Effects of Tradipitant on Satiation, Gastric Volume, Gastric Accommodation, and Gastric Emptying in Healthy Volunteers: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effects of Tradipitant on Satiation, Gastric Volume, Gastric Accommodation, and Gastric Emptying in Healthy Volunteers (NCT04849559), a randomized phase 1, phase 2 study. The primary outcome is Fasting Gastric Volume as Measured by Single Photon Emission Computed Tomography (SPECT).

2. Clinical Question

This is a question about a physiological measurement in healthy volunteers, not a clinical-outcome comparison in people selected for a diagnosed condition. The registry’s brief summary describes the broader aim as evaluating tradipitant relative to placebo across satiation and several measures of gastric function. Fasting gastric volume is the primary outcome listed in the record, while the broader aims include gastric accommodation and emptying as well as satiation.

The posted primary summaries are descriptive: they state the median fasting gastric volume and interquartile range in each arm. Those summaries help show the central value and spread of the measurements, but they do not by themselves establish whether an arm difference is statistically reliable. The registry record lists no analyses, so it does not provide a reported inferential comparison for this primary question.

3. Trial Design

The registry describes a randomized, parallel-group, placebo-controlled study at a single center. The official title calls it double-blind, while the registry’s masking classification is quadruple. Both arms received an oral capsule: tradipitant in one arm and placebo in the other. The study is classified as Phase 1 and Phase 2.

The enrollment listed in the record is 27. The primary outcome is specified for completed subjects, and the posted summaries give 11 participants for tradipitant and 13 for placebo. These outcome-specific counts need not match the enrollment figure: enrollment describes the trial record, whereas the primary summaries refer to the population used for that outcome. The registry does not explain the reasons for any difference between those counts.

The study began on 2021-02-01, had a primary completion date of 2021-09-24, and is marked completed. The primary outcome timeframe is 9 Days. The record identifies fasting gastric volume measured by single photon emission computed tomography (SPECT) as the primary endpoint, with results expressed in mL as a median and interquartile range.

Randomization and masking are design features intended to reduce the influence of selection and expectations on treatment assignment and outcome assessment. A parallel design means participants are assigned to an arm and the arm summaries are compared, rather than describing a crossover sequence. The registry does not report details of the randomization procedure, allocation concealment, or how masking was maintained. Those aspects should not be inferred from the design labels alone.

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:

Analysis population for the primary outcome, as defined in the registry: Completed subjects

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 Fasting Gastric Volume as Measured by Single Photon Emission Computed Tomography (SPECT), measured over 9 Days.

The primary endpoint is fasting gastric volume measured by SPECT. Gastric volume is a physiological measure of the amount of material in the stomach under the fasting measurement conditions recorded for the study. SPECT is the measurement method named in the registry. The result is reported in mL, and the assessment is associated with a 9 Days timeframe.

The registry lists the endpoint statistic as the median and its dispersion as the interquartile range. The median is the central observation when measurements are ordered. The interquartile range describes the span from the lower to the upper quartile, giving a sense of the distribution’s middle portion without assuming that measurements are symmetrically distributed. This can be useful when a small study’s measurements are skewed or when a few values might strongly affect a mean.

For tradipitant, the reported median is 178.8 mL, with interquartile range endpoints of 158.0 and 217.0. For placebo, the median is 191.1 mL, with endpoints of 169.2 and 216.9. These are arm-level summaries, not an adjusted treatment effect or a test of whether the arms differ. The registry does not report a corresponding inferential analysis.

The primary outcome addresses one aspect of gastric function. It does not, on its own, describe every outcome named in the study’s broader aims, nor does it establish how any measured difference relates to symptoms or clinical benefit.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation depends on distinguishing descriptive summaries from inferential comparisons. The primary outcome is described by a median and interquartile range in each arm. These quantities summarize observed distributions. They do not, by themselves, quantify uncertainty in the difference between the randomized groups.

What do the median and interquartile range describe?

The median is the middle value after observations are ordered. It is less sensitive than the mean to unusually high or low values, which can be helpful when a measurement has a skewed distribution. The interquartile range spans the middle half of the observations, from the lower quartile to the upper quartile. It communicates spread in the observed data rather than uncertainty about a population-level treatment effect.

For fasting gastric volume, the registry reports the median and interquartile range in each arm. These summaries can be read as descriptions of the measurements among completed subjects. They do not account for other study features through adjustment, and they do not indicate the probability that one treatment is better than another. The record does not report a model or a test for this endpoint.

Why is a direct comparison needed?

A randomized trial’s treatment question concerns a contrast between arms. A direct analysis can estimate that contrast and describe its uncertainty, using a method appropriate to the outcome, design, and analysis population. A confidence interval for the contrast is one way to express precision. A p-value, when reported, addresses compatibility with a specified null hypothesis under the test assumptions; it does not measure the size or clinical importance of an effect.

