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 Study on the Effects of Intravenous Dexmedetomidine on Pain in Patients Undergoing Elective Spinal Surgery (NCT03325972), a randomized phase 4 study. The primary outcome is Morphine Equivalents Used During the First 48 Hours Post-Surgery.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03325972 |
| Phase | Phase 4 |
| Condition | Chronic Pain |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 83 |
| Arms in the primary outcome | 2 |
| Lead sponsor | NYU Langone Health |
| Results posted | Yes |
2. Clinical Question
Population
Adults undergoing elective lumbar spinal fusion were the intended population. The registry summary describes eligibility as being over the age of 18 and undergoing lumbar spinal fusion. Chronic pain is listed as the condition. The record reports enrollment of 83, while the study summary describes a plan to enroll One hundred ten subjects. The reasons for the difference between the planned enrollment and the recorded enrollment are not reported in the registry record.
Intervention
The intervention was an intraoperative intravenous infusion of dexmedetomidine. The registry describes dexmedetomidine as an alpha-2-adrenergic agonist commonly used for sedation and as an adjunct to general anesthetics. The record does not report the dose or infusion schedule.
Comparator
The comparator was placebo saline, described in the summary as normal saline infusion. The trial was randomized, double-blind and placebo-controlled. Further details about allocation concealment and how masking was maintained are not reported in the registry record.
Primary question
The primary outcome asks how much morphine, expressed as morphine milligram equivalent (MME), participants received during the first 48 hours after surgery. The posted results give the median and inter-quartile range in each arm. A formal between-arm analysis for this primary outcome is not reported in the registry record, so the group summaries alone do not establish whether the observed difference is compatible with chance or estimate its precision as a comparative effect.
3. Trial Design
This was a randomized, prospective, double-blind, placebo-controlled, parallel-group Phase 4 study. Participants undergoing lumbar spinal fusion were assigned to intraoperative intravenous dexmedetomidine or placebo saline. The registry lists NYU Langone Health as the sponsor and marks the study as completed. The recorded start date is 2016-09-14, and the primary completion date is 2022-02-22.
The registry record reports enrollment of 83. Its study summary describes an intended enrollment of One hundred ten subjects, with 55 in each arm. These are different record elements: the actual recorded enrollment should not be mistaken for the planned enrollment, and the reasons for the difference are not reported in the registry record. The outcome-specific numbers of participants also vary across the posted outcomes. Reasons for those differences, including whether they reflect missing observations, eligibility for a particular analysis or another issue, are not reported in the registry record.
The summary describes follow-up for approximately six weeks after surgery. The primary outcome concerns morphine-equivalent use during the first 48 hours post-surgery. Listed secondary outcomes include pain scores at 48 hours and six weeks, morphine equivalents at six weeks, pressor use, recovery scores and lengths of stay. The record lists 12 outcome measures, while 11 secondary outcomes are posted. The registry does not report a detailed statistical analysis plan, the planned handling of missing outcome values, the analysis population for each outcome, or whether any interim analyses were conducted. Those omissions limit what can be concluded about how the posted analyses relate to 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
| Stage | IV Dexmedetomidine | Placebo |
|---|---|---|
| STARTED | 33 | 31 |
| COMPLETED | 18 | 13 |
| NOT COMPLETED | 15 | 18 |
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 | IV Dexmedetomidine | Placebo | Total |
|---|---|---|---|---|
| Participants analysed | 33 | 31 | 64 | |
| Age, Continuous | years | 63.2 (SD 8.8) | 59.9 (SD 10.8) | 61.5 (SD 9.9) |
| Sex: Female, Male: Female | Participants | 19 | 16 | 35 |
| Sex: Female, Male: Male | Participants | 14 | 15 | 29 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 2 | 2 | 4 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 31 | 29 | 60 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 2 | 1 | 3 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 3 | 2 | 5 |
| Race (NIH/OMB): White | Participants | 25 | 27 | 52 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 3 | 1 | 4 |
| Region of Enrollment: United States | participants | 33 | 31 | 64 |
6. Primary Endpoint
The registry lists the primary outcome as Morphine Equivalents Used During the First 48 Hours Post-Surgery, measured over Up to 48 Hours Post-Surgery (Day 2).
