Efficacy of Intravenous Ibuprofen Compared to Intravenous Ketorolac for Pain Control Following Arthroscopic Knee Surgery: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Efficacy of Intravenous Ibuprofen Compared to Intravenous Ketorolac for Pain Control Following Arthroscopic Knee Surgery (NCT01901393), a randomized phase 4 study. The primary outcome is Efficacy of Pain Relief (Pain Intensity at Rest).

2. Clinical Question

The central statistical question is whether the observed group difference is precise enough to distinguish it from no difference in mean VAS scores. The registry reports a mean of 30.0 units for IV ibuprofen and 32.0 for ketorolac, with a mean difference of 2.0 units for ketorolac relative to IV ibuprofen. The confidence interval spans values on both sides of no difference. These results describe the recorded groups and the uncertainty around their average scores; they do not establish that the treatments are equivalent or that either treatment is effective compared with no treatment.

3. Trial Design

NCT01901393 is listed as a completed phase 4 study of intravenous ibuprofen compared with intravenous ketorolac for pain control following arthroscopic knee surgery. The registry describes the design as randomized, triple-masked, and parallel-group, and the official title describes a multicenter, prospective, randomized, double-blind study. The registry does not explain the difference between the masking terms in those descriptions or identify which trial roles were masked.

The record lists enrollment of 100. The two active arms are IV ibuprofen, described as 800mg, and ketorolac, described as 30mg. For the primary VAS outcome, the reported arm counts are 50 for IV ibuprofen and 49 for ketorolac. The record does not give a participant flow account explaining how the enrollment figure relates to those outcome counts, so exclusions, withdrawals, and the reasons for any missing measurements cannot be determined from the posted results.

The primary endpoint is mean pain intensity at rest, assessed with a visual analog scale at the first possible time after surgery, an expected average of 6 hours. The study also lists outcomes concerning rescue medication use, time to first rescue medication, patient satisfaction, and serious adverse events. A numeric comparison is posted for time to first rescue medication. Other details of the endpoint definitions and their assessment procedures are not reported in the registry record.

The record lists Cumberland Pharmaceuticals as sponsor and gives the study dates as 2013-07 for start and 2014-08 for primary completion. It does not report the original sample-size justification, the planned primary analysis, the allocation procedure beyond randomization, or an interim-analysis plan. Those omissions limit the ability to assess how closely the posted analysis follows the original protocol.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: This analysis was performed on all subject who completed the VAS at Rest Immediately Following their Procedure

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: The Intent-to-Treat population consisted of all subjects who were enrolled and received at least a partial dose of investigational medicinal product.

6. Primary Endpoint

The registry lists the primary outcome as Efficacy of Pain Relief (Pain Intensity at Rest), measured over First possible time post-surgery, an expected average of 6 hours.

The primary endpoint is pain intensity at rest, measured using a visual analog scale. The registry describes a 100 mm horizontal line anchored by No Pain and Worst Possible Pain. A respondent marks the point representing their pain, and the distance from the No Pain anchor is recorded in millimeters. Scores range from 0 for No Pain to 100 for Worst Possible Pain. Because higher positions on this scale represent more pain, the group means describe the average reported pain intensity rather than a count of people who experienced pain.

The endpoint is a continuous measure: each participant can have a score at any point along the scale, and the analysis compares average scores between groups. A mean provides a compact summary of the group’s central score, while the standard deviation describes how much individual scores vary around that group mean. The primary outcome description specifies measurement at rest immediately following the procedure, at the first possible time after surgery; the expected average timing was 6 hours. The timing is therefore tied to the postoperative assessment, rather than a measure of pain over the entire recovery period.

A continuous pain score can capture gradations that a simple yes-or-no outcome would not, which is useful when asking whether average reported intensity differs between treatment groups. However, an average difference does not show the full distribution of individual experiences, and the registry does not provide a threshold for a change considered clinically important. That threshold is not reported in the registry record.

7. Results Posted in the Registry

• Ketorolac: mean 32.00 versus 30.00 on control; difference 2.00 (95% CI -8.27 to 12.27), standardized effect d = 0.08; z-test p = 0.703.