Separate arm summaries do not supply either of these inferential quantities. In particular, interquartile ranges are not confidence intervals. Their overlap cannot be used as a formal test, and their endpoints do not show the uncertainty in the difference between medians. Because the registry lists no analyses, no direct inferential result can be attributed to the sponsor from this record.

What does the randomized parallel design contribute?

Random allocation is intended to make treatment groups comparable on average with respect to measured and unmeasured characteristics at assignment. It does not guarantee that small groups will be identical, and it does not remove the need to report how the outcome comparison was conducted. A parallel design assigns participants to one study arm for the comparison. The registry also identifies placebo control and masking, but it does not describe allocation concealment, the randomization sequence, or the practical masking procedures.

Adjustment can be used in some analyses to account for prespecified characteristics or improve precision, but the registry record does not report whether an adjusted model was planned or used. No adjustment should be inferred from the arm summaries. Likewise, the record does not state whether the analysis followed randomized assignment regardless of treatment completion, or whether a different population was used.

Why can distribution shape matter?

As a general statistical point, the choice of summary and analysis should reflect the outcome distribution and the question of interest. A mean-based method targets an average difference and may require assumptions about the distribution of the outcome or model residuals. A median-based method focuses on a different feature of the distribution. If data are skewed or include influential observations, robust or distribution-free approaches may be considered. The registry does not report which considerations guided the endpoint statistic or any inferential method.

Over-dispersion is a general issue in some statistical models when observed variability exceeds what the model assumes. It can make standard errors too small if ignored. This concept cannot be assessed from the registry’s median and interquartile-range summaries alone, and the record does not identify a model for which over-dispersion would apply.

What can the planning illustrations establish?

Sample-size calculations based on an observed effect are planning illustrations, not observed power. In general, such illustrations depend on assumptions about the target effect, significance level, allocation, and statistical approximation. They describe what a future design might require under those assumptions; they do not change the precision of the completed trial or prove that its result is conclusive. The registry record does not report the trial’s own sample-size justification or planning assumptions. No numeric planning estimate should be inferred from the posted primary summaries.

Because no sponsor analysis is posted, there is no sponsor inferential result to replace with a recalculation. The arm-level figures can be described as reported, but a new estimate or test should not be constructed from the summaries alone. Any such analysis would require explicit assumptions and could not be presented as the trial’s reported result.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists 4 outcome measures, while the study’s stated aims cover satiation, gastric volume, gastric accommodation, and gastric emptying. It identifies fasting gastric volume as the primary outcome. The record does not report a multiplicity strategy, such as a hierarchy of testing or an adjustment for making multiple statistical comparisons. It also lists no analyses, so no multiplicity-adjusted or unadjusted inferential results are posted.

Multiplicity is a general concern when several outcomes or comparisons are tested. The more tests considered, the greater the chance that an apparently notable result could arise by chance under a collection of null hypotheses. Statistical plans may address this by prioritizing outcomes, controlling an overall error rate, or treating secondary findings as exploratory. Which, if any, approach was used in this trial is not reported in the registry record.

The primary outcome population is described as completed subjects. The record does not report how many randomized participants lacked a primary measurement, why outcome data may be unavailable, how missing values were handled, or whether any participants were excluded from the analysis. It also does not provide a detailed definition of the completed-subject population. These omissions prevent assessment of the missing-data assumptions or of the impact of exclusions.

As a general matter, missingness can affect interpretation if the probability of having an observed measurement is related to treatment assignment or to the outcome itself. Different assumptions about missing data can produce different estimates. No missing-data method or sensitivity analysis is reported for this trial, so the potential influence of missing outcomes cannot be evaluated from the registry record.

11. 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.

Most frequent non-serious adverse event terms

The safety summaries report serious adverse events and other adverse events separately. In the tradipitant arm, 0 serious adverse events were reported among 13 at risk, and 4 other adverse events were reported among 13 at risk. In the placebo arm, 0 serious adverse events were reported among 14 at risk, and 4 other adverse events were reported among 14 at risk. Deaths are reported as 0 in each arm.

These are event counts in the safety record, not estimates of a comparative risk. The record does not give event-level details for the other adverse events in the posted summary, and no serious adverse-event terms are listed. Counts alone do not establish whether an event was caused by study treatment. The registry also does not post a statistical comparison of safety outcomes.

As a general point, a zero count in a study does not prove that an event cannot occur. Small safety datasets can provide limited information about uncommon harms, and an observed count is not a precise estimate of future risk. The figures should therefore be read as the events recorded in this trial, not as a guarantee of safety or as evidence that the arms have equivalent safety profiles.

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

The primary result means that the registry reports arm-specific medians and interquartile ranges for fasting gastric volume measured by SPECT in completed subjects. The median is 178.8 mL for tradipitant and 191.1 mL for placebo. The reported interquartile range endpoints are 158.0 and 217.0 for tradipitant, and 169.2 and 216.9 for placebo. These descriptions characterize the recorded values; they are not a formal estimate of the effect of assignment to tradipitant compared with placebo.

