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 Study to Assess the Safety, Pharmacokinetics, and Efficacy of Baloxavir Marboxil in Healthy Pediatric Participants From Birth to < 1 Year With Influenza-Like Symptoms (NCT03653364), a na phase 3 study. The primary outcome is Number of Participants With Adverse Events (AEs) and Serious Adverse Events (SAEs).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03653364 |
| Phase | Phase 3 |
| Condition | Influenza |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 49 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Hoffmann-La Roche |
| Results posted | Yes |
2. Clinical Question
Population
The study enrolled otherwise healthy pediatric participants from birth to <1 year who had influenza-like symptoms. The registry record reports 49 participants enrolled. It does not report the participants’ age distribution, whether influenza infection was confirmed for each participant, or other detailed baseline characteristics.
Intervention
Participants received baloxavir marboxil as a single oral dose on Day 1. The dose was based on body weight and age. The registry record identifies safety, pharmacokinetics, and efficacy as areas of assessment, but the posted primary outcome concerns adverse events and serious adverse events.
Comparator
There was no comparison arm. The study is recorded as single-group, with allocation listed as not applicable and masking listed as none. Consequently, the results describe the treated group; they do not provide a randomized estimate comparing baloxavir marboxil with a control treatment or no treatment.
Primary question
The primary question was how many participants experienced adverse events or serious adverse events from Day 1 up to Day 29. The endpoint counts participants, not the total number of event episodes. It is a safety description within the treated group, not a test of whether the drug caused an event or changed risk relative to a comparator.
3. Trial Design
This completed Phase 3 study is described as multicenter, single-arm, and open-label. It enrolled 49 participants and evaluated baloxavir marboxil in otherwise healthy pediatric participants from birth to <1 year with influenza-like symptoms. The listed condition is influenza. The study began on 2019-01-23, and its primary completion date is 2023-04-03.
All participants in the treatment group were to receive a single oral dose of baloxavir marboxil on Day 1, with the dose based on body weight and age. The registry lists no allocation between treatment groups and no masking. The design therefore has no concurrent control group for estimating what might have occurred without baloxavir marboxil or under a different treatment. Findings describe events and measurements in the group that received the study drug.
The primary outcome was the number of participants with adverse events and serious adverse events, assessed from Day 1 up to Day 29. The registry also lists pharmacokinetic outcomes, including plasma concentrations and measures such as AUC0-inf, Cmax, Tmax, and apparent half-life, along with time to alleviation of influenza signs and symptoms, duration of fever, and duration of symptoms. The registry record lists 20 outcome measures, but does not list statistical analyses. Results for the pharmacokinetic and symptom outcomes are not reported in the registry record.
The safety-evaluable population included all participants who received at least one dose, whether or not they had follow-up assessments. The adverse-event figures use a denominator of 48, while enrollment is reported as 49. The registry record does not explain the difference between these figures.
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: A total of 49 pediatric participants from birth to \<1 year with influenza-like symptoms were enrolled in this study to receive baloxavir marboxil. Out of the 49 participants, one participant was screened and enrolled by accident but was not dosed.
Overall Study
| Stage | Baloxavir Marboxil |
|---|---|
| STARTED | 49 |
| COMPLETED | 46 |
| NOT COMPLETED | 3 |
Reasons for not completing this period:
| Reason | Baloxavir Marboxil |
|---|---|
| Withdrawal by Subject | 1 |
| Enrolled in Error | 1 |
| Death | 1 |
Analysis population for the primary outcome, as defined in the registry: Safety-evaluable population included all participants who received at least one dose of treatment regardless of whether they had any follow-up assessments.
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.
Population: Safety-evaluable population included all participants who received at least one dose of treatment regardless of whether they had any follow-up assessments.
| Characteristic | Unit | Baloxavir Marboxil |
|---|---|---|
| Participants analysed | 48 | |
| Age, Continuous | days | 206.5 (SD 106.08) |
| Sex: Female, Male: Female | Participants | 23 |
| Sex: Female, Male: Male | Participants | 25 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 15 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 22 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 11 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 1 |
| Race (NIH/OMB): Asian | Participants | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 26 |
| Race (NIH/OMB): White | Participants | 21 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Participants With Adverse Events (AEs) and Serious Adverse Events (SAEs), measured over From Day 1 up to Day 29.
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint counts participants with adverse events and serious adverse events from Day 1 up to Day 29. It is a participant-level measure: it concerns how many people experienced an event, rather than the total number of event episodes. The registry defines an adverse event broadly as an untoward medical occurrence after administration of a pharmaceutical product, whether or not considered related to that product. The definition includes unfavorable signs, symptoms, diseases, and abnormal laboratory findings.
