The Efficacy and Safety of Local Anesthetic Infusion With Ropivacaine: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Efficacy and Safety of Local Anesthetic Infusion With Ropivacaine (NCT00930046), a randomized na study. The primary outcome is Morphine.

2. Clinical Question

The trial also lists pain intensity measured with the FLACC scale, on a 0-10 point scale, as a secondary outcome. No result for that measure is reported in the registry record. The study’s stated hypothesis concerned pain relief, systemic opioid use, and opioid-related side effects; the posted primary measure addresses morphine use rather than pain intensity directly. Consequently, the primary outcome alone does not describe every aspect of the proposed clinical question.

3. Trial Design

The registry record describes a randomized, triple-masked, parallel-group trial of wound-catheter infusions after surgical correction of ureteropelvic junction stenosis. One group received ropivacaine and the comparison group received normal saline. The record gives an enrollment of 15. It does not report the details of random sequence generation, allocation concealment, or which people were masked. The label “triple” indicates the recorded masking category, but the identities of the masked roles are not reported in the registry record.

The study was sponsored by Boston Children's Hospital. Its recorded start date is 2009-04-24, and its primary completion date is 2011-09-06. The status is listed as terminated. The reason for termination, the timing of the status change, and whether termination affected data collection or analysis are not reported in the registry record. The phase is recorded as NA.

The primary outcome is total morphine used in the first 48 hours immediately after surgery, expressed in mg/kg per 48 hours. The primary outcome entries report 7 in the ropivacaine group and 5 in the normal saline group, alongside the means and standard deviations. Safety entries use different at-risk counts: 8 for ropivacaine and 7 for normal saline. The record does not explain why the counts associated with the outcome and safety entries differ. Those counts should therefore be understood in the context of their specific outcome records, not treated as interchangeable.

The registry record lists FLACC pain intensity as a secondary outcome, but does not give a result for it. It lists 2 outcome measures and 0 analyses. Details of the statistical analysis plan, including any planned adjustment, interim analysis, or sample-size justification, are not reported in the registry record. The recorded status and these missing details limit what can be concluded about how the trial was conducted and how its results were intended to be interpreted.

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:

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 Morphine, measured over 48 hours.

The primary endpoint is the total amount of morphine used during the first 48 hours immediately after surgery, recorded in mg/kg per 48 hours. The registry record describes the endpoint as a mean with standard deviation. It reports a mean of 2.2 and standard deviation of 1.8 for the ropivacaine group, and a mean of 3.5 and standard deviation of 1.8 for the normal saline group. The outcome entries list 7 and 5, respectively.

Morphine use is relevant to the trial’s stated aim because the investigators proposed that local anesthetic infusion might reduce the need for systemic opioid use after surgery. It is an indicator of opioid consumption, not a direct measure of pain intensity. The listed secondary measure, FLACC pain intensity, addresses pain using a distinct scale, but its result is not reported in the registry record. The morphine endpoint thus describes one part of the intended evaluation, while leaving pain scores and other aspects of the stated hypothesis unresolved.

As general statistical context, a mean describes the average outcome in a group, while a standard deviation describes how spread out individual observations are around that mean. Neither value alone supplies an estimate of the uncertainty in a between-group comparison. The registry record does not report an estimable comparison for this continuous endpoint, so the displayed group summaries should not be mistaken for a completed statistical test.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The main outcome is continuous: morphine use is expressed as a numerical amount in mg/kg per 48 hours. The registry record summarizes it using a mean and standard deviation. The posted mean is 2.2 in the ropivacaine group and 3.5 in the normal saline group; each group has a reported standard deviation of 1.8. These are descriptive statistics, rather than a complete comparison between randomized groups.

What do the mean and standard deviation describe?

As general statistical context, the mean is the arithmetic average of observed values in a group. The standard deviation describes how dispersed those values are around the group mean. A standard deviation is not a confidence interval and does not directly communicate the precision of a comparison between groups. Precision depends on the amount of information available and the variability, as well as the statistical method used.

The outcome records list 7 for the ropivacaine group and 5 for the normal saline group. These are the counts associated with the primary outcome summaries. The safety records instead list 8 and 7 at risk. Since the registry record does not explain the difference, the counts should not be combined or substituted for one another. The record also does not state why observations may be absent from one outcome record or whether any outcome data were excluded.

What can a randomized comparison estimate?

In general, random assignment is intended to make treatment groups comparable, on average, with respect to factors known and unknown at the time of assignment. A comparison can then estimate the difference in outcomes associated with assignment to the two groups, subject to the trial’s conduct, missing data, and analysis choices. Here, randomization is recorded, but the registry record does not report the sequence-generation or allocation-concealment procedures. It also does not provide an estimable two-arm comparison for the primary continuous outcome.

