This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for The Effect of Dexamethasone on the Duration of Interscalene Nerve Blocks With Ropivacaine or Bupivacaine (NCT00801138), a randomized na study. The primary outcome is The Duration of the Interscalene Nerve Block Which is Time to First Administration of Pain Medication After Block.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00801138 |
| Phase | NA |
| Condition | Anesthesia, Local, Shoulder Surgery |
| Allocation | Randomized |
| Design model | Factorial |
| Masking | Triple |
| Enrollment | 218 |
| Arms in the primary outcome | 4 |
| Lead sponsor | The Cleveland Clinic |
| Results posted | Yes |
2. Clinical Question
Population
Participants were patients undergoing shoulder surgery with an interscalene nerve block. The registry record lists 218 participants enrolled. Further eligibility criteria and details about the analysis population are not reported in the registry record.
Intervention
The intervention arms combined dexamethasone 8 mg with either 30 ml of 0.5% ropivacaine or 30 ml of 0.5% bupivacaine. Dexamethasone was mixed into the local anaesthetic for the block.
Comparator
The corresponding comparator arms used 30 ml of 0.5% ropivacaine plus 2 ml of 0.9% saline, or 30 ml of 0.5% bupivacaine plus 2 ml of 0.9% saline. Thus, the four arms represent each local anaesthetic with either dexamethasone or saline.
Primary question
The primary question was whether adding dexamethasone changes the duration of the interscalene nerve block, measured as the time to first administration of pain medication after the block. The study summary also describes a question about whether the magnitude of the effect differs between the two local anaesthetics. Formal results for those comparisons are not reported in the registry record.
3. Trial Design
The registry record describes a randomized, triple-masked, factorial trial. The four groups combine two local anaesthetics, ropivacaine and bupivacaine, with two additives: dexamethasone or saline. The ropivacaine groups received 30 ml of 0.5% ropivacaine; the bupivacaine groups received 30 ml of 0.5% bupivacaine. In the comparator arms, 2 ml of 0.9% saline was added. In the dexamethasone arms, dexamethasone 8 mg in 2 ml was mixed with the local anaesthetic.
Enrollment was 218. The posted primary-outcome group sizes were 54, 56, 54 and 54, respectively. Random allocation is reported, but the method used to generate or conceal the allocation is not reported in the registry record. Triple masking is recorded; which people were masked and how masking was maintained are not reported in the registry record.
The study is listed as phase NA, and its status is terminated. The record lists a start of 2008-11 and primary completion of 2010-11. The reason for termination and whether the trial stopped according to its original plan are not reported in the registry record. The sponsor is The Cleveland Clinic. Although the design is described as factorial, a detailed analysis plan for the two factors or their interaction is not reported in the registry record. The record lists three secondary outcomes: time to first report of pain, median maximum visual analogue scale pain scores at rest, and total three-day opioid consumption in oral oxycodone equivalent.
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
| Stage | Group 1 | Group 2 | Group 3 | Group 4 |
|---|---|---|---|---|
| STARTED | 54 | 56 | 54 | 54 |
| COMPLETED | 54 | 56 | 54 | 54 |
| NOT COMPLETED | 0 | 0 | 0 | 0 |
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.
| Characteristic | Unit | Group 1 | Group 2 | Group 3 | Group 4 | Total |
|---|---|---|---|---|---|---|
| Participants analysed | 54 | 56 | 54 | 54 | 218 | |
| Age, Continuous | years | 55 (44 to 65) | 60 (51 to 68) | 59 (49 to 68) | 58 (53 to 64) | 58 (50 to 66) |
| Sex: Female, Male: Female | Participants | 21 | 19 | 21 | 22 | 83 |
| Sex: Female, Male: Male | Participants | 33 | 37 | 33 | 32 | 135 |
6. Primary Endpoint
The registry lists the primary outcome as The Duration of the Interscalene Nerve Block Which is Time to First Administration of Pain Medication After Block, measured over Postoperative day 1, 2 and 3.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Inter-Quartile Range |
| Unit | hours |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the duration of the interscalene nerve block, operationalized as the time from the block to the first administration of pain medication. It is reported in hours as a median with an inter-quartile range. The registry record gives the timeframe as postoperative day 1, 2 and 3.
