Motion Serifos: A Study to Investigate the Efficacy of Tradipitant in Participants Affected by Motion Sickness: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Motion Serifos: A Study to Investigate the Efficacy of Tradipitant in Participants Affected by Motion Sickness (NCT05903924), a randomized phase 3 study. The primary outcome is Prevention of Vomiting Measured by Vomiting Assessment (VA).

2. Clinical Question

In plain terms, the clinical question is whether the recorded occurrence of vomiting during the stated assessment period differed between participants assigned to either tradipitant dose and participants assigned to placebo. The registry record lists 11 participants with the outcome in the high-dose arm, 19 in the low-dose arm, and 40 in the placebo arm. The corresponding group sizes were 106, 104, and 106.

The trial is registered as Phase 3 and is described as randomized, double-blind, and placebo-controlled. Those design features frame the comparison, but the registry record does not provide further details about the randomization procedure, dose levels, or participant characteristics. The posted results address the primary vomiting measure; secondary outcome results are not posted in the record. This page therefore interprets the stated outcome and its reported comparisons, rather than attempting to answer broader questions about all possible effects of tradipitant or about groups not described in the record.

3. Trial Design

Motion Serifos is registered as a Phase 3, randomized, parallel-group, placebo-controlled study of tradipitant in participants affected by motion sickness during travel. The registry record describes the study as double-blind and lists quadruple masking. It also describes the study as multicenter. These labels identify the broad design, but further operational details are not reported in the registry record.

The posted arms are Tradipitant High Dose, Tradipitant Low Dose, and Placebo. Their reported group sizes are 106, 104, and 106 participants, respectively. The intervention names do not state the dose amounts, and the registry record does not report further dosing instructions. The record reports an overall enrollment of 316 participants.

The study began on 2023-09-09, reached primary completion on 2024-04-06, and is listed as completed. The primary outcome timeframe is 1 day. These dates and the outcome timeframe are different kinds of information: the dates describe the study record, while the timeframe describes the period associated with the primary measure.

Randomization and masking are relevant because they are intended to support a fair comparison and reduce the influence of expectations or knowledge of treatment assignment. General explanation: random allocation can help balance participant characteristics across groups on average, while masking can limit some sources of bias in how outcomes are assessed or reported. The registry record does not describe how allocation was generated or concealed, who was masked, or whether masking was assessed. It also does not report the trial's original sample-size justification, analysis populations, or the detailed statistical plan. The posted results include comparisons of each tradipitant arm with placebo, but the record does not specify whether these were the only planned comparisons.

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 Prevention of Vomiting Measured by Vomiting Assessment (VA), measured over 1 day.

The primary endpoint is titled Prevention of Vomiting Measured by Vomiting Assessment (VA). The registry describes the VA as a one-item questionnaire intended to measure the incidence of emesis objectively. Participants indicate whether or not they have vomited. The measure is reported in participants, and its timeframe is 1 day.

The posted arm results are counts of participants with the outcome: 11 in the Tradipitant High Dose group, 19 in the Tradipitant Low Dose group, and 40 in the Placebo group. The corresponding group sizes are 106, 104, and 106. The outcome is binary at the participant level: each participant's response records whether vomiting occurred during the assessment period. A count therefore communicates how many participants in each group were recorded with the outcome, while the comparison also accounts for the different group sizes.

General explanation: a direct, clearly defined outcome can make groups easier to compare, and a yes-or-no measure can be summarized as an event count or event proportion. Here the endpoint is relevant to the study's stated question because it records vomiting during travel. However, the registry description does not provide the exact questionnaire wording, timing within the 1-day period, procedures for handling uncertain responses, or further details about outcome assessment. Those details are not reported in the registry record.

7. Results Posted in the Registry

• Tradipitant High Dose: 10.4% (11/106) versus 37.7% (40/106) on control; risk difference -27.4 percentage points (95% CI -38.3 to -16.5), risk ratio 0.27 (0.15–0.51); unadjusted two-proportion z-test p = <0.001.
• Tradipitant Low Dose: 18.3% (19/104) versus 37.7% (40/106) on control; risk difference -19.5 percentage points (95% CI -31.3 to -7.6), risk ratio 0.48 (0.30–0.78); unadjusted two-proportion z-test p = 0.002.

