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 Airway Dimension Study in Children Undergoing MRI Sedated With Propofol and Dexmedetomidine (NCT01505933), a randomized phase 2 study. The primary outcome is Cross-sectional Area (CSA) of the Upper Airway at the Level of Soft Palate, Base of the Tongue and Tip of the Epiglottis.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01505933 |
| Phase | Phase 2 |
| Condition | Airway Remodeling |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 24 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Milton S. Hershey Medical Center |
| Results posted | Yes |
2. Clinical Question
Population
Children undergoing MRI with sedation are the stated population. The registry summary explains that sedation is used to support completion of MRI while maintaining respiratory and hemodynamic stability, and identifies limited access to the patient during MRI as a safety consideration. The research rationale mentions children with upper-airway disorders, but specific eligibility criteria and the characteristics of enrolled children are not reported in the registry record.
Intervention
One study arm received dexmedetomidine. The registry describes it as a sedative with analgesic properties and states that the study was intended to assess how the drugs affect upper-airway dimensions. Dosing, administration details and any titration rules are not reported in the registry record.
Comparator
The comparison arm received propofol. The registry summary describes propofol as commonly used for pediatric MRI sedation and notes its predictability and rapid onset and offset. These are descriptions in the study rationale, not results of the comparison. The arm descriptions do not provide further details about how either drug was administered.
Primary question
The primary endpoint is mean cross-sectional area of the upper airway at the soft palate, base of the tongue and tip of the epiglottis. The clinical question is whether these airway measurements differ between the dexmedetomidine and propofol arms under the stated measurement conditions. The registry record does not report the group means, a between-arm estimate, confidence intervals or a statistical test for this comparison, so it does not establish the direction or precision of any difference.
3. Trial Design
This is a randomized, parallel-group Phase 2 study of dexmedetomidine compared with propofol for sedation in children undergoing MRI. The registry records an enrollment of 24 and identifies the study as single masked. It does not state who was masked, how masking was maintained, or whether masking was successful. The arm descriptions contain no additional information about allocation procedures or treatment administration.
The listed condition is Airway Remodeling. The registry summary frames the rationale around the need for sedation during MRI, respiratory and hemodynamic stability, and the difficulty of accessing a patient during imaging. It describes the research aim as assessing the effects of the two drugs on the upper airway and validating their use in children with upper-airway disorders. That rationale should not be read as evidence that the enrolled participants all had a particular airway disorder; eligibility criteria and participant characteristics are not reported in the registry record.
The study start is recorded as 2012-02, and primary completion is recorded as 2017-12-01. Its status is terminated. The registry record does not state why the study was terminated, whether the planned enrollment was reached, or whether termination affected the collection or reporting of outcome data. The sponsor is Milton S. Hershey Medical Center.
Random allocation is intended to reduce systematic differences between treatment groups, while a parallel design assigns participants to one arm rather than comparing treatments within the same participant. These are general design features; they do not guarantee balanced groups in a small study. The registry does not report the randomization method, allocation concealment, recruitment flow, protocol deviations or the number of participants contributing primary outcome data.
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.
Before assignment: 1 participant was excluded prior to assignment group
Overall Study
| Stage | Dexmedetomidine | Propofol |
|---|---|---|
| STARTED | 10 | 14 |
| COMPLETED | 10 | 14 |
| NOT COMPLETED | 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 | Dexmedetomidine | Propofol | Total |
|---|---|---|---|---|
| Participants analysed | 10 | 14 | 24 | |
| Age, Continuous | years | 4 (2 to 5) | 3.5 (2 to 5) | 3.75 (2 to 5) |
| Sex: Female, Male: Female | Participants | 6 | 7 | 13 |
| Sex: Female, Male: Male | Participants | 4 | 7 | 11 |
| 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 | 0 | 0 | 0 |
| Race (NIH/OMB): White | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 10 | 14 | 24 |
| Region of Enrollment: United States | participants | 10 | 14 | 24 |
6. Primary Endpoint
The registry lists the primary outcome as Cross-sectional Area (CSA) of the Upper Airway at the Level of Soft Palate, Base of the Tongue and Tip of the Epiglottis, measured over When expired sevoflurane is 0% during the procedure on an average of 5 - 10 mins after discontinuation of sevoflurane, airway measurements will be done.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | mm2 |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is the mean cross-sectional area (CSA) of the upper airway, measured in mm2 at the level of the soft palate, base of the tongue and tip of the epiglottis. Cross-sectional area describes the size of an airway section at a specified anatomical location. Measuring at these locations provides anatomical measurements rather than a direct measure of clinical outcomes such as respiratory events or successful completion of MRI.
