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 A Study of EDP-938 in Non-hospitalized Adults With RSV Who Are at High Risk for Complications. (NCT05568706), a randomized phase 2 study. The primary outcome is Time to Resolution of RSV Lower Respiratory Tract Disease (LRTD) Symptoms.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT05568706 |
| Phase | Phase 2 |
| Condition | RSV Infection |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 187 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Enanta Pharmaceuticals, Inc |
| Results posted | Yes |
2. Clinical Question
Population
Non-hospitalized adults with acute respiratory syncytial virus infection who were considered at high risk for complications. The primary endpoint was evaluated in the modified intent-to-treat population: randomized participants who tested positive for RSV using the central RT-qPCR test and received at least one dose of assigned study drug.
Intervention
EDP-938, administered orally at 800 mg once daily. The study was designed to assess its efficacy and safety during acute RSV infection.
Comparator
Matching placebo, administered once daily. The study was randomized and double-blind, with a parallel-group design.
Primary question
How long did it take for lower respiratory tract disease symptoms to resolve in each study arm? Resolution required all four specified symptoms—cough, shortness of breath, wheezing, and coughing up phlegm or sputum—to be rated zero or one on the RiiQ Scale at two consecutive timepoints. The posted primary results give a median and 95% confidence interval for each arm, but do not report a formal comparison between arms.
3. Trial Design
This phase 2b trial was randomized, double-blind, placebo-controlled, and parallel-group. The registry lists 187 participants enrolled. EDP-938 was given orally at 800 mg once daily; the comparison group received matching placebo once daily. The stated study population was non-hospitalized adults with confirmed acute RSV infection who were at high risk for complications.
The study start date was 2022-11-29, the primary completion date was 2025-06-23, and the record lists the trial as completed. The primary endpoint covered Day 1 through Day 33. Its analysis population was the modified intent-to-treat population, defined as randomized participants with a positive central RT-qPCR RSV test who received at least one dose of assigned study drug.
The reported denominators vary across outcomes. For the primary endpoint, the arm-level sample sizes are 100 for EDP-938 and 54 for placebo. Several posted secondary outcomes use 115 and 60, while the safety figures use 121 and 65. These differences indicate that the analyses do not all use the same denominators; the registry record does not fully explain the reasons for each difference. The primary endpoint description states that participants without resolution before Day 33 were censored at Day 33. Other details of the endpoint analysis and the handling of additional missing observations are not reported in the registry record.
The registry lists eight types of secondary outcome, including symptom resolution, symptom severity, impact on daily life, RSV-related complications, hospitalization, and mortality. It records 36 outcome measures and 25 posted secondary outcomes. The record does not report a detailed protocol for the statistical analyses or explain how the multiple outcomes were prioritized.
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 | EDP-938 | Placebo |
|---|---|---|
| STARTED | 123 | 64 |
| COMPLETED | 116 | 60 |
| NOT COMPLETED | 7 | 4 |
Reasons for not completing this period:
| Reason | EDP-938 | Placebo |
|---|---|---|
| Adverse Event | 0 | 1 |
| Protocol Violation | 1 | 0 |
| Withdrawal by Subject | 6 | 2 |
| Death | 0 | 1 |
Analysis population for the primary outcome, as defined in the registry: Modified Intent-to-Treat (mITT) population: all randomized subjects positively diagnosed with RSV using the central RT-qPCR test who receive at least one dose of assigned study drug. Subjects without resolution prior to Day 33 are censored at Day 33. Subjects who meet the resolution definition at baseline are excluded from the analysis.
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: Modified Intent-to-Treat (mITT) population: all randomized subjects positively diagnosed with RSV using the central RT-qPCR test who receive at least one dose of assigned study drug.
