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 Oral Camostat Compared With Standard Supportive Care in Mild-Moderate COVID-19 Patients (NCT04524663), a randomized phase 2 study. The primary outcome is Area Under the Curve (AUC) of Shedding of SARS-CoV-2 Virus.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04524663 |
| Phase | Phase 2 |
| Condition | Covid19 |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 49 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Stanford University |
| Results posted | Yes |
2. Clinical Question
Population
People with mild-to-moderate COVID-19 were eligible for the study. The primary endpoint analysis included patients with nasal-swab data. The registry lists enrollment as 49, while the reported primary endpoint analysis includes 22.0 participants in the camostat group and 24.0 in the placebo group.
Intervention
Participants in the camostat group received camostat mesilate for 10 days in addition to standard of care treatment.
Comparator
The comparison group received placebo to match camostat mesilate for 10 days, also in addition to standard of care treatment. The contrast is therefore between adding camostat and adding placebo to standard care, not between camostat and no care.
Primary question
The primary question was whether the groups differed in the area under the curve of SARS-CoV-2 shedding, measured using cycle-threshold values from self-collected nasal swabs on days 1-10. The endpoint summarizes repeated viral-load measurements over that period; it is not a direct measure of symptom resolution or clinical worsening.
3. Trial Design
The registry describes a Phase 2, randomized, double-blinded, parallel-group study. Participants were assigned to camostat mesilate or placebo, with both groups also receiving standard of care treatment. The registry lists Stanford University as the sponsor and the study status as completed. Enrollment is listed as 49.
The study began on 2020-12-19, and the primary completion date is 2021-05-15. The registry summary describes four study visits over a period of up to 28 days. The assigned study treatment was taken for 10 days. The trial’s primary outcome timeframe was days 1-10, while several secondary outcomes were assessed up to 28 days.
For the primary endpoint, the reported analysis included patients with nasal-swab data: 22.0 in the camostat group and 24.0 in the placebo group. The registry does not explain the difference between enrollment and the analyzed numbers, nor does it report a fuller account of exclusions or missing nasal-swab data. Other outcome analyses have their own reported group sizes, so the analyzed population varies by endpoint.
Randomization and double blinding can help limit differences in treatment assignment and expectations between groups. The registry record does not report the randomization procedure, allocation concealment details, or how blinding was maintained and assessed. It also does not report a detailed protocol for standard of care. Those omissions limit how fully the design can be assessed from the registry alone.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Camostat Mesilate | Placebo |
|---|---|---|
| STARTED | 25 | 24 |
| COMPLETED | 25 | 22 |
| NOT COMPLETED | 0 | 2 |
Reasons for not completing this period:
| Reason | Camostat Mesilate | Placebo |
|---|---|---|
| Withdrawal by Subject | 0 | 2 |
Analysis population for the primary outcome, as defined in the registry: Patients with nasal swab data are included in 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.
| Characteristic | Unit | Camostat Mesilate | Placebo | Total |
|---|---|---|---|---|
| Participants analysed | 25 | 24 | 49 | |
| Age, Continuous | years | 37.88 (SD 13.47) | 40.54 (SD 14.27) | 39.18 (SD 13.79) |
| Sex: Female, Male: Female | Participants | 10 | 7 | 17 |
| Sex: Female, Male: Male | Participants | 15 | 17 | 32 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 6 | 9 | 15 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 18 | 13 | 31 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Race/Ethnicity, Customized: American Indian/Alaska Native | Participants | 1 | 0 | 1 |
| Race/Ethnicity, Customized: Asian | Participants | 5 | 4 | 9 |
| Race/Ethnicity, Customized: Native Hawaiian or other Pacific Islander | Participants | 1 | 0 | 1 |
| Race/Ethnicity, Customized: Black or African American | Participants | 1 | 0 | 1 |
| Race/Ethnicity, Customized: White | Participants | 12 | 7 | 19 |
| Race/Ethnicity, Customized: More than one race | Participants | 0 | 1 | 1 |
| Race/Ethnicity, Customized: Unknown | Participants | 1 | 0 | 1 |
| Race/Ethnicity, Customized: Other | Participants | 2 | 6 | 8 |
| Region of Enrollment: United States | Participants | 25 | 24 | 49 |
| Anterior nares RT-PCR Ct | cycles | 19.40 (17.17 to 24.40) | 21.58 (17.98 to 26.84) | 20.87 (17.33 to 25.06) |
| Duration of Symptoms | days | 5.00 (2.75 to 6.00) | 4.50 (3.75 to 5.00) | 5.00 (3.00 to 6.00) |
| Number of Symptoms | symptoms | 6 (3 to 7) | 6 (4 to 8) | 6 (3 to 8) |
| Body Mass Index | kg/m^2 | 27.81 (24.89 to 33.36) | 28.00 (24.97 to 30.15) | 27.81 (24.89 to 32.09) |
| Aspartate Aminotransferase | units/L | 25.00 (21.00 to 29.00) | 30.00 (24.75 to 35.00) | 27.00 (22.00 to 35.00) |
