Ropivacaine Block Alone or With Perineural or Systemic Dexamethasone for Pain in Shoulder Surgery: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Ropivacaine Block Alone or With Perineural or Systemic Dexamethasone for Pain in Shoulder Surgery (NCT01450007), a randomized phase 4 study. The primary outcome is Duration of Sensory Blockade.

2. Clinical Question

The study was designed to distinguish a possible local effect of dexamethasone at the injection site from an effect associated with systemic absorption. The registry’s stated hypothesis was that perineural dexamethasone would yield longer sensory blockade than ropivacaine alone and than ropivacaine with intravenous dexamethasone. The posted results give group means and standard deviations for the primary outcome, together with a sponsor-reported analysis comparing the two dexamethasone groups. These results describe the observed duration of sensory blockade; they do not by themselves establish the biological pathway responsible for any difference.

3. Trial Design

This was a completed, randomized, quadruple-masked, parallel-group phase 4 study sponsored by Mayo Clinic. The registry lists enrollment of 130 participants and three treatment groups. Participants were recruited sequentially and assigned to groups at random in equal ratios, according to the registry summary. The treatment descriptions used saline in the block and intravenous injection as needed to distinguish the routes of dexamethasone administration while maintaining the described injection volumes.

The placebo group received ropivacaine with saline in the block and intravenous saline. The dexamethasone-block group received ropivacaine mixed with dexamethasone and intravenous saline. The dexamethasone-IV group received ropivacaine mixed with saline and intravenous dexamethasone. Thus, the planned contrast was not simply dexamethasone versus no dexamethasone: it also compared the route of administration.

The trial started in 2012-05, had primary completion in 2015-05, and is listed as completed. The registry record identifies the primary outcome as duration of sensory blockade, measured in hours and described as a mean with standard deviation. It also lists postoperative opioid dose at approximately 24 hours after surgery, time until first dose of analgesic, and patient satisfaction with pain control as secondary outcomes. Results are posted for the first two secondary outcomes; a result for patient satisfaction with pain control is not reported in the registry record.

For the primary outcome, the posted group sizes are 42 for dexamethasone block, 37 for dexamethasone IV, and 41 for placebo. The sponsor-reported primary analysis is an ANOVA comparing the two dexamethasone groups, with p = 0.001. It does not include the placebo group in the listed comparison. The registry record does not report a sample-size justification, the full statistical analysis plan, interim analyses, or details about how missing outcome data were handled. Those omissions limit what can be concluded about the trial’s original planning and analysis procedures.

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: 238 patients were screened; of these 41 were excluded because they did not meet inclusion criteria, and 67 were excluded because they declined to be in the study.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Patients will be included in the primary analysis on the basis of intention to treat.

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 Duration of Sensory Blockade, measured over Within 48 hours.

The primary endpoint was duration of sensory blockade, expressed in hours. It was defined as the interval from the time of the block until the patient reported complete resolution of sensory blockade in the shoulder. The registry specifies assessment within 48 hours and describes the outcome as a mean with standard deviation. This endpoint is intended to capture how long the sensory effect of the block persists, which directly addresses the study’s question about whether dexamethasone, and its route of administration, is associated with longer blockade.

A continuous measure such as duration can retain information about the amount of time observed, rather than reducing the outcome to a simple event/no-event classification. Reporting a group mean gives a measure of the average duration, while the standard deviation describes how variable individual durations were within that group. These are descriptive summaries; neither alone indicates how certain the group difference is. For that, the comparison estimate and its confidence interval are useful.

The endpoint also depends on patient report of complete resolution. That makes the recorded duration a patient-reported time point, rather than a direct measurement of a biological process at the nerve. The registry record does not describe a more detailed assessment schedule or explain how the reported time was collected. The definition therefore supports interpretation as reported duration of sensory blockade, while leaving the measurement procedure beyond that definition not reported in the registry record.

The registry identifies the primary analysis population as intention to treat. This means the stated plan was to analyze participants according to their randomized assignment, but the registry record does not provide the operational details or clarify how every participant with an unavailable measurement was included in the analysis.

