Local Infusion of Ropivacaine for Post-Op Pain Control After Osseocutaneous Free Flaps: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Local Infusion of Ropivacaine for Post-Op Pain Control After Osseocutaneous Free Flaps (NCT03349034), a randomized phase 2 study. The primary outcome is Post-Operative Pain at Donor-Site.

2. Clinical Question

The clinical problem described in the registry is pain at the site from which tissue is taken for reconstruction. The study focuses on local, targeted analgesia rather than on reconstructive success. Its primary outcome is pain at rest, assessed at 8, 16, 24, 32, 40 and 48 hours. The scale ranges from 0-100, with higher scores indicating more pain.

The registry also names opioid consumption, range of motion, distance ambulated, strength, and the American Pain Society-Patient Outcome Questionnaire as secondary outcomes. Those measures address pain management and recovery from different angles, but their numerical results are not reported in the registry record. The primary question is therefore clear from the stated outcome and comparison, while the posted record does not provide an estimated between-group difference or its uncertainty.

3. Trial Design

The registry classifies this as a phase 2, randomized, parallel-group trial with quadruple masking. It lists an enrollment of 24 and a completed status. The record identifies the sponsor as Icahn School of Medicine at Mount Sinai. The study start is recorded as 2017-09-13, and primary completion as 2019-09-30.

Participants were assigned to local ropivacaine infusion or local saline infusion. The record labels the treatment arms “Test Group” and “Control Group,” and the safety results use the labels “Ropivacaine” and “Saline Placebo.” Quadruple masking is recorded, but the record does not specify which people or roles were masked. The method used to generate the random sequence, the allocation-concealment procedures, and the details of the infusion regimen are not reported in the registry record.

A parallel-group design compares groups assigned to different interventions over the study period. In general, random assignment is intended to make groups comparable on average, including on factors that may affect outcomes, but it does not guarantee that every characteristic will be balanced in a small trial. Masking can reduce the influence of expectations on care, reporting, and outcome assessment; its practical effect depends on who is masked and whether masking is maintained. Those operational details are not reported in the registry record.

The enrollment figure is not a count of participants with primary-outcome observations at every assessment. The number analyzed, the analysis population, withdrawals, and missing outcome measurements are not reported in the registry record. The record also lists no analyses. As a result, the design classification and planned comparison can be described, but the actual analytic sample and its relationship to enrollment cannot be evaluated from this record.

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 Post-Operative Pain at Donor-Site, measured over 8, 16, 24, 32, 40 and 48 hours.

The primary endpoint is post-operative pain at the donor site. It is assessed at rest using a visual analogue pain scale at 8, 16, 24, 32, 40 and 48 hours. The scale is a 100 millimeter line marked from “no pain” to “worst pain”; the participant marks the point that reflects the pain they feel, and a researcher measures the position. Scores range from 0-100, with higher scores indicating more pain. The outcome is specified as a mean with standard deviation.

This measure is used to capture the participant’s own experience of pain, rather than relying only on medication use or a clinician’s judgment. Measuring at rest focuses the assessment on pain without describing a movement or activity challenge. Repeated assessments over the first 48 hours can describe how pain changes during the stated post-operative period. In general, the mean gives a group-level summary of scores, while the standard deviation describes how spread out those scores are around the mean. Neither alone shows the precision of a comparison between groups.

The registry identifies several assessment times but does not report a single summarized primary comparison or numerical primary-outcome results. It therefore does not show whether the groups differed at any particular assessment or across the period. The handling of multiple assessment times in the primary analysis is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies a randomized, parallel-group phase 2 trial and a continuous primary outcome summarized as a mean with standard deviation. It does not report the statistical analysis used for the primary comparison. The explanations below describe general statistical ideas relevant to this kind of outcome; they do not assert that any particular method was used in this trial.

What does the mean describe?

For a continuous outcome such as a pain score, the mean is the arithmetic average of observed scores in a group. It offers a compact description of the group’s typical score, but it can be influenced by unusually high or low observations. A mean is most informative alongside a description of variability and the number of observations contributing to it. The registry specifies standard deviation as the measure of dispersion, but the numerical group means, standard deviations, and analysis counts are not reported in the registry record.

The standard deviation describes how dispersed individual scores are around their group mean. A larger standard deviation indicates more variation among measured scores; it is not the uncertainty of the mean itself and is not a confidence interval for a treatment comparison. A standard error or confidence interval for the difference would address precision more directly. These quantities depend on the observations included and on the analysis method.

How should a group comparison be understood?

In general, an unadjusted comparison of means describes the difference between the average scores in the randomized groups without accounting for other measured variables. An adjusted comparison may account for prespecified covariates and can differ from an unadjusted estimate. The registry does not report whether the primary analysis was adjusted, how any covariates were selected, or which estimator was used. No numerical group comparison is reported, so there is no effect estimate to interpret.

A confidence interval expresses statistical uncertainty around an estimate under the assumptions of the analysis. It is useful to consider both the values included in the interval and the width of that interval: a wide interval indicates less precision than a narrow one. The interval does not establish that every value within it is equally likely, nor does it capture every source of uncertainty, such as measurement limitations or bias. The primary-outcome confidence interval is not reported in the registry record.