For a continuous outcome, an analysis might estimate a difference in group means and quantify uncertainty around that estimate. This trial’s record does not post such an estimate, a confidence interval, or a p-value for morphine use. The means alone cannot be used to infer the result of a formal test. The record’s note that a two-arm continuous comparison is missing or not estimable is a direct limitation on interpretation, not a reason to replace the sponsor’s analysis with an improvised calculation.

What does the stated sample-size approach mean?

The registry record describes planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between groups, and a normal approximation. In general, a sample-size illustration asks how many participants per arm might be needed under stated assumptions to detect a target effect with a chosen probability of detection. Such an illustration is planning information, not a measure of the probability that the observed result is true and not “observed power.” The record does not report a trial-specific sample-size justification or enough numerical planning results in the registry record to assess them. It also does not report the effect fractions used for each illustration.

General statistical context is useful when reading these assumptions. A two-sided significance level describes a testing convention that considers departures in either direction. Equal allocation means the illustration assumes the same planned number of participants in each group. A normal approximation is a mathematical approach for estimating sampling behavior. These assumptions do not show that the trial used that analysis, nor do they document its original design rationale. The statistical plan is not reported in the registry record.

Why does variability matter?

Variation in individual morphine use affects how precisely group averages can be compared. General statistical methods account for this variation when estimating uncertainty. In other settings, over-dispersion—greater variability than a model assumes—can make standard errors too small and confidence intervals too narrow if not handled appropriately. That general issue does not establish that over-dispersion occurred in this trial. The registry record does not describe a model, diagnostics, or a variance adjustment, so no claim about those methods can be made.

Masking can reduce the influence of expectations on care or assessment, depending on who is masked and how masking is maintained. The trial is labelled triple-masked, but the masked roles and procedures are not reported in the registry record. The parallel-group model indicates that groups were followed as separate treatment arms rather than described as a crossover. The record does not give additional details on treatment adherence, catheter use, or how outcome measurements were collected.

For this trial, the statistical methods that can be described confidently are limited to the recorded design labels, the mean and standard deviation summaries, and the stated assumptions for planning illustrations. The analysis procedure for the primary comparison, handling of missing values, any adjustment for other variables, and any interim analyses are not reported in the registry record. The absence of those details means that readers cannot assess the full analysis pathway or reproduce an inferential result from the registry entries.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Ropivacaine Group", "Normal Saline Group")
n   <- c(7, 5)
m   <- c(2.2, 3.5)
sp  <- c(1.8, 1.8)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Ropivacaine Group  7  2.200  1.800  0.535  3.865
CARM  Normal Saline Group  5  3.500  1.800  1.265  5.735

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists morphine use as the primary outcome and FLACC pain intensity as a secondary outcome. It records 2 outcome measures and 0 analyses. No result for FLACC pain intensity is reported in the registry record. Nor does the record give a statistical plan describing how the outcomes were prioritized, whether multiple comparisons were anticipated, or how multiplicity was to be handled.

As general statistical context, testing several outcomes can increase the chance of finding at least one apparently notable result by chance. A prespecified hierarchy or adjustment can address some multiplicity concerns, but whether either approach was planned for this trial is not reported in the registry record. Since no secondary outcome result is posted, the available record does not support interpretation of a multiplicity-adjusted or unadjusted secondary analysis.

The primary endpoint summaries have outcome counts of 7 in the ropivacaine group and 5 in the normal saline group. Safety entries give at-risk counts of 8 and 7. The reasons for these different counts are not reported in the registry record. There is no description of missing-data mechanisms, exclusions, imputation, or analysis populations. It is therefore not possible to determine from the record whether the primary outcome analysis followed an intention-to-treat, per-protocol, or other population definition.

General statistical context: missing outcomes can affect both the representativeness of group summaries and the validity of a comparison, depending on why values are missing and how the analysis handles them. Without the disposition of participants or a missing-data plan, the potential effect of missingness cannot be evaluated. No assumptions about those reasons or methods should be made. The registry record does not report interim analyses or a sample-size justification.

12. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The safety entries list 8 at risk in the ropivacaine group and 7 at risk in the normal saline group. In each group, the number with a serious adverse event is recorded as 0, the number with another adverse event is 0, and deaths are 0. No serious adverse-event terms are listed. These counts describe the safety information in the registry record; they are not a detailed account of event monitoring or adjudication.

The safety denominators differ from the counts attached to the primary outcome summaries, which are 7 for ropivacaine and 5 for normal saline. The registry record does not explain this difference. Safety counts and efficacy-outcome counts should therefore be read as specific to their respective entries rather than assumed to refer to the same analysis population.

As general statistical context, zero recorded events do not establish that an intervention has zero risk. With limited observations, uncommon events may not occur in the recorded data even when they remain possible. The registry record does not provide event definitions, follow-up beyond the stated postoperative period, or details about how adverse events were collected. The zero counts should be reported as observed in this record, without interpreting them as proof of safety or attributing causality.

