This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for A Study to Evaluate the Efficacy and Safety of Rivaroxaban Venous Thromboembolism (VTE) Prophylaxis in Ambulatory Cancer Participants (NCT02555878), a randomized phase 3 study. The primary outcome is Percentage of Participants With Time to First Occurrence of Primary Efficacy Endpoint (Composite and Components).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02555878 |
| Phase | Phase 3 |
| Condition | Neoplasms |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Triple |
| Enrollment | 841 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Janssen Research & Development, LLC |
| Results posted | Yes |
2. Clinical Question
Population
Ambulatory adults with various cancer types who were initiating systemic cancer therapy and considered at high risk of venous thromboembolism (VTE). The primary analysis population is described as the Intent-to-treat population, consisting of all randomized participants.
Intervention
Rivaroxaban 10 mg orally once daily for 180 days.
Comparator
A matching placebo tablet orally once daily for 180 days.
Primary question
Among the randomized participants, what was the time to first occurrence of the primary VTE composite endpoint in each group, and how did the groups compare? The endpoint included specified deep vein thrombosis and pulmonary embolism events, as well as VTE-related death. The registry record describes the endpoint but does not report the group results or a treatment-effect estimate, so the comparative answer is not reported in the registry record.
The question is framed around prevention of VTE during systemic cancer therapy, not around every possible clotting event or all-cause mortality alone. The composite combines events that may differ in presentation and clinical severity. A time-to-first-event approach focuses on when the first qualifying event occurred for a participant; later qualifying events do not create additional first events for that endpoint. The posted record does not give the number of primary endpoint events, the observed percentages by group, a confidence interval, or a p-value. Consequently, the design and endpoint can be described, but the magnitude and precision of any group difference cannot be evaluated from the registry record.
3. Trial Design
The study is registered as a Phase 3, randomized, parallel-group trial with triple masking. It enrolled 841 participants. The trial compared rivaroxaban with placebo in ambulatory participants with cancer who were receiving systemic cancer therapy and were at high risk of VTE. The intervention descriptions specify a once-daily oral tablet for 180 days in each group: rivaroxaban 10 mg in the active-treatment group and a matching placebo in the comparator group.
The registry lists the study as completed. Its recorded start date is 2015-09-11, and its primary completion date is 2018-08-24. These dates describe the registered study timeline; they do not provide the timing of individual outcomes or the duration of follow-up for each participant. The primary endpoint timeframe is stated as up to Day 180.
Randomization is intended, in general, to make treatment groups comparable at the point of assignment with respect to measured and unmeasured characteristics, subject to chance. Masking can reduce the influence of treatment knowledge on participant experience, care, and outcome assessment. The record describes the trial as triple-masked and says that the primary endpoint events were adjudicated by an independent, blinded Clinical Endpoint Committee. The specific roles covered by triple masking are not reported in the registry record.
The primary endpoint population is the Intent-to-treat population, defined in the record as all randomized participants. The record does not report the allocation ratio, details of the randomization procedure, eligibility thresholds, or the planned sample-size justification. These design details should not be inferred from the total enrollment or the randomized label.
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: Deaths which were primary cause of treatment discontinuation (up to Day 180) are reported in participant flow excluding deaths which occurred after discontinuation.
Overall Study
| Stage | Placebo | Rivaroxaban 10 mg |
|---|---|---|
| STARTED | 421 | 420 |
| Treated | 404 | 405 |
| COMPLETED | 255 | 270 |
| NOT COMPLETED | 166 | 150 |
Reasons for not completing this period:
| Reason | Placebo | Rivaroxaban 10 mg |
|---|---|---|
| Lost to Follow-up | 2 | 3 |
| Withdrawal by Subject | 48 | 48 |
| Adverse Event | 12 | 8 |
| Death | 74 | 59 |
| Protocol Violation | 1 | 2 |
| Physician Decision | 12 | 13 |
| Other | 17 | 17 |
Analysis population for the primary outcome, as defined in the registry: The Intent-to-treat (ITT) population consisted of all randomized participants.
