Evaluation of the Safety and Efficacy of Razuprotafib in Hospitalized Subjects With Coronavirus Disease 2019: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of the Safety and Efficacy of Razuprotafib in Hospitalized Subjects With Coronavirus Disease 2019 (NCT04511650), a randomized phase 2 study. The primary outcome is Number and Percent of Subjects Who Were Alive and Free of Respiratory Failure Prior to Day 7 and Day 28.

2. Clinical Question

The clinical question is framed around respiratory status and survival during hospitalization. The endpoint treats death before an assessment timepoint as the worst outcome, rather than counting a subject who died as alive and free of respiratory failure. Respiratory failure includes invasive mechanical ventilation, specified forms of respiratory support, or a clinical diagnosis where those therapies were needed but unavailable because of resource limitation.

This is a question about outcomes in a randomized, placebo-controlled Phase 2 study, not a basis for conclusions about treatment effectiveness. The registry record describes a dose-escalation part and a proof-of-concept part, but does not report the primary outcome results by dose and timepoint. It therefore does not establish the size, direction, or precision of any treatment-group difference.

3. Trial Design

The registry describes a Phase 2, randomized, double-blind, placebo-controlled, parallel-group, multicenter study with dose escalation and proof-of-concept components. Its allocation model is listed as sequential, and masking is listed as triple. These design labels describe the planned structure; they do not, by themselves, establish how every operational decision was made or whether any particular analysis was conducted.

The study was planned to include two parts. Part 1 comprised dose escalation, while Part 2 comprised the proof-of-concept safety and efficacy period. The brief summary states that razuprotafib was administered 3 times daily, every 8 hours, to hospitalized subjects with moderate to severe COVID-19 receiving standard of care therapy. The listed treatment arms were Razuprotafib 10 mg, Razuprotafib 20 mg, and placebo.

Enrollment is listed as 31. The registry records a start date of 2020-10-21, primary completion on 2021-02-26, and status as terminated. The reason for termination is not reported in the registry record. The registry record also does not report how enrollment was distributed among the arms, whether every planned part was carried out, or the timing and basis for the termination.

Randomization is intended to support a fair comparison by assigning participants to groups according to a chance-based process, while masking can reduce the influence of expectations on care or assessment. These are general design principles; the registry labels do not provide operational details about the randomization sequence, who was masked, or how masking was maintained. The registry record does not report a sample-size justification or enough information to reconstruct the trial’s full design rationale.

The parallel-group structure means the planned comparison is between groups assigned to different regimens, rather than a within-subject crossover. The listed sequential model should not be taken as evidence of interim analyses, a particular stopping rule, or an adaptive design. Those details 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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: The Full Analysis (FA) Population included subjects who received at least 1 dose of study drug and had at least 1 post-dose efficacy evaluation. The FA Population was a subset of the ITT Population which was defined as all subjects randomized. Note: The overall number of participants analyzed represents the total number of participants in each treatment group for the FA Population. Count of participants who were alive and free of respiratory failure on Days 7 and 28 were included in analyses.

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Number and Percent of Subjects Who Were Alive and Free of Respiratory Failure Prior to Day 7 and Day 28, measured over Baseline up to Day 7 and Day 28.

The primary endpoint is the number and percentage of subjects alive and free of respiratory failure before Day 7 and Day 28. It is a binary outcome at each specified assessment timepoint: a subject either meets the combined survival-and-respiratory-status condition or does not. The endpoint description calls for results summarized by treatment arm as proportions, with a confidence interval for the difference between response rates and a p-value using the Cochran-Mantel-Haenszel method.

Respiratory failure is defined broadly. It includes invasive mechanical ventilation; high-flow nasal cannula with heated, humidified oxygen at flow rates >20L/min and a fraction of delivered oxygen of at least 0.5; noninvasive positive pressure ventilation; extracorporeal membrane oxygenation; or a clinical diagnosis of respiratory failure when one of those therapies was needed but could not be administered because of resource limitation. Death before Day 7 or Day 28 was imputed as the worst outcome for that timepoint.