| Alanine Aminotransferase | units/L | 25.00 (20.00 to 35.00) | 34.50 (20.00 to 48.50) | 29.00 (20.00 to 44.50) |
| Uric acid | mg/dL | 5.10 (4.40 to 5.85) | 5.00 (3.88 to 5.85) | 5.10 (4.05 to 5.85) |
| Creatinine | mg/dL | 0.87 (0.68 to 0.97) | 0.86 (0.67 to 0.98) | 0.87 (0.68 to 0.98) |
6. Primary Endpoint
The registry lists the primary outcome as Area Under the Curve (AUC) of Shedding of SARS-CoV-2 Virus, measured over Days 1-10.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Inter-Quartile Range |
| Unit | cycles*days |
| Endpoint classification | Time-to-Event Analysis |
The primary endpoint was the area under the curve (AUC) of SARS-CoV-2 shedding during days 1-10. It was calculated from cycle-threshold (Ct) measurements obtained by reverse transcription-polymerase chain reaction testing of self-collected nasal swabs. The calculation used the exact collection times and the trapezoidal rule. The endpoint is reported in cycles*days.
A Ct value describes how many PCR cycles are needed for viral RNA to reach a detectable level. The registry explains that higher Ct values correspond to lower viral copy numbers. It also gives reference points: Ct values of 20 correspond to approximately 2.12 x 106 viral copies per milliliter, while a Ct value of 40 is undetectable and is the lower limit of detection for this test.
An AUC combines measurements across the observation period into a single summary. In general, this can represent both the level and duration of a measured signal, rather than focusing on a single swab. Here, it is a summary of Ct measurements over days 1-10—not a direct count of viral particles, a time-to-clearance measure, or a clinical outcome. Its interpretation must account for the fact that higher Ct values indicate lower viral copy numbers.
The registry reports the group medians and interquartile ranges. The endpoint was chosen to assess viral shedding over time, consistent with the study’s stated aim of evaluating the duration of viral shedding. The registry record does not report a clinical threshold for a meaningful difference in this AUC measure.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The median AUC was 95.3 cycles*days in the camostat group and 93.0 cycles*days in the placebo group. The reported median difference (net) was 0.59, with a 95% confidence interval from -8.14 to 9.32 and p = 0.89. The confidence interval includes zero and spans values on either side of it. The posted analysis therefore does not establish a clear difference between the groups on this endpoint.
The group-level interquartile ranges were 66.7 to 124.0 for camostat and 68.0 to 124.0 for placebo. These describe the spread of the middle half of the observed values in each group; they are not confidence intervals for the group medians. Their overlap is consistent with substantial similarity in the observed distributions, but overlap alone is not a formal test of a treatment contrast.
In general, a confidence interval describes a range of estimates compatible with the data and the statistical model, subject to the model’s assumptions. It is not a guarantee that the true effect lies inside the interval, and it does not assign probabilities to individual values within it. The p-value is also not the probability that the null hypothesis is true. It describes how unusual data at least as incompatible with the null as those observed would be under the model and null hypothesis.
The primary endpoint is a viral-shedding measure, not a direct measure of symptoms, clinical worsening, or patient experience. The result should therefore be interpreted specifically as an analysis of the reported Ct-based AUC during days 1-10. It cannot, by itself, answer whether the groups differed on every other outcome in the trial.
The primary endpoint analysis included patients with nasal-swab data. The registry record does not report the reasons that some enrolled participants are not represented in that analysis, or how missing measurements were handled. If the availability of swabs is related to participant condition or treatment assignment, the observed analysis may not fully represent all randomized participants. The record does not provide enough detail to assess that possibility.
The sponsor-reported result is a regression-based median difference with a broad interval around the estimate. The posted evidence should be read as uncertain about the size and direction of any group difference, rather than as proof of equivalence or proof that an effect is absent. The record does not report a predefined equivalence margin or a non-inferiority framework.
9. Statistical Methods Explained
What does the primary summary measure?
The endpoint is an AUC formed from Ct measurements over days 1-10. In general, an area under a curve compresses a series of measurements into one summary, incorporating information across time. It can be useful when a single measurement would not represent the trajectory. The trapezoidal rule approximates the area between observed measurements by treating successive observations as connected by straight-line segments. The registry says exact collection times were used, so the spacing of measurements contributes to the calculation.
