This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record.
1. Trial at a Glance
IMvigor211 was a randomized, parallel-group phase 3 treatment trial comparing atezolizumab with chemotherapy in participants with locally advanced or metastatic urothelial bladder cancer. The registry identifies overall survival as the single registered primary endpoint and reports three primary-endpoint statistical analyses.
| Feature | IMvigor211 |
|---|---|
| Trial | IMvigor211 |
| Phase | Phase 3 |
| Condition | Bladder Cancer |
| Population described in trial title | Participants with locally advanced or metastatic urothelial bladder cancer |
| Design | Randomized, parallel-group |
| Masking | None |
| Primary purpose | Treatment |
| Enrollment | 931 |
| Primary endpoint | Overall Survival (OS) |
| Primary endpoint type | Time-to-event |
| Results posted | Yes |
| Statistical analyses posted | 3 |
| Lead sponsor | Hoffmann-La Roche |
| Sponsor type | Industry |
| ClinicalTrials.gov | NCT02302807 |
2. Clinical Question
The central statistical question was whether atezolizumab differed from chemotherapy with respect to overall survival in participants with locally advanced or metastatic urothelial bladder cancer. The registry identifies the hypothesis type for the posted primary analyses as superiority.
Population
Participants with locally advanced or metastatic urothelial bladder cancer, described under the registry condition of bladder cancer.
Intervention
Atezolizumab (MPDL3280A), described in the registry as an engineered anti-PDL1 antibody.
Comparator
Chemotherapy using vinflunine, paclitaxel, or docetaxel, according to the reported comparison groups.
Primary question
Does atezolizumab demonstrate a different overall-survival experience from the specified chemotherapy comparison under a superiority framework?
3. Trial Design
Atezolizumab
- Atezolizumab (MPDL3280A)
- Registry description: engineered anti-PDL1 antibody
- Assigned as one randomized treatment group
Chemotherapy
- Vinflunine
- Paclitaxel
- Docetaxel
- Reported statistical comparisons use chemotherapy as the comparator group
The registry reports an enrollment of 931 and two study arms. The ClinicalTrials.gov record does not provide a randomization ratio, arm-specific randomized sample sizes, treatment doses, treatment schedules, stratification factors, crossover rules, interim-analysis specifications, or missing-data procedures. Those design details are therefore not reconstructed here.
4. Endpoints
| Endpoint | Registry definition / time frame | Type |
|---|---|---|
| Overall Survival (OS) | Between randomization and death due to any cause, up to approximately 25 months after first participant enrolled. | Time-to-event |
The registry further defines OS as time from randomization to death from any cause. This definition is important statistically because participants who remain alive at the end of their observed follow-up do not have an observed death time and therefore contribute censored time-to-event information.
5. Statistical Methodology
Time-to-event analysis
Overall survival is a time-to-event endpoint because the outcome records both whether death occurred and the time from randomization until death. This structure differs from a simple binary endpoint measured at a single fixed time point.
Log-rank test
The registry identifies the log-rank test as the normalized statistical method for the primary analysis in the IC2/3 chemotherapy versus IC2/3 atezolizumab comparison. The log-rank framework compares the survival experience of randomized groups across observed event times rather than comparing only the proportion alive at one selected time point.
The log-rank test is designed for censored time-to-event data. Its test statistic evaluates whether the observed pattern of events over follow-up differs from what would be expected under the null comparison.
Hazard ratio
The effect measure reported for all three primary analyses is the hazard ratio (HR). A hazard ratio compares the instantaneous event rates between groups within a time-to-event modeling framework. An HR below 1 means the estimated event rate is lower in the numerator group relative to the denominator group, under the direction of the reported comparison.
An HR below 1 indicates a lower estimated instantaneous event rate in the atezolizumab group relative to chemotherapy under this orientation. It does not directly give a probability of survival, an absolute risk difference, or a median survival difference.
Confidence intervals
Each posted primary analysis with an estimate includes a two-sided 95% confidence interval. The interval describes statistical uncertainty around the estimated hazard ratio under the analysis framework. It should not be interpreted as a range containing the individual treatment effect for 95% of participants.
Intention-to-treat analysis
The registry analysis text explicitly defines the ITT population as all randomized participants, irrespective of whether the assigned treatment was actually received. An ITT analysis preserves the treatment comparison created by randomization and avoids redefining treatment groups based on post-randomization treatment receipt.