A serious adverse event is defined by its significance or consequences, including being fatal or life-threatening, requiring hospitalization or prolonging an existing hospitalization, causing persistent or significant disability or incapacity, being a congenital anomaly or birth defect, or being medically significant or requiring intervention to prevent such outcomes. The endpoint is used to characterize safety events observed during the specified follow-up period.
These definitions do not make the endpoint a causal measure. An event can meet the adverse-event definition without being considered related to treatment. In a single-arm study, the observed counts describe the treated participants but cannot establish how many events would have occurred under a comparator. The registry record does not report an adjusted estimate, a confidence interval, or a comparative safety analysis for this endpoint.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted safety figures describe a group of 48 participants at risk for the adverse-event summaries. Within that group, 2 participants are listed with serious adverse events and 11 with other adverse events. A death count of 1 is also reported. These are counts in the treated group, not estimates of excess risk attributable to baloxavir marboxil. The registry record does not report a comparison group or an adjusted analysis that could separate treatment effects from other explanations.
The serious adverse-event terms listed are lower respiratory tract infection and choking, each shown with 2.1%. Those entries identify terms in the record; the listed percentage alone does not establish causality. The record does not report the relationship of each event to treatment, nor does it give details that connect the reported death to a particular event or to the drug. Such relationships should not be inferred from the counts or terms.
The sample is described as 49 enrolled, while the safety summaries use 48 at risk. Because the registry record does not explain this difference, the two figures should be kept distinct rather than treated as interchangeable. The safety population definition includes everyone who received at least one dose regardless of follow-up assessments, so inclusion in the population does not itself establish complete observation through Day 29.
The primary endpoint is descriptive, and the study is single-arm and open-label. It can report what was recorded among participants who received the dose, but it cannot provide a like-for-like estimate against an untreated or alternative-treatment group. The registry record lists efficacy and pharmacokinetic outcomes, but their numerical results are not reported in the registry record. The available safety counts therefore do not answer whether symptom duration, fever duration, or pharmacokinetic measures differed from a comparator.
Precision also cannot be fully judged from the posted summaries. No confidence interval or other uncertainty estimate for the event counts is reported in the registry record. In general, a confidence interval describes the range of estimates compatible with the observed data under a specified statistical method; it does not remove design limitations or establish causation. Without reported uncertainty estimates and without a comparison arm, the counts are best read as an account of events recorded in this cohort, not as a precise comparative treatment effect.
A planning illustration based on an assumed two-arm comparison would not turn this single-arm study into a randomized comparison. Its assumptions are for planning, not a description of observed power or evidence of a treatment effect. The registry record does not report a trial-specific sample-size justification or statistical analysis plan.
9. Statistical Methods Explained
The central statistical distinction is between a descriptive count and a comparative effect estimate. The primary outcome counts participants with adverse events and serious adverse events in the baloxavir marboxil group. Because the design is single-arm, the observed counts can describe that cohort but cannot estimate a difference between treatment and control. There is no concurrent control group against which to assess whether the event frequency was higher, lower, or similar.
What does a participant count represent?
The endpoint counts people who experienced qualifying events during the specified period, from Day 1 up to Day 29. A participant-level count differs from a count of event episodes: a person can have more than one event, but the endpoint as titled concerns participants with events. The posted figures report 2 participants with serious adverse events and 11 with other adverse events among 48 at risk. They should not be summed to create a total number of affected participants, because the registry record does not state whether categories overlap or provide a combined count.
The event definitions also matter. An adverse event is not necessarily caused by the study drug; the registry definition explicitly allows events that are not considered related to treatment. Seriousness is based on specified consequences or medical significance. It is distinct from whether an event is judged related to treatment. The registry record does not report event-by-event causality assessments, timing, or detail sufficient to make those judgments independently.
Why does the design constrain inference?
In a randomized comparison, treatment groups can be compared under the study’s allocation process, with statistical methods used to estimate differences and uncertainty. Here, allocation is not applicable and there is only one group. The observed event frequency can reflect the participants’ underlying health, influenza-like illness, other circumstances, treatment, or combinations of these factors. A one-group count cannot disentangle those explanations. Open-label status also means the study is not masked, though the registry record does not describe how this affected event collection or assessment.
In general, a confidence interval communicates uncertainty around an estimate, conditional on the data and method used. It does not correct a missing comparator, eliminate bias, or prove a causal explanation. No confidence interval for the primary safety counts is reported in the registry record. Accordingly, the posted counts should be interpreted as observed descriptive results, without a numerical uncertainty range or comparative estimate.