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 Use of Rescue Med Will be Measured

• 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 errors.
• Result:
  • Ketorolac: mean 1.20 versus 1.20 on control; difference 0.00 (95% CI -0.29 to 0.29), standardized effect d = 0.00; z-test p = 1.000.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between Ketorolac and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes address aspects of postoperative care that are related to pain but distinct from the primary resting VAS score. They include rescue medication use, time to first rescue medication, patient satisfaction, and serious adverse events. Together, these outcomes can provide context on subsequent care and patient experience, while the primary endpoint focuses on reported pain intensity at a particular postoperative assessment.

The posted secondary comparison concerns time to first rescue medication. Its group means are both 1.2 hours, and its confidence interval is -0.291 to 0.291 hours for the stated mean difference. This result describes timing among the groups as recorded; it does not establish that rescue-medication use overall was the same, because timing and whether medication was used are different outcomes. The registry does not provide a full comparative numeric result for every listed secondary outcome in the information available for interpretation.

Secondary outcomes can be useful for seeing whether a broader pattern is compatible with the primary result, but they should not be treated as independent confirmation without considering how many outcomes were assessed and how the analyses were planned. When multiple comparisons are examined, the chance of at least one apparently notable result can increase. Adjustment, outcome prioritization, and interpretation rules can address that concern, but the registry record does not report a multiplicity strategy for these secondary analyses.

The secondary results are also less decisive when methods, missing-data handling, and analysis populations are not fully described. Their role is best viewed as contextual rather than as a replacement for the primary comparison. They measure different domains and should not be combined into a single conclusion without a prespecified method for doing so. The registry does not report such a combined analysis or a hierarchy that establishes how secondary findings should affect the primary interpretation.

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

• Rescue Medication Use in Post-operative Period
• Time to First Use of Rescue Med Will be Measured
• Patient Satisfaction
• Incidence of Serious Adverse Events

9. Statistical Interpretation

10. Statistical Methods Explained

What does a difference in means represent?

The primary analysis summarizes the VAS scores in each arm with a mean and standard deviation, then reports a difference between the two group means. The registry comparison places ketorolac as the second group and IV ibuprofen as the reference group: the listed means are 32.0 and 30.0, respectively, and the estimated difference is 2.0 units. This is a between-group contrast at the postoperative assessment. It is not a within-person change from a preoperative score, because no baseline pain comparison is reported for this endpoint.

As a general statistical point, the mean is useful for a continuous outcome because it uses the numerical scale directly and summarizes the group average. It can be affected by unusually high or low observations, and it does not describe the shape of the score distribution. The standard deviation is a measure of spread among observations, not the uncertainty in the estimated mean. Here the registry gives standard deviations of 27.0 and 25.1 for the two groups. Those values describe variation in pain scores within the arms; they should not be read as confidence limits for the group means.

What does the confidence interval add?

The reported 95% confidence interval for the mean difference is -8.266 to 12.27. A confidence interval gives a range of estimates compatible with the observed data under the assumptions of the analysis method. In repeated use of a correctly specified procedure, intervals constructed in this way would cover the target value at the stated rate. For an individual trial, the interval is a measure of uncertainty about the population mean difference, not a guarantee that the true value lies within those endpoints.

Because this interval covers negative and positive values, the data do not pin down the direction of the underlying difference. Its endpoints also indicate that the estimate is not highly precise. The interval is about the difference in group averages; it is not an interval for individual pain scores and does not show how much scores overlap between participants. The registry does not report a clinically important difference threshold that could be used to judge whether values within the interval would matter clinically.

How should the p-value be read?

The unadjusted p-value for the primary comparison is 0.703. As a general concept, a p-value describes how unusual data at least as inconsistent with a specified null model would be if that model and the analysis assumptions held. It is not the probability that the null model is true, the probability that the result occurred by chance, or a measure of treatment importance. A large p-value does not prove that there is no effect. In this case, the p-value is consistent with the broad uncertainty visible in the confidence interval.

The registry calls the result unadjusted. It does not report the precise test used to calculate the p-value, whether the comparison was adjusted for any baseline variables, or how the primary analysis was defined in the protocol. Therefore, the p-value should be read as the posted unadjusted result rather than as evidence of a particular statistical model or testing procedure.

Why does variability matter?