This is a time-to-event measure: the event is the first administration of pain medication, and the recorded time describes how long it takes for that event to occur. It is used as an observable measure related to block duration; it is not a direct measurement of every aspect of nerve-block function or pain experience. The endpoint also depends on when medication is requested, offered, or administered, and the registry record does not describe those procedures in detail.
A median gives the middle of the observed distribution, while the inter-quartile range describes the central spread of observations between the lower and upper quartiles. These quantities describe the group’s distribution; they are not confidence intervals for a treatment effect. The registry record does not report a confidence interval or a formal between-group estimate for this endpoint.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record reports a median time to first pain medication of 11.8 hours for Group 1, ropivacaine with saline, with an inter-quartile range of 9.7 to 13.8 hours. For Group 2, bupivacaine with saline, the median is 14.8 hours and the inter-quartile range is 11.8 to 18.1 hours. Group 3, ropivacaine with dexamethasone, has a median of 22.2 hours and an inter-quartile range of 18.0 to 28.6 hours. Group 4, bupivacaine with dexamethasone, has a median of 22.4 hours and an inter-quartile range of 20.5 to 29.3 hours.
As posted, the two dexamethasone groups have larger median times than the two saline groups. This is a descriptive pattern in the reported arm summaries. It does not, by itself, establish the size or statistical uncertainty of a treatment effect. The registry record does not report formal comparisons, confidence intervals for between-group effects, or p-values. It also does not report an analysis testing whether the dexamethasone comparison differs between ropivacaine and bupivacaine.
The inter-quartile ranges describe variation among participants within each group. Their overlap or separation is not a substitute for a formal comparison, and the ranges do not indicate the precision of a difference between group medians. The reported group sizes are 54, 56, 54 and 54, but sample size alone does not establish how precisely a comparison is estimated; that depends on the analysis and the data distribution, among other considerations.
The primary endpoint is a time-to-event outcome, but the posted summaries are medians and inter-quartile ranges rather than a reported survival-model estimate. The registry record does not report whether censoring occurred, how it was handled, or whether every participant had an observed event. It is therefore not possible to infer those analysis details from the summaries. The posted results should be read as descriptive arm-level results, not as a complete account of the randomized comparison.
The record also lists secondary outcomes, but numerical results for them are not included in the available registry results. No conclusions about those outcomes can be drawn from the primary endpoint summaries. The trial is marked terminated, and the reason is not reported in the registry record. That status does not explain the observed results or the absence of formal comparisons.
9. Statistical Methods Explained
The statistical interpretation depends on distinguishing the reported summaries from treatment-effect estimates. The registry record presents an outcome value for each of four groups. Those are descriptive summaries of time to first pain medication. A formal treatment comparison would ordinarily state the contrast being estimated and how uncertainty around that contrast is quantified. Such comparison results are not reported in the registry record.
What a median describes
A median is a measure of the centre of a distribution. It is the point that divides ordered observations into a lower and an upper half. Medians are often useful when an outcome has a skewed distribution or when unusually high or low observations make the arithmetic mean less representative of a typical observation. The record identifies the primary outcome summary as a median, with an inter-quartile range. This supports describing the typical observed time and the spread of the central part of the group’s observations, but it does not show the full distribution.
What the inter-quartile range describes
The inter-quartile range runs from the lower quartile to the upper quartile. It gives information about the variability of participant-level times within a group. It is not a confidence interval for the median and is not an uncertainty interval for a treatment contrast. A formal comparison could have uncertainty that is wider or narrower than might be guessed from looking at the group ranges. The registry record does not report confidence intervals for the group medians or for between-group estimates.
How the factorial structure matters
In general, a factorial design studies combinations of intervention factors. In this trial, the combinations are ropivacaine or bupivacaine and dexamethasone or saline. A factorial analysis could address the contribution associated with adding dexamethasone, the contribution associated with the local anaesthetic, and whether the dexamethasone comparison differs across the local anaesthetics. These questions require a specified analysis and corresponding estimates. The registry record does not report such estimates or a detailed statistical plan. The four arm medians should therefore not be treated as proof of a particular main effect or interaction.
Why a formal comparison needs more than group summaries
A treatment-effect estimate expresses a defined contrast between groups or factors. Its uncertainty describes how compatible the observed data are with a range of possible underlying effects, under the assumptions of the analysis. A confidence interval is one common way to display that uncertainty. A p-value, when used, summarizes how unusual the data would be under a specified null hypothesis and analysis model. Neither a confidence interval nor a p-value for the primary comparison is reported in the registry record. A visual comparison of medians cannot supply either quantity.
