Switching From DAPT to Dual Pathway Inhibition With Low-dose Rivaroxaban in Adjunct to Aspirin in Patients With Coronary Artery Disease: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Switching From DAPT to Dual Pathway Inhibition With Low-dose Rivaroxaban in Adjunct to Aspirin in Patients With Coronary Artery Disease (NCT04006288), a randomized phase 4 study. The primary outcome is Maximal Platelet Aggregation (MPA%) by Light Transmittance Aggregometry (LTA).

2. Clinical Question

The study is focused on a laboratory measure of platelet response, rather than a clinical event outcome. The registry describes a randomized study in which patients were assigned either to maintain DAPT or to switch to DPI. It reports six regimen-specific outcome groups: three continued DAPT groups and three groups switching from the corresponding DAPT regimen to aspirin plus rivaroxaban.

The clinical question therefore has a treatment-switching component and a pharmacodynamic component. It asks whether the platelet aggregation measure differs across the assigned treatment strategies at the specified assessment time. The registry’s stated objectives also include feasibility, but a separate numerical feasibility outcome is not reported in the registry record. The posted primary outcome is the comparison of MPA% at 30 days, expressed as a median and interquartile range for each group.

3. Trial Design

This was a completed phase 4, randomized, open-label, parallel study sponsored by the University of Florida. The registry lists coronary artery disease as the condition and an enrollment of 90. The study began on 2019-09-06, reached primary completion on 2022-01-31, and has a completed status.

The study concerned people with coronary artery disease taking DAPT as standard care. The registry describes random assignment to maintain DAPT or switch to DPI. The six listed treatment groups correspond to aspirin with clopidogrel, prasugrel, or ticagrelor, and aspirin plus rivaroxaban after each of those three DAPT regimens. Each listed regimen was specified for 30 days. The DPI regimen was aspirin 81mg/qd plus rivaroxaban 2.5mg/bid.

The registry labels the design parallel and reports no masking. It does not describe the sequence-generation method, concealment of allocation, the process used to form or assign the three DAPT cohorts, or whether randomization was stratified by the starting P2Y12 inhibitor. Those details are not reported in the registry record, so the assignment process cannot be characterized more specifically.

The primary endpoint was maximal platelet aggregation measured at 30 days by light transmittance aggregometry using the CATF cocktail as agonist. The registry reports group medians and interquartile ranges. The outcome counts are 14 for the aspirin-and-clopidogrel group and its corresponding switch group, and 15 for each of the other four groups. A reason for the difference between these outcome counts and the adverse-event risk counts is not reported in the registry record.

The registry presents no inferential analysis entries and no posted secondary outcome measures. The protocol’s sample-size justification, planned duration of follow-up beyond the stated endpoint timeframe, and any interim analysis plan 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.

Before assignment: Patients treated with either aspirin (81mg/qd) plus clopidogrel, aspirin (81mg/qd) plus ticagrelor (90mg/bid), or aspirin (81mg/qd) plus prasugrel (10mg/bid) were identified. Each cohort was randomized 1:1 to either maintain DAPT or to DPI. DPI consists in treatment with aspirin (81mg/qd) plus rivaroxaban (2.5mg/bid). Patients randomized to DAPT will continue their guideline recommended DAPT regimens.

Overall Study

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.

Only the first 6 of 7 groups are shown.

6. Primary Endpoint

The registry lists the primary outcome as Maximal Platelet Aggregation (MPA%) by Light Transmittance Aggregometry (LTA), measured over 30 days.

The primary endpoint is maximal platelet aggregation (MPA%) measured by light transmittance aggregometry (LTA), with the CATF cocktail used as the agonist. The registry gives the unit as percentage of MPA and sets the timeframe at 30 days. The posted summaries are medians with interquartile ranges.

