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 Use of Dexmedetomidine in Acute Stroke and Cerebral Vasospasm Interventions (NCT01845441), a randomized phase 2 study. The primary outcome is Numbers of Patient Movements (Events) That Delay or Adversely Affect the Procedure Performance and Safety..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01845441 |
| Phase | Phase 2 |
| Condition | Stroke, Brain Ischemia, Vasospasm, Intracranial |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 7 |
| Arms in the primary outcome | 2 |
| Lead sponsor | University Hospitals Cleveland Medical Center |
| Results posted | Yes |
2. Clinical Question
Population
Patients undergoing endovascular treatment for acute ischemic stroke or cerebral vasospasm. The registry record also lists stroke, brain ischemia, intracranial vasospasm, and intracranial hemorrhage among the conditions.
Intervention
Dexmedetomidine sedation during the procedure. The record describes a continuous intravenous infusion beginning before catheterization and ending at the end of the procedure.
Comparator
The control approach was to attempt the procedure without sedation. At the attending physician’s discretion, fentanyl and/or midazolam boluses could be used to address movement that interfered with procedure performance.
Primary question
How did the recorded frequency of patient-movement intervals that delayed or adversely affected procedure performance and safety compare between the dexmedetomidine and control arms?
The clinical question links sedation strategy with movement during a procedure in which the patient’s neurologic status is also relevant. The registry describes the aim as comparing dexmedetomidine with other standard sedative medications while maintaining neurologic function. The listed secondary outcomes concern preservation of the neurologic examination and maintenance of an optimal sedation target in both groups.
The primary outcome is not a direct measure of neurologic recovery or the success of the endovascular procedure. It is a procedural measure: whether movement was recorded as an event during one-minute assessment intervals, with the resulting event intervals standardized by procedure duration. That makes the outcome relevant to procedural conditions, but it does not by itself establish how well neurologic function was preserved. Results for the secondary outcomes are not reported in the registry record.
3. Trial Design
The registry record describes a randomized, double-masked, parallel-group phase 2 trial. The listed enrollment is 7, and the record status is terminated. The start is recorded as 2012-04 and primary completion as 2021-12. A reason for termination is not reported in the registry record.
The intervention arm received dexmedetomidine during the procedure. The control arm followed usual care, described as attempting the intervention without sedation, with fentanyl and/or midazolam available as discretionary intravenous boluses to control movement affecting the procedure. Thus, the contrast is between a planned dexmedetomidine infusion and a control strategy that could include rescue sedatives; it is not necessarily a comparison of dexmedetomidine with no sedative exposure in every control participant.
The primary outcome was assessed during the procedure, for up to 4 hours. The record describes continuous monitoring of patient movement, with an assessment every one minute. The primary endpoint description says the number of one-minute intervals in which an event occurred was divided by the procedure’s total minutes to obtain a standardized value. It explains that this approach was intended to support comparison across procedures of varying duration and to make event assessment more systematic than counting movements directly.
For the primary outcome, the posted results list 3 participants in each arm. The endpoint record notes that data were not collected for one patient in the dexmedetomidine arm. The registry record does not explain the relationship between those endpoint counts and the listed enrollment. It also does not report details of sequence generation, allocation concealment, masking procedures, eligibility criteria, or a statistical analysis plan.
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 | Dexmedetomidine Arm | Control Arm |
|---|---|---|
| STARTED | 4 | 3 |
| COMPLETED | 4 | 3 |
| NOT COMPLETED | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: Data was not collected for one patient in the Dexmedetomidine arm.
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 | Dexmedetomidine Arm | Control Arm | Total |
|---|---|---|---|---|
| Participants analysed | 4 | 3 | 7 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 3 | 3 | 6 |
| Age, Categorical: >=65 years | Participants | 1 | 0 | 1 |
| Sex: Female, Male: Female | Participants | 4 | 1 | 5 |
| Sex: Female, Male: Male | Participants | 0 | 2 | 2 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 | 0 | 0 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 2 | 3 | 5 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 2 | 0 | 2 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 1 | 0 | 1 |
| Race (NIH/OMB): White | Participants | 2 | 3 | 5 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 1 | 0 | 1 |
6. Primary Endpoint
The registry lists the primary outcome as Numbers of Patient Movements (Events) That Delay or Adversely Affect the Procedure Performance and Safety., measured over Primary outcome will be assessed during the procedure, up to 4 hours..
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Standard Deviation |
| Unit | Events |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint concerns patient movements that delay or adversely affect procedure performance and safety. Rather than counting each movement episode as a discrete event, assessors were to determine at one-minute intervals whether an event had occurred. The resulting number of event intervals was then divided by the total minutes in the procedure, producing a duration-standardized measure as described in the registry record.