7. Results Posted in the Registry

• Dexamethasone Block: mean 16.90 versus 13.80 on control; difference 3.10 (95% CI 1.14 to 5.06), standardized effect d = 0.68; z-test p = 0.002.
• Dexamethasone IV: mean 18.20 versus 13.80 on control; difference 4.40 (95% CI 2.03 to 6.77), standardized effect d = 0.85; z-test p = <0.001.

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.

Post Operative Opioid Dose at 24 Hours

• 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:
  • Dexamethasone Block: mean 12.20 versus 24.10 on control; difference -11.90 (95% CI -17.15 to -6.65), standardized effect d = -0.99; z-test p = <0.001.
  • Dexamethasone IV: mean 17.10 versus 24.10 on control; difference -7.00 (95% CI -13.83 to -0.17), standardized effect d = -0.46; z-test p = 0.044.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Dexamethasone Block 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 Dexamethasone IV than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Time Until First Dose of Analgesic

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • Dexamethasone Block: mean 8.40 versus 8.40 on control; difference 0.00 (95% CI -2.25 to 2.25), standardized effect d = 0.00; z-test p = 1.000.
  • Dexamethasone IV: mean 9.20 versus 8.40 on control; difference 0.80 (95% CI -1.56 to 3.16), standardized effect d = 0.15; z-test p = 0.506.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Dexamethasone Block 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 Dexamethasone IV and the control. The interval gives the range of effects that remain compatible with the data.

Taken together, the posted secondary outcomes present a mixed pattern. The opioid-dose summaries and the reported overall test indicate group differences, with lower observed doses in the dexamethasone groups than in placebo. By contrast, the group means for time until first analgesic are close, and the reported overall test does not indicate evidence of a group difference. These secondary outcomes do not all tell the same story, and they measure different aspects of postoperative analgesia.

The opioid outcome is related to the primary duration-of-blockade question, but it is not interchangeable with it. Opioid dose reflects medication use over a specified postoperative period, whereas the primary endpoint is a patient-reported duration until sensory blockade resolves. Time until first analgesic is another distinct measure. Similarity or difference in one measure does not guarantee a matching pattern in another, and these results should be considered alongside the endpoint definitions and observation periods.

The registry lists patient satisfaction with pain control as a secondary outcome, but results for that outcome are not reported in the registry record. Consequently, the posted secondary results do not provide a complete account of all listed secondary outcomes.

Secondary analyses generally carry less inferential weight than a prespecified primary outcome because multiple outcomes and contrasts create more opportunities for chance findings. The registry record does not report whether a multiplicity adjustment, hierarchy, or other procedure was used. The posted pairwise recalculations are unadjusted, and the sponsor-reported overall ANOVA p-values do not resolve multiplicity across the full set of outcomes. These results are useful as supporting evidence and for describing patterns, but they should not be treated as independent confirmation of the primary result.

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

• Post Operative Opioid Dose at 24 Hours
• Time Until First Dose of Analgesic
• Patient Satisfaction With Pain Control

9. Statistical Interpretation

10. Statistical Methods Explained

What does a mean difference represent?

For a continuous outcome, a mean difference expresses the difference between the average values in two groups, in the outcome’s original units. For duration of sensory blockade, the unit is hours. The reported pairwise recalculations use placebo as the reference: a positive estimate means the dexamethasone group’s observed mean was higher. For opioid dose, the unit is mg morphine equivalents, and a negative estimate means the dexamethasone group’s observed mean was lower than placebo’s. The sign depends on which group is subtracted from which, so estimates should be read together with the named comparison.

A mean difference is useful because it describes the size and direction of a contrast rather than only whether a statistical test crossed a threshold. It is still a summary of group averages: it does not show every participant’s response or how much the individual distributions overlap. The group standard deviations provide information about within-group variation, but do not fully describe the shape of the data.

What does a confidence interval add?