In general, platelet aggregation is a laboratory measure of how platelets respond under a specified test condition. LTA assesses changes in light transmission as platelets aggregate in a sample. An agonist is used to prompt that response; the CATF cocktail defines the stimulus used for this endpoint. The resulting MPA% summarizes the maximum aggregation response recorded during the test. It is a pharmacodynamic measure, meaning that it describes a biological response to the treatment regimen rather than directly counting clinical events.

Such a measure is relevant to this study because its stated objective is to compare the pharmacodynamic profiles of continued DAPT and DPI after a treatment switch. A 30-day assessment gives a defined time point for comparing the groups. The registry does not report a threshold defining a clinically important change in MPA%, nor does it report how this laboratory measure relates to later clinical outcomes. Therefore, the endpoint describes platelet response in the study setting; by itself, it does not establish a difference in clinical event risk.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a median describe?

The median is the middle value when observations are ordered. It is a measure of central tendency that is less influenced by extreme values than the arithmetic mean. The posted MPA% summaries use medians, consistent with the registry’s specification of the endpoint as a median with interquartile range. A median describes the center of the observed group values; it does not, on its own, describe how uncertain that center is as an estimate for a wider population.

What does an interquartile range describe?

In general, the interquartile range (IQR) runs from the 25th percentile to the 75th percentile. It contains the middle half of observed values and describes their spread. It is not a confidence interval. A confidence interval, in general, is an interval estimate intended to communicate uncertainty in an estimated quantity, such as a group difference or population parameter. No confidence intervals are posted for the primary outcome, so the precision of a treatment contrast cannot be read directly from the registry results.

Why keep the starting regimens separate?

The posted endpoint is organized around three DAPT regimens and the corresponding switch from each regimen. Comparisons within each starting regimen address the question of continuing that particular DAPT regimen versus switching to aspirin plus rivaroxaban. The groups have different observed medians and spreads, so combining them into one summary could obscure regimen-specific patterns. A pooled comparison would require a defined analysis method and a clear rationale; neither is reported in the registry record.

In general, a treatment contrast should be defined before analysis, including which groups are compared and which outcome scale is used. The registry states that MPA% is compared between DAPT and DPI for each DAPT regimen, but it does not post the statistical method used to estimate or test those contrasts. No p-values or other inferential analysis entries are reported. Consequently, the medians and IQRs can be described, but the statistical evidence for between-group differences cannot be assessed from the posted results.

What does randomization contribute?

In general, randomization assigns participants to treatment strategies by chance, which can help make groups comparable with respect to measured and unmeasured characteristics. The registry identifies the study as randomized, but the allocation sequence, concealment procedures, and details of assignment within the regimen cohorts are not reported in the registry record. The open-label designation means the study was not masked; the registry does not explain how that feature was handled in measurement or analysis. These omissions do not change the reported outcome values, but they limit how fully the design and risk of bias can be evaluated.

How should planning sample sizes be understood?

In general, a sample-size planning calculation uses assumptions about a target effect, variability, significance level, allocation, and statistical method to illustrate the number of participants that might be needed for a planned study. Such a calculation is not a description of the number actually observed and is not “observed power.” The registry record describes planning illustrations based on the observed effect, a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It also specifies that the effect to detect is a stated fraction of the observed effect. Numerical planning results are not reported in the registry record. Those assumptions should not be treated as the original design justification; the trial’s own sample-size justification is not reported in the registry record.

In general, over-dispersion occurs when outcome variability is greater than expected under a model’s assumptions. It matters because underestimated variability can make uncertainty appear too small and statistical tests too optimistic. The posted primary endpoint is continuous and summarized with medians and IQRs; the registry does not report a fitted model or indicate that an over-dispersion adjustment was used. This concept is therefore general statistical context, not a description of an analysis reported for this study.

What can be concluded from descriptive summaries?

