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 Dose-Finding Study of Favipiravir in the Treatment of Uncomplicated Influenza (NCT01068912), a randomized phase 2 study. The primary outcome is Clinical Efficacy of 2 Dose Regimens of Favipiravir Compared With Placebo in Treating Patients With Influenza.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01068912 |
| Phase | Phase 2 |
| Condition | Influenza |
| Allocation | Randomized |
| Design model | Factorial |
| Masking | Quadruple |
| Enrollment | 530 |
| Arms in the primary outcome | 3 |
| Lead sponsor | MDVI, LLC |
| Results posted | Yes |
2. Clinical Question
Population
Adults with uncomplicated influenza were enrolled in a multicenter study. The primary efficacy analysis used the ITTI Population, defined in the registry record as patients who received at least 1 dose of study drug, had available efficacy data after randomization, and tested positive for influenza A or B by PCR assay or culture tests on Day 1. The recorded size of that population was N=333. The registry’s primary endpoint description specifies age groups of 20 to less than 65 years and 65 years or older, with different temperature thresholds.
Intervention
One experimental regimen was low-dose favipiravir: 1000 mg twice a day for 1 day, followed by 400 mg twice a day for 4 days. The other was high-dose favipiravir: 1200 mg twice a day for 1 day, followed by 800 mg twice a day for 4 days.
Comparator
The comparator group received placebo. The registry describes the study as randomized, double-blind and placebo-controlled, and records quadruple masking. It also classifies the model as factorial, but the particular factor structure is not reported in the registry record.
Primary question
The primary question was how long it took from first study-drug administration until all 6 primary influenza symptoms were alleviated and oral temperature was below the age-specific threshold. The registry reports median times and 95% confidence intervals for each of the three groups, plus a Gehan-Wilcoxon test across the listed groups. The record does not provide a separate pairwise test or a treatment-effect estimate with a confidence interval.
3. Trial Design
This was a Phase 2, randomized, double-blind, placebo-controlled multicenter study evaluating two doses of favipiravir in adult patients with uncomplicated influenza. The registry lists the trial as completed and records enrollment of 530. The recorded start was 2010-02 and the primary completion was 2012-04. These are registry dates; they do not, by themselves, describe when each participant was followed or when individual outcomes occurred.
Participants were assigned to a low-dose favipiravir regimen, a high-dose favipiravir regimen, or placebo. The low-dose schedule was 1000 mg twice a day for 1 day, then 400 mg twice a day for 4 days. The high-dose schedule was 1200 mg twice a day for 1 day, then 800 mg twice a day for 4 days. The registry records quadruple masking as well as double blinding in the study title and summary. It does not identify which groups of people were masked under the quadruple-masking label.
The model is recorded as factorial, but the registry record does not describe the factors, their levels, or how they relate to the three listed groups. It is therefore not possible to reconstruct the factorial structure from this description alone. Nor is a detailed randomization procedure, allocation ratio, or method for concealing assignments reported in the registry record.
The primary efficacy population was the ITTI Population, recorded as N=333. It included patients who received at least 1 dose, had available efficacy data after randomization, and tested positive for influenza A or B by PCR assay or culture tests on Day 1. That population definition is narrower than enrollment and differs from the safety group denominators posted for adverse events. The registry does not explain all reasons for that difference or provide a participant-flow account in the information summarized for this analysis.
The primary outcome was a time-to-event measure: time from first study-drug administration until symptom and fever criteria were met. Group summaries are medians with 95% confidence intervals. The reported inferential analysis is a Gehan-Wilcoxon test listed for all three groups. A detailed statistical analysis plan, sample-size justification, and planned interim analyses are not reported in the registry record.
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
| Stage | 1: Low Dose Favipiravir | 2: High Dose Favipiravir | Placebo |
|---|---|---|---|
| STARTED | 134 | 195 | 201 |
| COMPLETED | 123 | 173 | 186 |
| NOT COMPLETED | 11 | 22 | 15 |
Reasons for not completing this period:
| Reason | 1: Low Dose Favipiravir | 2: High Dose Favipiravir | Placebo |
|---|---|---|---|
| Adverse Event | 2 | 3 | 2 |
| Withdrawal by Subject | 5 | 6 | 6 |
| Lost to Follow-up | 3 | 7 | 3 |
| Protocol Violation | 0 | 2 | 0 |
| aggravation influenza | 1 | 1 | 1 |
| other underlying illness | 0 | 3 | 3 |
Analysis population for the primary outcome, as defined in the registry: The primary analysis population for efficacy analyses was the ITTI Population (N=333), defined as all patients who received at least 1 dose of study drug with any available efficacy data after randomization and who tested positive for influenza A or B by PCR assay or culture tests on Day 1 using determinations.