Ct values have an inverse relationship to viral copy numbers as described in the registry: higher Ct values correspond to lower viral copy numbers. This direction matters when interpreting an AUC of Ct values. It should not be casually described as an AUC of viral copies, because the endpoint is defined on the Ct scale. The registry does not report a threshold for a clinically important AUC difference.
Why are medians and interquartile ranges reported?
The primary endpoint is summarized by a median and an interquartile range. In general, the median is the middle of an ordered set of observations and is less affected than the mean by very large or very small values. The interquartile range describes the central half of the observations. Neither summary gives the full distribution, and an interquartile range is not a confidence interval for the median.
The primary comparison is reported as a median difference (net) from linear regression, with a 95% confidence interval and a p-value. In general, regression can estimate a contrast between groups and may account for specified model terms. The registry record does not identify any covariates or adjustments used in this primary regression. The reported interval is the uncertainty estimate for the contrast under the analysis model, not a range containing most individual participant results.
How should time-to-event analyses be understood?
Some secondary outcomes concern time until an event, including cessation of shedding and symptom resolution. The registry reports hazard ratios from Cox proportional hazards models. In general, a hazard ratio compares event rates over time among people who have not yet experienced the event, under the model. It is not the same as a ratio of median times and is not a direct statement about the number of days gained or lost. The proportional-hazards assumption concerns whether the relative event rate is reasonably stable over time. The registry record does not report diagnostics or other details assessing this assumption.
A confidence interval for a hazard ratio expresses uncertainty about that model-based comparison. For the reported results, the intervals include 1. In general, a hazard ratio of 1 corresponds to equal hazards under the model; values on either side indicate different relative hazards, with the interpretation depending on how the event and groups are coded. These analyses should be read using the sponsor-reported estimates, not by deriving a different estimate from the medians.
What does the binary outcome comparison add?
Clinical worsening is reported as a count of participants, with a Fisher exact p-value in the sponsor’s analysis. In general, Fisher’s exact test evaluates whether the distribution of a binary outcome differs between groups and is often used for small samples or sparse counts. It does not, by itself, estimate a confidence interval for a treatment effect. A separate unadjusted risk-difference calculation is also available for this outcome; such a recalculation is a simple comparison based on the posted counts and is not a substitute for the sponsor’s analysis.
How do planning illustrations differ from trial power?
The registry’s planning illustrations for the time-to-event comparisons use stated assumptions: a two-sided significance level of 0.05, equal allocation, a normal approximation, and an effect defined as a stated fraction of the observed effect. The time-to-event illustrations express the required total number of events. In general, such calculations explore the scale of a future study under assumptions; they do not indicate the probability that this completed trial detected an effect. They are planning illustrations, not observed power, and they do not establish the design assumptions used for this trial. The registry record does not report a sample-size justification for the trial itself.
What is not documented?
The registry record does not report the detailed statistical analysis plan, covariate adjustments for the primary model, interim analyses, or a missing-data strategy. It also does not report the multiplicity procedure, if any, for the several outcomes. These details affect how confidently the reported estimates can be evaluated and how secondary results should be interpreted. The posted p-values and intervals remain useful descriptions of the reported analyses, but they do not resolve questions the record leaves undocumented.
10. Analyses Reported by the Sponsor
| Method | Estimate | 95% CI | P-value |
|---|---|---|---|
| Regression, Linear | Median Difference (Net) 0.59 | -8.14 to 9.32 | 0.890 |
The sponsor’s primary analysis reports a median difference (net) of 0.59, with a 95% confidence interval from -8.14 to 9.32 and p = 0.89. The group medians were 95.3 cycles*days for camostat and 93.0 cycles*days for placebo. The interval includes zero, and the p-value does not indicate strong evidence of a difference under the reported model.
No separate recalculated primary estimate is reported in the registry record. The group medians alone cannot reproduce the sponsor’s regression-based comparison, because the regression estimate may depend on participant-level data and model details that are not reported. Accordingly, there is no competing recalculated primary result to set against the sponsor’s estimate. The registry record does not describe the regression covariates or other model specifications, limiting independent assessment of the analysis.
For clinical worsening, an unadjusted risk-difference recalculation is available from the posted counts, while the sponsor reports a Fisher exact p-value of 0.49. These answer related but not identical statistical questions: one expresses an unadjusted difference in observed risks, while the other reports a test of association. The sponsor’s analysis is the reported trial analysis; the simple recalculation is supplementary and should not replace it.