| Characteristic | Unit | EDP-938 | Placebo | Total |
|---|---|---|---|---|
| Participants analysed | 115 | 60 | 175 | |
| Age, Continuous | years | 68.0 (SD 14.29) | 68.1 (SD 15.46) | 68.0 (SD 14.66) |
| Sex: Female, Male: Female | Participants | 69 | 45 | 114 |
| Sex: Female, Male: Male | Participants | 46 | 15 | 61 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 72 | 29 | 101 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 43 | 31 | 74 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 1 | 0 | 1 |
| Race (NIH/OMB): Asian | Participants | 4 | 2 | 6 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 1 | 1 | 2 |
| Race (NIH/OMB): Black or African American | Participants | 11 | 2 | 13 |
| Race (NIH/OMB): White | Participants | 98 | 54 | 152 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 1 | 1 |
6. Primary Endpoint
The registry lists the primary outcome as Time to Resolution of RSV Lower Respiratory Tract Disease (LRTD) Symptoms, measured over Day 1 through Day 33.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | 95% Confidence Interval |
| Unit | days |
| Endpoint classification | Time-to-Event Analysis |
The primary endpoint was time to resolution of RSV lower respiratory tract disease symptoms, measured in days from the first dose. It focused on four symptoms: cough, shortness of breath, wheezing, and coughing up phlegm or sputum. Resolution was defined as the first of two consecutive timepoints at which each symptom had a RiiQ Scale score of zero or one. Requiring the threshold at consecutive assessments makes the endpoint reflect sustained symptom improvement rather than a single isolated rating.
Time to resolution is a time-to-event outcome: the event is meeting the stated resolution definition, and the measured duration is the time until that event. The registry reports the median time in each arm, with a 95% confidence interval, over Day 1 through Day 33. Participants who had not met the definition before Day 33 were censored at Day 33, meaning the event time was not observed within the specified follow-up period.
This endpoint captures the timing of symptom resolution, rather than only whether symptoms were resolved at one fixed assessment. It also focuses specifically on lower respiratory tract symptoms, not all RSV symptoms or complications. The registry record does not report a formal between-arm analysis for the primary endpoint.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted primary results give a median time to resolution of lower respiratory tract disease symptoms of 5.0 days for EDP-938, with a 95% confidence interval of 4.0 to 7.0 days. For placebo, the median is 4.1 days, with a 95% confidence interval of 3.0 to 5.9 days. These are arm-specific estimates. The registry record does not report a formal comparison of the two medians, a hazard ratio, or a p-value for the primary endpoint. The median values alone therefore do not establish whether the observed difference is statistically distinguishable from chance.
A confidence interval conveys uncertainty around an estimate. In general, a 95% confidence interval describes the range of values compatible with the data and the method used, under repeated use of that method. It is not a guarantee that the true value lies within the particular interval, and it does not by itself provide a test of the difference between treatment arms. In this trial, the intervals are reported separately for each arm; a comparison requires an appropriate analysis of the time-to-event data, which is not reported in the registry record.
The analysis populations also matter. The primary endpoint uses 100 EDP-938 participants and 54 placebo participants, whereas the enrollment total is 187. The primary population is restricted to randomized participants who tested positive by central RT-qPCR and received at least one dose. Thus the enrollment total and primary endpoint denominators describe different sets of participants. The record does not provide a full accounting of why each participant is absent from the primary endpoint analysis.
Secondary outcomes include complication, hospitalization, and mortality measures, alongside several symptom-related measures. The posted complication count is 5 among 115 EDP-938 participants and 3 among 60 placebo participants; the accompanying unadjusted risk-difference estimate is -0.006, with a 95% confidence interval from -0.073 to 0.06 and p = 0.845. For hospitalization, the counts are 2 and 3, respectively, and the unadjusted risk-difference estimate is -0.033, with a 95% confidence interval from -0.093 to 0.028 and p = 0.219. For all-cause mortality, the counts are 0 and 1; the unadjusted risk-difference estimate is -0.017, with a 95% confidence interval from -0.049 to 0.016 and p = 0.165. These sparse outcomes have substantial uncertainty, and the registry reports no formal secondary analyses.
The posted secondary comparisons are unadjusted recalculations from summary data, not reported sponsor analyses. They should be read as descriptive and exploratory. The record does not report a multiplicity adjustment or a prespecified statistical hierarchy for interpreting the many outcomes. No individual secondary p-value should be treated as confirmatory evidence in isolation.
9. Statistical Methods Explained
The primary endpoint is a time-to-event measure. Each participant’s event is defined as the first time the four specified lower respiratory tract symptoms meet the resolution threshold at two consecutive assessments. The registry reports the median time for each arm and a 95% confidence interval. It does not report a hazard ratio or a formal statistical comparison for this endpoint.
What does the median represent?