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: The Safety Population, defined as all patients who received study drug, was used for demographic and baseline characteristics and safety analyses, unless otherwise indicated.
| Characteristic | Unit | 1: Low Dose Favipiravir | 2: High Dose Favipiravir | Placebo | Total |
|---|---|---|---|---|---|
| Participants analysed | 132 | 189 | 197 | 518 | |
| Age, Continuous | years | 42.2 (20 to 79) | 42.6 (20 to 75) | 42.7 (20 to 80) | 42.5 (20 to 80) |
| Sex: Female, Male: Female | Participants | 73 | 102 | 109 | 284 |
| Sex: Female, Male: Male | Participants | 59 | 87 | 88 | 234 |
| Race/Ethnicity, Customized: Asian | participants | 3 | 7 | 4 | 14 |
| Race/Ethnicity, Customized: Black or African American | participants | 17 | 22 | 23 | 62 |
| Race/Ethnicity, Customized: Hispanic or Latino | participants | 15 | 25 | 29 | 69 |
| Race/Ethnicity, Customized: Mestizo | participants | 14 | 20 | 17 | 51 |
| Race/Ethnicity, Customized: Native Hawaiian or other Pacific Islander | participants | 2 | 2 | 1 | 5 |
| Race/Ethnicity, Customized: White | participants | 72 | 103 | 115 | 290 |
| Race/Ethnicity, Customized: Other | participants | 7 | 7 | 6 | 20 |
| Race/Ethnicity, Customized: More than one race, including Hispanic or Latino | participants | 0 | 3 | 2 | 5 |
| Race/Ethnicity, Customized: More than one race, excluding Hispanic or Latino | participants | 2 | 0 | 0 | 2 |
| Region of Enrollment: United States | participants | 85 | 120 | 128 | 333 |
| Region of Enrollment: Peru | participants | 24 | 36 | 36 | 96 |
| Region of Enrollment: Australia | participants | 7 | 9 | 8 | 24 |
| Region of Enrollment: South Africa | participants | 8 | 10 | 8 | 26 |
| Region of Enrollment: Chile | participants | 2 | 9 | 7 | 18 |
| Region of Enrollment: New Zealand | participants | 6 | 5 | 10 | 21 |
| Rapid Antigen Test Result: Type A Positive | participants | 77 | 113 | 124 | 314 |
| Rapid Antigen Test Result: Type B positive | participants | 30 | 45 | 43 | 118 |
| Rapid Antigen Test Result: Type A and B positive | participants | 6 | 5 | 2 | 13 |
| Rapid Antigen Test Result: Influenza negative | participants | 19 | 26 | 28 | 73 |
| Virus type identification: A (H1N1) pdm | participants | 39 | 32 | 39 | 110 |
| Virus type identification: A (H3N2) | participants | 29 | 67 | 66 | 162 |
| Virus type identification: B | participants | 20 | 23 | 20 | 63 |
| Virus type identification: Other | participants | 1 | 0 | 0 | 1 |
| Virus type identification: Neither | participants | 43 | 67 | 72 | 182 |
6. Primary Endpoint
The registry lists the primary outcome as Clinical Efficacy of 2 Dose Regimens of Favipiravir Compared With Placebo in Treating Patients With Influenza, measured over 22 weeks.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | 95% Confidence Interval |
| Unit | hours |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint measures elapsed time from first study-drug administration to a combined symptom-and-temperature milestone. The milestone required alleviation of all 6 primary influenza symptoms and oral temperature measurements below the specified age-based threshold: below 38.0°C for patients aged 20 to less than 65 years and below 37.8°C for patients aged 65 years or older.
The registry defines a symptom as alleviated when its score had decreased to 1 or below. All 6 symptom scores had to meet that criterion, and the decrease had to remain unchanged for 21.5 hours. The event therefore represents meeting a sustained, combined clinical definition, rather than a single symptom change or a single temperature reading. Time is recorded in hours, and the registry lists the outcome timeframe as 22 weeks.
Time-to-event outcomes can retain information about when an event occurs, rather than reducing follow-up to whether it happened by one chosen time. A median describes the middle of the observed time distribution: it is a summary of the time by which half the relevant observations have reached the defined event, under the analysis method used. A shorter time corresponds to reaching this endpoint sooner. This general interpretation does not establish why the event occurred or whether a difference between groups is caused by treatment.