Descriptive statistics organize the observed data without themselves testing a hypothesis. Here, each median and IQR communicates the central value and middle spread for a treatment group at 30 days. The summaries do not quantify a between-group effect, adjust for baseline characteristics, or establish that a pattern is unlikely to be due to chance. Because the registry does not report the inferential method, analysis population, or treatment-contrast estimates, these details cannot be reconstructed from the posted summaries alone.

10. Multiplicity, Missing Data and Analysis Populations

The primary endpoint is described as a comparison of DAPT and DPI for each of three DAPT regimens. Considering multiple regimen-specific comparisons raises a general multiplicity question: when several statistical tests are made, the chance of at least one false-positive finding can increase if each test is judged independently at the same threshold. Common approaches include prespecifying a primary contrast, adjusting the testing threshold, or using a hierarchical testing strategy. Which, if any, approach was planned or used is not reported in the registry record.

The registry lists one primary outcome measure and no posted secondary outcome measures. It does not report inferential analysis entries, p-values, confidence intervals, or an adjustment for multiple comparisons. The six descriptive group summaries do not by themselves reveal whether or how multiplicity was addressed.

The endpoint counts are 14 for the clopidogrel group and its corresponding switch group, and 15 for the other four groups. The registry does not explain the difference between these endpoint counts and the adverse-event risk counts of 15 in each group. It does not report whether any endpoint data were missing, why the outcome counts differ, or how missing observations were handled. Reasons for missingness, if any, are not reported in the registry record.

The analysis population is also not specified. It is not reported whether the primary endpoint summaries were based on all randomized participants, participants who received assigned treatment, or participants with an available measurement. The registry does not report an intention-to-treat definition, per-protocol criteria, exclusions, or sensitivity analyses. These are important details for understanding how the randomized groups were represented in the reported outcome summaries, but they cannot be inferred from the group counts alone.

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 non-serious adverse event terms

The registry reports serious adverse events, other adverse events, and deaths separately for each of the six treatment groups. For serious adverse events, the count affected is 0 in every group; the risk count is 15 in each group. Deaths are reported as 0 in every group. For other adverse events, 1 participant is listed in the group switching from aspirin and clopidogrel to aspirin and rivaroxaban, with a risk count of 15. The other groups each have 0 affected, with 15 at risk.

These counts are descriptive. They indicate the events recorded in the registry for the groups and do not provide a comparative safety estimate, confidence interval, or formal test. The study enrolled 90 participants, but the adverse-event summaries are shown by group with 15 at risk in each. The registry does not provide additional detail about event definitions, severity grading beyond the serious-versus-other classification, timing, causality assessment, or whether participants experienced more than one event.

Zero recorded serious adverse events or deaths in these groups should not be read as proof that such events cannot occur. The counts describe what was reported during the study, and the limited group sizes constrain how much can be learned about uncommon events. The registry does not report a longer-term safety assessment beyond the listed study information.

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

The posted results describe 30-day maximal platelet aggregation for six regimen-specific groups. They show the median and interquartile range for participants who continued aspirin with clopidogrel, prasugrel, or ticagrelor, and for participants who switched from each corresponding regimen to aspirin plus rivaroxaban. The values provide a descriptive view of the laboratory outcome in these groups.

They do not establish a statistically significant difference between any pair of groups. The registry does not report treatment-contrast estimates, confidence intervals, p-values, or an inferential analysis method. Nor do the summaries show whether differences in platelet aggregation correspond to differences in clinical events. The primary endpoint is a pharmacodynamic measurement, not a direct measure of ischemic recurrence, bleeding, or another clinical outcome.

The study’s stated objectives include assessing the feasibility of switching and comparing pharmacodynamic profiles. The registry provides the primary endpoint summaries and adverse-event counts, but a separate numerical feasibility result is not reported in the registry record. As a result, the extent to which the study achieved its feasibility objective cannot be judged from the posted information alone.

Randomization is an important feature of the design, but the registry does not describe its implementation or the analysis population. The outcome groups are small, and no uncertainty intervals for the medians or treatment contrasts are posted. The findings should therefore be understood as limited descriptive evidence about a laboratory measure at the stated time point, not as a definitive estimate of treatment effect.

