Treat COVID-19 Patients With Regadenoson: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Treat COVID-19 Patients With Regadenoson (NCT04606069), a randomized phase 1, phase 2 study. The primary outcome is Proportion of Patients Alive and Free of Respiratory Failure Through the 30-day Trial..

2. Clinical Question

3. Trial Design

The registry lists this as a randomized, triple-masked, parallel-group Phase 1 and Phase 2 trial sponsored by the University of Maryland, Baltimore. The listed enrollment is 5, and the study status is completed. The registry dates the study start as 2021-05-06 and primary completion as 2023-04-24. Those dates describe the record; they do not establish when individual participants were enrolled or followed.

The study compares intravenous regadenoson with an intravenous saline placebo control. The active-arm description specifies a loading infusion followed by continuous infusion. The control-arm description specifies saline for an initial infusion followed by continuous infusion for 6 hours. The posted summary does not give further details about the infusion apparatus or complete administration procedures.

The registry’s primary outcome is the proportion alive and free of respiratory failure through 30 days. It defines respiratory failure by use of at least one of several respiratory-support modalities. A secondary outcome is change in inflammatory cytokine levels before, during, and after drug infusion.

The posted arm results list 5 participants in the active arm and 0 in the control arm. This is important when interpreting a trial listed as randomized and parallel: the design description alone does not ensure that both groups have analyzable outcome data. The registry’s outcome population description says the site was instructed, following DSMB recommendations, to enroll 5 participants in the regadenoson arm for a safety assessment. Enrollment was paused for safety review of those participants’ data; the record says approval was later given to resume enrollment, but the posted results still list no control participants.

The registry does not report the intended allocation ratio, masking procedures, or a detailed protocol in the record described by these results. It also does not report a formal sample-size justification. These omissions limit how fully the planned design can be reconstructed from the registry entry.

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

Analysis population for the primary outcome, as defined in the registry: Following the DSMB recommendations, our site was told to enroll 5 participants in the RA group to assess safety. The enrollment was paused for a safety review of the data from the 5 participants. After a review of the preliminary data, we were approved to resume enrollment per the randomization schema. However, at the time of approval peak COVID rates had declined and despite substantial screening efforts, no eligible participants were enrolled. Therefore, the control arm is zero.

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: Following the DSMB recommendations, our site was told to enroll 5 participants in the RA group to assess safety. The enrollment was paused for a safety review of the data from the 5 participants. After a review of the preliminary data, we were approved to resume enrollment per the randomization schema. However, at the time of approval peak COVID rates had declined and despite substantial screening efforts, no eligible participants were enrolled. Therefore, the control arm is zero.

6. Primary Endpoint

The registry lists the primary outcome as Proportion of Patients Alive and Free of Respiratory Failure Through the 30-day Trial., measured over 30 Days.

The primary endpoint is the proportion of patients alive and free of respiratory failure through the 30-day trial. It combines survival with avoidance of specified respiratory-support measures. Respiratory failure is defined as requiring at least one of endotracheal intubation and mechanical ventilation; high-flow nasal cannula with the stated flow and oxygen-fraction criteria; noninvasive positive pressure ventilation or CPAP; or ECMO.

This kind of endpoint is used to express whether participants reached a clinically consequential status over a defined follow-up period. Combining survival with respiratory-support criteria means that being alive alone is not enough to meet the endpoint if a participant required one of the listed modalities. Conversely, the endpoint does not describe every aspect of illness, recovery, symptoms, or lung inflammation. The secondary cytokine outcome addresses changes in inflammatory markers, which is distinct from the clinical status captured by the primary endpoint.