In general, the median time is the time by which half of the participants in the relevant analysis population have experienced the event, according to the analysis method. It describes the center of the event-time distribution and is less influenced by unusually long times than a mean can be. With censored observations, estimation must account for participants whose event was not observed during follow-up. The registry states that participants without resolution before Day 33 were censored at Day 33, but the specific estimation method is not reported in the registry record.
How should the confidence intervals be read?
In general, a confidence interval represents uncertainty in an estimate under a specified statistical method. The primary results report separate 95% confidence intervals for the median in each arm. Those intervals describe uncertainty around the arm-specific medians; they are not a confidence interval for the difference between arms. Overlap or non-overlap of separate intervals is not a substitute for a direct comparison. A suitable analysis of the time-to-event outcome would use the event and censoring information, but the statistical method and comparative result are not reported in the registry record.
What does censoring mean?
In general, censoring occurs when the event time is not observed during the period available for analysis. A participant censored at Day 33 is not treated as having had symptom resolution at that time; instead, the observation indicates that resolution had not occurred before the stated censoring point. Time-to-event methods use the observed follow-up without assigning an unobserved event time. The registry description also begins to describe handling of participants who meet the resolution definition at a certain point, but that text is incomplete, so the full rule is not reported in the registry record.
How should secondary comparisons be interpreted?
For the posted binary outcomes, the registry includes simple unadjusted recalculations from the arm-level counts. A risk difference expresses the difference between the event proportions in the two groups; its sign depends on the stated comparison order. A confidence interval that includes zero is compatible with no difference under the method used, as well as with effects in either direction. A p-value measures how incompatible the observed data are with a specified null model, subject to the assumptions of the test; it does not measure the probability that a treatment effect is real. These calculations are not listed as reported analyses in the registry. If a discrepancy between a recalculation and the sponsor’s own result were present, the sponsor’s own analysis would take precedence; the record does not flag a discrepancy.
What do the planning illustrations mean?
General sample-size calculations estimate how many participants per arm a hypothetical future study might need under stated assumptions. They are not observed power for this completed trial, and they do not change the uncertainty in the results already observed. The posted planning illustrations use a two-sided significance level of 0.05, equal allocation, a normal approximation, and effects set at stated fractions of the observed effect. For the complication outcome, the illustration gives 16,443 participants per arm for 80% power when planning for 100% of the observed effect, and 29,717 when planning for 75% of the observed effect. For hospitalization, the corresponding values are 480 and 953 participants per arm. These examples are planning outputs, not estimates of a required sample size for the original trial; the registry explicitly distinguishes them from the trial’s own design.
For time-to-event sample-size illustrations, the record states that totals refer to events, while other illustrations refer to participants per arm. The primary result does not have a reported time-to-event comparison, so a primary-endpoint planning illustration is not available in the posted results. The registry record does not report the trial’s original sample-size justification, interim analyses, or complete statistical analysis plan.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists a primary endpoint alongside numerous secondary outcomes and a total of 36 outcome measures. Testing multiple outcomes creates a multiplicity problem: in general, as more hypotheses are examined, the chance of obtaining at least one apparently unusual result by chance can increase. Statistical plans often address this through prespecified outcome hierarchies, adjustment procedures, or by explicitly treating secondary analyses as exploratory. Such procedures and a hierarchy for this trial are not reported in the registry record. The posted binary comparisons are unadjusted and should not be interpreted as if they were multiplicity-controlled confirmatory tests.
Missing-data and analysis-population details also constrain interpretation. The primary endpoint population is defined as randomized participants with a positive central RT-qPCR result who received at least one dose. Participants without resolution before Day 33 are censored at Day 33. The registry description is truncated after beginning an additional rule about participants who meet the resolution definition, so the full handling of event timing is not available. Other missing-data rules, sensitivity analyses, and the extent of missing observations are not reported in the registry record.
Denominators differ across the primary outcome, secondary outcomes, and safety summaries. The primary outcome uses 100 and 54 participants; the complication, hospitalization, and mortality outcomes use 115 and 60; safety outcomes use 121 and 65. These denominator differences may reflect outcome-specific analysis populations or available observations, but the reason for each difference is not reported in the registry record. Enrollment of 187 does not by itself explain who contributed data to each analysis.