6. Primary Results: Overall Survival
ClinicalTrials.gov reports three primary-endpoint analyses for Overall Survival. All three use the ITT population as defined in the ClinicalTrials.gov record. The comparisons differ in the chemotherapy and atezolizumab group definitions used by the registry.
IC2/3 Chemotherapy vs IC2/3 Atezolizumab
Hazard ratio for overall survival
95% CI: 0.63–1.21 · P = 0.4134
Two-sided 95% confidence interval · Superiority hypothesis
| Feature | Reported result |
|---|---|
| Endpoint | Overall Survival (OS) |
| Time frame | Between randomization and death due to any cause, up to approximately 25 months after first participant enrolled |
| Analysis population | Intent To Treat (ITT): all randomized participants, irrespective of whether assigned treatment was actually received |
| Groups compared | IC2/3 Chemotherapy vs IC2/3 Atezolizumab |
| Method | Log Rank |
| Effect measure | Hazard Ratio (HR) |
| Estimate | 0.87 |
| 95% CI | 0.63–1.21 |
| P-value | 0.4134 |
| Hypothesis type | Superiority |
An HR of 0.87 means that, under the reported comparison and time-to-event framework, the estimated instantaneous rate of death for IC2/3 atezolizumab relative to IC2/3 chemotherapy was approximately 87% of the corresponding chemotherapy rate. Expressed as a relative difference, this corresponds to an estimated 13% lower hazard in the direction of the atezolizumab comparison.
The HR does not mean that 13% of patients benefited, that mortality was reduced by exactly 13% for every individual, or that survival probability was 13 percentage points higher. It is a relative time-to-event measure rather than an absolute risk measure.
The two-sided 95% CI of 0.63–1.21 shows substantial uncertainty around the point estimate. Because the interval includes 1, values representing lower, similar, and higher hazards remain compatible with the interval under the stated statistical framework.
The reported P = 0.4134 addresses the evidence against the specified null hypothesis; it does not measure the magnitude of the treatment effect. The p-value should therefore not be interpreted as a percentage probability that the treatment works or as a measure of clinical importance.
For a time-to-event analysis, interpretation of a single HR also depends on the underlying hazard structure and the assumptions of the model used to obtain it. The ClinicalTrials.gov record identifies the log-rank method for this comparison but do not provide enough detail to independently assess proportional-hazards assumptions or the construction of any corresponding Cox model.
IC1/2/3 Chemotherapy vs IC1/2/3 Atezolizumab
Hazard ratio for overall survival
95% CI: 0.71–1.05 · P-value not reported in the registry analysis
Two-sided 95% confidence interval · Superiority hypothesis
| Feature | Reported result |
|---|---|
| Endpoint | Overall Survival (OS) |
| Time frame | Between randomization and death due to any cause, up to approximately 25 months after first participant enrolled |
| Analysis population | Intent To Treat (ITT): all randomized participants, irrespective of whether assigned treatment was actually received |
| Groups compared | IC1/2/3 Chemotherapy vs IC1/2/3 Atezolizumab |
| Method | Not reported |
| Effect measure | Hazard Ratio (HR) |
| Estimate | 0.87 |
| 95% CI | 0.71–1.05 |
| P-value | Not reported in the registry analysis |
| Hypothesis type | Superiority |
An HR of 0.87 corresponds to an estimated instantaneous death rate approximately 87% as large in the atezolizumab group as in the chemotherapy group, using the direction of the reported comparison. In relative terms, that is an estimated 13% lower hazard for atezolizumab.
This does not mean that individual patients experienced a 13% reduction in their probability of death, nor does it provide an absolute survival difference. Hazard ratios summarize relative event rates rather than directly reporting absolute treatment benefit.
The two-sided 95% CI of 0.71–1.05 is narrower than the first reported interval but still crosses 1. The point estimate is therefore not sufficient on its own to characterize the statistical evidence for a difference.
The ClinicalTrials.gov record does not report a formal p-value or the statistical method for this particular analysis. It would therefore be inappropriate to reconstruct or infer a p-value from the reported HR and confidence interval and present that inferred value as a registry result.
As with other hazard-ratio analyses, the interpretation concerns the time-to-event process and depends on the assumptions and censoring structure underlying the analysis. The ITT definition helps preserve the randomized comparison, but the ClinicalTrials.gov record does not provide enough information to evaluate additional modeling or censoring assumptions.