A confidence interval gives a range of values compatible with the estimate under the assumptions of the analysis. It conveys precision as well as direction. A narrower interval indicates greater precision than a wider interval on the same scale. If an interval includes no difference, the data are compatible with both a difference in either direction and no difference under the interval’s statistical framework. If it excludes no difference, that is evidence against the no-difference value in that unadjusted comparison. The interval does not give the probability that the true effect lies within its endpoints, nor does it account for every possible source of bias or analytic uncertainty.

The registry’s sponsor-reported primary analysis is an ANOVA. ANOVA is a method for assessing whether group means differ, considered collectively. An omnibus ANOVA p-value does not, by itself, identify which particular pair of groups differ or quantify a pairwise difference. The primary ANOVA listed in the record compares the two dexamethasone groups. The record does not report the corresponding estimate or interval, so the p-value cannot convey the size or precision of that contrast by itself.

Why distinguish sponsor analyses from recalculations?

The posted pairwise recalculations are simple, unadjusted comparisons derived from the group summary statistics. They provide mean differences, confidence intervals, and p-values for dexamethasone versus placebo. The sponsor-reported analysis is a separate ANOVA for the comparison of the two dexamethasone groups. Because the questions and comparison groups differ, the results answer different statistical questions. The recalculations do not replace the sponsor’s analysis, and the record does not identify a discrepancy between them.

An unadjusted p-value is calculated without accounting for the fact that multiple comparisons may have been considered. When many outcomes or contrasts are examined, the chance of at least one apparently notable result arising by chance can increase. Adjustment procedures or a prespecified testing hierarchy can address this issue, but whether such procedures were planned for this study is not reported in the registry record. The reported p-values should therefore be interpreted as the results of the specific comparisons listed, not as evidence that all multiplicity concerns have been resolved.

What does variability mean in these results?

The standard deviation describes the spread of observations around the group mean. The primary outcome standard deviations differ across groups, as do those for the secondary outcomes. When variability is large relative to the difference in means, estimates can be less precise unless the study has enough observations to characterize the groups. In general, unequal variability can also affect whether the assumptions of a particular comparison method are appropriate. The registry identifies ANOVA for the sponsor-reported tests but does not report diagnostic checks, transformations, or alternative methods, so those details are not reported in the registry record.

In general, skewness, outliers, and unequal variances can influence mean-based analyses, especially with limited group sizes. A mean and standard deviation remain interpretable summaries, but they may not fully describe a distribution if it is highly asymmetric. The registry record does not report distributional diagnostics or a robustness analysis for these outcomes. This is a general consideration for continuous outcomes, not evidence that a particular assumption was violated in this trial.

What can p-values say?

A p-value measures how incompatible the observed data are with a specified null hypothesis, under the assumptions of the test. A smaller p-value indicates greater incompatibility with that null model; it does not measure the size or clinical importance of a difference. It also does not give the probability that the null hypothesis is true. Estimates and confidence intervals are needed to understand magnitude and precision, and study design and conduct are relevant to assessing whether an estimated contrast can be interpreted causally.

The registry reports a p-value for the sponsor’s primary ANOVA and overall secondary-outcome ANOVAs. The pairwise results are unadjusted recalculations. These should be distinguished in interpretation because they address different contrasts and may not use the same inferential procedure. The record does not report a complete statistical analysis plan or details of multiplicity control, missing-data methods, or model diagnostics.

11. Confidence Intervals and Precision

The primary pairwise recalculations give an estimate and a 95% confidence interval for each dexamethasone group compared with placebo. For dexamethasone block versus placebo, the mean difference is 3.1 hours, with an interval from 1.144 to 5.056 hours. For dexamethasone IV versus placebo, the mean difference is 4.4 hours, with an interval from 2.032 to 6.768 hours. Both intervals are above no difference, but neither is an interval for the direct perineural-versus-intravenous contrast.