The registry also does not report interim analyses, a full statistical analysis plan, or the trial’s sample-size justification. The posted planning illustrations are based on observed effects and stated hypothetical assumptions; they are not evidence of the original design rationale. Without these details, the posted results cannot establish how all analyses were selected, how missing observations were handled beyond the stated censoring rule, or whether the secondary outcomes were prespecified in a way that controls false-positive risk.
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 |
|---|---|---|---|
| EDP-938 | 2 | 121 | 1.7% |
| Placebo | 4 | 65 | 6.2% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| EDP-938 | 0 of 115 |
| Placebo | 1 of 60 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| EDP-938 | 27 of 121 |
| Placebo | 16 of 65 |
Most frequent serious adverse event terms
| Event term | Organ system | EDP-938 | Placebo |
|---|---|---|---|
| Influenza | Infections and infestations | 1 of 121 | 0 of 65 |
| Pneumonia | Infections and infestations | 0 of 121 | 1 of 65 |
| Pneumonia bacterial | Infections and infestations | 0 of 121 | 1 of 65 |
| Acute respiratory failure | Respiratory, thoracic and mediastinal disorders | 0 of 121 | 1 of 65 |
| Asthma | Respiratory, thoracic and mediastinal disorders | 1 of 121 | 0 of 65 |
| Chronic obstructive pulmonary disease | Respiratory, thoracic and mediastinal disorders | 0 of 121 | 1 of 65 |
| Cardiac failure chronic | Cardiac disorders | 0 of 121 | 1 of 65 |
| Systemic inflammatory response syndrome | General disorders | 0 of 121 | 1 of 65 |
| Renal impairment | Renal and urinary disorders | 0 of 121 | 1 of 65 |
Most frequent non-serious adverse event terms
| Event term | Organ system | EDP-938 | Placebo |
|---|---|---|---|
| Diarrhoea | Gastrointestinal disorders | 4 of 121 | 1 of 65 |
| Nausea | Gastrointestinal disorders | 1 of 121 | 2 of 65 |
| Asthma | Respiratory, thoracic and mediastinal disorders | 2 of 121 | 1 of 65 |
| Faeces soft | Gastrointestinal disorders | 1 of 121 | 1 of 65 |
| Asthenia | General disorders | 2 of 121 | 0 of 65 |
| Fatigue | General disorders | 1 of 121 | 1 of 65 |
| Glomerular filtration rate decreased | Investigations | 2 of 121 | 0 of 65 |
| Dysgeusia | Nervous system disorders | 2 of 121 | 0 of 65 |
| Abdominal pain | Gastrointestinal disorders | 1 of 121 | 0 of 65 |
| Constipation | Gastrointestinal disorders | 1 of 121 | 0 of 65 |
Serious events with the highest arm-level rate: pneumonia (1.5%), pneumonia bacterial (1.5%), acute respiratory failure (1.5%), chronic obstructive pulmonary disease (1.5%), cardiac failure chronic (1.5%).
The safety summaries report serious adverse events in 2 of 121 participants receiving EDP-938 and 4 of 65 receiving placebo. Other adverse events are reported for 27 of 121 and 16 of 65, respectively. The record reports no deaths in the EDP-938 group and 1 in the placebo group. These are counts within the safety groups, whose denominators differ from those used for the primary endpoint.
The registry lists six serious adverse event terms at 1.5% each: pneumonia, pneumonia bacterial, acute respiratory failure, chronic obstructive pulmonary disease, cardiac failure chronic, and systemic inflammatory response syndrome. The listing does not establish that these terms represent distinct participants; the registry record does not provide enough detail to determine overlap or event-level context.
Safety counts describe reported events in this study and should be interpreted with their denominators and the limited amount of information about event timing, duration, severity, and relatedness. The registry record does not report a comparative statistical analysis of these safety outcomes. Differences in raw counts alone do not establish a causal relationship or a reliable between-group difference.
12. What the Result Does, and Does Not, Mean
The posted primary results describe the median time to resolution of the specified lower respiratory tract symptoms in each arm. The estimates are 5.0 days for EDP-938 and 4.1 days for placebo, each with its own 95% confidence interval. They do not include a reported formal comparison, so the record does not establish whether the arm-level difference is statistically distinguishable from chance. The confidence intervals also show that each median is estimated with uncertainty.
The endpoint is specific: it concerns four lower respiratory tract symptoms meeting a defined threshold at consecutive assessments. It does not directly measure resolution of every RSV symptom, prevention of complications, hospitalization, or recovery in all aspects of daily life. Those questions appear among the secondary outcomes, but they have their own definitions and analysis populations.