Chemotherapy vs Atezolizumab
Hazard ratio for overall survival
95% CI: 0.73–0.99 · P-value not reported in the registry analysis
Two-sided 95% confidence interval · Superiority hypothesis
| Feature | Reported result |
|---|---|
| Endpoint | Overall Survival (OS) |
| Time frame | Between randomization and death due to any cause, up to approximately 25 months after first participant enrolled |
| Analysis population | Intent To Treat (ITT): all randomized participants, irrespective of whether assigned treatment was actually received |
| Groups compared | Chemotherapy (Vinflunine, Paclitaxel, or Docetaxel) vs Atezolizumab |
| Method | Not reported |
| Effect measure | Hazard Ratio (HR) |
| Estimate | 0.85 |
| 95% CI | 0.73–0.99 |
| P-value | Not reported in the registry analysis |
| Hypothesis type | Superiority |
The reported HR of 0.85 indicates an estimated instantaneous death rate approximately 85% as large in the atezolizumab group relative to chemotherapy, under the direction of the reported comparison. This corresponds to an estimated 15% lower hazard for atezolizumab.
The HR is not an absolute reduction in mortality and does not mean that 15% of participants avoided death because of treatment. It also does not establish how the effect varies across individual follow-up times or patients.
The two-sided 95% CI of 0.73–0.99 is relatively close to 1 at its upper boundary. The interval quantifies uncertainty around the estimated HR and indicates that the estimate is more precise than an interval extending much farther from the point estimate, while still leaving the boundary close to the null value of 1.
No p-value is in the ClinicalTrials.gov record. The confidence interval and point estimate can be described directly, but a formal p-value should not be invented or back-calculated and then represented as if it were reported by the registry.
The registry labels this analysis as a superiority hypothesis. Superiority interpretation is distinct from non-inferiority: there is no non-inferiority margin reported in the ClinicalTrials.gov record, so none is introduced here. The ClinicalTrials.gov record also do not state whether this comparison had a separately allocated multiplicity-adjusted alpha level.
7. What the Three Primary Analyses Show Statistically
The three posted analyses all concern the same registered primary endpoint, Overall Survival, but they use different reported comparison labels. The numerical results should therefore be presented individually rather than silently collapsing them into one estimate.
| Comparison | HR | 95% CI | P-value | Method reported |
|---|---|---|---|---|
| IC2/3 Chemotherapy vs IC2/3 Atezolizumab | 0.87 | 0.63–1.21 | 0.4134 | Log Rank |
| IC1/2/3 Chemotherapy vs IC1/2/3 Atezolizumab | 0.87 | 0.71–1.05 | Not reported | Not reported |
| Chemotherapy vs Atezolizumab | 0.85 | 0.73–0.99 | Not reported | Not reported |
A useful statistical lesson is that a point estimate alone is not enough. The HR describes the estimated relative event rate, the confidence interval describes uncertainty around that estimate, and the p-value—when reported—addresses evidence against a specified null hypothesis. These quantities answer related but different questions.
8. Secondary Endpoint Results
the ClinicalTrials.gov record states that 11 outcome measures are posted in total. However, the ClinicalTrials.gov record contains three analyses, all identified as Primary and all concerning Overall Survival. No secondary endpoint estimates, confidence intervals, p-values, or formal statistical analyses are reported here.
For that reason, this page does not assign numerical results to secondary endpoints. Doing so would require information beyond the ClinicalTrials.gov record.
9. Safety Results
The ClinicalTrials.gov record provides serious adverse-event counts by randomized arm. The reported figures are based on the stated affected/at-risk counts.
| Safety measure | Affected / at risk |
|---|---|
| Chemotherapy (Vinflunine, Paclitaxel, or Docetaxel) | 189 / 443 |
| Atezolizumab | 192 / 459 |
The counts show the number affected and the corresponding number at risk as reported by the registry. The ClinicalTrials.gov record does not provide a formal statistical comparison, confidence interval, p-value, adverse-event grading breakdown, exposure duration, or event-specific safety table.
10. Statistical Methods Explained
Why is overall survival a time-to-event endpoint?
OS records the time from randomization until death from any cause. Unlike a binary outcome assessed at one fixed date, OS retains information about when events occur. Participants who are still alive at the end of their observed follow-up are censored rather than treated as if death had occurred.
Why use a log-rank test?