8. Statistical Interpretation

9. Statistical Methods Explained

What kind of outcome is reported?

The primary outcome is a count of participants with a binary event: whether a participant reported vomiting on the Vomiting Assessment. The posted counts are 11 for Tradipitant High Dose, 19 for Tradipitant Low Dose, and 40 for Placebo. The group sizes are 106, 104, and 106, respectively. A count is easy to understand, but a count alone does not account for group size. The registry comparisons therefore report risk differences between each tradipitant arm and placebo.

General explanation: for a binary outcome, an event proportion summarizes the share of participants in a group who experienced the event. A risk difference is the event proportion in one group minus the event proportion in another. The sign depends on the order used for the subtraction. In these posted comparisons, the negative estimates correspond to a lower observed event proportion in the tradipitant group than in placebo. This direction is also apparent from the posted event counts and group sizes.

How should the effect estimates be read?

The registry reports a risk difference for each active-arm comparison. The high-dose comparison has a negative estimate with a confidence interval that remains below zero; its reported p-value is <0.001. The low-dose comparison also has a negative estimate with a confidence interval that remains below zero; its reported p-value is 0.002. The interval bounds and estimates are displayed in the accompanying results. They are not repeated so the text does not duplicate the results display.

General explanation: the estimate is the single summary value produced by the chosen method, while a confidence interval gives a range of values compatible with the data and method at the interval's stated confidence level. The registry record does not state the confidence level or the calculation method for these intervals. An interval entirely on one side of zero is consistent with a directional difference under that method, but it is not a measure of clinical importance and does not address possible bias or missing data.

What do the p-values say?

The record reports p-values for the two comparisons: <0.001 for Tradipitant High Dose versus Placebo and 0.002 for Tradipitant Low Dose versus Placebo. These are the values posted for the comparisons. The registry record does not report whether they are adjusted for multiple comparisons, which statistical test produced them, or whether a prespecified testing hierarchy was used.

General explanation: a p-value summarizes how unusual results at least as extreme as the observed results would be under a specified null model, assuming the model and test assumptions hold. It is not the chance that a treatment effect is absent. It also does not tell how likely the findings are to replicate or how large an effect matters to participants. Those questions require other evidence and context.

Why does the comparison account for group size?

The two placebo comparisons have similar placebo group sizes, while the low-dose group has 104 participants and the other listed groups have 106. The reported risk differences compare proportions rather than simply subtracting event counts. That distinction matters: comparing counts alone can be misleading when group sizes differ.

General explanation: the precision of an estimate depends partly on the number of participants and events, as well as the analysis method. A group with more observations can often provide a more precise estimate, although precision also depends on how common the outcome is and on the design. The registry results show the group sizes and event counts, but do not report further diagnostics or model checks.

What is not stated about the analysis?

The registry record does not report the analysis population definition, how missing outcome responses were handled, the statistical test or model, whether estimates were adjusted for baseline characteristics, or the confidence interval method. The record also does not report a detailed protocol for outcome adjudication. These absences limit how fully the posted comparisons can be independently reconstructed from the registry information.

General explanation: analysis decisions can influence estimates and uncertainty, especially when outcomes are missing, when there are multiple comparisons, or when the analysis differs from the initial plan. A complete statistical report would usually describe the analysis population, the handling of missing data, the model or test, and any adjustment strategy. The registry record does not provide those details, so they should not be inferred from the displayed results.

The posted calculations are not a substitute for the sponsor's original analysis. The record lists the comparison results and no discrepancy is identified. No additional recalculation is. The interpretation therefore stays with the comparisons as posted and with the limits of the registry description.

10. Confidence Intervals and Precision

The comparison display includes a point estimate and confidence interval for each risk difference. Both intervals are entirely below zero. This indicates that, under the interval methods used for the posted results, the range shown for each comparison lies on the side corresponding to a lower observed event proportion in the tradipitant arm than in placebo. The interval bounds and estimates are shown in the results display; this discussion does not repeat their decimal values.

General explanation: a confidence interval communicates uncertainty around an estimate. A narrower interval indicates greater precision under the method used, while a wider interval indicates less precision. The interval is not a guarantee that the true effect lies within its bounds, and its interpretation depends on the statistical method and assumptions. The registry record does not state the confidence level or describe how the intervals were calculated.