What do the planning assumptions mean?
A planning illustration may ask how many participants per arm would be required under specified assumptions for a hypothetical comparison. The stated assumptions include a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a fraction of the observed effect. Those are assumptions for a hypothetical planning calculation. They do not describe this single-arm study’s allocation, and they do not establish that the study had a particular probability of detecting an effect. Sample-size illustrations are not observed power.
Interpreting such an illustration also depends on the effect used as its starting point and the assumptions used to translate that effect into a comparison. The registry record does not report a trial-specific sample-size justification. The posted safety information does not give a comparative effect for the primary endpoint from which a two-arm effect estimate could be interpreted. Any planning result should therefore remain separate from the clinical evidence represented by the observed counts.
What is not reported about the analysis?
The registry record lists 20 outcome measures and 0 analyses. It does not report the statistical methods used to analyze the primary endpoint, a prespecified hypothesis test, confidence intervals, or a multiplicity strategy. The record also does not report a model for repeated events or an adjustment for participant characteristics. These methods should not be assumed. With participant counts, the descriptive result can be stated directly, but an inferential claim requires a method and assumptions that are not documented in the registry record.
General statistical interpretation should keep the endpoint, population, and design aligned. The endpoint is a count of participants meeting event definitions; the population is safety-evaluable participants who received at least one dose; and the design is single-group. A conclusion that goes beyond a description of events in that population would require additional design features or analysis details that are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 20 outcome measures, spanning safety, pharmacokinetics, and influenza signs and symptoms, and lists 0 analyses. It does not report how the primary outcome was prioritized relative to secondary outcomes for statistical testing, whether any hypotheses were prespecified, or whether a multiplicity procedure was planned. Multiplicity refers generally to the increased chance of obtaining apparently notable findings when many statistical questions are examined. Without a reported testing strategy or analyses, no multiplicity-adjusted interpretation can be made from the registry record.
Missing-data handling is also not reported in the registry record. The safety-evaluable population is defined to include all participants who received at least one dose, regardless of whether they had follow-up assessments. That definition clarifies who can enter the population, but does not explain how missing event assessments were handled, whether follow-up was complete, or how missing information affected the endpoint summary.
The registry reports 49 participants enrolled and 48 at risk in the adverse-event summaries. It does not explain the difference. No further analysis-population details, exclusions, or reasons for non-inclusion are reported in the registry record. No imputation method or sensitivity analysis is reported. As a result, the posted counts can be described using their stated denominator, but the completeness and handling of outcome data cannot be evaluated from the recorded information.
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 |
|---|---|---|---|
| Baloxavir Marboxil | 2 | 48 | 4.2% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Baloxavir Marboxil | 1 of 48 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Baloxavir Marboxil | 11 of 48 |
Most frequent serious adverse event terms
| Event term | Organ system | Baloxavir Marboxil |
|---|---|---|
| Lower respiratory tract infection | Infections and infestations | 1 of 48 |
| Choking | Respiratory, thoracic and mediastinal disorders | 1 of 48 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Baloxavir Marboxil |
|---|---|---|
| Diarrhoea | Gastrointestinal disorders | 8 of 48 |
| Vomiting | Gastrointestinal disorders | 6 of 48 |
Serious events with the highest arm-level rate: lower respiratory tract infection (2.1%), choking (2.1%).
The registry reports 2 participants with serious adverse events and 11 with other adverse events among 48 at risk in the baloxavir marboxil group. It separately lists 1 death. These are reported counts, not evidence by themselves that treatment caused an event. The record defines adverse events to include occurrences that may or may not be related to the study drug.
Lower respiratory tract infection and choking are the listed serious adverse-event terms, each reported as 2.1%. The record does not provide event-level narratives, timing, treatment relatedness, or a stated link between either term and the death. The death count should therefore be read as a separate reported safety figure, without assigning a cause or relationship that is not reported in the registry record.
The denominator is important: the safety summaries use 48 at risk, whereas enrollment is 49. The registry record does not explain the difference. These group-level numbers describe the observed safety reporting in the study population and do not support a direct comparison with another treatment or with no treatment.
12. What the Result Does, and Does Not, Mean
The results establish that adverse events and serious adverse events were recorded among participants who received baloxavir marboxil, using a safety denominator of 48 and a follow-up period from Day 1 up to Day 29. The record lists 2 participants with serious adverse events, 11 with other adverse events, and 1 death. It also identifies lower respiratory tract infection and choking as serious adverse-event terms, each reported as 2.1%.