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Inter-Quartile Range |
| Unit | morphine milligram equivalent (MME) |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the amount of morphine administered during the first 48 hours following surgery, expressed in morphine milligram equivalents (MME). MME converts opioid medication amounts to a common scale, allowing opioid use to be described in a shared unit. The registry reports this outcome as a median with an inter-quartile range, rather than as a mean and standard deviation. A median describes the middle of the observed distribution, while the inter-quartile range describes the interval from the lower to the upper quartile. These summaries can be useful when measurements are skewed or include unusually high values, because the median is less influenced by extreme observations than the mean.
The posted median was 180.0 MME in the IV dexmedetomidine arm, with an inter-quartile range of 120.0 to 309.5, and 142.5 MME in the placebo arm, with an inter-quartile range of 76.5 to 211.5. These are descriptive arm summaries. The registry record does not report a primary-outcome comparison estimate, confidence interval or p-value. Therefore, the summaries describe the observed distributions but do not quantify the uncertainty around a difference between arms or provide a formal test of the primary question.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
For the primary outcome, the posted median amount of morphine equivalents was 180.0 MME in the IV dexmedetomidine arm and 142.5 MME in the placebo arm during the first 48 hours after surgery. The corresponding inter-quartile ranges were 120.0 to 309.5 and 76.5 to 211.5. The median is a useful description of the center of each observed distribution, and the inter-quartile range shows the spread of the middle portion of observations. Neither summary, on its own, is a comparative treatment-effect estimate with quantified uncertainty.
A primary-outcome confidence interval, hypothesis test or adjusted analysis is not reported in the registry record. It is therefore not possible to use the posted primary summaries to determine how precisely the between-arm difference is estimated or whether a formal primary comparison met a prespecified statistical criterion. The trial's primary result should be read as descriptive arm-level information, not as evidence that one intervention caused more or less opioid use.
The posted secondary outcomes offer additional descriptive and recalculated comparisons, but they do not replace the missing primary-outcome analysis. For the secondary outcomes with recalculated comparisons, the estimates are unadjusted calculations from the posted summary statistics. The confidence intervals for these comparisons include their respective null values, and their unadjusted p-values are greater than 0.05. These results do not establish a difference between arms. At the same time, an interval that includes the null can encompass both no difference and effects in either direction; it is not proof that the arms are equivalent.
The secondary pain summaries do not show a uniform direction across the measured time points: the observed mean pain score is higher in the dexmedetomidine arm at 48 hours and lower at six weeks. The pressor-use comparison is also imprecise. These outcomes are secondary, and their unadjusted results carry less weight than a prespecified primary analysis, particularly when the registry does not report a multiplicity strategy. The registry record does not report whether any secondary outcome analyses were adjusted for baseline characteristics or other covariates.
Planning illustrations based on observed secondary effects are not evidence of the trial's power or a retrospective measure of whether the study was adequately sized. They are hypothetical sample-size calculations under stated assumptions, not observed trial results. In particular, they should not be used to infer that a nonsignificant or imprecise result represents no effect. Overall, the posted record supports description of observed outcome distributions and limited unadjusted secondary comparisons, but not a definitive inferential conclusion about the primary outcome.
9. Statistical Methods Explained
Statistical interpretation depends on the form of each outcome and the summaries used to report it. The primary outcome is a continuous quantity, morphine-equivalent use, reported as a median and inter-quartile range. Secondary pain scores are reported as means and standard deviations, while pressor use is reported as counts of participants. These summaries describe different features of the data and are not interchangeable.
What does a median and inter-quartile range describe?