The log-rank test is designed to compare survival distributions while accounting for the timing of events and right censoring. Instead of reducing every participant to a simple yes/no outcome at one arbitrary time, it evaluates the accumulated difference in observed versus expected events across follow-up.
What does an HR of 0.87 mean?
With the comparison oriented as atezolizumab relative to chemotherapy, an HR of 0.87 means the estimated instantaneous death rate is 87% of the chemotherapy rate under the relevant time-to-event framework. The corresponding relative interpretation is an estimated 13% lower hazard. It is not a 13-percentage-point improvement in survival probability.
What does the 95% CI tell us?
A 95% confidence interval describes the statistical uncertainty surrounding the estimated hazard ratio. For example, the reported interval of 0.73–0.99 places the point estimate of 0.85 within a range extending close to the null value of 1. The interval is not a range of individual patient effects.
Why does the p-value not measure effect size?
A p-value evaluates the compatibility of the observed data with a specified null hypothesis under the statistical model. It depends on both the magnitude of an observed difference and the amount of information available. The hazard ratio itself is the effect estimate; the confidence interval describes its precision. Consequently, a p-value should not be read as a measure of how large or clinically important an effect is.
Why does ITT matter?
The registry defines ITT as all randomized participants, irrespective of whether the assigned treatment was actually received. An ITT analysis maintains the original randomized comparison rather than allowing post-randomization treatment receipt to redefine who belongs to each efficacy group. This distinction is particularly important in randomized trials because treatment adherence and discontinuation occur after randomization.
Why should the three HRs not simply be averaged?
The three analyses use different comparison labels: IC2/3, IC1/2/3, and the overall chemotherapy-versus-atezolizumab comparison. The ClinicalTrials.gov record does not provide the statistical relationship among these analyses, their multiplicity hierarchy, or a rule for combining them. An average would therefore create a new statistic that was not reported by the registry and whose interpretation is not established by the ClinicalTrials.gov record.
11. Understanding the Hazard Ratio More Deeply
An HR such as 0.85 is a relative measure. It tells us about the ratio of estimated event rates between treatment groups within the time-to-event framework. It does not directly tell us the absolute difference in the probability of being alive at a particular time.
The point estimate is only one summary of the data. The accompanying 95% CI is essential because it indicates how precisely the HR has been estimated. The reported analyses illustrate why an HR should never be interpreted without its interval.
A hazard ratio is a population-level comparative statistic. It does not imply that every participant experiences the same proportional change in their personal risk of death. Individuals can have very different event times even when the overall trial produces a single HR.
The HR answers an effect-size question: how do estimated event rates compare? The p-value addresses evidence against a null hypothesis. These are complementary quantities and should not be substituted for one another.
12. Intention-to-Treat Analysis
The registry's analysis population definition is explicit: all randomized participants, irrespective of whether the assigned treatment was actually received. This is the core ITT principle.
Why randomization is preserved
Once participants have been randomized, analyzing them according to their assigned group maintains the comparison established by the randomization process.
Why treatment receipt is different
Whether a participant actually received the assigned treatment is a post-randomization characteristic and can be influenced by events occurring after assignment.
What ITT does not solve
ITT does not eliminate censoring, missing follow-up, treatment discontinuation, or other practical complications of time-to-event analysis.
What the registry supplies
The registry-reported analysis text defines the ITT population but does not provide additional missing-data or censoring rules.
13. Censoring and Time-to-Event Interpretation
OS analyses generally require a distinction between participants who have experienced the event and participants whose event has not been observed during available follow-up. The registry's OS definition supplies the event itself—death from any cause—but the ClinicalTrials.gov record does not provide detailed censoring rules.
The survival function represents the probability that the event time T exceeds a specified time t. Kaplan-Meier estimation is one standard way to estimate this function when observations may be right-censored.
For the IMvigor211 registry record, the reported primary endpoint is explicitly time-to-event and the normalized primary method is the log-rank test. The ClinicalTrials.gov record does not report Kaplan-Meier estimates, median OS, numbers of deaths, censoring counts, or survival probabilities at particular time points, so none are added to this page.