The widths of the intervals describe the precision of these recalculated contrasts. They indicate a range of values compatible with each estimate under the unadjusted comparison method. They do not account for possible multiplicity, missing-data uncertainty, or sources of bias that are not represented in the calculation. The interval for a pairwise contrast should not be interpreted as the range of individual participants’ outcomes.

The sponsor-reported primary ANOVA has p = 0.001, but the registry record does not report its effect estimate or confidence interval. That means the significance test is available without a corresponding interval that would communicate the size and precision of the sponsor’s stated route comparison. The group means can orient the reader to the observed direction, but cannot supply the missing estimate or interval.

In general, confidence intervals are most informative when considered alongside the outcome’s units, the estimate’s direction, and the study design. They express statistical uncertainty conditional on the analysis, not certainty about a treatment effect in every setting. Here, the posted intervals concern unadjusted comparisons with placebo, and should not be generalized to the sponsor’s distinct ANOVA contrast between dexamethasone routes.

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 displays are planning illustrations based on observed effects, not a reconstruction of the trial’s original design. For the continuous outcomes, the entries are participants per arm. They are not total event counts; total event counts are relevant to time-to-event planning displays, and these outcomes are continuous. The 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 as a stated fraction of the observed effect. The trial’s own original sample-size assumptions and justification are not reported in the registry record.

The 80% power column gives the illustrated number of participants per arm for a planned study to have 80% power under those assumptions and at the specified effect size. The 90% power column gives the corresponding number per arm for 90% power. Power is the probability, under the assumed effect and model, of detecting a difference at the chosen significance level. Higher target power generally requires more participants, and a smaller effect to detect requires more participants than a larger one.

The rows using 100%, 75%, and 50% of the observed effect show how planning requirements change if a future study aims to detect a fraction of the observed estimate rather than the full observed estimate. These are hypothetical planning scenarios and depend on the observed effect being a suitable planning basis. They are not evidence that the completed trial had a particular probability of detecting its result. This is not observed power.

In reading the displays, keep the comparison and outcome in view: planning figures are specific to the effect and variability used for that contrast. They should not be added across arms or interpreted as the trial’s actual enrollment unless the display explicitly describes the relevant design. The registry’s stated planning illustration uses equal allocation between two arms, even though the completed trial had three randomized groups.

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 = 3.100; pooled standard deviation σ = 4.563.
2. n = 2 × (1.96 + 0.842)² × 4.563² / 3.100² = 34.0, rounded up to 35 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 <- 3.1                      # observed difference in means
sigma <- 4.56265030193831                     # 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(1450007)
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 = 35 (80% power), 46 (90% power)
 75% of observed effect: n per arm = 61 (80% power), 81 (90% power)
 50% of observed effect: n per arm = 137 (80% power), 183 (90% power)
power.t.test: 35 
Simulated power at n = 35 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. Analyses Reported by the Sponsor

The registry’s sponsor-reported primary analysis is an ANOVA comparing the dexamethasone-block and dexamethasone-IV groups, with p = 0.001. The record does not provide an effect estimate or confidence interval for that analysis. The posted group means are 16.9 hours for dexamethasone block and 18.2 hours for dexamethasone IV, but the sponsor’s p-value should not be mistaken for a quantified estimate of the difference between those means.

The recalculated primary comparisons instead compare each dexamethasone group with placebo. They are simple, unadjusted analyses based on the posted means, standard deviations, and group sizes. They answer whether each dexamethasone strategy differs from placebo, not whether the two routes differ from one another. Thus, their confidence intervals and p-values do not duplicate or replace the sponsor’s route comparison.

The registry record does not flag a discrepancy between posted results and recalculations. The sponsor’s analysis remains the reported analysis for its stated contrast, while the recalculations add unadjusted placebo contrasts. Since the sponsor’s analysis is an omnibus ANOVA and its estimate and interval are not reported, readers should keep the reported test result separate from the pairwise estimates. The record does not report enough detail to determine whether the sponsor conducted additional pairwise testing or applied a multiplicity procedure.