General statistical reasoning distinguishes variation among people from uncertainty in the estimated group difference. The standard deviations describe the former. The standard errors listed for the group means, 3.818 and 3.586, describe the latter at the level of each group mean under the calculation used. Larger variation among observations tends to make precise estimation more difficult unless there is enough information to offset it. The comparison’s pooled standard deviation is 26.08, and the reported standardized effect size is 0.077. These are summaries of the observed comparison; they are not measures of clinical importance on their own.

For count outcomes, over-dispersion is a concern when the observed variability exceeds what a chosen count model assumes. The primary endpoint is continuous, so that count-data issue is not the central concern for this mean comparison. More generally, selecting an analysis that reflects the outcome’s distribution is important, but the specific distributional checks and analysis diagnostics are not reported in the registry record.

What can the planning illustration tell readers?

The sample-size planning figures use the observed effect as a starting point and show illustrations for detecting the full observed effect or a stated fraction of it. They are based on a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The calculations give participants per arm, rather than a total across arms. The registry does not report whether the trial’s original design used these assumptions or this calculation, and the planning illustration is not a description of the trial’s original design.

As a general point, power is the probability that a specified procedure will detect an effect of a particular size under the assumptions used to plan a study. Planning for a smaller effect requires more information to distinguish that effect from random variation, so the required number of participants increases as the target effect shrinks. The listed values are planning illustrations, not observed power, and they do not alter the interpretation of the result that was actually recorded.

Overall, the posted summaries allow a reader to understand the group means, their observed variability, and the uncertainty around their difference. They do not supply enough detail to reconstruct the full statistical analysis plan or confirm whether all protocol-specified analyses were followed. Those details are not reported in the registry record.

11. Confidence Intervals and Precision

The primary mean difference is 2.0 units, with a 95% confidence interval from -8.266 to 12.27. Since higher VAS scores represent greater pain intensity and the comparison is ketorolac relative to IV ibuprofen, the positive estimate corresponds to a higher observed average score in the ketorolac group. The interval extends to negative values as well as positive ones, so it does not precisely determine which group would have the lower mean in the population.

Precision is about how tightly the data estimate the contrast, not whether the estimate is important. The interval includes no difference and also allows a range of possible differences in either direction. Without a prespecified threshold for clinical importance, the registry results do not identify which values within that range would matter clinically. Such a threshold is not reported in the registry record.

The confidence interval refers to the estimated difference between group averages. It does not describe the range of pain scores among participants, which is instead reflected in the group standard deviations of 27.0 and 25.1. Nor does it show the probability that a particular participant would have a better or worse experience with either treatment. Those individual-level questions are not answered by the reported mean comparison.

The interval and the unadjusted p-value of 0.703 tell a consistent story of uncertainty, but they answer different questions: the interval shows a range of compatible mean differences, while the p-value summarizes compatibility with a specified null model under the analysis assumptions. The registry does not report enough methodological detail to independently assess those assumptions or the exact inferential procedure. The estimate should therefore be interpreted with the uncertainty visible in the interval and the limits of the registry’s analysis reporting in mind.

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 expressed as participants per arm. They are not total event counts: the registry’s planning assumptions specify that time-to-event calculations, if present, would use total events, while other calculations use participants per arm. The displayed primary-outcome planning figures therefore refer to participants in each treatment group.

The illustration assumes a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It uses the observed effect as its reference and also considers target effects described as 75% and 50% of that observed effect. For 100% of the observed effect, the figures are 2,669 participants per arm for 80% power and 3,573 participants per arm for 90% power. For 75% of the observed effect, they are 4,745 and 6,352 participants per arm, respectively. For 50% of the observed effect, they are 10,675 and 14,291 participants per arm, respectively.

In plain language, the 80% power column gives the illustrative number of participants per arm for a design with an 80% chance of detecting the specified target effect under those assumptions. The 90% power column gives the corresponding number for a 90% chance. A smaller target effect is harder to distinguish from random variation, so the planning figures require more participants per arm as the target shrinks.

These are planning illustrations based on the observed effect, not observed power. The trial’s original sample-size justification and design assumptions are not reported in the registry record, so these figures should not be treated as evidence about the investigators’ original planning or as a post hoc measure of what the completed trial could detect.