The posted result is 100% for the regadenoson arm, with n=5, and no control-arm value, with n=0. Because there is no reported control outcome, the endpoint cannot provide a comparative estimate of the difference between regadenoson and placebo. The record does not report a confidence interval for the active-arm proportion. Thus, the number describes the posted observations but gives limited information about the range of outcomes that might be seen in a larger population.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

For a binary endpoint such as alive and free of respiratory failure, the basic descriptive statistic is the proportion of participants meeting the defined condition. In this record, the active-arm result is reported as 100% with n=5. A proportion summarizes the observed group; by itself, it does not show how likely the same result is to occur in a wider population, nor does it compare outcomes between groups. The control-arm count is n=0 and its outcome value is absent, so the essential information needed for a two-arm comparison is not available in the posted results.

What a confidence interval would describe

General statistical explanation: a confidence interval communicates uncertainty around an estimated quantity, using a specified method and assumptions. For a proportion, the interval reflects both the observed proportion and the amount of information in the sample. With a small sample, the estimate can be sensitive to the outcome of an individual participant, and the uncertainty is usually important to show alongside the point estimate. The registry does not report an interval for the primary outcome. No interval should be inferred from the point estimate alone.

A confidence interval for each arm would still not answer the comparative question as directly as a treatment-effect estimate with its own interval. A comparative estimate requires outcome information in both arms. Since the control arm has no posted outcome data, no comparative interval can be calculated or interpreted from these results. The registry’s record does not report a sponsor analysis that supplies such a comparison.

Why the group comparison is not estimable

General statistical explanation: a randomized trial usually evaluates a contrast between outcomes in assigned groups. The contrast might be expressed on an absolute or relative scale, depending on the endpoint and analysis plan. The choice of scale and method should be specified in advance and interpreted with its uncertainty. Here, the posted active-arm proportion and the absent control-arm proportion do not allow either kind of treatment contrast. Reporting a numerical comparison would require inventing or imputing control data, which the registry does not provide.

The registry labels the trial randomized, triple-masked, and parallel. These design labels describe the stated study structure, not the completeness of the posted results. Randomization can reduce systematic differences between groups on average when the design is implemented and analyzed as planned; masking can reduce some forms of influence on care or assessment. Neither design feature removes uncertainty from a very small observed group, supplies missing outcomes, or guarantees that a treatment effect can be estimated from the posted record. The actual allocation ratio and detailed masking procedures are not reported in the registry record.

What the sample-size assumptions mean

General statistical explanation: sample-size planning considers the effect a study aims to detect, a significance level, allocation, and assumptions about the outcome and analysis. A planning calculation is not a finding about the trial’s observed effect, and it is not observed power. The registry’s planning assumptions describe a two-sided significance level of 0.05, equal allocation, and a normal approximation; the effect to detect is expressed as a fraction of the observed effect. The record does not report numerical planning estimates in the registry record analyzed for this explanation, nor does it report a formal design justification. The planning assumptions should not be mistaken for evidence that the trial met its intended enrollment or had a particular power.

General statistical explanation: normal approximations can be convenient, but their performance depends on the data and the model being used. For a binary outcome in a very small group, approximation-based calculations may not capture uncertainty well. More generally, when data are over-dispersed relative to a model’s assumptions, variability is greater than the model expects and standard errors or intervals can be misleading if that extra variation is ignored. The registry does not report an over-dispersion assessment or a model-based primary analysis, so this is a general consideration rather than a claim about the trial’s analysis.

The planning description also distinguishes time-to-event calculations, which use a total number of events, from other calculations, which are expressed as participants per arm. That distinction describes how those illustrations are framed; it does not mean that an event-based analysis or a particular sample-size target was used for the primary endpoint. The record does not post the numerical planning values or enough details to reconstruct them.

Descriptive safety counts

General statistical explanation: adverse-event counts are usually interpreted with their denominators and the period over which events were collected. A count of zero in a small group says that no events of that category were recorded among those participants in the available safety data. It does not prove that the event cannot occur, and it does not establish a difference from another treatment. Here, the registry lists five regadenoson participants at risk and zero control participants at risk. The absence of control participants prevents a comparative safety analysis, and the record does not provide a more detailed analysis method.