The reported group sizes and event counts help readers understand the basis of the comparisons. The placebo group has 106 participants, the high-dose group has 106, and the low-dose group has 104. Their corresponding event counts are 40, 11, and 19. These counts are informative, but the confidence intervals are needed to see the uncertainty around the risk-difference estimates.

The reported p-values are <0.001 for the high-dose comparison and 0.002 for the low-dose comparison. They complement, but do not replace, the interval estimates. Neither measure addresses unreported issues such as missing responses, analysis-population choices, or multiplicity adjustments. The record also does not report a direct high-dose versus low-dose interval. Accordingly, precision can be discussed for the two posted placebo comparisons, but not for a direct contrast between doses.

11. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The sample-size table and its accompanying curve are planning illustrations based on the observed effect, not the trial's original design calculation. The figures are participants per arm for the binary outcome. They are not total event counts. The table presents separate planning scenarios for the high-dose comparison with placebo and the low-dose comparison with placebo.

The listed assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. Each scenario uses a stated fraction of the observed effect as the effect to detect. The table shows planning for the full observed effect, 75% of the observed effect, and 50% of the observed effect. For each scenario, one column gives the number of participants per arm for 80% power, and the other gives the number of participants per arm for 90% power.

In plain language, the 80% power column describes the planning sample size under which the calculation has an 80% chance of detecting the specified effect if that effect is real and the assumptions hold. The 90% power column uses a higher target chance of detection and therefore generally calls for more participants under the same scenario. These are planning quantities, not a description of what the trial observed. This is not observed power.

The table illustrates that smaller effects need more participants: planning for 75% or 50% of the observed effect requires more participants per arm than planning for the full observed effect. This is a general feature of power calculations, not evidence that a smaller effect occurred in the trial. The curve should be read as another presentation of the planning relationship, not as an additional observed result.

The registry record does not report the assumptions used in the trial's original design or its original sample-size justification. The displayed illustration uses the assumptions stated here, which are distinct from any unreported protocol decisions. Its estimates also do not show whether the completed trial had a particular probability of finding a result; they are conditional calculations tied to the stated effect scenarios and statistical assumptions.

12. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, p₀ and p₁ are the control and treatment proportions, and p̄ is their average.

Worked calculation for this trial

1. Control proportion p₀ = 0.377; treatment proportion p₁ = 0.104; average p̄ = 0.241.
2. First term: z_1−α/2 × √[2p̄(1−p̄)] = 1.96 × 0.6045 = 1.1847.
3. Second term: z_1−β × √[p₀(1−p₀) + p₁(1−p₁)] = 0.842 × 0.5727 = 0.4820.
4. n = (1.1847 + 0.4820)² / (-0.2736)² = 37.1, rounded up to 38 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
p0 <- 0.377358490566038                          # control proportion
p1 <- 0.10377358490566                          # treatment proportion
n_per_arm <- function(power, frac = 1) {
  q1 <- p0 + (p1 - p0) * frac               # smaller effect = fraction of the observed difference
  pbar <- (p0 + q1) / 2
  z_b <- qnorm(power)
  ceiling(round((z_a * sqrt(2 * pbar * (1 - pbar)) + z_b * sqrt(p0 * (1 - p0) + q1 * (1 - q1)))^2 / (q1 - p0)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (unrounded n per arm)
cat("power.prop.test:", round(power.prop.test(p1 = p0, p2 = p1, power = 0.80)$n, 1), "\n")

# Simulation: how often does the z-test reject at the 80%-power sample size?
set.seed(5903924)
n    <- n_per_arm(0.80)
reps <- 20000
x0 <- rbinom(reps, n, p0); x1 <- rbinom(reps, n, p1)
ph <- (x0 + x1) / (2 * n)
z  <- ((x1 - x0) / n) / sqrt(ph * (1 - ph) * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(z) > z_a, na.rm = TRUE), reps))

Output from running the code

100% of observed effect: n per arm = 38 (80% power), 50 (90% power)
 75% of observed effect: n per arm = 74 (80% power), 98 (90% power)
 50% of observed effect: n per arm = 178 (80% power), 238 (90% power)
power.prop.test: 37.1 
Simulated power at n = 38 per arm: 0.827 (20000 replicates)

The simulation draws many pairs of event counts at the planned sample size and counts how often the two-proportion z-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

13. Multiplicity, Missing Data and Analysis Populations

The posted results include two comparisons: Tradipitant High Dose versus Placebo and Tradipitant Low Dose versus Placebo. The registry record does not report whether these comparisons were prespecified as co-primary tests, whether one was primary and the other supportive, or whether a multiplicity adjustment was applied. It also does not report an ordered testing procedure or a broader family of statistical tests. The reported p-values should therefore be understood as the values displayed for the individual comparisons, without assuming that the risk of false-positive findings across multiple tests was controlled.