General statistical explanation: the median is the value at the center of an ordered distribution. The inter-quartile range spans the middle half of that distribution, from the lower quartile to the upper quartile. Together, these summaries describe a typical value and the spread of central observations without assuming that the data are symmetric. They do not show the full distribution, and they do not by themselves provide a standard error, confidence interval for the median, or comparison between randomized arms. The registry record does not report the primary outcome's comparative estimate or inferential test.
How should mean differences be read?
General statistical explanation: a mean difference is the mean in one group minus the mean in the comparator group. A confidence interval gives a range of values compatible with the observed data under the analysis assumptions; narrower intervals indicate greater precision. If an interval includes zero for a difference, the data do not rule out no difference at the corresponding confidence level. This does not demonstrate that the groups are equivalent, because the interval can also include potentially meaningful differences. The recalculated secondary mean differences are unadjusted estimates from posted summary statistics, not sponsor-reported analyses.
The posted pain-score summaries include a mean difference of 0.74 for 48-hour scores, with a confidence interval from -0.278 to 1.758 and an unadjusted p-value of 0.154. At six weeks, the recalculated mean difference is -0.26, with a confidence interval from -1.777 to 1.257 and an unadjusted p-value of 0.737. These estimates are expressed in score units. Their intervals include zero, so the recalculated comparisons do not rule out no mean difference. No analysis adjusting for other variables is reported in the registry record.
How should a risk difference be interpreted?
General statistical explanation: a risk difference compares the proportion of participants with an event in one group with the proportion in the comparator group. A value of zero represents equal proportions. A confidence interval around a risk difference expresses uncertainty in the comparison. The posted intraoperative pressor-use comparison has a recalculated risk difference of 0.112, with a confidence interval from -0.111 to 0.336 and an unadjusted p-value of 0.325. The interval includes zero. This is an unadjusted comparison, not proof of equal risk or evidence of a causal effect.
The secondary comparison calculations also report relative measures, including a risk ratio and an odds ratio. General statistical explanation: a risk ratio compares proportions directly, whereas an odds ratio compares event odds. Their null value is one rather than zero. These measures can be difficult to interpret when event counts are sparse, and should be considered alongside the absolute event counts and their uncertainty. No sponsor-reported analysis is listed for these secondary outcomes.
What do p-values and confidence intervals contribute?
General statistical explanation: a p-value describes how unusual data at least as extreme as those observed would be under a specified null model and its assumptions. It is not the probability that the null hypothesis is true, nor does it measure the size or clinical importance of an effect. Confidence intervals complement p-values by showing a range of effect estimates compatible with the data and model. Both depend on the analysis method and the data included. The registry record does not report a formal test for the primary endpoint, so secondary p-values cannot answer the primary question.
How should sample-size illustrations be used?
The planning illustrations are based on observed effects, use a two-sided significance level of 0.05, assume equal allocation, and use a normal approximation. They show participants per arm for 80% power and participants per arm for 90% power when planning for 100%, 75% or 50% of the observed effect. These calculations are illustrations, not the trial's own design justification. The record does not report the trial's sample-size assumptions or justification. The illustrations are not observed power: they do not measure the probability that this completed trial detected an effect. General statistical explanation: planning calculations depend on assumptions about the target effect, variability, allocation and analysis. Changing those assumptions changes the estimated sample size.
Because the primary result is reported only with medians and inter-quartile ranges, the secondary mean-based calculations should not be transferred to it. The registry does not report a method for comparing the primary medians. It also does not report whether the primary endpoint was analyzed according to an intention-to-treat principle, or how missing observations were handled. These are important elements for assessing the estimand and uncertainty of a randomized-trial comparison.
10. Multiplicity, Missing Data and Analysis Populations
The registry record does not report how multiplicity was handled. This matters because several secondary outcomes are listed, including outcomes measured at different postoperative times and outcomes with different measurement scales. When many outcomes are examined, the chance of at least one apparently unusual result can increase, even if there is no true effect. General statistical explanation: multiplicity procedures can control the overall false-positive rate or organize outcomes into a prespecified hierarchy. Without a reported strategy, unadjusted secondary p-values should not be treated as if they were protected confirmatory tests.