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 | Placebo | Rivaroxaban 10 mg | Total |
|---|---|---|---|---|
| Participants analysed | 421 | 420 | 841 | |
| Age, Continuous | years | 61.9 (SD 11.19) | 62.1 (SD 11.22) | 62 (SD 11.2) |
| Sex: Female, Male: Female | Participants | 215 | 198 | 413 |
| Sex: Female, Male: Male | Participants | 206 | 222 | 428 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 69 | 63 | 132 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 312 | 314 | 626 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 40 | 43 | 83 |
| Race/Ethnicity, Customized: White | Count of Participants | 346 | 352 | 698 |
| Race/Ethnicity, Customized: Black | Count of Participants | 18 | 13 | 31 |
| Race/Ethnicity, Customized: Asian | Count of Participants | 5 | 6 | 11 |
| Race/Ethnicity, Customized: Other | Count of Participants | 21 | 10 | 31 |
| Race/Ethnicity, Customized: Not reported | Count of Participants | 31 | 39 | 70 |
| Region of Enrollment: Belgium | Participants | 3 | 10 | 13 |
| Region of Enrollment: Brazil | Participants | 55 | 48 | 103 |
| Region of Enrollment: Bulgaria | Participants | 15 | 19 | 34 |
| Region of Enrollment: Canada | Participants | 0 | 3 | 3 |
| Region of Enrollment: Czech Republic | Participants | 25 | 12 | 37 |
| Region of Enrollment: France | Participants | 29 | 34 | 63 |
| Region of Enrollment: Germany | Participants | 60 | 53 | 113 |
| Region of Enrollment: Italy | Participants | 17 | 15 | 32 |
| Region of Enrollment: Russian Federation | Participants | 59 | 61 | 120 |
| Region of Enrollment: United Kingdom | Participants | 30 | 19 | 49 |
6. Primary Endpoint
The registry lists the primary outcome as Percentage of Participants With Time to First Occurrence of Primary Efficacy Endpoint (Composite and Components), measured over Up to Day 180.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Percentage of participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is the percentage of participants with time to first occurrence of a composite efficacy endpoint, assessed up to Day 180. The composite comprises objectively confirmed symptomatic or asymptomatic lower extremity proximal deep vein thrombosis, symptomatic lower extremity distal deep vein thrombosis, symptomatic upper extremity deep vein thrombosis, symptomatic non-fatal pulmonary embolism, incidental pulmonary embolism, or VTE-related death. Events were to be adjudicated by an independent blinded Clinical Endpoint Committee.
A composite endpoint can capture several related event types within one outcome definition. In general, this can increase the number of outcome events available for analysis compared with focusing on a single component, but interpretation depends on which components occur and how they contribute to the overall result. Components can differ in symptoms, detection, and clinical importance; a composite result does not by itself show the result for each component.
The time-to-first framing identifies the first qualifying event for each participant during the stated timeframe. The registry record describes the endpoint definition but does not report the primary event counts or group percentages. Component-specific results for this primary composite are also not reported in the registry record, so the contribution of individual event types cannot be assessed.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record supplies the question, treatment groups, endpoint definition, and primary analysis population, but it does not report the primary endpoint results. In particular, no group-specific primary endpoint percentages, event counts, treatment-effect estimate, confidence interval, or p-value are reported in the registry record. Therefore, the posted information does not establish the direction, size, or statistical precision of the primary comparison.
The endpoint is a time-to-first-event composite assessed up to Day 180. In general, a comparison of such outcomes needs to be interpreted in light of both how many participants experience an event and when those events occur. The registry record gives the endpoint timeframe and definition, but does not provide event-time summaries or a description of the statistical comparison used for the primary endpoint. The amount of follow-up available for each participant is not reported in the registry record.
It is also important that the primary outcome is a composite. A group difference in a composite could reflect one component more than another. Without the component results, the relative contribution of deep vein thrombosis, pulmonary embolism, and VTE-related death cannot be evaluated. The record names the qualifying components but does not report their individual event counts or estimates.
The listed safety counts are descriptive information, not a substitute for the missing primary endpoint results. For serious adverse events, the record lists 128 affected participants among 404 at risk in the placebo group and 134 among 405 at risk in the rivaroxaban group. For the other adverse-event grouping, it lists 145 among 404 at risk in the placebo group and 138 among 405 at risk in the rivaroxaban group. Death counts are listed as 106 and 85, respectively. The record does not provide a statistical comparison for these counts, nor does it state in the available information the specific event definitions and observation windows needed to interpret them fully. These counts alone do not show whether a difference is attributable to treatment.
Thus, the registry supports a description of the planned comparison and the posted safety counts, but not a conclusion about the primary efficacy comparison. A lack of reported primary results is not evidence that the groups had the same outcome; it means that the comparative result is not reported in the registry record.