The record lists no discrepancy flag between the sponsor analysis and the available recalculations. The recalculated binary comparison should nevertheless be understood as an unadjusted analysis of posted summary counts, not as a reconstruction of the sponsor’s full analysis.
11. Multiplicity, Missing Data and Analysis Populations
The study reports a primary endpoint and several secondary outcomes. In general, testing multiple outcomes without an adjustment or a prespecified hierarchy increases the chance of a false-positive finding somewhere among the tests. This does not mean that every secondary result is invalid; it means that isolated secondary p-values require caution and should be interpreted in the context of the full analysis plan.
The registry record does not report whether multiplicity was controlled, whether particular secondary outcomes were designated as confirmatory, or whether a testing sequence was prespecified. It also does not report interim analyses or stopping rules. These details are relevant to judging the strength of evidence and whether the reported tests should be interpreted as confirmatory or exploratory.
The primary endpoint population is defined as patients with nasal-swab data. The registry reports 22.0 participants in the camostat group and 24.0 in the placebo group for that analysis, compared with enrollment listed as 49. The record does not report why the analysis counts differ from enrollment, the extent or timing of missing swabs, or how missing measurements were handled. It does not describe an intention-to-treat analysis population or explain whether all randomized participants were included in each analysis.
Other outcome analyses report different group sizes, so the available results do not all represent the same analysis population. The registry record does not explain the reasons for those differences. In general, missing outcome data can affect results if the probability of missingness is related to treatment assignment or outcome status. Without information about the missing-data process and methods, the direction or importance of any potential bias cannot be assessed from the record.
The absence of these details is an interpretive limitation, not evidence that the analysis was necessarily conducted incorrectly. It means that readers cannot fully evaluate the prespecification of analyses, the handling of missing observations, or the role of multiple testing using the registry record alone.
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 |
|---|---|---|---|
| Camostat Mesilate | 0 | 25 | 0.0% |
| Placebo | 3 | 24 | 12.5% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Camostat Mesilate | 0 of 25 |
| Placebo | 0 of 24 |
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 |
|---|---|
| Camostat Mesilate | 2 of 25 |
| Placebo | 10 of 24 |
Most frequent serious adverse event terms
| Event term | Organ system | Camostat Mesilate | Placebo |
|---|---|---|---|
| Liver function tests | Investigations | 0 of 25 | 1 of 24 |
| Hypotension | Vascular disorders | 0 of 25 | 1 of 24 |
| Dyspnea | Respiratory, thoracic and mediastinal disorders | 0 of 25 | 1 of 24 |
| Suidical ideation | Psychiatric disorders | 0 of 25 | 1 of 24 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Camostat Mesilate | Placebo |
|---|---|---|---|
| Liver function test (LFT) elevation | Investigations | 1 of 25 | 4 of 24 |
| Rash | Skin and subcutaneous tissue disorders | 0 of 25 | 4 of 24 |
| Diarrhea | Gastrointestinal disorders | 1 of 25 | 2 of 24 |
Serious events with the highest arm-level rate: liver function tests (4.2%), hypotension (4.2%), dyspnea (4.2%), suidical ideation (4.2%).
The adverse-event figures describe events recorded in the registry, not proof that a study treatment caused them. For serious adverse events, the registry reports zero affected participants in the camostat group and 3 affected participants in the placebo group. The numbers at risk were 25 and 24, respectively. No deaths were reported in either group.
The registry lists liver function tests, hypotension, dyspnea, and “Suidical ideation” among the top serious-event terms, each with a reported value of 4.2%. The record does not provide enough detail to determine the timing, duration, clinical course, or relationship to study treatment for these terms. A term’s appearance in an adverse-event listing should not be read as a causal attribution.
Other adverse events were reported for 2 participants in the camostat group and 10 in the placebo group, with 25 and 24 participants at risk, respectively. These figures are descriptive. The registry record does not provide a detailed breakdown of event severity, exposure time, or treatment attribution, and the group sizes are small. Consequently, the counts do not establish comparative safety or rule out uncommon harms.
13. What the Result Does, and Does Not, Mean
The primary result describes a comparison of a viral-shedding measure derived from nasal-swab Ct values during days 1-10. The reported median difference was 0.59, with a 95% confidence interval from -8.14 to 9.32 and p = 0.89. The estimate is imprecise enough to include values on both sides of zero. The analysis does not establish a clear group difference on this endpoint.
This is not proof that the groups were equivalent. Equivalence requires a prespecified margin and an analysis designed to assess whether the uncertainty lies within that margin; the registry record does not report such a margin. Nor does a non-significant p-value prove that there is no effect. It indicates that the reported analysis did not provide strong evidence against its null hypothesis under the model used.