The registry lists zero analyses. It does not report the statistical method used for the primary endpoint, a prespecified estimator, confidence-interval method, hypothesis test, adjustment procedure, or detailed handling of missing observations. Therefore, interpretation should remain at the level of the posted descriptive counts and outcome value rather than assuming an unreported inferential method.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists one secondary outcome concerning changes in inflammatory cytokine levels before, during, and after drug infusion, and counts two outcome measures overall. It lists zero analyses. The record does not report a multiplicity strategy, such as prioritizing outcomes, adjusting significance thresholds, or controlling an overall error rate across multiple tests. Since no inferential analyses are posted, there are no reported multiplicity-adjusted conclusions to interpret.

Missing-data handling is not reported in the registry record. The primary result lists five participants in the regadenoson arm and zero in the control arm. This absence of control-arm outcome data is central to interpretation, but the record does not describe its cause, whether any outcomes were missing after enrollment, or whether any participants were excluded from an analysis. It would be inappropriate to label the absence as a particular missingness mechanism or assume that an imputation method was used.

The analysis populations are not described in detail. The registry does not say whether the primary result is based on all randomized participants, participants who received treatment, participants with available outcomes, or another defined population. It does not report a prespecified intention-to-treat approach or per-protocol analysis. The outcome population description does state that enrollment was directed to the regadenoson group for a safety assessment and that enrollment was paused for review. The detailed relationship between this safety process and the posted analysis population is not reported.

The record also does not report interim efficacy analyses, stopping boundaries, or a planned sequence of hypothesis tests. It does describe a safety review following DSMB recommendations after five regadenoson participants. That statement establishes that a safety review occurred in the described context, but it does not establish that an interim efficacy test was conducted or explain the review’s statistical procedures.

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.

The registry reports zero serious adverse events among 5 regadenoson participants at risk, zero other adverse events among 5 at risk, and zero deaths. The placebo group has 0 participants listed at risk, with no event counts available for a meaningful comparison. These are observed counts, not estimates of comparative risk.

A zero count means that no events in the reported category were recorded among the listed participants at risk. It does not show that the risk is zero in a larger population. With only five participants in the active group, the observations provide limited information about less common events or the range of possible safety outcomes. A zero in the control column should not be interpreted as evidence of no events in a populated control group, because the listed control at-risk count is zero.

The registry does not give detailed definitions for serious and other adverse events, the safety observation period, event-level descriptions, or a statistical comparison. It also does not report confidence intervals for these counts. The DSMB-related safety review described in the record provides context for the enrollment pause, but the posted counts alone do not describe the review’s findings or procedures. The counts should therefore be read as limited descriptive safety information, not as proof of safety or as a treatment comparison.

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

The posted data establish that the registry reports a primary endpoint value of 100% for the regadenoson arm, with five participants listed, and no value for a control arm with zero participants listed. They also report zero serious adverse events, zero other adverse events, and zero deaths among the five regadenoson participants at risk. These are the direct descriptive observations available in the record.

They do not establish whether regadenoson performed better, worse, or similarly to placebo on the primary endpoint. A comparison requires outcome information from both arms. The randomized, triple-masked design labels do not substitute for the absent control result. No p-value, treatment-effect estimate, or confidence interval is posted, and the registry lists zero analyses.

The active-arm point estimate should not be read as a precise prediction for other patients. The group is small, and the record does not quantify uncertainty around the 100% value. The result also concerns a particular composite status through 30 days; it is not a general measure of all symptoms, inflammatory activity, or longer-term outcomes. The cytokine outcome is listed separately, and its numerical results are not included in the information summarized by the posted primary result.

Likewise, the safety counts do not demonstrate that adverse events cannot occur or that regadenoson is safer than placebo. There are no control participants listed at risk, and the active group is small. The zero counts describe what was recorded for the participants listed, not a guarantee about risks in a larger population.