The registry supplies group medians and confidence intervals but does not report details about censoring, the handling of participants who did not reach the milestone, or the construction of the endpoint analysis set beyond the stated ITTI definition. Those details matter when interpreting a time-to-event result and are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted median time was 100.4 hours in the low-dose favipiravir group, with a 95% confidence interval from 82.4 to 119.8 hours. In the high-dose group, the median was 86.5 hours, with a 95% confidence interval from 79.2 to 102.1 hours. In the placebo group, the median was 91.9 hours, with a 95% confidence interval from 70.3 to 105.4 hours. A smaller median represents a shorter time to the endpoint as defined in the registry.
These are separate group summaries. Their ordering alone does not establish that one regimen differs from placebo, nor does it quantify a reliable treatment effect. The reported confidence intervals express uncertainty around each group’s median under the analysis used; they are not direct confidence intervals for differences between groups. The registry does not post a pairwise effect estimate and confidence interval for either favipiravir regimen versus placebo.
The reported inferential result is a Gehan-Wilcoxon test with p = .05, listed for the three groups together. This is evidence from a test of the group time-to-event distributions, not a reported estimate of the size or direction of a particular pairwise contrast. The registry does not state whether the test was intended as an omnibus comparison, how the p-value should be interpreted relative to a prespecified threshold, or whether additional analyses were planned. The p-value should therefore be read alongside the limited description of the analysis rather than as a complete account of the evidence.
In general, a p-value describes how compatible the observed data are with a specified null model under the assumptions of the test; it is not the probability that the null hypothesis is true, nor a measure of clinical importance. A value reported as .05 is not enough on its own to establish the magnitude, precision, or practical meaning of a difference. The record does not provide an effect estimate for the test, so the extent of any group separation cannot be recovered from the p-value alone.
The confidence intervals for the group medians overlap. In general, overlap or non-overlap of separate group confidence intervals is not a substitute for a direct test or confidence interval for a between-group contrast. The sponsor’s reported test is the posted inferential analysis; there is no registry-posted, estimable two-arm recalculation for this endpoint to provide a separate comparison.
The efficacy analysis population was the ITTI Population, N=333, while the adverse-event groups have different at-risk counts. Those populations and denominators should not be treated as interchangeable. The registry record does not give enough detail to explain all differences in analysis populations, missing outcome data, or follow-up. Overall, the posted material supports describing the group summaries and the reported test, but not making a more detailed claim about the size or precision of either regimen’s contrast with placebo.
9. Statistical Methods Explained
Time-to-event endpoint: The outcome is elapsed time until participants meet a defined event criterion. Here, that event combines alleviation of all 6 primary symptoms with an oral-temperature threshold, and requires the symptom-score decrease to remain unchanged for 21.5 hours. The event definition determines what the time value means: it is not simply the time to first improvement, nor the time to resolution of any one symptom. The registry records hours as the unit and 22 weeks as the timeframe.
A time-to-event analysis can use information about the timing of an event. In general, some participants may not have a recorded event during the period in which they are observed, or their observation may end for another reason. Such observations can be censored rather than treated as if an event occurred at the end of observation. Whether and how censoring was handled for this endpoint is not reported in the registry record. That omission limits independent assessment of the analysis.
Median: The median is a measure of the center of a distribution. For a time-to-event outcome, it describes the time at which the estimated event experience reaches the halfway point under the analysis method. It is less sensitive to very long or short observations than an arithmetic mean. A median is still only one summary: it does not show the full distribution, how quickly events accumulated at different times, or whether the groups differed throughout follow-up. The registry reports a median for each group.
Confidence interval: A confidence interval gives a range of values that are compatible with the observed data under the statistical method and its assumptions. A 95% confidence interval is a procedure with a long-run coverage interpretation under repeated use when those assumptions hold. It is not a guarantee that the particular interval contains the true value, and it is not a range containing 95% of individual participants’ times. The posted intervals apply separately to each group median. They do not directly estimate the difference between a favipiravir group and placebo.
Gehan-Wilcoxon test: The registry lists this test for the three groups. In general, the Gehan-Wilcoxon approach is a rank-based method for comparing time-to-event distributions, with weighting that gives relatively more influence to earlier event times than some other rank-based approaches. The test’s interpretation depends on its assumptions and on the endpoint and censoring structure. The registry does not provide enough detail to evaluate those features, nor does it provide a pairwise result. The listed p-value is .05.