The registry specifies measurement when expired sevoflurane is 0% during the procedure, on an average of 5 - 10 mins after discontinuation of sevoflurane. At each anatomical level, measurements are to be obtained over three successive respiratory cycles and averaged. Averaging across respiratory cycles is a way to reduce the influence of short-term variation in a measurement; that is a general measurement principle, not evidence about the reliability of measurements in this study.
The outcome is designated as a mean with standard deviation as its dispersion measure. A mean describes the group’s central value, while a standard deviation describes variability among observations; neither alone gives the precision of a comparison between arms. The registry record does not report the arm-specific endpoint values or a between-arm estimate. The rationale for using airway dimensions is to assess anatomical effects of sedation, but the record does not establish how a change in CSA relates to a particular clinical benefit or harm.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a randomized comparison, but it does not report numerical results for the primary endpoint. There are no posted arm-specific means or standard deviations for the airway CSA measurements at the soft palate, base of the tongue or tip of the epiglottis. A between-arm difference, confidence interval and p-value are also not reported in the registry record. Consequently, the direction, magnitude and statistical precision of the primary comparison cannot be evaluated from the information recorded.
The registry lists 0 analyses. It also indicates that the primary outcome has several categories or time points and was not reduced to one comparison. This is important for interpretation: a single summary claim about the primary endpoint would require knowing which anatomical levels or time points were analyzed, how comparisons were defined and how any multiplicity was handled. Those details are not reported in the registry record. The listed outcome description specifies measurement at multiple anatomical levels, but no results by level are posted.
The enrollment entry is 24. The safety record separately gives denominators of 10 for dexmedetomidine and 14 for propofol. These entries describe different aspects of the record and should not be treated as evidence that the primary endpoint was available for every enrolled participant. The number contributing primary outcome data, missing measurements and reasons for missingness are not reported in the registry record.
A confidence interval, when reported, gives a range of values compatible with the data and the analysis assumptions; its width indicates precision. A p-value, when reported, addresses compatibility of the data with a specified statistical null model, not clinical importance. Neither can be reconstructed from arm sizes alone, and neither is reported for this primary outcome. The study’s terminated status does not itself identify why it ended or what conclusions its investigators reached.
Accordingly, the posted record supports a description of the question and measurement plan, but not a conclusion that either sedative produced larger or smaller airway dimensions. It also does not establish equivalence or absence of a difference. Those interpretations require outcome estimates and their uncertainty, which are not reported in the registry record.
9. Statistical Methods Explained
What does the randomized parallel design contribute?
Randomization assigns participants to study arms using a chance-based process. Its purpose is to make treatment groups comparable on average with respect to factors that might affect outcomes, including factors that were not measured. In an individual study, randomization does not ensure that all characteristics are balanced, and group sizes can differ. The registry identifies the study as randomized and parallel, but the method used to generate the sequence and conceal assignments is not reported in the registry record.
In a parallel design, measurements in one arm are compared with measurements in another arm. This differs from a crossover design, where participants receive multiple treatments at different times. The record does not describe paired or repeated treatment comparisons. It does specify repeated respiratory-cycle measurements at each anatomical level, which are averaged to obtain the stated endpoint. Those repeated measurements are part of the measurement procedure and should not be mistaken for independent participants.
What does the endpoint summary describe?
The endpoint is a continuous measurement: cross-sectional area in mm2. A group mean summarizes its central value, and a standard deviation describes the spread of individual measurements around that mean. The standard deviation is not the same as the standard error or a confidence interval. The latter quantities describe uncertainty in an estimate, whereas the standard deviation describes variability in observations.
For a comparison of means, an analysis may estimate the difference between groups and report a confidence interval. In general, the estimate describes the size and direction of the observed contrast, while the interval communicates its precision under the analysis assumptions. A narrow interval indicates more precision than a broad interval, but interpretation still depends on the outcome and the clinically relevant scale. The registry record does not report a mean difference or confidence interval for the primary endpoint.
Why does measurement timing matter?
The registry ties the measurement to a specified procedural condition: expired sevoflurane is 0%, with airway measurements on an average of 5 - 10 mins after discontinuation of sevoflurane. Standardizing when measurements are collected can help make observations more comparable across participants. Whether this timing was followed consistently, and whether deviations occurred, are not reported in the registry record.
The plan to average measurements across three successive respiratory cycles can reduce the influence of momentary fluctuation. Averaging does not remove all measurement error, and it does not establish that observers measured the anatomy consistently. Information about measurement equipment, assessor training, reliability checks and assessor masking is not reported in the registry record.
How should significance and precision be understood?
A statistical test generally compares observed data with a null model, such as a model in which the groups have no mean difference. A p-value describes how compatible the data are with that model under the test assumptions. It does not give the probability that the null model is true, and it does not by itself communicate the size or clinical importance of an effect. No primary-outcome p-value is reported in the registry record.