9. Statistical Methods Explained
The registry identifies a randomized, parallel-group comparison and defines the primary analysis population as all randomized participants. It describes the primary outcome as a percentage of participants with time to first occurrence of a composite endpoint. However, the detailed statistical analysis plan, the exact primary comparison method, and the primary outcome estimates are not reported in the registry record. The methods below explain general statistical concepts relevant to this kind of endpoint; they should not be read as a description of methods confirmed for this trial.
What does randomization contribute?
In general, random assignment aims to create groups that are comparable at the start of a study. Because assignment is governed by chance, some differences between groups can still occur, especially in a finite sample. Randomization does not guarantee that every prognostic factor is balanced, and it does not eliminate uncertainty in the estimated treatment effect. The record states that allocation was randomized, but the particular sequence-generation and concealment procedures are not reported in the registry record.
What does a time-to-first composite measure?
A time-to-first endpoint records whether a participant experiences at least one event meeting the composite definition and the time at which the first such event occurs. Combining several event types can make the outcome broader, but it means the overall result represents the composite rather than any one component. A composite should therefore be read alongside component results when those are available. The registry record does not report primary component results.
Time-to-event methods can account for the fact that participants may have different lengths of observed follow-up. A participant who has not experienced an event by the end of observed follow-up is often treated as censored at that point in analyses designed for time-to-event data. Censoring is a statistical way to represent incomplete event-time observation; it does not mean that an event occurred. The handling of censoring and the follow-up information used for this trial are not reported in the registry record.
How should a percentage be read?
In general, a percentage of participants with an event describes the proportion of an analyzed group who met the outcome definition over a stated period. Its interpretation depends on the population included, the event definition, and the way missing outcome information is handled. A percentage alone does not convey uncertainty. A confidence interval, when reported, gives a range of values compatible with the data under the chosen statistical model and assumptions. The registry record does not report confidence intervals for the primary endpoint.
What would a treatment-effect estimate add?
A treatment-effect estimate expresses the comparison between groups using a specified scale. The choice of scale matters: different scales answer different questions and can have different interpretations. An estimate is generally more informative when accompanied by an interval estimate and a clear description of the analysis population and method. Neither the primary treatment-effect estimate nor its uncertainty is reported in the registry record, and no unadjusted recalculation can be made from the posted primary outcome information.
What does a p-value tell a reader?
In general, a p-value summarizes how inconsistent data are with a specified null hypothesis under a stated statistical model. It is not the probability that the null hypothesis is true, and it does not measure the size or clinical importance of an effect. A p-value is best considered with the effect estimate, its uncertainty, the endpoint definition, and the analysis plan. A primary endpoint p-value is not reported in the registry record. The significance threshold and the method planned for the primary comparison are also not reported.
Why might over-dispersion matter?
General explanation: over-dispersion occurs when observed variability is greater than a statistical model expects. If a model assumes less variability than is present, standard errors and uncertainty estimates can be misleading. The relevance of over-dispersion depends on the outcome and model. The posted primary endpoint is described as a percentage and a time-to-first composite, but the registry does not report a model or indicate that over-dispersion was assessed. It would therefore be inappropriate to claim that a particular over-dispersion adjustment was used or needed.
How does the analysis population affect interpretation?
In general, an Intent-to-treat analysis retains participants in their randomized groups, regardless of whether they completed assigned treatment. This preserves the comparison created by randomization and estimates the effect of assignment under the analysis definition. The registry identifies all randomized participants as the primary population, but does not report the number analyzed for the primary outcome or details of how missing outcome data were handled. The exact analysis procedures and estimand are not reported in the registry record.
These distinctions matter because design labels alone do not determine the actual analysis. Randomization, masking, an endpoint definition, and a named population describe important features, but they do not reveal the estimator, variance calculation, censoring approach, or missing-data assumptions. Without posted primary results and analysis details, no treatment-effect calculation or assessment of statistical precision can be made.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists multiple outcomes, including the primary composite and secondary outcomes such as symptomatic VTE events or VTE-related deaths, all-cause mortality, arterial thromboembolic events, visceral VTE, and additional composite efficacy outcomes. When a study evaluates multiple outcomes or performs multiple comparisons, the chance of at least one apparently notable result can increase. General methods to address multiplicity include prespecifying a hierarchy, adjusting significance thresholds, or treating secondary analyses as exploratory. The multiplicity strategy for this trial is not reported in the registry record.