This kind of combined endpoint is used to capture both survival and a clinically consequential level of respiratory support, rather than treating either dimension alone as the primary measure. That rationale is general; it does not establish the endpoint’s performance in this study. The registry record does not report the number or percentage meeting the endpoint, the confidence intervals, or the p-values. It therefore does not allow the treatment-group contrast to be assessed from the primary outcome.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The methods described for the primary outcome combine a binary response measure with a between-group comparison. The registry specifies descriptive summaries by treatment arm, proportions, a 95% confidence interval for the difference between response rates, and a Cochran-Mantel-Haenszel (CMH) p-value. The confidence interval is specified to use the normal approximation method. The registry record does not report the resulting estimates or enough detail to reconstruct them.

What does a proportion describe?

For a binary outcome, a proportion expresses the share of assessed participants meeting the defined response condition. Here the condition is being alive and free of respiratory failure before a stated timepoint. Reporting the arm-specific proportions would describe each arm separately; comparing them would address the difference between response rates. The actual proportions and the difference are not reported in the registry record.

A confidence interval describes statistical uncertainty around an estimate under the method and assumptions used. A narrower interval generally represents greater precision, while a wider interval represents less precision. The planned 95% confidence interval is for the difference between response rates, not simply for one arm’s response rate. Because its limits are not reported, the precision and the range of differences compatible with the analysis cannot be assessed.

What is the normal approximation?

As a general statistical method, a normal approximation uses a normal distribution to estimate uncertainty for a statistic that has an approximately normal sampling distribution. It can be convenient for comparing proportions, but its performance depends on the data and the adequacy of the approximation. The registry specifies this approach for the confidence interval, but does not report checks of its suitability or alternative interval methods. Without the outcome counts and interval limits, no independent assessment of the approximation is possible.

What does the CMH method contribute?

The Cochran-Mantel-Haenszel method is a general approach to testing an association between treatment group and outcome while accounting for stratification. Its use can be appropriate when a comparison is organized across strata, but the registry record does not describe the strata, whether stratification factors were used, or how they were selected. The method’s mention alone does not reveal the exact model or adjustment. No CMH test statistic or p-value is reported for the primary endpoint.

A p-value is a measure of how incompatible the observed data are with a specified null hypothesis under the assumptions of the analysis. It does not measure the probability that a treatment works, nor does it indicate the size or clinical importance of a difference. Interpretation would require the effect estimate and its interval as well as the analysis context. Those primary results are not reported in the registry record.

Why do the timepoints and endpoint definition matter?

The primary outcome is assessed before Day 7 and Day 28, so it is not a single undifferentiated measurement. Each timepoint has its own response status, and a result at one timepoint would not automatically describe the result at the other. The endpoint also combines survival and respiratory failure status. The treatment contrast could therefore be difficult to interpret without the component information, even if the overall endpoint estimates were available. Component-level results for the primary endpoint are not reported in the registry record.

The definition counts several forms of respiratory support and includes a clinical diagnosis when indicated treatment could not be administered because of resource limitation. This broad definition is intended to capture respiratory failure across different care circumstances. As a general measurement issue, differences in assessment or access to support can affect how an endpoint is classified; the registry record does not report whether such issues occurred or how they were monitored.

How should planning illustrations be read?

The stated planning assumptions describe calculations based on the observed effect, a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is described as a fraction of the observed effect. These are planning illustrations, not evidence of the trial’s original sample-size rationale and not observed power. Sample-size calculations are prospective tools: they show what sample size might be needed under specified assumptions. They do not show the probability that a completed trial has demonstrated a true effect.

The primary outcome has multiple categories or timepoints and is not reduced to one comparison for the planning illustrations. The registry record does not report a sample-size justification for the study or an analysis that resolves the multiple timepoints into a single primary contrast. The displayed assumptions should not be taken as the trial’s prespecified statistical plan.