15. Multiplicity, Missing Data and Analysis Populations

Multiplicity arises when several outcomes, groups, or contrasts are tested. Even if each test is performed at a conventional threshold, considering many tests can increase the chance that at least one result appears notable by chance. This matters in a trial with a primary outcome, multiple secondary outcomes, and potential pairwise contrasts among three groups.

The registry identifies one primary endpoint and lists secondary outcomes, but the full statistical analysis plan and any multiplicity strategy are not reported in the registry record. The sponsor-reported primary test is an ANOVA comparing the two dexamethasone groups. The secondary results include overall ANOVAs, while the displayed pairwise recalculations are unadjusted comparisons with placebo. No claim about adjustment or a testing hierarchy can be made from the information recorded.

The primary analysis population is described as intention to treat. This identifies the intended principle for assigning participants to analysis groups, but the registry record does not report the number of missing primary measurements, how missing values were handled, or whether the posted group summaries include every randomized participant. It also does not describe imputation, sensitivity analyses, or reasons for missingness. These details matter because analyses based only on participants with observed outcomes can be affected if missingness is related to outcome or group assignment.

The registry lists enrollment of 130, while the primary outcome groups contain 42, 37, and 41 participants. The record does not explain the relationship between total enrollment and the group sizes contributing to this outcome. For the opioid outcome and time-to-first-analgesic outcome, some posted group sizes differ from the primary group sizes. Reasons for these differences and the handling of unavailable outcomes are not reported in the registry record.

These omissions do not establish that the analysis was inappropriate; they limit independent assessment of how multiplicity and missing data may affect uncertainty. Interpretation should distinguish the prespecified primary question, the sponsor-reported analyses, and unadjusted recalculations, rather than treating every reported p-value as if it represented one isolated confirmatory test.

16. 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

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: hospital admission for fall (2.7%), hospital admission for bowel infection (2.7%), motor vehicle accident with fractured sternum (2.7%), pneumonia (2.4%).

The registry reports serious adverse events in 0 of 42 participants in the dexamethasone-block group, 3 of 37 in the dexamethasone-IV group, and 1 of 41 in the placebo group. Other adverse events are listed for 8 of 42, 2 of 37, and 5 of 41 participants, respectively. These counts are descriptive and should be read with their group sizes; they do not alone establish that an event was caused by a study treatment or that the observed groups differ reliably in safety.

The serious-event terms listed include hospital admission for fall, hospital admission for bowel infection, motor vehicle accident with fractured sternum, and pneumonia, with the registry reporting percentages of 2.7%, 2.7%, 2.7%, and 2.4%, respectively. The record does not provide a fuller account of event timing, relatedness, severity criteria, or comparative statistical analyses. Death counts are not reported in the registry record. The relatively limited number of participants and events means these figures are best treated as a record of what was reported, not as a precise estimate of comparative risk.

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

The results describe outcomes among participants in a randomized study of ropivacaine interscalene block with perineural dexamethasone, intravenous dexamethasone, or placebo. For the primary endpoint, the posted means are higher in both dexamethasone groups than in placebo. The recalculated pairwise comparisons with placebo have confidence intervals above no difference. These observations address the recorded duration of sensory blockade in this trial.

They do not establish that one route of dexamethasone is superior to the other. The sponsor-reported ANOVA comparing the two dexamethasone groups has p = 0.001, but the registry does not report the estimate or confidence interval for that contrast. The observed means are not a substitute for that missing quantified comparison. Nor do placebo comparisons establish whether any observed association is due to local neuronal activity or systemic absorption. The trial’s biological explanation is a hypothesis, not a mechanism demonstrated by the posted endpoint summaries.

The data also do not establish that a longer sensory blockade necessarily corresponds to better overall pain control, lower risk, or a preferred treatment strategy. The secondary outcomes measure different aspects of postoperative experience and use, and the registry does not report results for patient satisfaction. Statistical differences are not automatically measures of clinical importance; the registry record does not state a threshold for a clinically meaningful difference.