Missing-data handling is also not reported in the registry record. The posted outcome-specific participant counts vary, and the record does not explain why. It does not say whether values were unavailable, whether participants were excluded from particular analyses, or whether any imputation or sensitivity analysis was used. No explanation should be inferred from the differing counts alone.
The analysis populations are not described in sufficient detail in the registry record. It does not report whether analyses followed intention-to-treat, per-protocol or another principle, or whether exclusions after randomization occurred. It also does not report baseline characteristics by arm or any adjustment variables for the posted comparisons. These omissions limit assessment of whether each comparison retains the benefits of randomization and how representative each outcome-specific analysis is of the randomized groups.
The registry record does not report an interim-analysis plan, stopping boundaries, or a detailed protocol-level statistical analysis plan. It is also not reported whether the primary outcome was tested using a prespecified method. These items cannot be reconstructed from the posted summaries. In the absence of these details, the safest reading distinguishes the descriptive primary summaries from the recalculated, unadjusted secondary comparisons and avoids treating secondary p-values as definitive evidence.
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 |
|---|---|---|---|
| IV Dexmedetomidine | 0 | 33 | 0.0% |
| Placebo | 0 | 31 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| IV Dexmedetomidine | 1 of 33 |
| Placebo | 0 of 31 |
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 |
|---|---|
| IV Dexmedetomidine | 1 of 33 |
| Placebo | 2 of 31 |
Most frequent non-serious adverse event terms
| Event term | Organ system | IV Dexmedetomidine | Placebo |
|---|---|---|---|
| Asthma | Respiratory, thoracic and mediastinal disorders | 1 of 33 | 1 of 31 |
| Bradycardia | Cardiac disorders | 0 of 33 | 1 of 31 |
The posted serious adverse event counts are zero in both arms. The record separately reports one death in the IV dexmedetomidine group and none in the placebo group. Other adverse events are reported for one participant in the dexmedetomidine group and two in the placebo group. The numbers at risk differ by outcome and arm: serious adverse events are reported against 33 and 31 participants, and other adverse events against 33 and 31 participants, respectively. These counts should be read with their stated denominators rather than assumed to share a common analysis population.
Small event counts provide limited precision for comparisons. A count of zero serious adverse events in an arm does not establish that the underlying risk is zero, and the posted figures do not quantify comparative uncertainty. The registry record does not report further details about event types, timing, severity beyond the serious-event classification, attribution, or the relationship between the death counts and adverse-event categories. No causal connection should be inferred from these summaries. They describe recorded events; they do not establish that either intervention caused or prevented an event.
12. What the Result Does, and Does Not, Mean
The posted primary outcome describes morphine-equivalent use during the first 48 hours after surgery in the two randomized arms. The median is 180.0 MME in the dexmedetomidine arm and 142.5 MME in the placebo arm, with inter-quartile ranges of 120.0 to 309.5 and 76.5 to 211.5. These summaries allow readers to compare the observed centers and central spreads, but they do not provide a formal estimate of the primary between-arm effect or its precision.
The primary-outcome comparison, confidence interval and p-value are not reported in the registry record. Without those details, it is not possible to determine whether the observed separation in medians is consistent with random variation under a prespecified test, or to assess the range of comparative effects compatible with the data. The absence of a reported test is not evidence that the groups were the same, and the summaries do not show that one intervention caused a change in opioid use.
Secondary outcomes provide additional descriptions of pain scores and other postoperative measures, but their unadjusted recalculated comparisons are not a substitute for the primary analysis. Their confidence intervals include the null values, and the record does not report a multiplicity strategy. These results do not establish equivalence, nor do they justify selecting one outcome or time point as decisive after seeing the results.
More generally, a randomized design supports a comparative question, but the credibility and interpretation of a particular estimate also depend on how outcomes were analyzed, how missing data were handled and whether the analysis followed the planned approach. Several of these details are not reported in the registry record. The findings therefore support a cautious description of the posted outcomes, not a medical recommendation or a definitive claim that dexmedetomidine does or does not affect pain or opioid use.