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 = 2.000; pooled standard deviation σ = 26.077.
2. n = 2 × (1.96 + 0.842)² × 26.077² / 2.000² = 2,668.7, rounded up to 2,669 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                      # observed difference in means
sigma <- 26.0771021728251                     # 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(1901393)
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 = 2,669 (80% power), 3,573 (90% power)
 75% of observed effect: n per arm = 4,745 (80% power), 6,352 (90% power)
 50% of observed effect: n per arm = 10,675 (80% power), 14,291 (90% power)
power.t.test: 2669.6 
Simulated power at n = 2,669 per arm: 0.801 (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 record does not report a statistical analysis plan describing how the primary and secondary outcomes were to be tested, whether outcomes were prioritized, or how multiplicity was to be handled. This matters because examining several outcomes can increase the chance of observing an apparently notable result even when there is no underlying difference. Methods such as adjustment or a prespecified testing hierarchy can control interpretation across multiple comparisons, but no such approach is reported for this study.

The primary p-value is explicitly unadjusted. The registry does not indicate whether it is the sole primary test, whether any covariate-adjusted analysis was planned, or whether the confidence interval was derived from the same model or test as the p-value. A reported unadjusted value can still be described as posted, but it cannot be assumed to account for other outcomes, subgroup comparisons, or analysis choices.

Missing-data handling is also not reported in the registry record. The primary outcome population is described as subjects who completed the VAS at rest immediately following the procedure. That description identifies the population used for the endpoint, but it does not explain whether any eligible participants lacked a score, why a score might be missing, how missing values were handled, or whether the analysis followed intention-to-treat principles. The group counts for the primary result are recorded, but a participant-flow account and reasons for differences between enrollment and outcome counts are not reported.

The record does not report a protocol-defined analysis population, sensitivity analyses for missing outcomes, or an interim-analysis plan. Nor does it provide the original sample-size justification or enough analysis detail to confirm whether the posted comparison follows the planned method. These omissions do not change the numerical results, but they limit assessment of the risk of selective reporting and the robustness of the inferences.

The registry lists zero separate analysis records. That does not erase the posted outcome summaries and comparisons, but it means the record does not supply a separate analysis entry documenting model specifications or analysis decisions. Accordingly, the primary result is most appropriately treated as the registry’s posted unadjusted comparison, with the unreported analysis and missing-data details kept in view.

15. Safety Results

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

Other (non-serious) adverse events

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

The serious adverse event figures report zero affected participants among 51 at risk in the IV ibuprofen group and zero among 49 at risk in the ketorolac group. The other adverse event figures likewise report zero affected participants among 51 at risk for IV ibuprofen and zero among 49 at risk for ketorolac. These are counts recorded for the stated groups and risk populations; they do not establish that no adverse events occurred outside the categories or reporting periods captured in the registry.

The record lists incidence of serious adverse events as a secondary outcome, but it does not provide serious adverse event terms in the posted summary. The death counts are not reported in the registry record. A zero count in the posted categories should be read narrowly: it describes what was recorded, not proof that an event is impossible or that no safety concern exists.

Adverse-event counts also require context about ascertainment, follow-up duration, and completeness of reporting. The registry does not report enough detail to assess those aspects or compare risk with a non-treatment group. The figures are descriptive safety information for this trial, not a standalone assessment of overall safety.

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

The registry results describe a randomized comparison of IV ibuprofen and ketorolac for postoperative pain after arthroscopic knee surgery. At the primary assessment, mean VAS scores were 30.0 for IV ibuprofen and 32.0 for ketorolac. The estimated difference was 2.0 units, with a 95% confidence interval from -8.266 to 12.27 and an unadjusted p-value of 0.703. These results show a small observed separation between the group averages, but the interval is broad enough to include differences in either direction.

That pattern does not demonstrate that the treatments have identical effects. A failure to distinguish a difference in this analysis is not the same as proof of equivalence. Equivalence or non-inferiority conclusions require a prespecified margin and a design and analysis suited to that question; such a margin is not reported in the registry record. Nor does a comparison between two active treatments establish how either would compare with placebo or no treatment.

The result is specific to the endpoint and assessment described: pain intensity at rest, measured using a VAS at the first possible post-surgery time, with an expected average timing of 6 hours. It does not directly answer questions about pain at other times, pain during activity, longer-term recovery, or individual responses. The registry does not report a threshold for a clinically important difference, so the mean contrast cannot be translated into a definitive judgment about clinical importance from the posted data alone.

