Effect of Dexmedetomidine of Gastrointestinal Motility: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effect of Dexmedetomidine of Gastrointestinal Motility (NCT04798482), a na phase 4 study. The primary outcome is Intra-anal Sphincter Pressure (IASP) 1 Minute After Dexmedetomidine Administration.

2. Clinical Question

3. Trial Design

This is a Phase 4 interventional study with a single group and no masking. The registry lists allocation as not applicable and describes the study as open label. The intervention is dexmedetomidine; all participants were to have baseline manometry measurements followed by administration of the drug and subsequent manometry measurements. This before-and-after structure does not include a separate randomized control arm.

The registry records enrollment of 22. It identifies the condition as anesthesia and describes the study rationale in relation to children undergoing anorectal manometry. The actual age range, eligibility criteria, recruitment setting, and participant characteristics are not reported in the registry record. The registry lists the study as completed, with a start date of 2021-09-14 and a primary completion date of 2022-11-15.

The primary endpoint is intra-anal sphincter pressure at 1 minute after dexmedetomidine administration, expressed as a mean with standard deviation and measured in mmHg. The registry also records three outcome measures overall, but does not give numerical findings for the primary endpoint in the record summarized by these results. The number of registered analyses is zero. Detailed statistical methods, the analysis population, and the handling of repeated measurements are not reported in the registry record.

Because the study has no concurrent comparator, any before-and-after difference would be observed over time within the study group. Such a design can describe measurements around administration, but it cannot by itself separate a drug-associated change from other influences that occur over the same period. The registry record does not report enough outcome information to assess whether a change was observed.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Intra-anal Sphincter Pressure (IASP) 1 Minute After Dexmedetomidine Administration, measured over 1 minute.

Intra-anal sphincter pressure (IASP) is a manometric measurement of pressure in the anal sphincter. The registered primary endpoint is IASP measured 1 minute after dexmedetomidine administration, in mmHg. The endpoint is specified as a continuous measure summarized by a mean and standard deviation.

The study rationale concerns whether dexmedetomidine affects gastrointestinal smooth muscle and anal manometry measurements. A pressure measure is relevant to that question because manometry records pressure in the anorectal region. The registry describes baseline measurements before administration and measurements afterward, making the timing of measurement central to interpreting the endpoint. However, details of the specific measurement protocol, including the number of readings contributing to the value and how those readings were combined, are not reported in the registry record.

The endpoint description identifies a post-administration measurement, but a numerical mean, standard deviation, sample size for the endpoint, and comparison with baseline are not reported in the registry record. Consequently, the magnitude and direction of any pressure change, and the precision with which it was estimated, cannot be assessed from the reported endpoint information. The registered measure is an observation about pressure; it is not, by itself, a measure of whether a procedure was completed or whether a participant could follow commands.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary endpoint as a continuous measurement summarized by a mean and standard deviation. It does not report the actual endpoint values or a detailed statistical analysis plan. The explanations below describe general statistical concepts; they should not be read as methods confirmed to have been used in this study.

What do a mean and standard deviation describe?

General: A mean describes the average value in a group of observations. A standard deviation describes how spread out individual values are around that average. They answer different questions: the mean describes the central level, while the standard deviation describes participant-to-participant variability. Neither is reported numerically for the primary endpoint in the registry record, so the average pressure and its observed spread cannot be evaluated.

For a before-and-after design, separate means at each time point could describe the average pressure before and after administration. A mean of individual changes would instead describe the average within-participant change. These quantities are related but not interchangeable: the variability of individual changes depends on how measurements within each participant are related. The registry record does not say whether the primary analysis used paired changes, separate time-point summaries, or another approach.

What does a confidence interval add?

General: A confidence interval gives a range of values compatible with the data and the statistical procedure used. Its width conveys uncertainty: a wider interval indicates less precision, while a narrower interval indicates greater precision under the method's assumptions. The interval is not a guarantee that the true value lies within that particular range. No confidence interval for the primary endpoint is reported in the registry record, so its precision cannot be assessed.

A p-value, when used, addresses how compatible the observed data are with a specified null model, under the assumptions of the test. It does not measure the size or clinical importance of a change, and it does not establish causation. The registry record lists no analysis results or p-values for the primary outcome. The significance level mentioned in the planning assumptions is 0.05, but that assumption does not establish which inferential test, if any, was used for the study's observed measurements.