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

The registry record documents a randomized comparison of ropivacaine and normal saline wound-catheter infusions after surgery, with morphine use in the first 48 hours as the primary outcome. The reported group means are 2.2 mg/kg per 48 hours for ropivacaine and 3.5 mg/kg per 48 hours for normal saline, with a standard deviation of 1.8 in each group. These values describe the posted group summaries. They do not establish a statistically supported comparison because the registry record says values are missing or not estimable for a two-arm continuous-endpoint comparison.

Accordingly, the data do not show how precise an estimated treatment contrast would be, and no confidence interval or p-value is reported for the primary outcome. The summaries also cannot establish that the groups are equivalent or that one intervention is superior. Those conclusions require an interpretable comparison and appropriate uncertainty information, neither of which is available in the registry record.

The trial’s stated hypothesis included pain relief and reduced systemic opioid use. Morphine consumption speaks to opioid use but is not itself a direct pain score. Although FLACC pain intensity is listed as a secondary outcome, no result is reported. The registry record therefore does not allow a complete account of the proposed pain and opioid questions. The safety entries record no serious adverse events, other adverse events, or deaths in the listed groups, but those counts do not prove absence of risk.

The record lists the trial as terminated and enrollment as 15. It does not report the reason for termination, a complete participant disposition, the planned statistical analysis, or a trial-specific sample-size justification. These gaps are consequential when assessing completeness and reliability. The posted results support a cautious description of the reported summaries and event counts; they do not support broader claims about treatment effects or safety.

14. Why This Trial Matters Statistically

This trial is statistically noteworthy because its registry record illustrates the difference between descriptive group summaries and an inferential comparison. Means and standard deviations can show how outcomes were summarized within groups, but they do not by themselves answer whether the groups differ with useful precision. The record reports morphine-use summaries but states that a two-arm comparison for the continuous endpoint is missing or not estimable. Without an estimate and its uncertainty, readers cannot assess the comparative result statistically.

The primary outcome counts and safety at-risk counts also differ. The record does not explain why. Keeping endpoint-specific denominators visible is important: a count attached to one analysis should not be assumed to describe another. Incomplete information about participant disposition and analysis populations can make it difficult to understand which observations contributed to each result.

The trial also separates a measure of opioid consumption from the secondary measure of pain intensity. That distinction matters because a change in opioid use is not interchangeable with a change in a pain score. Since the FLACC result is not reported, the available information does not cover both outcomes named in the registry record.

Finally, the terminated status and absent analysis details invite careful rather than speculative interpretation. The record does not state why the trial was terminated or whether termination changed its intended analyses. It also does not report the statistical plan or sample-size justification. These limitations do not erase the descriptive information that is posted, but they constrain the conclusions that can be drawn from it. The key statistical lesson is to distinguish what the record measures, what it summarizes, and what it does not estimate.

15. 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 is limited by the absence of an estimable two-arm comparison for the primary continuous endpoint. It reports group means and standard deviations, but no comparison estimate, confidence interval, or p-value. The information therefore does not quantify the uncertainty around a treatment contrast. The record also lists 0 analyses, so the intended inferential procedure is not documented.

Outcome counts are not the same as safety at-risk counts: the primary outcome entries list 7 and 5, while safety entries list 8 and 7. Reasons for the different counts and a participant disposition are not reported in the registry record. It is not possible to determine which analysis population was used, whether outcome values were missing, or how missingness was handled.

FLACC pain intensity is listed as a secondary outcome, but its result is not reported. This leaves the stated pain-assessment question unanswered in the posted outcome information. Safety reporting is also sparse: zero serious events, other adverse events, and deaths are recorded, but no serious-event terms are listed and further collection or follow-up details are not reported.

The trial is marked terminated, but the reason for termination and its effect on planned enrollment, data collection, or analysis are not reported. The registry record does not identify the masked roles, describe randomization procedures, or provide a statistical analysis plan or trial-specific sample-size justification. These omissions do not show that particular procedures were absent; they mean their use cannot be established from the registry record. The stated enrollment of 15 should not be interpreted as the number contributing to each outcome, given the distinct outcome-specific counts.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: The Efficacy and Safety of Local Anesthetic Infusion With Ropivacaine — NCT00930046.
• Registry record last updated 2020-04-28; status last verified 2020-02.
• Results first posted 2020-04-28.
• 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.

19. Record Summary

The registry record for NCT00930046 describes a randomized, triple-masked, parallel-group trial sponsored by Boston Children's Hospital. It compares ropivacaine with normal saline delivered through wound catheters after surgical correction of ureteropelvic junction stenosis. The recorded enrollment is 15, and the status is terminated. The recorded start date is 2009-04-24 and the primary completion date is 2011-09-06.

The primary outcome is total morphine use in mg/kg per 48 hours during the first 48 hours after surgery. The record reports group means and standard deviations but no estimable two-arm comparison. FLACC pain intensity is listed as a secondary outcome without a posted result. Safety entries record zero serious adverse events, zero other adverse events, and zero deaths in each group. The registry record does not report why the trial was terminated, the full analysis plan, or the reasons for the different outcome and safety counts.