. These details are relevant to understanding the risk of baseline imbalance and the possibility that study procedures or outcome reporting differed by group. The record’s single-masked designation does not identify the masked parties or describe how masking was maintained.

The relationship between the enrollment figure of 71 and the primary outcome denominators of 23, 20, and 20 is not explained. Participant flow, withdrawals, exclusions, missing ratings, and the handling of incomplete follow-up are not reported in the registry record. The endpoint description identifies the highest pain rating and assessment days, but does not explain how repeated ratings were combined or how a participant with an incomplete set of ratings was classified.

The posted summaries do not include participant-level data or detailed distributions. This limits assessment of the time-to-first-pain mean and standard deviation, including whether a small number of unusually long or short times influenced the averages. The record also does not provide further detail about analgesic measurement, recovery-unit outcomes, discharge timing, or sleep duration, despite their mention in the study summary.

The original analysis plan, multiplicity handling, analysis populations, and sample-size justification are not reported. The secondary analyses are not reported by the registry, and recalculated comparisons are unadjusted. Safety reporting is limited to group counts and a listed serious-event term; details on event timing, attribution, and deaths are not reported. Together, these gaps mean the posted results are informative about the recorded summaries, but do not permit a full evaluation of trial conduct, all prespecified outcomes, or the robustness of the original analysis.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Continuous Interscalene Block Results in Superior Recovery Throughout the First Postoperative Week — NCT01881776.
• Registry record last updated 2014-06-04; status last verified 2013-07.
• Results first posted 2014-06-04.
• 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 record describes a completed, prospective, randomized, single-masked, parallel-group trial of CISB, SISB, and GA for outpatient arthroscopic rotator cuff repair. Enrollment is listed as 71. The primary outcome is the number of participants with a highest NRS pain rating of 4 or higher during the first postoperative week, with recorded group counts of 19 of 23 for SISB, 5 of 20 for CISB, and 11 of 20 for GA.

Two secondary outcomes are posted: time to first pain and consumption of at least one analgesic dose. The registry record does not report secondary analyses, the original analysis plan, multiplicity handling, or the reasons outcome denominators differ from enrollment. The primary comparisons discussed are unadjusted recalculations from the posted summaries. The results describe specific recorded outcomes and should be interpreted with their uncertainty and reporting limitations in mind.