For time-to-event outcomes, methods may account for participants whose event time is not observed during the relevant period. General time-to-event methods can also use event timing rather than reducing the outcome to a single binary status. Whether there was censoring in this trial, and which model or method was used, are not reported in the registry record. The posted medians and inter-quartile ranges do not reveal those details.
Dispersion and model assumptions
General statistical methods often make assumptions about the form of the outcome distribution or the relationship between model variance and its mean. Over-dispersion, in general, means that variability is greater than a model assumes. If unaccounted for, it can make standard errors too small and statistical evidence appear more precise than it is. The registry record does not report an over-dispersion assessment or a model for the primary endpoint, so there is no basis for attributing any particular model assumption to this trial.
The record describes sample-size planning assumptions in general terms: a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect to detect expressed as a fraction of the observed effect. It also notes that time-to-event planning uses a total number of events under the Schoenfeld approach, while other planning outputs are participants per arm. These are planning conventions, not results about the observed trial. Numerical planning illustrations are not reported in the registry record, and the trial’s own sample-size justification is not reported. Any planning illustration based on an observed effect is not observed power and should not be read as evidence that the trial had a particular probability of detecting an effect.
Finally, the registry record contains arm-level outcome summaries but no reported formal analysis entries. It does not state which analysis population was used, how missing observations were handled, or whether the analysis followed the randomized assignment. These omissions limit what can be concluded about the estimation procedure, even though the reported group summaries can be described directly.
10. Multiplicity, Missing Data and Analysis Populations
The trial lists a primary outcome and three secondary outcomes. The primary outcome is time to first administration of pain medication. The secondary outcomes are time to first report of pain, median maximum visual analogue scale pain scores at rest, and total three-day opioid consumption in oral oxycodone equivalent. A trial with multiple outcomes or multiple comparisons raises a multiplicity question: if many hypotheses are tested, the chance of at least one apparently notable result can increase. General approaches include defining a testing hierarchy or adjusting inference, but the registry record does not report whether any approach was planned or used.
No formal comparison results are reported for the primary outcome, and numerical results for the secondary outcomes are not reported in the registry record. Thus, the available results do not permit an assessment of multiplicity adjustment or a comparison of findings across outcomes.
Missing-data methods and analysis populations are also not reported in the registry record. It does not say how many participants contributed to each outcome, whether any observations were missing, how missingness was handled, or whether participants were analyzed according to randomized assignment. For a time-to-event outcome, handling of participants without a recorded event is also not described. These details matter because the analyzed data and the assumptions used for incomplete observations can affect estimates and their uncertainty. The group counts listed with the primary outcome do not answer all of these questions.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Group 1 | 0 | 54 | 0.0% |
| Group 2 | 0 | 56 | 0.0% |
| Group 3 | 0 | 54 | 0.0% |
| Group 4 | 0 | 54 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Group 1 | 0 of 54 |
| Group 2 | 0 of 56 |
| Group 3 | 0 of 54 |
| Group 4 | 0 of 54 |
The registry record lists zero participants with serious adverse events in each group: 0 of 54 in Group 1, 0 of 56 in Group 2, 0 of 54 in Group 3, and 0 of 54 in Group 4. It also lists zero participants with other adverse events in each group: 0 of 54, 0 of 56, 0 of 54, and 0 of 54, respectively. No serious adverse-event terms are listed. Death counts are not reported in the registry record.
These entries describe what the registry reports; they should not be interpreted as proof that no adverse events occurred. The record does not provide definitions, event-specific detail, the safety observation window, or methods for collecting and adjudicating events. Zero reported affected participants is not the same as demonstrating that an event is impossible or that the interventions have no safety risks. The listed group sizes are the numbers at risk for the adverse-event summaries, but the record does not provide further information about safety follow-up or missing safety data.
12. What the Result Does, and Does Not, Mean
The posted primary-outcome summaries describe the time to first pain medication in the four randomized groups. The two groups receiving dexamethasone have medians of 22.2 hours and 22.4 hours, while the saline groups have medians of 11.8 hours and 14.8 hours. The corresponding inter-quartile ranges describe the spread of observed times within each group. These values show a descriptive pattern in the registry results; they are not a formal estimate of the causal effect of adding dexamethasone.