14. Multiplicity and the Three Posted Analyses
Three primary-endpoint analyses are posted, all for Overall Survival. The ClinicalTrials.gov record identifies them as superiority analyses but do not state a multiplicity-adjustment strategy, alpha allocation, hierarchical testing sequence, or formal relationship among the three comparisons.
| Analysis | Role | What is reported |
|---|---|---|
| IC2/3 Chemotherapy vs IC2/3 Atezolizumab | Primary | HR 0.87; 95% CI 0.63–1.21; P = 0.4134; Log Rank |
| IC1/2/3 Chemotherapy vs IC1/2/3 Atezolizumab | Primary | HR 0.87; 95% CI 0.71–1.05; method and p-value not reported |
| Chemotherapy vs Atezolizumab | Primary | HR 0.85; 95% CI 0.73–0.99; method and p-value not reported |
Multiplicity matters whenever several statistical questions are evaluated because the chance of obtaining at least one apparently unusual result can increase with the number of tests. The correct interpretation depends on the prespecified testing strategy. Since that strategy is not contained in the ClinicalTrials.gov record, this page reports the analyses individually without assigning an unreported multiplicity adjustment.
15. Interim Analysis, Crossover, and Other Design Features
| Design topic | Information posted on ClinicalTrials.gov for IMvigor211 |
|---|---|
| Interim analysis | Not reported in the ClinicalTrials.gov record. |
| Crossover | Not reported in the ClinicalTrials.gov record. |
| Factorial design | Not reported; the registry design model is parallel. |
| Non-inferiority margin | Not applicable to the registry-reported description; the posted analyses are labeled superiority. |
| Missing-data / imputation method | Not reported in the ClinicalTrials.gov record. |
| Stratification factors | Not reported in the ClinicalTrials.gov record. |
| Bayesian methods | Not reported in the ClinicalTrials.gov record. |
This distinction is important. Absence of a design detail from the ClinicalTrials.gov record is not evidence that the underlying trial protocol lacked that feature. It means only that the ClinicalTrials.gov record does not support a more specific description.
16. Trial Timeline
Trial start
The registry lists January 13, 2015 as the trial start date.
Primary completion
The registry lists March 13, 2017 as the primary completion date.
Current registry status in the ClinicalTrials.gov record
the ClinicalTrials.gov record identifies the study status as COMPLETED.
17. Statistical Interpretation of the Primary Results
What the estimates say
The three reported OS hazard ratios are 0.87, 0.87, and 0.85. All are below 1 in the reported atezolizumab-versus-chemotherapy direction.
What the intervals say
The reported 95% CIs are 0.63–1.21, 0.71–1.05, and 0.73–0.99. Their widths and positions show that the precision and statistical implications differ across the analyses.
What the p-value says
Only the first registry-reported analysis includes a p-value, 0.4134. The other two analyses should not be assigned inferred p-values.
What is not reported
The ClinicalTrials.gov record does not provide median OS, survival probabilities at selected time points, event counts, Kaplan-Meier estimates, or subgroup results.
The most important statistical discipline is to keep the point estimate, uncertainty, and hypothesis-test evidence separate. For example, an HR below 1 is descriptive of the estimated direction and relative magnitude. Whether that estimate provides sufficient evidence against a null hypothesis depends on the confidence interval, p-value when reported, and prespecified inferential framework.
18. Important Limitations and Interpretation Issues
- Limited endpoint detail: the ClinicalTrials.gov record identifies Overall Survival as the sole registered primary endpoint but do not provide detailed information about the other posted outcome measures.
- Incomplete statistical-method reporting: the statistical method is log-rank, but only the first of the three posted analyses explicitly reports Log Rank. The other two do not report a formal method in the ClinicalTrials.gov record.
- Incomplete p-value reporting: only the first primary analysis reports a p-value. It would be inappropriate to derive unreported p-values and present them as registry results.
- No reported multiplicity strategy: three primary-endpoint analyses are reported, but the data do not specify alpha allocation, hierarchical testing, or another multiplicity-control procedure.
- No reported stratification factors: the ClinicalTrials.gov record does not identify any stratification variables, so none are attributed to the trial.
- No detailed censoring rules: the OS definition is reported, but detailed rules for censoring are not.
- No subgroup results: the statistical analyses posted on ClinicalTrials.gov contain no subgroup estimates, so subgroup consistency cannot be assessed from this dataset.
- No median OS: median survival is not contained in the ClinicalTrials.gov record and therefore is not reported here.
- No proportional-hazards assessment: hazard-ratio interpretation can depend on the behavior of hazards over time, but the ClinicalTrials.gov record does not report a proportional-hazards diagnostic.