A p-value is a measure of how compatible the observed data are with a specified null hypothesis, given the statistical model and its assumptions. It is not the probability that the null hypothesis is true, nor is it a measure of the size or clinical importance of an effect. The record does not report a p-value for the primary comparison or identify the test used. The planning assumptions mention a two-sided significance level of 0.05, but that assumption is not a reported test result.

Why do the assessment times matter?

The primary endpoint is measured repeatedly at 8, 16, 24, 32, 40 and 48 hours. In general, repeated observations from the same participant are correlated: a participant’s score at one assessment may be related to that participant’s score at another. A method that accounts for this correlation can produce different uncertainty estimates from a method that treats every observation as independent. The analysis method, the approach to combining or comparing assessment times, and the primary time-specific contrast are not reported in the registry record.

When outcomes are examined at several times, the interpretation depends on which comparisons were planned and how multiplicity was handled. In general, testing several contrasts without a strategy can increase the chance of at least one apparently unusual result under a no-effect scenario. Adjustment procedures can address this issue, although they may change the uncertainty or threshold used for inference. The registry record does not report an approach to multiplicity or identify a single primary time-specific analysis.

What is over-dispersion, and does it apply?

Over-dispersion is a general concern for certain count outcomes when variability exceeds what a chosen model expects. It is not a central concept for the listed continuous pain-score endpoint, which is summarized using a mean and standard deviation. This trial’s registry record does not identify a count model for the primary outcome. Other secondary outcomes may require different methods depending on their measurement and distributions, but their analysis methods are not reported.

How should the planning illustrations be read?

The stated planning assumptions describe calculations based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. The effect to detect is expressed as a stated fraction of the observed effect. These are planning illustrations, not observed power and not evidence that the trial was designed around those assumptions. In general, such calculations depend on the chosen effect, variability, allocation, and statistical assumptions; they do not demonstrate that a study had a particular probability of detecting its actual effect. No sample-size justification from the trial’s own design is reported in the registry record.

The registry lists zero analyses. The statistical plan, outcome-analysis population, missing-data method, and handling of protocol deviations are not reported in the registry record. Consequently, readers cannot verify the model assumptions, reproduce the primary comparison, or assess whether the posted results follow a prespecified analysis plan. Those gaps limit statistical interpretation independently of the trial’s randomized design.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome is assessed at 8, 16, 24, 32, 40 and 48 hours. The registry does not describe whether the analysis focused on a particular time, compared groups separately at each time, or summarized the trajectory across the assessment period. It also does not report a multiplicity adjustment or identify a hierarchy of primary and secondary comparisons. Without those details, any collection of time-specific tests, if conducted, would be difficult to interpret as a single confirmatory analysis.

Several secondary outcomes are listed: opioid consumption, range of motion, distance ambulated, strength, and the American Pain Society-Patient Outcome Questionnaire. The record does not report their analysis methods or results. In general, evaluating multiple outcomes can raise the chance of finding an apparently notable result by chance; interpretation depends on which outcomes were prespecified and how multiplicity was handled. That strategy is not reported in the registry record.

Missing-data handling and analysis populations are also not reported in the registry record. The record does not state how many participants completed each pain assessment, whether any observations were excluded, how incomplete follow-up was handled, or whether the analysis followed intention-to-treat, per-protocol, or another population definition. The enrollment of 24 should not be interpreted as the number with complete primary-outcome data.

In general, missing outcomes can affect both the estimated group comparison and its precision, particularly if missingness is related to pain or treatment assignment. Statistical methods can make assumptions about missing observations, but their appropriateness depends on why data are missing and what information remains available. The record does not describe those assumptions or any sensitivity analyses. As a result, the robustness of a primary result to missing data cannot be evaluated from the registry record.

11. 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 5% reporting threshold.

The safety record lists 8 participants at risk in the saline placebo group and 10 in the ropivacaine group. It reports zero serious adverse events and zero deaths in each group. For other adverse events, it likewise reports zero affected participants in the listed at-risk groups. These are the event counts recorded for the safety information, not a demonstration that adverse events cannot occur.

Zero recorded events should be interpreted in context. The groups listed for safety are limited in size, and the registry record does not report the safety observation period, event-collection procedures, severity definitions beyond the serious-event category, or whether all participants had complete safety follow-up. The enrollment figure should not be used to replace the group-specific at-risk figures in this safety summary.

In general, when no events are observed, the data still allow uncertainty about the underlying event risk. A zero count does not establish equivalence between interventions, rule out uncommon events, or describe events that were not captured. The safety figures also do not answer the primary pain question. They report adverse-event counts, whereas the primary endpoint is a continuous pain score measured at specified post-operative times.

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

The registry record describes a trial designed to compare local ropivacaine infusion with local saline infusion for donor-site pain after osseocutaneous free-flap surgery. It states the primary outcome, the assessment times, and the direction of the pain scale. It does not report a numerical primary-outcome comparison. Therefore, the record does not show whether average pain scores were higher or lower in either group, how large any difference was, or how precisely it was estimated.