Why does the design affect the analysis?

General: When the same participants are measured before and after an intervention, the observations are paired. A paired analysis accounts for the fact that two measurements from one participant may be more similar to each other than measurements from different participants. Treating paired observations as independent can misrepresent uncertainty. The study description indicates measurements before and after administration, but the registry record does not specify the analysis method or confirm how many participants had both measurements.

The absence of a separate control group also limits interpretation. A within-person comparison can describe a temporal change, but does not automatically distinguish the effect of the intervention from other changes over time, measurement variability, or factors associated with the procedure. This is a general limitation of uncontrolled before-and-after comparisons, not a finding about the cause of any change in this study.

How should the planning illustration be understood?

General: A sample-size planning illustration describes how many participants might be needed for a hypothetical study under stated assumptions. The registry assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a fraction of an observed effect. That hypothetical two-arm setup differs from the registered single-group design. Any such illustration is not the trial's original sample-size justification and is not observed power. The original sample-size justification is not reported in the registry record.

Over-dispersion is a general concern when observations vary more than a statistical model assumes. If the model understates variability, uncertainty estimates may be too small and tests may appear more decisive than warranted. Whether over-dispersion was relevant to this continuous pressure endpoint, and whether any adjustment was used, are not reported in the registry record. No statistical model or diagnostic procedure is described.

In general, a complete interpretation of a continuous endpoint would benefit from the number analyzed, the measurement summaries, an estimate of the before-and-after change, and an uncertainty interval. The registry record does not report those numerical results for the primary outcome. It therefore does not permit assessment of the observed effect size, the spread of measurements, or the precision of an estimate.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Dexmedetomidine")
n   <- c(20)
m   <- c(62.9)
sp  <- c(4.5)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Dexmedetomidine  20  62.900  4.500  60.794  65.006

11. Multiplicity, Missing Data and Analysis Populations

The registry lists three outcome measures and zero analyses. It does not report a statistical plan explaining how outcomes were prioritized beyond identifying IASP at 1 minute as the primary endpoint. It also does not report whether investigators adjusted for testing multiple outcomes or multiple time points. The use of any multiplicity procedure is therefore not reported in the registry record.

General: When several outcomes or comparisons are tested, the chance of at least one apparently unusual result can increase. A prespecified primary outcome helps focus interpretation, while adjustment procedures can address some forms of multiple testing. These general considerations do not establish that a particular method was needed or used in this study.

The number of participants with complete primary endpoint measurements is not reported in the registry record. Reasons for missing measurements, exclusions, and the handling of missing data are also not reported. There is no information about whether an analysis used all available measurements, only complete before-and-after pairs, or another approach. The analysis population is not reported in the registry record.

These omissions limit assessment of how the registered enrollment relates to the endpoint analysis and whether missingness could affect the result. They also prevent evaluation of whether the reported endpoint, if available elsewhere, reflects the planned analysis. No inference about the amount or consequences of missing data can be made from the registry information.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The adverse-event listing records 20 participants at risk for serious adverse events and zero affected. It also records 20 participants at risk for other adverse events and zero affected. The death count is zero, and no serious adverse event terms are listed.

These are counts in the registry safety record. The enrollment count is 22, so the safety denominator should not be treated as equivalent to enrollment or assumed to describe the endpoint analysis population. The reason the safety counts use 20 participants, the adverse-event collection period, and the procedures used to collect or classify events are not reported in the registry record.

General: A zero count means no events of the specified category were recorded among the listed participants at risk in that record. It does not establish that an event is impossible or that none occurred outside the recorded population or observation period. The registry does not provide additional detail about event definitions or follow-up, so the safety figures should be interpreted as the recorded counts rather than as a complete characterization of risk.

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

The registry record establishes that the study was designed to observe anorectal manometry measurements before and after dexmedetomidine, with intra-anal sphincter pressure at 1 minute identified as the primary endpoint. It does not report the numerical endpoint findings. As a result, the posted information does not show whether pressure rose, fell, or remained similar, nor how variable the measurements were.