- Safety scope: serious adverse-event counts are reported, but no formal statistical safety comparison or detailed adverse-event classification is provided.
- Analysis-population scope: ITT is explicitly defined for the primary analyses, but the ClinicalTrials.gov record does not provide additional efficacy populations or per-protocol analyses for comparison.
19. Why This Trial Matters Statistically
IMvigor211 is a useful teaching case because the registry record illustrates how a randomized clinical trial can generate several layers of statistical information from a single time-to-event endpoint.
| Concept | How it appears in IMvigor211 |
|---|---|
| Randomization | The study is identified as randomized with a parallel design. |
| ITT analysis | The primary analysis population is explicitly defined as all randomized participants, irrespective of whether assigned treatment was received. |
| Time-to-event endpoint | Overall Survival is defined as time from randomization to death from any cause. |
| Log-rank test | The normalized statistical method is log-rank, with Log Rank explicitly reported for one primary analysis. |
| Hazard ratio | All three primary analyses use HR as the effect measure. |
| Confidence interval | Each primary analysis supplies a two-sided 95% CI. |
| P-value interpretation | One primary analysis reports P = 0.4134, illustrating the distinction between an effect estimate and a hypothesis-test result. |
| Multiplicity | Three primary-endpoint analyses are posted, while the ClinicalTrials.gov record does not specify an adjustment strategy. |
| Safety analysis | Serious adverse-event affected/at-risk counts are reported by arm. |
| Registry transparency | The ClinicalTrials.gov record make it possible to distinguish reported numerical results from statistical details that are not reported. |
20. A Practical Framework for Reading IMvigor211
Because the endpoint is time-to-event, the analysis must account for both event timing and censoring.
An HR below 1 indicates a lower estimated event rate in the atezolizumab group when the comparison is oriented as atezolizumab relative to chemotherapy.
The confidence interval should be considered alongside the point estimate rather than treating the HR as an exact population quantity.
A p-value evaluates evidence against a null hypothesis; it does not quantify the size of the treatment effect.
A statistically careful analysis distinguishes unavailable information from information that was actually reported.
21. Clinical Biostats Perspective on Evidence Reporting
A strong clinical-trial results page should preserve the distinction between what the registry reports and what statistical reasoning allows us to infer. IMvigor211 provides a particularly clear example.
The reported HRs can be translated into relative hazard language, but that translation does not create absolute survival estimates. The confidence intervals can be interpreted as measures of uncertainty, but they do not provide a distribution of individual patient outcomes. The one reported p-value can be explained as a hypothesis-test quantity, but it does not become an effect-size metric.
Likewise, the absence of a reported p-value for two analyses is itself statistically relevant. A rigorous analysis should not fill that gap by reverse engineering a number and presenting it as if it were reported. The same principle applies to unreported stratification, crossover, interim monitoring, missing-data procedures, and subgroup analyses.
22. Related Tutorials
Learn more about the methods used in this trial:
23. Related Statistical Calculators
24. Sources
- ClinicalTrials.gov: NCT02302807 — IMvigor211.
- PubMed: PMID 33902955.
- PubMed: PMID 33241650.
- PubMed: PMID 31542806.
- PubMed: PMID 29562804.
- PubMed: PMID 29268948.
Continue through the Clinical Biostats statistical library
Use the trial's endpoint and analysis concepts to explore deeper material on survival analysis, clinical-trial methodology, and statistical calculation.
25. Record Summary
IMvigor211 is a completed randomized phase 3 trial with 931 participants, two parallel treatment arms, and Overall Survival as the registered primary time-to-event endpoint. The ClinicalTrials.gov record reports three primary OS analyses with hazard ratios of 0.87, 0.87, and 0.85, accompanied by two-sided 95% confidence intervals of 0.63–1.21, 0.71–1.05, and 0.73–0.99, respectively. Only the first analysis supplies a p-value, 0.4134.
The central statistical lesson is the importance of reading the complete effect estimate rather than any single number in isolation. Hazard ratios describe relative time-to-event effects; confidence intervals describe uncertainty; p-values address hypotheses rather than effect magnitude; and ITT analysis preserves the randomized treatment comparison. The ClinicalTrials.gov record also illustrate the importance of not filling gaps in a registry record with unreported assumptions about subgroup analyses, censoring, multiplicity, interim monitoring, or secondary endpoints.