Reading a p-value: In general, a p-value is calculated under a null hypothesis and a statistical model. It represents how unusual data at least as incompatible with that null would be if the null model and its assumptions held. It does not measure the probability that a treatment is effective, the size of a group difference, or the chance that the result will repeat. Interpretation also depends on the analysis plan, including which comparisons and outcomes were prespecified. The relevant plan is not reported in the registry record.
Group estimates versus contrasts: Separate medians describe each group; a treatment contrast directly compares groups. For a contrast, an estimate and its uncertainty would show the scale and precision of the difference under a specified method. The registry supplies no such two-arm estimate for this endpoint. It is therefore not appropriate to derive one by subtracting the posted medians or to infer its confidence interval from the individual intervals. Those would be new calculations and would not reproduce the sponsor’s time-to-event analysis.
Analysis population: The primary efficacy population is described as the ITTI Population, N=333, consisting of patients who received at least 1 dose, had available efficacy data after randomization, and tested positive for influenza A or B by PCR assay or culture tests on Day 1. This defines who contributed to the primary efficacy analysis according to the record. It does not, on its own, explain how many randomized patients lacked efficacy data, how missing values were handled, or how the analysis addressed participants who did not meet the endpoint.
Planning illustrations: Any sample-size illustrations associated with the posted analysis are planning examples based on the observed effect, not observed power and not the trial’s own design justification. The stated illustration assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect set to a stated fraction of the observed effect. For time-to-event calculations, the illustrations refer to total events; for other endpoints, they refer to participants per arm. These assumptions do not establish that the original trial used the same design or analysis plan. The record does not report the original sample-size justification.
Multiplicity and model: Multiple outcomes or comparisons can increase the chance of a false-positive finding if no suitable analysis strategy is used. The registry lists one outcome measure and one analysis, but does not report whether other analyses were planned, how multiplicity was addressed, or whether interim analyses occurred. It labels the study model factorial, while details of the factors and their role in the reported comparison are not reported in the registry record. These gaps prevent a full reconstruction of the analysis plan.
10. Analyses Reported by the Sponsor
| Method | Estimate | 95% CI | P-value |
|---|---|---|---|
| Gehan-Wilcoxon | not reported | 0.050 |
The registry’s posted inferential result is the sponsor-reported Gehan-Wilcoxon analysis listed across the low-dose, high-dose, and placebo groups, with p = .05. The registry also reports the median time and 95% confidence interval separately for each group. It does not give a pairwise treatment-effect estimate or confidence interval for either favipiravir regimen versus placebo.
There is no estimable two-arm recalculation for this endpoint in the registry material, so a recalculated contrast cannot be set alongside the sponsor’s result. The group medians should not be subtracted to create a substitute contrast: that would not reproduce the reported time-to-event test or account for its analysis method. The sponsor-reported test is therefore the only posted inferential result available for this endpoint.
The p-value does not disclose the size of a contrast or which pair of groups accounts for the overall pattern. The registry record does not provide further test details, a confidence interval for a treatment contrast, or a complete statistical analysis plan. The sponsor’s analysis can be described as reported, but the information available does not permit a full independent reconstruction of it.
11. Multiplicity, Missing Data and Analysis Populations
The registry lists one outcome measure and one analysis. That is a description of what is posted, not proof that only one endpoint or comparison was considered during the study. The record does not report a prespecified multiplicity strategy, whether additional analyses were planned, or whether any interim analyses were performed. It also does not describe the complete statistical analysis plan. Consequently, the context needed to judge how the reported p-value relates to all planned testing is not available in the registry record.
The primary efficacy population is the ITTI Population, N=333. It is defined as patients who received at least 1 dose of study drug, had any available efficacy data after randomization, and tested positive for influenza A or B by PCR assay or culture tests on Day 1. This definition identifies the stated population for efficacy analyses, but the registry does not provide a full flow of participants from randomization to analysis or explain every exclusion from that population.
Missing outcome data can affect a time-to-event analysis, particularly when the reason for missingness is related to symptoms, treatment, or follow-up. In general, analysts need to specify how incomplete follow-up and participants without an observed event are treated. The registry record does not report the missing-data strategy, censoring rules, or sensitivity analyses for this endpoint. It therefore cannot establish how robust the result is to alternative assumptions about unavailable outcome information.
Safety denominators are reported separately by group and differ from the efficacy population definition. Those denominators should not be used to infer the composition of the ITTI Population or to fill gaps in the efficacy analysis. The record also labels the model factorial but does not report the factor structure, planned contrasts, or how the factorial label relates to the posted three-group test. These limitations leave uncertainty about the full set of comparisons and the handling of incomplete data.