Interpretation is also limited by what is not reported: the original sample-size justification, full analysis plan, missing-data procedures, multiplicity handling, and details of outcome collection beyond the endpoint definition. The results should therefore be read as the posted evidence for this trial and its specified outcomes, with uncertainty about aspects of analysis and conduct that cannot be assessed from the registry record.

18. Why This Trial Matters Statistically

Statistically, this trial illustrates why the comparison of interest matters as much as the p-value. The registry’s hypothesis centers on route of administration, while the recalculated pairwise results compare each dexamethasone group with placebo. Those contrasts are related but answer different questions. A significant comparison against placebo cannot, by itself, establish a difference between perineural and intravenous administration.

It also illustrates the distinction between an omnibus test and an effect estimate. The sponsor reports an ANOVA p-value for the route comparison, but no corresponding estimate or confidence interval is recorded. Without those quantities, the result does not communicate the magnitude or precision of the route contrast. Group means offer descriptive context but do not fill that reporting gap.

The trial has a continuous primary outcome and reports means and standard deviations, permitting interpretation in the endpoint’s original units. Confidence intervals for the simple recalculations help show uncertainty around placebo contrasts. At the same time, these intervals are unadjusted and do not resolve issues of multiple outcomes, missing observations, or analysis choices not described in the registry.

Finally, the secondary outcomes make clear that related endpoints need not show identical patterns. Opioid dose, time to first analgesic, and sensory-block duration each reflect different features of postoperative care. The statistical lesson is to retain the endpoint definitions, comparison groups, and analysis provenance when reading results, rather than collapsing them into a single claim about treatment effect.

19. 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 record gives limited detail about the primary outcome measurement beyond its definition as patient-reported time until complete sensory resolution within 48 hours. The assessment schedule, method for eliciting the report, and handling of values not observed before the end of that period are not reported in the registry record. Those details could affect how consistently duration was captured.

The sponsor’s primary ANOVA compares the two dexamethasone groups, but its effect estimate and confidence interval are not reported. The recalculated comparisons are against placebo and are unadjusted; they do not answer the direct route contrast. The full statistical analysis plan, multiplicity approach, and diagnostic checks for the continuous-outcome analyses are not reported in the registry record.

The record identifies intention to treat as the primary analysis population but does not explain missing-data handling or provide a reconciliation between total enrollment and outcome-specific group sizes. Reasons for different secondary-outcome sample sizes are also not reported. This makes it difficult to assess whether unavailable outcomes could affect the posted group comparisons.

The study was conducted in arthroscopic rotator cuff repair and the registry identifies shoulder injury as the condition. The record does not provide detailed participant characteristics, which limits assessment of how broadly the results apply to other patient groups or settings. The safety summary reports event counts but not detailed attribution, timing, or a comparative safety analysis. The record also lists patient satisfaction as a secondary outcome without posting its results. These limitations concern the available registry information and do not demonstrate that the study procedures or analyses were deficient.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Ropivacaine Block Alone or With Perineural or Systemic Dexamethasone for Pain in Shoulder Surgery — NCT01450007.
• Registry record last updated 2016-06-17; status last verified 2016-05.
• Results first posted 2016-05-17.
• 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.

23. Record Summary

NCT01450007 is a completed, randomized, quadruple-masked, parallel-group phase 4 trial sponsored by Mayo Clinic. It compared ropivacaine interscalene block with perineural dexamethasone, intravenous dexamethasone, or placebo in shoulder surgery. The registry lists enrollment of 130 participants.

The primary outcome was duration of sensory blockade within 48 hours. Posted group means were 16.9 hours for dexamethasone block, 18.2 hours for dexamethasone IV, and 13.8 hours for placebo. The sponsor-reported ANOVA comparing the two dexamethasone groups had p = 0.001, without a reported effect estimate or confidence interval. Unadjusted recalculations compare each dexamethasone group with placebo.

Secondary results were posted for postoperative opioid dose and time until first analgesic; patient satisfaction results are not reported in the registry record. Details about the original sample-size justification, multiplicity, and missing-data handling are not reported in the registry record.