The registry’s account of enrollment and safety review helps explain why the available evidence is limited: the site was directed to enroll five regadenoson participants for safety assessment, enrollment was paused for review, and the record says approval was given to resume enrollment. The posted outcome entries nevertheless do not provide a two-arm comparison. The most defensible interpretation is descriptive rather than comparative, with substantial limits on precision and generalization.

13. Why This Trial Matters Statistically

This trial illustrates why a study’s design labels and its posted analysis data need to be considered together. Randomization and masking are important design features, but a treatment comparison still depends on outcome information in the groups being compared. Here, the registry lists a parallel randomized trial but reports five active-arm participants and no control-arm participants for the primary outcome. That difference between design description and available result makes the limits of the evidence especially visible.

It also shows why denominators matter. A 100% result can sound definitive when presented alone, but its interpretation depends on the group size and uncertainty. With five participants listed and no confidence interval, the registry’s point estimate cannot convey how much the result might vary in a larger sample. Reporting the denominator alongside the percentage is essential to keep the scale of the evidence in view.

The record’s safety-review context is also statistically relevant. A review prompted enrollment decisions and a pause, while the posted result remains too limited for a two-arm efficacy estimate. This highlights that a trial may generate useful safety observations without producing an interpretable comparative clinical endpoint. Safety counts and efficacy comparisons answer different questions and require their own appropriate denominators and analyses.

Finally, the record demonstrates the value of transparent reporting of analysis populations, missing outcomes, uncertainty, and statistical methods. Those details are not reported in sufficient depth to reconstruct an inferential analysis. In their absence, disciplined interpretation means describing the posted observations, identifying what comparison cannot be made, and avoiding claims that go beyond the data.

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 lists no control participants with a primary outcome value. Although the trial is described as randomized and parallel, the posted outcome therefore cannot support a direct comparison with placebo. The record does not explain in detail why the control-arm count is zero or whether additional outcome data exist outside the posted entries.

The regadenoson arm includes only five participants in the posted result. The 100% point estimate has no reported confidence interval, and the record does not provide a precision estimate. This limits assessment of how stable the proportion might be beyond the participants recorded.

The registry’s outcome population description is incomplete at its end and does not give a full account of the randomization sequence, allocation ratio, or analysis set. The record does not specify whether every randomized participant was included in the reported outcome, how missing data were handled, or whether the result followed a prespecified analysis plan. Detailed statistical methods and the sample-size justification are not reported in the registry record.

There is also limited information about the secondary cytokine outcome in the posted results. Although a change in cytokine levels is listed, numerical results and analysis details are not reported in the registry record analyzed. The record does not provide outcome-specific estimates for each respiratory-support component, so the composite primary endpoint cannot be separated into its component events from these figures.

Safety interpretation is constrained by the same small active group and lack of a populated control group. Event definitions, collection period, and detailed safety-review findings are not reported. The completed status and study dates do not resolve these analytic limitations or establish that all planned analyses are available.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Treat COVID-19 Patients With Regadenoson — NCT04606069.
• Registry record last updated 2025-03-20; status last verified 2025-02.
• Results first posted 2025-03-20.
• 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

NCT04606069 is listed as a completed randomized, triple-masked, parallel Phase 1 and Phase 2 trial sponsored by the University of Maryland, Baltimore. It studied intravenous regadenoson versus saline placebo in adults described as having moderate to severe COVID-19. The listed enrollment is 5; the recorded start date is 2021-05-06 and primary completion date is 2023-04-24.

The primary outcome is the proportion alive and free of respiratory failure through 30 days. The posted value is 100% for the regadenoson arm, with n=5; the control arm has n=0 and no reported value. The registry also lists zero serious adverse events, zero other adverse events, and zero deaths among five regadenoson participants at risk, with no control participants at risk. A secondary outcome concerns changes in inflammatory cytokines. Because no control-arm outcome is posted and no analyses are listed, the primary result is descriptive rather than a comparative estimate.