The result does not show whether the observed difference between the medians is statistically distinguishable from sampling variation. The registry record lists no analyses and provides no confidence interval or p-value for the primary comparison. The interquartile ranges are measures of the distributions within the arms, not uncertainty intervals for the treatment contrast. No significance or equivalence conclusion can be drawn from these summaries alone.

The result also does not establish a clinical effect. Participants were healthy volunteers, and fasting gastric volume is a physiological measure. The registry does not provide evidence in this outcome record about symptoms, disease management, or outcomes in people with a diagnosed condition. Nor does this primary summary answer every question named in the broader study aim: values for the other outcomes are not available for interpretation.

The safety counts describe events recorded during the study. They do not establish that serious events are impossible, that other events were caused by treatment, or that the arms have the same safety profile. A trial’s observed counts and the uncertainty around event rates are different things; the registry does not report a comparative safety analysis.

In short, the record supports a descriptive account of fasting gastric volume and adverse-event counts in this completed study. It does not report inferential results needed to quantify the precision of a treatment comparison, details needed to evaluate missing outcome data, or findings that justify conclusions beyond the measured population and outcomes.

13. Why This Trial Matters Statistically

This trial is statistically informative as an example of why outcome summaries and treatment comparisons are not interchangeable. The registry presents medians and interquartile ranges for each arm, which describe the observed distributions. But a clinical trial question usually concerns the contrast between assigned groups. That contrast requires its own estimate and an expression of uncertainty. Without a posted analysis, a reader should not treat the difference between the arm medians as a complete answer.

The distinction is especially relevant when an endpoint is summarized by a median. The median communicates the center of a distribution in a way that can be less affected by extreme values than the mean. The interquartile range communicates the spread of the middle observations. Neither summary is a confidence interval for the between-arm effect. Reading the summaries correctly helps prevent an overconfident interpretation of a small physiological study.

The record also highlights the role of analysis populations. Enrollment is listed as 27, whereas the primary outcome summaries are labeled for completed subjects and report arm-specific counts. Those figures answer different record-keeping questions. Without an account of missing measurements, exclusions, or the analysis population, the reader cannot fully assess how the primary summaries relate to all randomized participants.

Finally, the study has several stated physiological aims, but only the primary outcome summary is available in the record described. Where multiple endpoints are considered, a transparent analysis plan and clear distinction between primary and exploratory results help readers interpret evidence without overemphasizing isolated findings. The registry does not report such a plan or posted analyses. The important statistical lesson is therefore about calibrated interpretation: the descriptive data are useful, while uncertainty and the scope of inference remain limited.

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 trial-specific limitation is that the registry posts descriptive primary outcome summaries but no statistical analyses. There is no reported estimate of the between-arm contrast, confidence interval, or p-value. As a result, the precision and statistical compatibility of the primary comparison cannot be evaluated from the record.

The primary outcome is specified for completed subjects. Although the record lists enrollment of 27 and arm-specific primary outcome counts, it does not explain participant flow, missing measurements, exclusions, or the reasons the outcome-specific counts differ from enrollment. This prevents assessment of whether outcome availability could have influenced the summaries.

The record does not provide the protocol’s sample-size justification, detailed statistical analysis plan, randomization procedure, allocation concealment, or masking procedures. It also does not report how multiplicity across the several stated aims was handled. These omissions limit evaluation of whether the analysis matched prespecified methods and how secondary outcomes should be interpreted.

The trial concerns healthy volunteers and a physiological endpoint measured over a 9 Days timeframe. The primary result therefore has a bounded scope: it does not, by itself, establish effects on clinical symptoms or outcomes in a patient population. The registry also does not post values for the other outcomes needed to assess the full set of stated study aims.

Safety interpretation is similarly constrained. The record gives adverse-event counts but no comparative statistical analysis or detailed terms for the other adverse events in this summary. Zero reported serious events should not be read as proof that serious events cannot occur. These limitations are specific to the information recorded and should not be replaced by assumptions about unreported methods or results.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Effects of Tradipitant on Satiation, Gastric Volume, Gastric Accommodation, and Gastric Emptying in Healthy Volunteers — NCT04849559.
• Registry record last updated 2024-04-16; status last verified 2021-04.
• Results first posted 2024-04-16.
• 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.

18. Record Summary

NCT04849559 is a completed, randomized, parallel, placebo-controlled study of tradipitant in healthy volunteers. The official title describes a single-center, double-blind study; the registry classification lists quadruple masking. The study is classified as Phase 1 and Phase 2, with enrollment of 27.

The primary outcome is fasting gastric volume measured by SPECT, reported in mL as a median and interquartile range for completed subjects, at a 9 Days timeframe. The reported medians are 178.8 for tradipitant and 191.1 for placebo. The registry lists no analyses, and the record does not report a formal comparison for this endpoint.

The safety record reports 0 serious adverse events and 0 deaths in each arm, with 4 other adverse events in each arm. Missing-data methods, multiplicity handling, and the trial’s sample-size justification are not reported in the registry record.