This approach is intended to address a practical problem: procedures can last for different lengths of time, so raw event counts may not be directly comparable across participants. Standardizing by procedure minutes can express the event burden relative to observed procedure duration. The record also says that scheduled one-minute assessments were intended to reduce subjective differences in deciding when a movement begins and ends.
The outcome remains dependent on how an event is judged and recorded. The registry does not report assessor agreement, blinding of the patient assessor, or additional validation of the measure. The posted outcome is labeled as a median with standard deviation, and its unit is listed as events; the record does not clarify the apparent relationship between that label and the duration-standardized calculation. Results are given as 30 for the dexmedetomidine arm and 36 for the control arm, with standard deviations of 27.07 and 25.87, respectively. These summaries alone do not show the distribution of individual participant values or the uncertainty around the between-arm contrast.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted primary-outcome summaries are a median of 30, with a standard deviation of 27.07, in the dexmedetomidine arm, and a median of 36, with a standard deviation of 25.87, in the control arm. Each arm’s reported endpoint count is 3. The registry record notes that data were not collected for one patient in the dexmedetomidine arm. These figures describe the posted summaries; they do not establish a statistically reliable difference between treatment strategies.
The record labels the endpoint as a median and reports standard deviations. A median describes the center of a distribution by its middle value, while a standard deviation describes spread around the mean. Reporting these together is possible, but the record does not explain why this summary pairing was chosen. With very few observations in each arm, a summary can be sensitive to individual values, and the reported standard deviations indicate substantial variability relative to the scale of the endpoint. Individual participant data and a confidence interval for the treatment contrast are not reported in the registry record.
The event measure is intended to account for procedure duration by standardizing the event intervals to total procedure minutes. That intention is important when procedure lengths vary, but the registry does not report individual procedure durations or the underlying event-interval counts. The displayed arm summaries therefore do not allow a reader to examine whether values were driven by particular procedures or how the standardized values were distributed.
No inferential analysis for the primary outcome is reported in the registry record. The record lists no posted analysis count, and the registry entries do not include a p-value, confidence interval, adjusted estimate, or statistical model. Consequently, the numerical separation between the arm summaries should not be treated as evidence that one strategy produced a reliably different movement outcome. A lack of an inferential result is not evidence that the strategies are equivalent; equivalence would require a suitable design and analysis, neither of which is reported.
The registry lists two secondary outcomes: preservation of the neurologic examination and maintenance of an optimal sedation target in both groups. Their results are not reported in the registry record. It is therefore not possible to assess those outcomes alongside the movement summaries or to judge whether the sedation strategies differed in neurologic assessment or sedation-target maintenance.
Safety counts are posted separately. The record lists zero serious adverse events, zero other adverse events, and zero deaths in each arm, with at-risk counts that differ from the endpoint counts. Those small denominators and the limited outcome reporting mean the safety figures are descriptive, not conclusive. They do not quantify the range of possible risks or support broad conclusions about safety.
9. Statistical Methods Explained
What does the primary endpoint summarize?
The registry describes an event-based assessment made at one-minute intervals. An interval counted when a patient movement delayed or adversely affected procedure performance or safety. The total event intervals were divided by the total procedure minutes to create a standardized value. In general, standardizing a count by time can make observations from periods of different lengths more comparable. It does not remove all differences between procedures or eliminate judgment in deciding whether an event occurred.
The reported outcome is labeled as a median with standard deviation. In general, a median is a measure of central location that is less affected by extreme values than a mean. A standard deviation describes dispersion around the mean, not around the median. The registry does not explain the choice to pair these summaries, and the underlying participant-level data are not reported. The posted summaries should therefore be read as the registry’s descriptions rather than as enough information to reconstruct the outcome distribution.
What can a confidence interval tell a reader?
In general, a confidence interval expresses the statistical uncertainty around an estimate and identifies a range of values compatible with the observed data under the method used. A narrow interval indicates greater precision than a wide interval. No confidence interval for the primary between-arm contrast is reported in the registry record. The arm summaries alone do not provide that measure of precision, and a reader should not infer it from the standard deviations.
Likewise, a p-value would address how compatible the observed data are with a specified statistical model and null hypothesis; it would not measure the size or clinical importance of an effect. No p-value for the primary outcome is reported in the registry record. The record does not report a model, an adjusted estimate, or details of a hypothesis test. No conclusion about statistical significance can be drawn from the posted arm summaries.
Why does the small amount of outcome data matter?