No recalculated primary comparison is presented in the registry record. In general, a simple recalculation from summary statistics would be unadjusted and would not replace a sponsor’s specified analysis. There is no reported primary result against which to make such a recalculation. The sponsor’s own analysis takes precedence if a discrepancy is identified, but a discrepancy is not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The primary endpoint covers both before Day 7 and Day 28. Assessing more than one timepoint can raise a multiplicity question: when several related hypotheses are tested, the chance of at least one apparently unusual result can increase unless the analysis addresses that structure. This is a general statistical concern, not a statement that the trial’s results were affected. A multiplicity adjustment, hierarchy, or other prespecified strategy is not reported in the registry record.

The registry lists 16 outcome measures and one analysis. The presence of several outcome measures also makes it important to know which comparisons were prespecified and how interpretation was controlled across outcomes. A detailed statistical analysis plan, including any multiplicity procedure, is not reported in the registry record. The available record does not establish whether additional analyses were conducted or how they were handled.

The endpoint description states that deaths before the relevant timepoint were imputed as the worst outcome. This is a specific rule for death, not a complete account of missing-data handling. The approach to other missing observations, missed visits, withdrawals, or incomplete assessments is not reported in the registry record. It is also not clear from the available population text how many participants contributed to each timepoint’s primary analysis.

The ITT Population is defined as all subjects randomized. The Full Analysis Population is described as subjects who received at least 1 dose of study drug and had at least 1 post-dose efficacy evaluation, and as a subset of the ITT Population. The population description ends before its remaining details are given. The analysis population actually used for the primary outcome, and the number analyzed by arm and timepoint, are not reported in the registry record. Therefore, the effect of exclusions or incomplete outcome data cannot be assessed.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: respiratory failure (22.2%), bacterial pneumonia (11.1%), septic shock (11.1%), post-procedural hemorrhage (11.1%), transient hypotension (11.1%).

The registry lists serious adverse events and other adverse events by arm, with participants at risk and participants affected. For serious adverse events, it reports Placebo: 2 affected among 10 at risk; Razuprotafib 10 mg: 2 among 9; and Razuprotafib 20 mg: 5 among 10. For other adverse events, it reports Placebo: 6 affected among 10 at risk; Razuprotafib 10 mg: 7 among 9; and Razuprotafib 20 mg: 8 among 10. Deaths are listed as 1 in each arm.

These are descriptive registry counts. They do not establish that a study drug caused an event, and they do not provide adjusted comparisons or uncertainty intervals. The listed terms among the leading serious adverse event entries include Respiratory Failure (22.2%), Bacterial pneumonia (11.1%), septic shock (11.1%), post-procedural hemorrhage (11.1%), Transient hypotension (11.1%), and COVID-19 viral pneumonia (10.0%). The denominator for each term is not reported in the registry record.

Safety counts should be interpreted with the group at-risk figures and the trial context in mind. The registry record does not report detailed timing, severity distributions beyond the serious-event classification, or the treatment attribution for individual events. These counts alone cannot establish comparative safety.

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

The registry record establishes that a Phase 2 randomized study of razuprotafib and placebo was conducted in hospitalized subjects with COVID-19, and it defines a primary outcome based on survival and respiratory failure. It also reports selected adverse-event counts. These details describe what the study was designed to examine and some of the safety information recorded.

The most important limitation for interpreting the primary question is that its results are not reported in the registry record. Without counts, response proportions, confidence intervals, or p-values for the Day 7 and Day 28 comparisons, the primary treatment-group contrast cannot be quantified. The available information therefore does not show whether one arm had a higher or lower response rate, how large any difference was, or how precise an estimate might be.

The record’s termination status does not explain the reason the study ended and does not, on its own, indicate the result. Likewise, the enrollment entry does not show how participants were distributed across the arms or how many were included in each endpoint analysis. The registered safety counts are informative as reported counts, but are not enough to infer causation or establish a comparative safety effect.