The primary outcome is not a direct measure of symptoms, clinical worsening, or other patient-centered outcomes. The secondary outcomes address some of those questions, but the posted results are limited and the registry does not report whether multiplicity was controlled. Those results should not be treated as definitive confirmation of a benefit or lack of benefit.
The trial’s findings also cannot be assumed to apply to people outside the study population or to different treatment settings. The registry describes patients with mild-to-moderate COVID-19, camostat or matching placebo for 10 days, and standard care in both groups. It does not provide detailed information about all characteristics of the participants or the standard-care regimen.
In short, the registry reports an uncertain primary comparison in a relatively small Phase 2 study, with incomplete reporting of analysis details and missing-data handling. It documents what was measured and the estimates reported, but it does not support a definitive conclusion about all clinical outcomes or establish causation for adverse events.
14. Why This Trial Matters Statistically
This trial is statistically instructive because it combines repeated biomarker measurements, a derived AUC endpoint, time-to-event outcomes, and a binary clinical outcome. Each endpoint requires a different interpretation. A Ct-based AUC summarizes measurements over a defined period, while a hazard ratio describes relative event rates over time under a model, and a count comparison concerns the occurrence of a binary outcome.
The primary endpoint also illustrates why scale and direction matter. Ct values are inversely related to viral copy numbers according to the registry, so an AUC of Ct values should not be casually described as an AUC of viral load. Careful labeling helps prevent a mathematically correct estimate from being given an incorrect clinical interpretation.
The record also highlights the distinction between estimation and testing. The primary confidence interval communicates uncertainty around the reported contrast, while the p-value addresses a specific null hypothesis under the analysis. Neither establishes equivalence or answers whether a difference is clinically meaningful. The registry does not report a threshold for meaningful change.
Finally, the outcomes are numerous and use different analysis populations, while multiplicity and missing-data procedures are not reported in the registry record. These are important considerations in Phase 2 trials, where results can guide later research but should be interpreted with attention to uncertainty and prespecification. The planning illustrations for time-to-event outcomes are not observed power and should not be mistaken for evidence about the trial’s ability to detect an effect.
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 study has small reported analysis groups, and the registry’s enrollment figure differs from the numbers included in the primary endpoint analysis. The record does not explain this difference or report how missing nasal-swab observations were handled. Because the primary endpoint depends on repeated samples collected over time, incomplete or irregular measurement could affect the AUC and the set of participants analyzed.
The endpoint is a Ct-based biomarker summary rather than a direct clinical outcome. The registry describes the relation between Ct and viral copy numbers but does not report a clinically meaningful threshold for the AUC. The result therefore has a clear measurement definition but limited interpretive context for judging the practical importance of a given difference.
Details needed to fully evaluate the analyses are not reported in the registry record. These include the primary regression specifications, covariate adjustments, multiplicity approach, missing-data strategy, interim analyses, and the sample-size justification. The record also does not provide diagnostic information for the Cox proportional hazards models or details about how standard care was implemented.
Secondary results cover different outcomes and analysis populations, and only some listed secondary outcomes have numeric results in the record. With multiple outcomes and no reported multiplicity procedure, isolated secondary findings warrant caution. The limited group sizes also restrict precision, particularly for uncommon events. These limitations do not negate the reported findings, but they constrain how broadly or conclusively they can be interpreted.
16. Related Tutorials
17. Related Statistical Calculators
18. Sources
- ClinicalTrials.gov: Oral Camostat Compared With Standard Supportive Care in Mild-Moderate COVID-19 Patients — NCT04524663.
- Registry record last updated 2022-06-10; status last verified 2022-06.
- Results first posted 2022-06-10.
- 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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19. Record Summary
NCT04524663 is a completed Phase 2 randomized, double-blinded, parallel-group study sponsored by Stanford University. It compared camostat mesilate for 10 days plus standard of care with matching placebo plus standard of care in people with mild-to-moderate COVID-19. Enrollment is listed as 49.
The primary endpoint was the AUC of SARS-CoV-2 shedding measured from self-collected nasal-swab Ct values during days 1-10. The reported median difference (net) was 0.59, with a 95% confidence interval from -8.14 to 9.32 and p = 0.89. The result does not establish a clear difference between the groups on this endpoint.
The registry lists six secondary outcomes and reports analyses for time until cessation of shedding, clinical worsening, and symptom resolution. The record does not report multiplicity handling, a detailed missing-data strategy, or the primary model’s specifications. Those omissions, along with differing analysis populations, limit interpretation of the findings.