12. 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 |
|---|---|---|---|
| 1: Low Dose Favipiravir | 2 | 132 | 1.5% |
| 2: High Dose Favipiravir | 0 | 189 | 0.0% |
| Placebo | 1 | 197 | 0.5% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0.8% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| 1: Low Dose Favipiravir | 47 of 132 |
| 2: High Dose Favipiravir | 65 of 189 |
| Placebo | 79 of 197 |
Most frequent serious adverse event terms
| Event term | Organ system | 1: Low Dose Favipiravir | 2: High Dose Favipiravir | Placebo |
|---|---|---|---|---|
| Vulval abscess | Infections and infestations | 1 of 132 | 0 of 189 | 0 of 197 |
| hepatic encephalopathy | Nervous system disorders | 1 of 132 | 0 of 189 | 0 of 197 |
| bronchial obstruction | Respiratory, thoracic and mediastinal disorders | 0 of 132 | 0 of 189 | 1 of 197 |
Most frequent non-serious adverse event terms
| Event term | Organ system | 1: Low Dose Favipiravir | 2: High Dose Favipiravir | Placebo |
|---|---|---|---|---|
| diarrhoea | Gastrointestinal disorders | 3 of 132 | 9 of 189 | 10 of 197 |
| headache | Nervous system disorders | 3 of 132 | 4 of 189 | 9 of 197 |
| nausea | Gastrointestinal disorders | 2 of 132 | 4 of 189 | 9 of 197 |
| blood uric acid increased | Investigations | 3 of 132 | 7 of 189 | 5 of 197 |
| blood fibrinogen increased | Investigations | 4 of 132 | 3 of 189 | 6 of 197 |
| dizziness | Nervous system disorders | 2 of 132 | 4 of 189 | 6 of 197 |
| alanine aminotransferase increase | Investigations | 0 of 132 | 3 of 189 | 6 of 197 |
| vomiting | Gastrointestinal disorders | 1 of 132 | 2 of 189 | 5 of 197 |
| blood triglycerides increased | Investigations | 2 of 132 | 2 of 189 | 4 of 197 |
| bronchitis | Infections and infestations | 0 of 132 | 5 of 189 | 2 of 197 |
Serious events with the highest arm-level rate: vulval abscess (0.8%), hepatic encephalopathy (0.8%), bronchial obstruction (0.5%).
The registry reports serious adverse events for the low-dose group among 132 at risk, with 2 affected; for the high-dose group among 189 at risk, with 0 affected; and for placebo among 197 at risk, with 1 affected. These are group-specific serious-event counts and denominators. Death counts are not reported in the registry record.
The listed serious-event terms include Vulval abscess at 0.8%, hepatic encephalopathy at 0.8%, and bronchial obstruction at 0.5%. The registry does not provide further context in this summary about the circumstances, timing, severity details beyond the serious-event classification, or attribution of these events. The terms and percentages should be read as the posted entries, not as a complete account of every event experienced during the study.
The broader adverse-event counts are 47 affected among 132 at risk in the low-dose group, 65 among 189 at risk in the high-dose group, and 79 among 197 at risk in the placebo group. These are not the serious-event counts. The record does not supply a comparative safety analysis or confidence intervals for these figures. Raw counts with different denominators do not by themselves establish whether event risks differ between groups, and the registry entries do not establish that an event was caused by study drug.
13. What the Result Does, and Does Not, Mean
The posted results describe time to a narrowly defined combined milestone: all 6 primary influenza symptoms had to reach scores of 1 or below, the decrease had to remain unchanged for 21.5 hours, and oral temperature had to fall below the age-specific threshold. The reported group medians and confidence intervals provide summaries of that endpoint for the low-dose, high-dose, and placebo groups. The Gehan-Wilcoxon test is the registry’s reported inferential comparison across those groups.
These statistics do not establish the size of a direct treatment contrast. The registry does not post pairwise estimates or confidence intervals comparing either favipiravir regimen with placebo. The group medians cannot be used to create those estimates without a new calculation, and such a calculation would not replace the reported time-to-event analysis. The p-value alone does not show which group pair may differ or how large any difference might be.
The result also pertains to the stated ITTI Population rather than automatically applying to all enrolled participants. The registry does not fully report missing-data handling, censoring, planned multiplicity procedures, or the detailed factorial structure. These gaps limit assessment of how the analysis was conducted and how broadly its results can be interpreted.