A confidence interval complements a test by showing a range of estimates compatible with the data and analysis assumptions. It can help distinguish a precise estimate from an imprecise one. Without an estimate and interval, the record cannot show whether the study rules out meaningful differences or remains compatible with a wide range of effects. Those results are not reported in the registry record.
What do the planning assumptions mean?
The planning illustration is described as using the observed effect, a two-sided significance level of 0.05, equal allocation between the two arms and a normal approximation. It is explicitly a planning illustration based on the observed effect, not the trial’s own design. The listed planning convention says that the effect to detect is a stated fraction of the observed effect and that continuous-outcome illustrations are expressed as participants per arm for 80% power. The actual observed primary effect and the resulting planning values are not reported in the registry record.
Such calculations ask how much information a future study might need under stated assumptions. They are not observed power, do not show that the completed study was adequately powered, and do not establish that an effect is real. Their relevance depends on the accuracy of the assumed effect and other model choices. No sample-size justification for the original trial is reported in the registry record.
Why can over-dispersion matter?
For count outcomes, over-dispersion means that variation exceeds what a simple count model expects. It can make standard errors too small if the model fails to allow for that extra variability. This is a general statistical point; the primary outcome in this study is continuous, and the registry does not report a count-based primary analysis. No model details for the primary outcome are reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The primary endpoint includes measurements at the soft palate, base of the tongue and tip of the epiglottis. The registry also lists secondary outcomes for anteroposterior and transverse airway diameter at those levels. Considering multiple outcomes or locations can create multiplicity: if many statistical tests are conducted, the chance of at least one apparently unusual result can increase. General approaches include specifying a primary comparison in advance, adjusting tests, or interpreting results as exploratory. The registry record does not report a multiplicity strategy.
The record specifically notes that the primary outcome has several categories or time points and was not reduced to one comparison. It lists 0 analyses. Thus, it does not provide a single inferential result that resolves the comparisons across anatomical levels or time points. The planned endpoint description explains how measurements were to be collected, but does not state which contrasts were prespecified or how they would be summarized statistically.
Missing-data handling is not reported in the registry record. The number of participants with usable measurements at each anatomical level, the amount and pattern of missingness, and reasons for missing observations are not reported. There is also no reported method for handling missing outcomes, such as a complete-case analysis or an imputation procedure. Without these details, the influence of incomplete measurements on the results cannot be assessed.
The analysis population is not reported in the registry record. In particular, the record does not say whether analyses followed assigned treatment, included only participants who received treatment, or used another population definition. The safety denominators do not establish the primary endpoint analysis population. These omissions limit assessment of how participants were included in any outcome analysis and whether departures from random assignment could affect interpretation.
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 | 0 | 10 | 0.0% |
| Propofol | 0 | 14 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Dexmedetomidine | 0 of 10 |
| Propofol | 0 of 14 |
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 | 0 of 10 |
| Propofol | 0 of 14 |
The registry records zero serious adverse events among the 10 participants at risk in the dexmedetomidine arm and zero among the 14 participants at risk in the propofol arm. It also records zero other adverse events among the 10 participants at risk in the dexmedetomidine arm and zero among the 14 participants at risk in the propofol arm. Deaths are recorded as 0 in both arms. The registry lists no top serious-event terms.
These entries describe events recorded in the registry, not proof that no adverse events occurred outside the recorded data. A zero count can occur when no event is observed in the recorded group, but it does not establish that the underlying risk is zero. The record does not report how adverse events were defined, the surveillance period, the completeness of reporting, or whether events were assessed as related to study treatment.
The safety denominators differ between arms, and the registry does not explain the reason. They should be read as the recorded numbers at risk for these adverse-event entries, not automatically as the number with a primary airway measurement. The registry does not provide event-level descriptions or precision estimates for the safety results. These figures alone cannot support a comparative safety conclusion.
12. What the Result Does, and Does Not, Mean
The study addresses a focused measurement question: how upper-airway dimensions compare between children assigned to dexmedetomidine or propofol during MRI sedation. The registry specifies a primary measure of cross-sectional area at three anatomical locations and describes when and how repeated respiratory-cycle measurements were to be averaged. This provides a framework for understanding what investigators intended to measure.
The record does not report the primary outcome results. It therefore does not show which arm had a larger mean CSA, how large any difference was, or how precisely a difference was estimated. It also does not establish that the treatments had equal effects. A lack of a posted estimate is not evidence of no effect; it means the relative measurements cannot be determined from this registry record.