The secondary outcomes add information about rescue medication timing, patient satisfaction, and serious adverse events, but they represent different dimensions and have reporting limitations. The registry does not provide a documented multiplicity strategy or complete details of missing-data handling and analysis populations. The appropriate conclusion is therefore bounded: the posted randomized-group summaries show no clearly resolved difference in mean resting VAS pain at the recorded assessment, while uncertainty and incomplete analysis detail prevent stronger claims about equivalence, clinical importance, or broader outcomes.

17. Why This Trial Matters Statistically

This trial illustrates why an estimated difference should be read together with its confidence interval. The group means are close, but the uncertainty interval extends across values that could favor either treatment. Looking only at the point estimate would conceal that uncertainty; looking only at whether the p-value crosses a threshold would also discard information about the range and direction of plausible effects.

It also shows the distinction between variability among people and precision in a group comparison. The standard deviations describe variation in individual VAS scores, while the confidence interval describes uncertainty in the estimated difference between group means. A continuous patient-reported measure can be summarized with a mean, but the mean does not reveal the distribution of scores or how experiences overlap between participants.

The sample-size illustration provides a further statistical lesson: planning depends on the target effect. Calculations based on smaller effects require more participants per arm under the stated assumptions. Because the illustration uses the observed effect and is not the original design justification, it should not be mistaken for a record of how the trial was planned or for observed power.

Finally, registry outcomes are easier to interpret when the analysis plan, missing-data rules, multiplicity handling, and participant flow are documented. Those details are not reported in the registry record. Their absence does not invalidate the posted summaries, but it limits how confidently a reader can assess whether analyses were prespecified and how robust the inferences are. This is a useful example of why transparent outcome reporting includes both numerical results and the methods needed to interpret them.

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 primary outcome is based on VAS scores for participants who completed the assessment at rest immediately following the procedure. The registry does not report how many eligible participants lacked a score, reasons for missingness, or whether any missing values were addressed through imputation or sensitivity analysis. Without that information, the potential effect of incomplete measurement on the comparison cannot be assessed.

The assessment is tied to a single postoperative measurement occasion described as the first possible time after surgery, with an expected average of 6 hours. The record does not provide a distribution of actual assessment times or show whether timing varied between participants or groups. The result therefore should not be generalized to pain at other recovery stages based on this endpoint alone.

The registry provides the scale range and anchors but does not report a clinically important difference threshold. That makes it difficult to judge how the estimated mean contrast and its interval relate to a threshold for meaningful change. It also does not provide the distribution of scores, subgroup results, or baseline pain summaries for this primary endpoint.

Other trial-specific uncertainties include the absence of a detailed participant flow account, a protocol-linked analysis plan, a reported multiplicity strategy, and the original sample-size rationale. The record’s design descriptions use both triple-masked and double-blind language without explaining how those terms were applied. These are limits on interpretation of the registry record, rather than proof that the trial procedures were inadequate.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Efficacy of Intravenous Ibuprofen Compared to Intravenous Ketorolac for Pain Control Following Arthroscopic Knee Surgery — NCT01901393.
• Registry record last updated 2016-03-14; status last verified 2016-02.
• Results first posted 2016-02-15.
• 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

NCT01901393 is a completed, randomized, parallel-group phase 4 study comparing intravenous ibuprofen with intravenous ketorolac for postoperative pain after arthroscopic knee surgery. The registry lists enrollment of 100 and describes the trial as triple-masked, while the official title describes it as double-blind. The primary outcome is mean pain intensity at rest measured by VAS at the first possible post-surgery assessment, expected on average at 6 hours.

The primary comparison reports mean scores of 30.0 for IV ibuprofen and 32.0 for ketorolac. The estimated mean difference is 2.0 units, with a 95% confidence interval of -8.266 to 12.27 and an unadjusted p-value of 0.703. The interval includes values in either direction and indicates uncertainty about the size and direction of the population difference.

Secondary outcomes include rescue medication use and timing, patient satisfaction, and serious adverse events. The registry record does not report the full analysis plan, multiplicity handling, missing-data methods, or original sample-size justification. The result is most appropriately read as a registry-posted comparison of group means, not as proof of equivalence or a broad conclusion about pain outcomes beyond the measured assessment.