The results also do not establish how these regimens compare in other populations, over longer follow-up, or for outcomes not reported in the registry. The registry record does not provide secondary outcome results, a sample-size justification, or a detailed statistical plan. Those absences limit the conclusions that can be drawn about precision, multiplicity, and generalizability.

13. Why This Trial Matters Statistically

This trial is statistically notable because it frames a treatment-switching question across three existing DAPT regimens rather than presenting one undifferentiated comparison. The posted endpoint summaries remain separated by the starting P2Y12 inhibitor, making clear that the observed platelet aggregation values vary across the regimen-specific groups. That structure matters when deciding what comparison a statistical analysis should target.

The study also illustrates the distinction between a biological or pharmacodynamic endpoint and a clinical outcome. MPA% measured by LTA at 30 days provides a laboratory description of platelet response under a specified test condition. It does not automatically quantify clinical benefit or harm. An analysis of this endpoint needs to be interpreted on its own terms, alongside—not as a substitute for—clinical outcomes.

Finally, the record highlights the importance of reporting inferential methods and uncertainty. Medians and IQRs are useful descriptive summaries, particularly when distributions may not be well represented by a mean and standard deviation. However, without treatment-contrast estimates, confidence intervals, p-values, and a stated analysis population, readers cannot judge the precision of comparisons or how the analysis handled multiple regimen-specific questions. The posted information supports a careful description of group outcomes, while leaving important questions about statistical evidence unanswered.

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.

Several trial-specific limitations affect interpretation of the posted results. The endpoint groups are small: the two clopidogrel-related groups have outcome counts of 14, and each of the four other groups has an outcome count of 15. The registry gives no confidence intervals for the medians and no estimate of the treatment contrast within any starting regimen. Precision therefore cannot be assessed directly from the posted results.

The registry identifies the study as randomized and open-label, but does not report the randomization procedure, allocation concealment, or how participants were assigned to the three starting-regimen cohorts. It also does not report the analysis population, handling of missing data, or reasons that outcome counts differ from adverse-event risk counts. These omissions limit assessment of the conduct and analysis.

Multiplicity is relevant because the primary outcome is described across three regimen-specific comparisons, but the planned testing strategy is not reported. No inferential results or secondary endpoint results are posted. The trial’s own sample-size justification and detailed statistical analysis plan are not reported in the registry record.

The primary endpoint is a laboratory measure at 30 days. The registry does not report a threshold for clinical importance or a link between the MPA% findings and longer-term clinical outcomes. The adverse-event summaries contain few recorded events, and further event detail and longer-term safety information are not reported in the registry record. These limitations mean the record supports description of the observed measurements and event counts, but not broad conclusions about clinical outcomes or longer-term safety.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Switching From DAPT to Dual Pathway Inhibition With Low-dose Rivaroxaban in Adjunct to Aspirin in Patients With Coronary Artery Disease — NCT04006288.
• Registry record last updated 2023-04-26; status last verified 2023-04.
• Results first posted 2023-04-26.
• 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

NCT04006288 is a completed phase 4, randomized, open-label, parallel study of people with coronary artery disease taking DAPT. The registry lists enrollment of 90 and sponsorship by the University of Florida. The study began on 2019-09-06, with primary completion on 2022-01-31.

The stated objectives were to assess the feasibility of switching from DAPT to DPI and compare pharmacodynamic profiles. DPI was aspirin 81mg/qd plus rivaroxaban 2.5mg/bid. The primary endpoint was MPA% measured by LTA using the CATF cocktail as agonist at 30 days. Results are posted as medians and interquartile ranges for three continued DAPT groups and their corresponding switch groups.

The registry reports no inferential analysis entries or secondary outcome measures. Further details of the statistical plan, missing-data handling, analysis population, and sample-size justification are not reported in the registry record.