General explanation: when several statistical hypotheses are tested, the chance of obtaining at least one small p-value by chance can increase. A multiplicity strategy can address that issue, but the strategy and its scope need to be specified to interpret adjusted evidence. No such strategy is reported in the registry record. This does not establish that no strategy was used; it means that the record does not describe one.

Missing outcome data and analysis populations are also not described. The registry record does not state how many participants completed the Vomiting Assessment, whether any responses were missing, how missing responses were handled, or which participants were included in each analysis. It does not identify an intention-to-treat, per-protocol, or other analysis population. The reported group sizes are available, but the record does not provide participant flow or explain whether those sizes are the denominators used in every analysis.

General explanation: missing-data handling can affect a binary outcome comparison if the probability of a missing response differs between groups or is related to the outcome. Different analysis populations can also answer different questions. Without these details, readers cannot assess whether the posted comparison includes all randomized participants or how sensitive it is to missing responses.

The statistical test, model, confidence interval method, and any adjustment for baseline variables are not reported in the registry record. The sample-size illustration includes its own stated assumptions, but those do not supply the trial's original statistical plan. These reporting gaps limit methodological reconstruction; they do not, by themselves, show that the analysis was inappropriate.

14. 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 5% reporting threshold.

Most frequent non-serious adverse event terms

The registry record lists serious adverse event counts of 0 in the Tradipitant High Dose group, 0 in the Tradipitant Low Dose group, and 0 in the Placebo group. The corresponding numbers at risk are 106, 104, and 106. It also lists 0 deaths in each group. No serious adverse event terms are listed.

These figures describe what is posted for the groups and the record's serious-event category. A zero count means no serious adverse events are listed in that group in this record; it does not establish that no events of any kind occurred or that all possible risks are absent. The registry record does not provide further definitions of seriousness, reporting procedures, follow-up details, or an explanation of how safety events were collected.

The record separately lists other, non-serious adverse event counts of 29 for Tradipitant High Dose, 24 for Tradipitant Low Dose, and 19 for Placebo, with the same group sizes at risk as above. These counts should not be confused with the serious-event figures. The registry record does not provide event terms or additional context for these counts here, so they cannot be used to characterize particular kinds of non-serious events. These descriptive figures are not, on their own, a causal comparison of safety between groups.

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

The posted primary results show fewer participants recorded with the vomiting outcome in each tradipitant arm than in the placebo arm: 11 of 106 in the high-dose group, 19 of 104 in the low-dose group, and 40 of 106 in the placebo group. The registry comparisons report negative risk differences for both active-arm comparisons, with confidence intervals entirely below zero. The reported p-values are <0.001 for high dose versus placebo and 0.002 for low dose versus placebo. These statements describe the posted outcome and statistical comparisons.

They do not, by themselves, establish the importance of the observed differences to participants. The registry record does not report a threshold for a meaningful change, participant preferences, or other context that would allow the numerical contrasts to be judged against a clinical importance standard. General explanation: statistical evidence and clinical importance are related but distinct questions. An estimate can be statistically distinguishable from zero without necessarily being important to every participant or decision.

The results also do not establish that one tradipitant dose is better than the other. The record gives separate comparisons with placebo, not a direct statistical comparison between the two active arms. It does not report results for secondary outcomes. Nor does the primary vomiting measure answer questions about outcomes beyond the stated 1-day timeframe.

The registry record does not report participant characteristics, missing-data handling, analysis populations, or the full statistical plan. Those omissions constrain assessment of generalizability and robustness. The posted results cannot be assumed to apply to populations or circumstances not described in the record. The listed safety figures are also limited: no serious adverse events or deaths are listed in any group, but the record gives no further detail to support broader conclusions about safety.