13. Why This Trial Matters Statistically
This trial is statistically instructive because the main clinical question is paired with a primary outcome reported using robust descriptive summaries, but without a posted comparative analysis. Medians and inter-quartile ranges can be appropriate ways to describe skewed quantities such as medication use. However, they do not by themselves answer the randomized comparison. A treatment-effect estimate and an uncertainty interval would help readers assess both direction and precision.
The record also illustrates why a completed randomized study should not be interpreted from its design label alone. Randomization and double masking are important design features, but the registry does not report enough detail to evaluate the primary analysis population, missing-data approach, multiplicity handling or sample-size justification. Reporting those elements allows readers to distinguish planned confirmatory analyses from descriptive or exploratory findings.
Secondary outcomes add clinical context, yet their measures and time points differ, and their unadjusted comparisons are imprecise. Reading several outcomes together without a reported multiplicity plan can encourage selective emphasis. The trial therefore highlights the value of prespecifying outcome priorities and analysis methods, and of reporting estimates with uncertainty for the primary endpoint.
Finally, planning calculations based on observed effects can help illustrate the scale of studies that might be needed under stated assumptions, but they are not retrospective evidence of power. Keeping those planning illustrations separate from observed results prevents a common interpretive error: treating a nonsignificant result as proof of no effect. The registry record gives enough information to describe several outcomes, but leaves key inferential questions unresolved.
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.
A central limitation of the posted record is that the primary outcome is reported only as arm-level medians and inter-quartile ranges. A comparative estimate, confidence interval and p-value are not reported in the registry record. This prevents a direct assessment of the precision of the primary comparison and makes it difficult to distinguish a descriptive difference from a statistically evaluated treatment effect.
There is also a difference between the recorded enrollment of 83 and the planned enrollment described as One hundred ten subjects. The reason for this difference is not reported in the registry record. Outcome-specific participant counts vary, but the record does not explain the reasons or describe how missing outcome data were handled. The analysis populations and any post-randomization exclusions are not reported.
The registry does not provide a detailed statistical analysis plan, sample-size justification, multiplicity procedure, or information about interim analyses. It does not report whether the primary analysis was adjusted, or which method was used to compare the primary medians. These missing details constrain interpretation of the secondary comparisons as well, since they are unadjusted recalculations and the number of outcomes raises multiplicity concerns.
The safety summaries have sparse event counts, and further information about event types, timing and attribution is not reported. The study summary describes follow-up for approximately six weeks, so the posted information addresses the listed perioperative and early postoperative outcomes rather than establishing longer-term effects. These limitations concern the available registry information; they do not establish that particular procedures were or were not conducted outside what the record reports.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Study on the Effects of Intravenous Dexmedetomidine on Pain in Patients Undergoing Elective Spinal Surgery — NCT03325972.
- Registry record last updated 2023-06-05; status last verified 2023-05.
- Results first posted 2023-03-21.
- 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
The registry describes a completed, randomized, double-blind, placebo-controlled, parallel-group Phase 4 study sponsored by NYU Langone Health. It evaluated intraoperative intravenous dexmedetomidine compared with placebo saline in people undergoing lumbar spinal fusion. Recorded enrollment was 83; the study summary described a planned enrollment of One hundred ten subjects. The primary outcome was morphine-equivalent use during the first 48 hours after surgery, reported by arm as a median and inter-quartile range.
The registry also lists pain, opioid-use, pressor-use, recovery and length-of-stay outcomes. Some secondary comparisons are recalculated from posted summary statistics and are unadjusted; no sponsor-reported secondary analyses are listed. A comparative primary analysis, missing-data methods, analysis populations and multiplicity procedures are not reported in the registry record. The results therefore support descriptive reading of the posted outcomes, while leaving important questions about primary-effect precision and the analysis strategy unresolved.