The safety entries provide serious-event and broader adverse-event counts by group, but they do not constitute a complete comparative safety analysis. No death counts are reported in the registry record. The posted counts cannot establish causation or supply a precise comparative estimate on their own.
In general, trial results are most informative when the outcome definition, population, analysis method, effect estimate, and uncertainty are considered together. Here, the registry provides the endpoint definition, group summaries, and one reported test, but not a complete set of pairwise effects or all analysis details. The findings should therefore be understood as a limited statistical description of the recorded trial results, not as a standalone judgment about treatment or as a substitute for clinical interpretation.
14. Why This Trial Matters Statistically
This trial illustrates why a clinical endpoint’s definition matters as much as its label. The outcome is not simply symptom improvement: it combines all 6 primary symptom scores, a temperature threshold that differs by age, and a requirement that the symptom-score decrease remain unchanged for 21.5 hours. That definition shapes what an event time represents and which changes count toward the outcome.
It also illustrates the distinction between a group summary and a treatment contrast. The registry reports a median and confidence interval for each group, plus a Gehan-Wilcoxon test across the listed groups. Those pieces of information answer different questions. Group-specific intervals describe uncertainty in each median; a contrast estimate would describe the size and precision of a particular between-group comparison. The latter is not posted for this endpoint.
The analysis population matters as well. The primary efficacy analysis uses the ITTI Population, N=333, while safety outcomes use separate group denominators. Understanding which participants contribute to each outcome is essential when comparing efficacy and safety descriptions. The registry’s limited information about missing data and participant flow makes that distinction especially important.
Finally, a reported p-value cannot replace a full statistical analysis plan. The record reports p = .05 but does not detail multiplicity, interim analyses, the factorial structure, or a pairwise effect estimate. This case shows how a result can be numerically concise yet leave important questions about magnitude, precision, and analysis context unanswered. It is a useful example of reading posted trial results cautiously without treating one test as the entire statistical story.
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 provide pairwise treatment-effect estimates or confidence intervals for either favipiravir regimen versus placebo. The posted medians and their separate confidence intervals do not directly supply those contrasts. The single reported Gehan-Wilcoxon p-value is listed across all three groups, and the record does not explain the test’s detailed implementation or provide a pairwise breakdown.
The analysis description is incomplete for independent evaluation. The registry does not report the full statistical analysis plan, sample-size justification, interim analyses, multiplicity strategy, censoring rules, missing-data handling, or sensitivity analyses. It labels the model factorial but does not describe the factors or explain their relationship to the three listed groups and the reported test.
The efficacy population is defined as the ITTI Population, N=333, but the record does not provide a complete participant-flow account or explain all differences between enrollment, efficacy analysis, and safety denominators. The endpoint timeframe is listed as 22 weeks, while the outcome itself is elapsed time from first study-drug administration; details needed to understand follow-up and incomplete event observation are not reported in the registry record.
Safety information is also limited. Serious and broader adverse-event counts are posted with group-specific at-risk denominators, but comparative estimates and uncertainty are not given. Death counts are not reported in the registry record. The listed serious-event terms do not, by themselves, establish causation or provide complete clinical context.
These limitations concern the detail available in the registry record. They do not establish that a procedure was or was not used; they mean that the procedure is not reported in the registry record and cannot be assessed from the posted information.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: Dose-Finding Study of Favipiravir in the Treatment of Uncomplicated Influenza — NCT01068912.
- Registry record last updated 2015-11-18; status last verified 2015-10.
- Results first posted 2014-03-27.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
19. Record Summary
This completed Phase 2 study evaluated low-dose and high-dose favipiravir against placebo in adults with uncomplicated influenza. The registry describes it as randomized, double-blind, placebo-controlled, multicenter, and quadruple-masked, and records enrollment of 530. The primary efficacy endpoint was time to sustained alleviation of all 6 primary influenza symptoms together with an age-specific oral-temperature threshold.
The primary efficacy analysis used the ITTI Population, N=333. The registry reports group medians with 95% confidence intervals and a Gehan-Wilcoxon test listed across the three groups, with p = .05. It does not post a pairwise effect estimate and confidence interval for either regimen versus placebo. Serious and broader adverse-event counts are listed by group; death counts are not reported in the registry record.
The registry does not report a full statistical analysis plan, missing-data strategy, multiplicity procedures, detailed factorial structure, or sample-size justification. The posted statistics can be described, but important details for independently assessing the analysis and the precision of between-group effects are not available.