General statistical interpretation depends on an estimate, its uncertainty, the design, outcome definitions, and the analysis population. Statistical significance alone would not establish clinical importance, and lack of statistical significance would not establish equivalence. In this case, the primary estimates themselves are absent, so neither kind of conclusion can be drawn from the registry record.

The appropriate reading is limited: the study addressed a clinically relevant outcome and recorded safety events, but the posted primary results do not permit an assessment of the efficacy comparison. The record does not establish that razuprotafib is effective or ineffective, nor does it establish that treatment groups were equivalent. Those conclusions require results and analysis details that are not reported in the registry record.

13. Why This Trial Matters Statistically

This study is statistically notable for combining randomized treatment assignment with a time-specific outcome that joins survival and respiratory status. Such a design can address a focused clinical question, but interpretation depends on clear outcome definitions, complete reporting at each timepoint, and transparent treatment-group estimates. The registry provides the endpoint definition and intended summary methods, while the primary outcome results are not reported.

The respiratory-failure definition covers invasive ventilation, specified noninvasive support, extracorporeal membrane oxygenation, and clinical need for such support when resource limitations prevent its use. That breadth makes the endpoint relevant across differing care circumstances, while also making consistent classification important. The registry record does not report details about assessment procedures or adjudication, so those aspects cannot be evaluated.

The study also illustrates why treatment-arm counts and a trial’s overall status are not substitutes for efficacy estimates. Enrollment is listed as 31, and status is terminated, but neither fact reveals the size or precision of the primary comparison. A credible interpretation requires the outcome data, the analysis population, and the handling of missing observations and multiple timepoints.

Finally, the record distinguishes descriptive safety reporting from an inferential comparison. Adverse-event counts can identify what was recorded in each arm, but without fuller context and analysis they do not establish causal differences. Transparent reporting of both benefits and harms is essential for judging the evidence; the primary results and several key analysis details are not reported in the registry record.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The principal limitation is that the registry record does not report primary outcome counts, proportions, confidence intervals, or p-values for either specified timepoint. The treatment-group contrast therefore cannot be estimated from the posted primary results. The reason for termination is not reported, so the implications of the terminated status cannot be determined from this record alone.

The registry describes the planned two-part structure but does not report whether each part was completed or how enrollment was distributed among arms. It also does not report the number analyzed in each arm at each timepoint. Although the ITT and Full Analysis populations are defined in part, the population description is truncated, and the exact population used for the primary analysis is not established.

The handling of deaths is specified as worst outcome imputation, but other missing-data procedures are not reported. Methods for addressing the two primary timepoints or multiplicity across the listed outcomes are also not reported. The record names CMH testing and a normal-approximation confidence interval, but does not describe any stratification factors or provide enough detail to reproduce the analysis.

Safety data are presented as counts, without the detail needed to assess event timing, treatment attribution, or comparative uncertainty. The denominator for the listed serious-event term percentages is not reported. A sample-size justification and the reason for choosing the enrollment target are not reported in the registry record. These gaps limit interpretation of both the planned inference and the available safety information.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Evaluation of the Safety and Efficacy of Razuprotafib in Hospitalized Subjects With Coronavirus Disease 2019 — NCT04511650.
• Registry record last updated 2023-06-08; status last verified 2023-06.
• Results first posted 2023-06-08.
• 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.

18. Record Summary

NCT04511650 is a Phase 2 randomized, double-blind, placebo-controlled, parallel-group study of razuprotafib in hospitalized subjects with moderate to severe COVID-19. The registry describes dose escalation and proof-of-concept parts, with Razuprotafib 10 mg, Razuprotafib 20 mg, and placebo arms. Enrollment is listed as 31; the status is terminated.

The primary endpoint is the number and percentage alive and free of respiratory failure before Day 7 and Day 28. Its description specifies descriptive arm-level proportions, a 95% confidence interval using the normal approximation, and CMH p-values. The primary outcome results and the reason for termination are not reported in the registry record. Safety counts are posted by arm, but are descriptive and do not establish causal effects.