This absence of a reported comparison is not a finding of no difference. It is also not evidence that one intervention has an advantage. Without outcome estimates and uncertainty measures, the statistical evidence about the primary question cannot be assessed from the registry record. The completed status and randomized design do not replace results.

The safety record reports zero serious adverse events, zero other adverse events, and zero deaths in the listed at-risk groups. These figures describe the registry’s recorded safety counts; they do not establish that risk is absent or that the groups are equivalent in safety. The limited at-risk group counts and unreported follow-up and collection details constrain what can be inferred.

More broadly, a trial result should be interpreted using the estimated effect, its uncertainty, the analysis population, missing-data handling, and the planned analysis. Those elements are not reported for the primary outcome in this record. The listed secondary outcomes likewise do not have numerical results in the registry record. Thus, the record identifies the clinical question and trial framework, but it does not support a conclusion about the comparative pain outcomes or recovery measures.

Any sample-size planning illustrations should be read as planning calculations based on their stated assumptions, not as observed power or as trial results. They cannot substitute for an effect estimate and its precision. The distinction is important: a planning calculation concerns what a design might detect under assumptions, whereas an outcome analysis describes what was observed in the trial.

13. Why This Trial Matters Statistically

This trial is statistically relevant because its primary outcome is a participant-reported continuous measure collected repeatedly during a defined post-operative period. Such an outcome raises practical questions about how to summarize change over time, how to account for correlations among repeated measurements, and which comparison should carry the primary interpretation. The registry record identifies the assessment schedule but does not report how these questions were addressed.

The randomized parallel-group design provides a structure for comparing two local infusion strategies. General statistical reasoning recognizes that randomization can reduce confounding on average, while small studies may still have substantial uncertainty and chance imbalance. The record lists an enrollment of 24, but the primary analysis population and numerical results are not reported. The randomization label alone cannot indicate the precision or reliability of a treatment-effect estimate.

The registry also illustrates why outcome registration and outcome reporting are different. The primary endpoint and secondary outcomes are named, but the registry record does not report numerical results or a primary comparison. Without estimates, uncertainty intervals, and analysis details, readers cannot assess the magnitude, precision, or robustness of the findings from the registry information.

Finally, the listed safety counts offer a limited descriptive account, not a broad conclusion about safety. Zero recorded events in the listed groups must be interpreted alongside the available at-risk counts and the absence of details on follow-up and event collection. Statistical interpretation depends not only on trial design labels, but also on transparent outcome results and analysis methods.

14. 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 most consequential limitation for statistical interpretation is that the registry record does not report numerical primary-outcome results or a summarized comparison between the treatment groups. It also does not report confidence intervals, p-values, or the statistical model used. The direction, magnitude, and precision of any primary effect therefore cannot be assessed.

The endpoint is assessed at 8, 16, 24, 32, 40 and 48 hours, but the record does not state how those measurements were combined or prioritized. It does not report how repeated measurements were modeled or whether multiple comparisons were adjusted. These omissions prevent evaluation of whether the primary analysis matches a clearly specified time-based question.

The enrollment is listed as 24, but the number analyzed for pain outcomes, the number completing each assessment, and the analysis population are not reported in the registry record. There is no description of withdrawals, missing observations, exclusions, or sensitivity analyses. These details are necessary to judge how incomplete follow-up might affect estimates and their precision.

The record identifies randomized allocation and quadruple masking, but does not describe sequence generation, allocation concealment, the people or roles masked, or whether masking was maintained. The dosing and infusion procedures are not described in the intervention summaries. The record also does not report a statistical analysis plan, a sample-size justification from the trial’s own design, baseline outcome distributions, or numerical results for secondary outcomes.

Safety information includes zero recorded events in the listed at-risk groups, but details of the observation period and adverse-event ascertainment are not reported. The record’s completed status does not resolve these reporting limitations. Collectively, these gaps mean that the study question and design can be described, but its comparative outcome findings cannot be independently evaluated from the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Local Infusion of Ropivacaine for Post-Op Pain Control After Osseocutaneous Free Flaps — NCT03349034.
• Registry record last updated 2020-11-17; status last verified 2020-10.
• Results first posted 2020-11-17.
• 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.

18. Record Summary

This completed phase 2 trial compared local ropivacaine infusion with local saline infusion after osseocutaneous free-flap surgery. It is recorded as randomized, parallel-group, and quadruple-masked, with enrollment of 24.

The primary outcome was donor-site pain at rest on a visual analogue pain scale, assessed at 8, 16, 24, 32, 40 and 48 hours. Scores range from 0-100, with higher scores indicating more pain. The registry record does not report a numerical primary comparison or its precision. Secondary outcomes are listed, but their numerical results and analysis methods are not reported in the registry record.

The safety results record zero serious adverse events, zero other adverse events, and zero deaths in the listed at-risk groups. Follow-up and event-collection details are not reported. The registry identifies the trial design and outcomes, but the available record does not establish comparative pain results.