The results do not establish the statistical uncertainty of a difference between groups. No confidence interval, p-value, or formal primary-outcome comparison is reported in the registry record. The reported medians cannot establish whether the observed pattern is compatible with a range of underlying effects, nor do they establish whether the pattern differs between ropivacaine and bupivacaine. The factorial design makes that latter question relevant, but an interaction estimate is not reported.
The endpoint is time to first pain medication, a measure linked to block duration rather than a complete measure of pain or recovery. The registry record does not give enough procedural detail to determine how medication timing was managed or how unobserved event times were handled. The listed secondary outcomes have no numerical results in the record, so the primary summaries do not answer questions about pain scores or opioid consumption.
The trial is marked terminated, but the reason for termination is not reported in the registry record. The status alone does not reveal whether it affected the results or why formal comparisons are absent. The adverse-event entries report zero affected participants in each group, but safety follow-up details and death counts are not reported. Taken together, the record supports a descriptive account of the listed arm summaries, not a definitive conclusion about efficacy or safety.
13. Why This Trial Matters Statistically
This trial is statistically notable because its factorial arrangement separates two intervention components in the design: the choice between ropivacaine and bupivacaine, and the addition of dexamethasone or saline. That arrangement can support questions about each factor and whether the association with dexamethasone depends on the local anaesthetic. However, the design alone does not answer those questions. The registry record reports group-level medians but no formal factor-specific or interaction estimates.
The primary outcome also illustrates why the summary measure matters. Time to first pain medication is a time-to-event outcome, and the median and inter-quartile range convey different information: the median locates the centre of the group distribution, while the range describes its central spread. Neither alone provides uncertainty for a contrast between randomized groups. Formal analysis and transparent reporting would be needed to evaluate the precision of the comparisons.
The record’s limited inferential reporting is important for readers interpreting randomized trials. Randomization and masking describe design features, but they do not replace reporting of the analysis method, analysis population, missing-data handling, and treatment-effect estimates. Without those details, the arm summaries should be interpreted as descriptive rather than as a complete statistical assessment.
The listed secondary outcomes could add context about pain and medication use, but their numerical results are not reported in the registry record. The serious and other adverse-event summaries are also limited to counts, with no event terms listed and death counts not reported. The trial therefore illustrates the distinction between a registered design and a fully reported analysis: the former identifies the questions and assigned groups, while the latter is needed to judge estimates, uncertainty, and the handling of multiple outcomes.
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 registry record does not report a formal statistical analysis of the primary outcome, including a treatment-effect estimate, confidence interval, p-value, or model specification. Although the design is factorial, estimates for the dexamethasone comparison, the local-anaesthetic comparison, and any interaction are not reported. Consequently, the arm-level medians do not quantify the uncertainty or statistical evidence for those comparisons.
Several details needed to interpret the primary endpoint are also absent. The record does not explain how the first administration of pain medication was recorded or standardized, whether any times were censored, or how participants without a recorded event were handled. It does not report the analysis population, missing-data procedures, or whether all randomized participants were included in the analysis. The outcome timeframe is listed as postoperative day 1, 2 and 3, but further measurement details are not reported.
The record lists three secondary outcomes without numerical results. It does not report a multiplicity strategy, detailed eligibility criteria, allocation concealment, the people covered by triple masking, or a detailed sample-size justification. The trial status is terminated, but the reason is not reported in the registry record. Safety reporting is limited: serious and other adverse-event counts are listed, no serious-event terms are listed, and death counts are not reported. These limitations constrain interpretation of both the descriptive results and the broader trial record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: The Effect of Dexamethasone on the Duration of Interscalene Nerve Blocks With Ropivacaine or Bupivacaine — NCT00801138.
- Registry record last updated 2017-05-01; status last verified 2017-03.
- Results first posted 2017-05-01.
- 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.
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18. Record Summary
NCT00801138 is a randomized, triple-masked, factorial trial sponsored by The Cleveland Clinic. It enrolled 218 participants undergoing shoulder surgery with an interscalene nerve block and is listed as terminated. The four groups received ropivacaine or bupivacaine, with either saline or dexamethasone 8 mg added. The primary outcome was time to first administration of pain medication, reported as a median with an inter-quartile range. The registry record lists arm-level summaries, but no formal comparisons or statistical analysis results. It also lists three secondary outcomes without numerical results. Serious and other adverse-event counts are zero in each group; death counts are not reported in the registry record. The reason for termination, analysis population, missing-data methods, and detailed statistical plan are not reported.