The record identifies the Intent-to-treat population for the primary endpoint and defines it as all randomized participants. It does not report the primary endpoint analysis set size, the number of participants with missing outcome data, or how missingness was handled. In general, missing data can affect estimates when the probability of missingness is related to participant characteristics or outcomes. Different assumptions and methods can lead to different results, so the handling approach is important for interpretation.
The record also does not report the specific primary statistical model, censoring rules, interim-analysis plans, or a complete analysis plan. These items should not be inferred from the Phase 3 designation or from the existence of a primary endpoint. Since the primary estimates themselves are not reported in the registry record, the effects of multiplicity decisions and missing-data methods cannot be assessed from the posted information.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Placebo | 128 | 404 | 31.7% |
| Rivaroxaban 10 mg | 134 | 405 | 33.1% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Placebo | 106 of 404 |
| Rivaroxaban 10 mg | 85 of 405 |
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 |
|---|---|
| Placebo | 145 of 404 |
| Rivaroxaban 10 mg | 138 of 405 |
Most frequent serious adverse event terms
| Event term | Organ system | Placebo | Rivaroxaban 10 mg |
|---|---|---|---|
| Malignant Neoplasm Progression | Neoplasms benign, malignant and unspecified (incl cysts and polyps) | 33 of 404 | 29 of 405 |
| Pyrexia | General disorders | 8 of 404 | 8 of 405 |
| Pneumonia | Infections and infestations | 4 of 404 | 10 of 405 |
| Febrile Neutropenia | Blood and lymphatic system disorders | 4 of 404 | 6 of 405 |
| Sepsis | Infections and infestations | 4 of 404 | 6 of 405 |
| General Physical Health Deterioration | General disorders | 4 of 404 | 5 of 405 |
| Abdominal Pain | Gastrointestinal disorders | 3 of 404 | 5 of 405 |
| Dehydration | Metabolism and nutrition disorders | 5 of 404 | 3 of 405 |
| Dyspnoea | Respiratory, thoracic and mediastinal disorders | 5 of 404 | 3 of 405 |
| Anaemia | Blood and lymphatic system disorders | 3 of 404 | 3 of 405 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Placebo | Rivaroxaban 10 mg |
|---|---|---|---|
| Nausea | Gastrointestinal disorders | 55 of 404 | 55 of 405 |
| Anaemia | Blood and lymphatic system disorders | 59 of 404 | 46 of 405 |
| Fatigue | General disorders | 32 of 404 | 44 of 405 |
| Diarrhoea | Gastrointestinal disorders | 36 of 404 | 34 of 405 |
| Neutropenia | Blood and lymphatic system disorders | 24 of 404 | 25 of 405 |
| Decreased Appetite | Metabolism and nutrition disorders | 25 of 404 | 21 of 405 |
| Vomiting | Gastrointestinal disorders | 17 of 404 | 28 of 405 |
| Constipation | Gastrointestinal disorders | 12 of 404 | 29 of 405 |
Serious events with the highest arm-level rate: malignant neoplasm progression (8.2%), pneumonia (2.5%), pyrexia (2.0%), febrile neutropenia (1.5%), sepsis (1.5%).
The registry lists serious adverse event counts as 128 participants affected among 404 at risk in the placebo group and 134 among 405 at risk in the rivaroxaban group. For the other adverse-event grouping, it lists 145 affected among 404 at risk in the placebo group and 138 among 405 at risk in the rivaroxaban group. Death counts are listed as 106 for placebo and 85 for rivaroxaban. These are registry counts; the record does not provide a statistical comparison for them in the information described.
The serious-event terms listed include malignant neoplasm progression (8.2%), pneumonia (2.5%), pyrexia (2.0%), febrile neutropenia (1.5%), sepsis (1.5%), and dehydration (1.2%). The posted information does not establish that these terms are treatment-caused, nor does it provide enough context to attribute the listed term percentages to a specific group. Adverse-event counts are descriptive and should be interpreted in light of definitions, exposure time, follow-up, and analysis methods. Those details are not reported in the registry record. The figures do not replace the missing primary efficacy comparison and should not be read as proof of benefit or harm.
12. What the Result Does, and Does Not, Mean
The registry record describes a randomized comparison of rivaroxaban and placebo in ambulatory adults with cancer initiating systemic therapy who were at high risk of VTE. It specifies the dose and treatment period, identifies the primary endpoint as a time-to-first composite, and defines the primary population as all randomized participants. These details allow readers to understand the question the study was designed to address.