These findings do not establish that baloxavir marboxil caused any particular event. The registry’s adverse-event definition includes occurrences regardless of whether they are considered related to treatment. A single-arm design also means the event counts cannot be compared with a control group in this study. The record does not provide a causal analysis, event-by-event relatedness, or uncertainty intervals for the counts.
The results do not establish whether the drug improved or worsened influenza symptoms, affected fever duration, or produced a particular pharmacokinetic profile. Those outcomes appear in the registry’s outcome list, but their numerical results are not reported in the registry record. Nor do the safety counts show how the study results compare with an alternative treatment or no treatment.
In general, a completed study can have results that answer some questions more directly than others. Here, the posted primary outcome is a descriptive safety endpoint in a treated cohort. The registry record does not report a randomized comparison, a detailed statistical analysis plan, or the results for the other listed outcomes. Conclusions should remain limited to the recorded counts and terms, the stated safety population, and the defined follow-up period.
13. Why This Trial Matters Statistically
This trial illustrates why the statistical question must match the design. A single-arm study can document adverse events among participants receiving a treatment, but it does not estimate a treatment-versus-control difference. The distinction is important when reading safety counts: events observed during treatment are not automatically events caused by treatment, especially when there is no concurrent comparison group.
The endpoint also illustrates the difference between counting participants and counting episodes. The primary outcome concerns participants with adverse events and serious adverse events, while the clinical meaning of each event depends on its definition, seriousness, timing, and relationship to treatment. The registry record provides broad definitions and summary counts, but not the event-level information needed to resolve all of those questions.
The study population is narrowly described as otherwise healthy pediatric participants from birth to <1 year with influenza-like symptoms. That context matters for interpretation; the results are not a general estimate for every pediatric population. The record reports 49 enrolled and a safety denominator of 48, without explaining the difference, and does not provide uncertainty estimates for the reported counts.
Finally, the registry lists a broad set of outcome measures, including pharmacokinetic and symptom outcomes, while listing 0 analyses. The distinction between outcomes named in a registry and results available for interpretation is essential. The safety figures can be read descriptively, but they do not answer the broader efficacy and pharmacokinetic questions in the absence of their numerical results and analysis details.
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 principal limitation for interpretation is the single-arm, open-label design. With no control group, the study cannot provide a direct estimate of how event frequency would differ under another treatment or no treatment. The posted safety counts are descriptive and cannot by themselves distinguish events related to treatment from events due to other causes.
The population is limited to otherwise healthy pediatric participants from birth to <1 year with influenza-like symptoms. The registry record does not report the age distribution, detailed participant characteristics, or whether influenza was confirmed. The results therefore cannot be assumed to characterize populations beyond the enrolled group.
Enrollment is reported as 49, while the adverse-event denominator is 48. The registry record does not explain the discrepancy. The safety population definition includes participants who received at least one dose regardless of follow-up assessments, but the record does not report completeness of follow-up or methods for handling missing safety observations. Event-level details, including timing and treatment relatedness, are not reported.
The primary observation period runs from Day 1 up to Day 29. The registry record does not report confidence intervals, an analysis plan, multiplicity handling, or a trial-specific sample-size justification. Although pharmacokinetic and symptom outcomes are listed, their numerical results are not reported in the registry record. These limitations constrain both the precision of the safety interpretation and the questions that can be answered from the posted results.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Study to Assess the Safety, Pharmacokinetics, and Efficacy of Baloxavir Marboxil in Healthy Pediatric Participants From Birth to < 1 Year With Influenza-Like Symptoms — NCT03653364.
- Registry record last updated 2024-05-17; status last verified 2024-05.
- Results first posted 2024-05-17.
- 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
This completed Phase 3 study evaluated a single oral dose of baloxavir marboxil in otherwise healthy pediatric participants from birth to <1 year with influenza-like symptoms. It is recorded as multicenter, single-arm, and open-label, with 49 participants enrolled. The dose was based on body weight and age and was given on Day 1.
The primary endpoint was the number of participants with adverse events and serious adverse events from Day 1 up to Day 29. The adverse-event summaries report 48 at risk, 2 participants with serious adverse events, 11 with other adverse events, and 1 death. Lower respiratory tract infection and choking are listed as serious adverse-event terms, each with 2.1%.
The registry lists 20 outcome measures and 0 analyses. Numerical results for the listed pharmacokinetic and symptom outcomes, a comparative analysis, and further statistical methods are not reported in the registry record. The safety results are descriptive for the treated group.