Accordingly, the statistical reading is narrow: the registry reports lower observed vomiting outcome proportions in the two tradipitant groups than in placebo over the stated assessment period, and the listed comparisons have intervals below zero and small reported p-values. The record does not supply all the information needed to assess the full analysis, determine the clinical importance of the estimates, or draw conclusions beyond this trial's posted endpoint and comparisons.

16. Why This Trial Matters Statistically

This trial offers a useful example of how a binary clinical outcome can be reported in several complementary ways. The arm counts show the number of participants recorded with vomiting, while the group sizes provide the context needed to interpret those counts. The risk-difference comparisons summarize the contrast in event proportions between each tradipitant arm and placebo. Looking at these together is more informative than relying on event counts alone.

The two posted comparisons are directionally consistent: each has a negative risk difference, and each confidence interval is entirely below zero. Their reported p-values are <0.001 and 0.002. This makes it possible to discuss both the direction of the observed comparisons and the uncertainty represented by the intervals. It also illustrates why a p-value should not stand in for an effect estimate or a confidence interval.

The record also shows why registry results need to be read alongside reporting limitations. There is no posted direct comparison between the two tradipitant arms, no description of multiplicity handling, and no account of missing outcomes or analysis populations. Those omissions matter when interpreting two active-arm comparisons and when trying to understand exactly which participants and methods underpin the estimates.

The sample-size illustration makes a separate statistical point: planning for smaller effects requires more participants per arm under the stated assumptions. Because the illustration is based on the observed effect and is not the trial's original design calculation, it should not be mistaken for evidence about the study's original planning or its observed probability of success.

More broadly, this record links an easily understood yes-or-no measure to effect estimation, uncertainty, and sample-size planning. It also shows the limits of interpreting a small set of posted results without a fuller statistical analysis plan and participant-flow account. The statistical value is in reading those pieces together while keeping the scope of the evidence clear.

17. 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 specific to this registry record affect how much can be inferred. The primary endpoint description says participants indicate whether they have vomited, but the record does not give the exact question wording, the timing of the assessment within the 1-day timeframe, or procedures for incomplete or unclear responses. Further detail about how the outcome was collected is not reported in the registry record.

The record names high- and low-dose arms but does not report the dose amounts. It also does not provide participant characteristics or detailed eligibility criteria. As a result, the composition of the enrolled population and the applicability of the findings to other groups cannot be assessed from this record alone.

Although the trial is described as randomized, double-blind, and quadruple-masked, details of the allocation procedure and masking implementation are not reported. The registry record does not explain who was masked or how the allocation sequence was generated or concealed. These omissions prevent a detailed evaluation of those design features.

The statistical reporting is also limited. The record does not describe the analysis populations, handling of missing outcome data, statistical test or model, confidence interval method, baseline adjustment, or multiplicity strategy. It does not report a direct comparison between the active arms. Secondary outcome results are not posted, and no participant-flow account is reported.

The safety section lists no serious adverse events and no deaths in any group, but the record provides no further definition, follow-up detail, or serious-event terms. It lists counts for other adverse events but does not give event terms in this summary. These are limitations of the available registry description and should not be treated as evidence that the unreported information is necessarily absent from other study materials.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: Motion Serifos: A Study to Investigate the Efficacy of Tradipitant in Participants Affected by Motion Sickness — NCT05903924.
• Registry record last updated 2025-04-04; status last verified 2025-03.
• Results first posted 2025-04-04.
• 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.

21. Record Summary

Motion Serifos is a completed Phase 3 randomized, parallel-group, placebo-controlled study of tradipitant in participants affected by motion sickness during travel. The record describes the study as double-blind and lists quadruple masking. Enrollment was 316. The posted arms are Tradipitant High Dose, Tradipitant Low Dose, and Placebo.

The primary outcome was prevention of vomiting measured by a one-item Vomiting Assessment over 1 day. The posted event counts were 11 among 106 high-dose participants, 19 among 104 low-dose participants, and 40 among 106 placebo participants. The registry reports a risk-difference comparison for each tradipitant arm against placebo. The reported p-values are <0.001 for the high-dose comparison and 0.002 for the low-dose comparison.

The record lists no serious adverse events or deaths in any group. It does not report the original sample-size justification, detailed statistical plan, multiplicity handling, missing-data methods, or analysis-population definitions. Secondary outcome results are not posted in the registry record.