The study rationale discusses respiratory and hemodynamic stability and limited access to patients during MRI. Those statements explain why the investigators considered sedation and airway dimensions relevant. They are not trial findings. CSA is an anatomical measurement, and the record does not report whether observed dimensions were associated with breathing events, MRI completion, or another clinical outcome.
The safety entries record no serious adverse events, other adverse events or deaths in either arm, using the stated denominators. These counts are limited to the registry entries and do not establish the absence of risk or provide a precise estimate of comparative safety.
The terminated status and lack of posted analyses further constrain interpretation. The reason for termination, outcome completeness, analysis population and statistical plan are not reported in the registry record. The appropriate reading is therefore descriptive: the record documents a randomized comparison and an intended airway measurement strategy, but it does not provide evidence from which to judge the magnitude, direction or clinical relevance of an airway difference.
13. Why This Trial Matters Statistically
This study is statistically notable because it focuses on an intermediate anatomical outcome rather than reporting only a broad clinical endpoint. Measuring airway CSA at specified locations makes the research question concrete, while the secondary diameter outcomes describe additional dimensions of the airway. The timing and respiratory-cycle averaging also illustrate how a measurement protocol can define the quantity being compared.
At the same time, the record shows why outcome definitions alone are not enough for statistical interpretation. Results require group estimates, an explicit contrast and information about uncertainty. With no primary means, between-arm estimate, confidence interval or p-value reported, readers cannot determine whether any observed difference was small, large, precise or uncertain. The entry that the primary outcome spans several categories or time points and was not reduced to one comparison further emphasizes the need for a clearly specified analysis strategy.
The randomized parallel design is relevant because it aims to support a fair comparison between sedative arms. But details about sequence generation, concealment, masking and analysis populations are absent from the registry record. These details help readers assess how well the design was implemented and whether the analyzed groups remained comparable.
The safety counts are also a reminder that event absence in a registry entry is not the same as proof of no risk. Denominators, follow-up and event definitions matter when interpreting zero recorded events. Finally, the terminated status makes transparency about completion, missing measurements and analysis especially important; those explanations are not reported in the registry record. The case illustrates how a scientifically focused question can still remain statistically unresolved when outcome estimates and analysis details are unavailable.
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 main limitation for interpretation is the absence of reported primary outcome results. The registry identifies the CSA measure and its anatomical locations but gives no group means, standard deviations, comparative estimate, confidence interval or p-value. The direction and precision of the comparison therefore cannot be assessed.
The primary outcome is described across multiple anatomical locations, and the record says it was not reduced to one comparison because it has several categories or time points. The registry lists 0 analyses and does not report which contrasts were planned, whether the analysis was adjusted for multiple comparisons, or how time points were handled. Secondary airway-diameter outcomes are listed, but their results are not reported in the registry record.
Enrollment is recorded as 24, while adverse-event denominators are recorded separately as 10 and 14. The number contributing to each airway measurement is not reported. The record does not describe recruitment flow, missing measurements, reasons for missing data, protocol deviations or the analysis population. It is therefore not possible to determine how complete the primary outcome data were or how participants entered any analysis.
Further design and measurement details are absent. The registry does not identify who was masked, specify the randomization or allocation-concealment method, or give dosing and administration details for either drug. It does not report measurement equipment, assessor reliability or deviations from the stated measurement timing. Participant characteristics and specific eligibility criteria are also not reported in the registry record.
The study is marked terminated, but the reason is not reported. The registry record does not state whether the planned study objectives were completed or how termination affected data collection. These limitations prevent a full assessment of study conduct and leave the comparative airway question unanswered in the posted results.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Airway Dimension Study in Children Undergoing MRI Sedated With Propofol and Dexmedetomidine — NCT01505933.
- Registry record last updated 2019-07-11; status last verified 2019-07.
- Results first posted 2019-07-11.
- 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 randomized, single-masked, parallel Phase 2 comparison of dexmedetomidine and propofol for sedation in children undergoing MRI. Enrollment is recorded as 24, the sponsor is Milton S. Hershey Medical Center, and the status is terminated. The study start is recorded as 2012-02, with primary completion on 2017-12-01.
The primary outcome is mean upper-airway cross-sectional area in mm2 at the soft palate, base of the tongue and tip of the epiglottis, measured under the stated sevoflurane timing condition and averaged across three successive respiratory cycles. Secondary outcomes are anteroposterior and transverse airway diameters at those anatomical levels.
The registry lists 0 analyses and does not report primary outcome estimates or inferential results. Adverse-event entries record zero serious adverse events, zero other adverse events and zero deaths in each arm, with denominators of 10 for dexmedetomidine and 14 for propofol. The reason for termination, missing-data handling, analysis populations and multiplicity strategy are not reported in the registry record.