The record does not report the primary outcome results. As a result, the magnitude and direction of the primary group comparison, its precision, and the contribution of individual endpoint components are not reported in the registry record. The absence of these values cannot be interpreted as showing no difference, and it cannot support a conclusion that either intervention was superior. The trial description says that superiority was the study purpose, but a stated purpose is not an observed result.
The listed adverse-event and death counts are also not enough to establish a causal treatment effect. They are not accompanied by a comparative statistical analysis, uncertainty estimates, or all contextual details needed for interpretation. Differences between descriptive counts may arise by chance, and their meaning depends on how events were defined and observed.
In general, evidence from a randomized trial is interpreted by considering the estimated effect, its uncertainty, the analysis population, the endpoint definition, and potential limitations. For this study, several of those result-level elements are not reported in the registry record. The posted information therefore supports a careful account of the study design and endpoint, but not a claim about whether rivaroxaban reduced the primary outcome compared with placebo.
13. Why This Trial Matters Statistically
This trial is statistically notable as a randomized, triple-masked, parallel-group study with a defined primary analysis population and a time-to-first composite endpoint. Those features describe a structured comparison in a population facing VTE risk during systemic cancer therapy. The primary endpoint also illustrates an important interpretive issue: composite outcomes can combine related events while still requiring attention to which components occur and how they contribute.
Enrollment was 841, and the record identifies the primary population as all randomized participants. Those design details alone do not establish the precision of a treatment-effect estimate. Precision depends on the observed outcome data and analysis, neither of which is reported for the primary comparison in the registry record. It would be inappropriate to infer the trial's statistical power or sample-size rationale from enrollment alone. The sample-size justification is not reported in the registry record.
The record also illustrates why trial registration details and posted results serve different purposes. The description of the study question and outcome definition explains what was to be assessed; it does not provide the observed comparative result. Likewise, a list of secondary outcomes does not reveal whether multiplicity was controlled or how those analyses were interpreted. The multiplicity strategy and detailed statistical plan are not reported in the registry record.
For statistical interpretation, the main issue is therefore not a small or uncertain estimate, but the absence of the primary estimate itself. Without event counts, group percentages, an effect estimate, and an uncertainty interval, readers cannot judge the size or precision of the primary comparison. This distinction is important: missing results should be described as unavailable rather than treated as evidence of equivalence or no effect.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The main limitation for interpreting this registry record is that primary endpoint results are not reported. There are no group-specific event counts or percentages, treatment-effect estimates, confidence intervals, or p-values for the primary comparison. As a result, efficacy cannot be assessed from the posted primary outcome information.
The composite endpoint includes several types of deep vein thrombosis, pulmonary embolism, and VTE-related death. Although the record defines these components, it does not report component-level results. The relative contribution of different events to the composite is therefore unknown. The primary endpoint timeframe is stated as up to Day 180, but participant-level follow-up and time-to-event summaries are not reported in the registry record.
Details needed to assess the statistical approach are also absent, including the primary comparison method, missing-data handling, censoring procedures, multiplicity strategy, interim analyses, and sample-size justification. These methods should not be presumed from the trial's phase or design labels.
The safety counts provide some descriptive information, but the available record does not establish a comparative statistical analysis or provide all context needed to interpret event frequencies. The serious-event term percentages are listed without enough information to determine their group attribution. These limitations restrict interpretation of the posted safety data as well as the primary efficacy question.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Study to Evaluate the Efficacy and Safety of Rivaroxaban Venous Thromboembolism (VTE) Prophylaxis in Ambulatory Cancer Participants — NCT02555878.
- Registry record last updated 2019-09-12; status last verified 2019-08.
- Results first posted 2019-09-12.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
NCT02555878 is a completed Phase 3 randomized, triple-masked, parallel-group study comparing rivaroxaban with placebo in ambulatory adults with cancer receiving systemic cancer therapy and at high risk for VTE. The registry lists enrollment of 841 participants and an intervention period of 180 days, with rivaroxaban 10 mg once daily or matching placebo.
The primary outcome was a time-to-first composite of specified deep vein thrombosis, pulmonary embolism, or VTE-related death events, assessed up to Day 180 and defined for the Intent-to-treat population. The record does not report the primary comparative results, treatment-effect estimate, confidence interval, or p-value. It lists serious and other adverse-event counts and selected serious-event terms, but detailed analysis methods, missing-data handling, and multiplicity procedures are not reported in the registry record.