With only 3 reported endpoint participants in each arm, estimates can be highly sensitive to the observations included. A single participant’s value can have a substantial influence on a group summary when the group is this small. The endpoint description also notes that data were not collected for one patient in the dexmedetomidine arm. The reason for that missing outcome and its handling in the analysis are not reported in the registry record.
Small samples also make it difficult to assess assumptions about the distribution of an outcome. In general, a normal approximation may be unreliable when data are sparse or strongly skewed. The record does not report a distributional assessment or an alternative method. The method used to calculate the displayed summaries and any treatment comparison is not reported.
How should the planning illustrations be read?
General sample-size planning uses assumptions about the effect to detect, the significance level, allocation, and statistical method. The planning assumptions associated with the posted illustrations describe a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. They use fractions of the observed effect as planning targets. These assumptions are illustrations based on the observed effect, not a description of the trial’s original design or a sample-size justification.
Such planning values are hypothetical estimates of the number of participants that could be needed under the stated assumptions. They are not observed power, do not change the amount of information collected in this trial, and do not establish that the original study was adequately powered. The registry record does not report its own sample-size calculation, design effect, or statistical plan. No additional planning assumptions should be inferred.
The record notes that a two-arm comparison for another endpoint could not be estimated because values were missing or not estimable. This illustrates a separate limitation from imprecision: without usable endpoint values, a comparison cannot be calculated from the posted data. The missing endpoint results should not be replaced with assumptions about what those results might have been.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists two secondary outcomes in addition to the primary movement endpoint: preservation of the neurologic examination and maintenance of an optimal sedation target in both groups. Their results are not reported in the registry record. The record does not describe a hierarchy of endpoints, a multiplicity adjustment, or a plan for handling multiple statistical tests. Without those details and the secondary results, the chance of false-positive findings across multiple tests cannot be assessed.
The primary outcome record states that data were not collected for one patient in the dexmedetomidine arm. The reason is not reported in the registry record. The record does not say whether the missing observation was excluded, imputed, or handled by another approach. It also does not identify an intention-to-treat, per-protocol, or other analysis population. Therefore, the reported endpoint counts should be understood as the counts attached to the posted outcome, not as a complete account of the analysis population.
The endpoint counts are 3 in each arm, while the listed enrollment is 7. The registry record does not explain the difference between those figures. No further reconciliation is possible from the posted information. There are no reported participant-level data or analysis details with which to evaluate the effect of missing outcomes, protocol deviations, or exclusions.
The record indicates that values were missing or not estimable for a two-arm comparison for another endpoint. Results for the two listed secondary outcomes are also absent. These gaps limit both the assessment of multiplicity and the interpretation of the trial as a whole. They should not be treated as evidence that the outcomes showed no difference.
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 |
|---|---|---|---|
| Dexmedetomidine Arm | 0 | 4 | 0.0% |
| Control Arm | 0 | 3 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Dexmedetomidine Arm | 0 of 4 |
| Control Arm | 0 of 3 |
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 |
|---|---|
| Dexmedetomidine Arm | 0 of 4 |
| Control Arm | 0 of 3 |
The registry record lists the following safety counts:
Dexmedetomidine arm: 4 at risk for serious adverse events, 0 serious adverse events; 4 at risk for other adverse events, 0 other adverse events; 0 deaths.
Control arm: 3 at risk for serious adverse events, 0 serious adverse events; 3 at risk for other adverse events, 0 other adverse events; 0 deaths.
These are descriptive counts within the safety record. The at-risk counts differ from the primary endpoint counts, and the registry does not explain the difference. The record does not provide event-level descriptions or serious adverse event terms; none are listed among the top serious terms.
Zero recorded events in these small groups does not establish that an event is impossible or that the strategies have equivalent safety. In general, a small study has limited ability to detect uncommon harms, and a count of zero does not provide a precise estimate of risk. The registry record does not report additional safety analyses, follow-up details, or a statistical comparison of adverse events. These figures should therefore be interpreted as the events recorded in the posted safety data, not as a comprehensive estimate of comparative safety.
12. What the Result Does, and Does Not, Mean
The posted results provide a limited descriptive account of the primary movement endpoint. The recorded median is 30 in the dexmedetomidine arm and 36 in the control arm, with standard deviations of 27.07 and 25.87, respectively. The endpoint count is 3 in each arm. The record notes missing data for one patient in the dexmedetomidine arm. Because no confidence interval, p-value, or treatment-effect estimate is reported, the precision and statistical compatibility of these summaries cannot be assessed.