The secondary event counts and unadjusted calculations provide descriptive information, not a complete confirmatory assessment. Several outcomes have few events, and the registry does not report multiplicity control or a formal analysis for the primary endpoint. The varying denominators and incomplete missing-data details further limit direct comparisons across outcomes.
These registry results do not, by themselves, establish that EDP-938 does or does not have an effect. They describe the posted arm-specific estimates, their uncertainty, and the limits of the reported analyses. A reader should distinguish the trial’s observed counts and medians from the unreported comparative analyses needed to support stronger statistical conclusions.
13. Why This Trial Matters Statistically
This trial illustrates why endpoint definitions and analysis populations are essential when interpreting clinical results. “Time to resolution” is not simply a count of participants symptom-free at one visit: it depends on the specified symptom threshold, the requirement for consecutive assessments, the time origin, the follow-up window, and how censored observations are handled. The registry provides several of these details, while leaving the estimation and comparative methods unreported.
It also demonstrates the difference between arm-specific estimates and a treatment comparison. Separate medians and confidence intervals describe each group, but do not themselves quantify the uncertainty in a between-group contrast. A formal comparison is needed to answer that statistical question. In this record, the primary comparison is not reported, so the reported medians should not be treated as a complete inferential result.
The secondary outcomes show another common challenge: multiple outcomes can address different clinical dimensions, but many unadjusted tests can make isolated findings difficult to interpret. Here, the record does not describe a multiplicity strategy, and the event counts for some outcomes are sparse. Descriptive counts and estimates are still informative, but they carry less weight than prespecified analyses with a clear inferential plan.
Finally, different denominators across outcomes underline the importance of understanding who contributed data to each analysis. The registry defines the primary modified intent-to-treat population and reports a censoring rule, but does not fully account for all denominator differences or missing-data procedures. These reporting gaps are central to statistical interpretation, rather than minor 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 main limitation for interpreting the primary result is the absence of a reported formal comparison between treatment arms. The registry gives a median and 95% confidence interval for each arm but no comparative estimate, p-value, or reported time-to-event analysis. Consequently, the posted primary figures do not quantify the uncertainty in the difference between arms.
The description of the primary endpoint’s analysis population is truncated after the censoring rule and the beginning of an additional rule. The full method for estimating medians, handling other missing observations, and conducting sensitivity analyses is not reported in the registry record. Although the modified intent-to-treat population is defined, the record does not fully explain the differences between the primary, secondary, safety, and total enrollment denominators.
Many secondary outcomes are listed, but the registry does not report analyses for most of them. The posted binary comparisons are unadjusted recalculations from summary statistics, and the record does not describe a multiplicity strategy. Counts for hospitalization and mortality are small, limiting the precision of those estimates. Secondary outcomes should not be treated as confirmatory evidence without the analysis plan and appropriate context.
The registry also does not report the original sample-size justification, interim analyses, or a complete statistical analysis plan. Planning illustrations based on observed effects are not substitutes for the trial’s original design rationale. Finally, the safety summaries provide counts and selected event terms, but limited information about event-level circumstances or comparative analysis. These constraints restrict what can be inferred from the posted record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Study of EDP-938 in Non-hospitalized Adults With RSV Who Are at High Risk for Complications. — NCT05568706.
- Registry record last updated 2026-08-19; status last verified 2026-06.
- Results first posted 2026-08-19.
- 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
NCT05568706 is a completed phase 2b randomized, double-blind, placebo-controlled parallel-group study of oral EDP-938 in non-hospitalized adults with confirmed RSV infection at high risk for complications. The EDP-938 regimen was 800 mg once daily; the comparator was matching placebo once daily. The registry lists 187 participants enrolled.
The primary endpoint was time to resolution of lower respiratory tract symptoms through Day 33. The posted arm-specific medians are 5.0 days for EDP-938 and 4.1 days for placebo, with separate 95% confidence intervals. A formal comparison for this endpoint is not reported in the registry record. Secondary outcomes include symptoms, impact, complications, hospitalization, and mortality; safety summaries report serious and other adverse events and deaths. Important details, including the full statistical analysis plan, multiplicity approach, and complete missing-data procedures, are not reported.