The design is single group and open label, with no separate control arm. A before-and-after observation can describe a change within participants, but any change would not alone demonstrate that dexmedetomidine caused it. Other time-related or measurement-related influences could contribute. The registry record does not report an estimated change or its uncertainty, so even a descriptive assessment is unavailable from the endpoint information.

The study rationale concerns sedation in the setting of pediatric anorectal manometry and whether smooth muscle function is affected. The registry record does not report results on procedure completion, ability to follow commands, or other clinical outcomes that would answer those broader questions. The primary endpoint is a pressure measurement, not a direct report of whether participants tolerated or completed the procedure.

The absence of endpoint results is not evidence of no change. It means the registry entry does not provide enough numerical information to characterize a change or its precision. Likewise, the safety count of zero recorded events among 20 participants at risk is a limited registry count, not proof that adverse events cannot occur. The record supports understanding the design and intended measurement, but not a conclusion about the observed physiological response or its clinical implications.

14. Why This Trial Matters Statistically

This study raises a statistical question about interpreting physiological measurements collected around a sedative administration. The design makes the relationship between repeated observations important: measurements before and after administration come from the same participants, rather than from independent treatment and control groups. General statistical methods for paired data can account for that dependence, but the registry record does not report which analysis was used.

The case also illustrates the distinction between a registered endpoint and a reported result. The registry identifies a specific continuous measure, its unit, summary type, and timing. Without the numerical mean, variability, change estimate, or uncertainty interval, readers cannot judge the size or precision of the observed response. Naming an endpoint alone is not enough to interpret its findings.

Another important issue is design-based inference. A single-group before-and-after comparison can describe measurements over time, but it does not provide the same basis for causal attribution as a controlled comparison. This is relevant when interpreting physiological changes that may also reflect measurement conditions or other influences. The record does not provide a comparator that could help distinguish these explanations.

Finally, enrollment, safety denominators, and endpoint analysis populations are distinct quantities. The registry records enrollment of 22 and safety counts based on 20 at risk, but does not report the number analyzed for the primary endpoint. Statistical interpretation depends on knowing which observations contributed to an estimate and how missing measurements were handled. These distinctions matter even when the question is focused on a single pressure measurement.

15. 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 numerical results for the primary endpoint. Without the endpoint mean, standard deviation, baseline measurement, or estimate of change, the observed response and its precision cannot be evaluated. The number of participants contributing to the primary endpoint is also not reported, so the relationship between the enrolled group and the analyzed measurements is unclear.

The single-group, open-label design has no concurrent control arm. Any before-and-after difference would be vulnerable to influences other than the intervention, and the design alone cannot establish causation. The registry does not report whether measurements were assessed by blinded personnel or whether procedures were standardized in a way that could address measurement-related bias.

Important protocol details are not reported in the registry record, including dexmedetomidine dose and administration details, specific eligibility criteria, participant characteristics, and the full manometry measurement procedure. The record also does not describe the statistical analysis, missing-data handling, or the analysis population. The number of registered outcome measures is three, but the handling of multiple outcomes is not reported.

The safety listing records 20 participants at risk, while enrollment is 22. The registry does not explain this difference, and the safety denominator cannot be assumed to be the endpoint denominator. Adverse-event ascertainment methods and follow-up duration are also not reported. Together, these omissions limit interpretation of both the efficacy-related measurement and the safety counts.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Effect of Dexmedetomidine of Gastrointestinal Motility — NCT04798482.
• Registry record last updated 2024-04-26; status last verified 2024-04.
• Results first posted 2024-04-26.
• 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.

19. Record Summary

NCT04798482 is a completed Phase 4, open-label, single-group interventional study sponsored by Boston Children's Hospital. The registry lists enrollment of 22, a start date of 2021-09-14, and a primary completion date of 2022-11-15. Dexmedetomidine was administered after baseline manometry measurements.

The primary endpoint is intra-anal sphincter pressure at 1 minute after administration, measured in mmHg and intended to be summarized as a mean with standard deviation. The record lists three outcome measures and zero analyses. It does not report numerical results for the primary endpoint, the endpoint analysis population, or detailed statistical methods.

The safety listing records zero serious adverse events, zero other adverse events, and zero deaths among 20 participants at risk. No serious adverse event terms are listed. The relationship between that safety denominator and the endpoint analysis population is not reported in the registry record.