The outcome is a procedural measure, based on movement events assessed at one-minute intervals and standardized by procedure duration. It does not directly measure stroke recovery, neurologic function over time, or technical success of the intervention. Although the registry lists neurologic examination and sedation-target maintenance as secondary outcomes, their results are not reported in the registry record.
The safety record lists zero serious adverse events, zero other adverse events, and zero deaths in each arm, with at-risk counts of 4 for the dexmedetomidine arm and 3 for the control arm. These observations are too limited to establish comparative safety or exclude uncommon events. The record also does not report why the trial was terminated.
In general, a randomized design can support a causal comparison when allocation, follow-up, outcome measurement, and analysis are adequately documented and implemented. Here, important details about those processes and the statistical analysis are not reported in the registry record. The posted summaries therefore do not establish that either strategy is superior, equivalent, or safer. They describe the available outcome observations, while leaving substantial uncertainty about both the estimated contrast and its precision.
13. Why This Trial Matters Statistically
This trial addresses a statistical challenge common to procedural research: how to compare movement during procedures that may differ in duration. The registry’s one-minute assessment approach attempts to make movement-event information more systematic, then standardizes the event intervals by total procedure minutes. That design choice makes the definition and measurement of the endpoint central to interpretation, not merely the arithmetic used to summarize it.
The posted outcome also illustrates why the number of participants and the completeness of reporting matter. The endpoint summaries are based on 3 participants in each arm, and the record notes missing data for one patient in the dexmedetomidine arm. With so few observations, group summaries may be unstable, and a small amount of missing information can be consequential. The absence of an inferential estimate means readers cannot assess the precision of the comparison.
Statistically, the study’s listed secondary outcomes could have added important context to a movement endpoint, particularly because the stated aim involves sedation and preservation of neurologic examination. However, those results are not reported in the registry record. The lack of a reported multiplicity approach also means the implications of considering multiple outcomes cannot be evaluated.
The record is a useful example of the difference between a trial’s design description, posted descriptive results, and evidence from a complete analysis. Randomization and masking are listed design features, but they do not substitute for clear outcome data, missing-data handling, analysis methods, and measures of uncertainty. Those details are needed to judge how much the observed summaries can support beyond a description of the recorded participants.
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.
Several limitations are specific to the posted record. The trial is listed as terminated, but the reason for termination is not reported in the registry record. The record lists an enrollment of 7, while the primary endpoint results list 3 participants per arm; it does not explain how those counts relate. It also notes that outcome data were not collected for one patient in the dexmedetomidine arm without reporting the reason or how the missing value was handled.
The primary endpoint description explains a standardized event measure, but the reported outcome is labeled as a median with standard deviation and has a unit listed as events. The record does not clarify how these labels relate to the described calculation. Individual values, procedure durations, event-interval counts, and the method used to calculate the summaries are not reported. The absence of confidence intervals, p-values, and a model or analysis method prevents assessment of the uncertainty around an arm comparison.
The registry does not report detailed eligibility criteria, allocation procedures, masking implementation, assessor agreement, or protocol deviations. It does not state the analysis population or describe a missing-data strategy. Results for the listed secondary outcomes are not reported, and no multiplicity plan is described. The safety counts are small and are not accompanied by event-level details or a comparative analysis.
The record’s control strategy allowed discretionary fentanyl and/or midazolam use, so the posted comparison is between dexmedetomidine and a usual-care approach that could include those sedatives. The registry does not report the frequency or timing of control-arm rescue medication use. These omissions make it difficult to characterize treatment exposure or assess the robustness and scope of the observed summaries.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Use of Dexmedetomidine in Acute Stroke and Cerebral Vasospasm Interventions — NCT01845441.
- Registry record last updated 2022-12-28; status last verified 2022-11.
- Results first posted 2022-12-28.
- 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.
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18. Record Summary
The registry record describes a phase 2, randomized, double-masked, parallel-group trial of dexmedetomidine versus a usual-care control approach for endovascular treatment of acute ischemic stroke or cerebral vasospasm. The listed enrollment is 7, and the trial status is terminated.
The primary endpoint concerns movement intervals that delayed or adversely affected procedure performance or safety, standardized by procedure duration. The posted median values are 30 for the dexmedetomidine arm and 36 for the control arm, with standard deviations of 27.07 and 25.87. The endpoint count is 3 in each arm; data were not collected for one patient in the dexmedetomidine arm.
The record lists zero serious adverse events, zero other adverse events, and zero deaths in both arms. Results for the listed secondary outcomes, reasons for termination, and details of the statistical analysis are not reported in the registry record. The available outcome information is descriptive and does not establish the precision or statistical significance of a treatment comparison.