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 Tamoxifen Citrate in Treating Patients With Metastatic or Recurrent Breast Cancer (NCT01124695), a na phase 2 study. The primary outcome is Progression-free Survival by CYP2D6 Status in 2 Categories.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01124695 |
| Phase | Phase 2 |
| Condition | Breast Cancer, Stage IV Breast Cancer |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 124 |
| Arms in the primary outcome | n/a |
| Lead sponsor | ECOG-ACRIN Cancer Research Group |
| Results posted | Yes |
2. Clinical Question
The trial asked whether progression-free survival differed according to CYP2D6 status among eligible, treated patients with metastatic breast cancer whose baseline sample could be evaluated for CYP2D6 phenotype. Its primary outcome was progression-free survival by CYP2D6 status in two categories. The registry record does not define those categories or report the resulting median survival estimates, confidence intervals, or a statistical comparison.
Population
Eligible and treated patients with metastatic breast cancer who had a baseline sample evaluable for CYP2D6 phenotype. The number in this analysis population is not reported in the registry record.
Intervention
Single-agent oral tamoxifen citrate. Patients were scheduled to receive it once daily on days 1-28, with treatment repeating every 28 days in the absence of disease progression or unacceptable toxicities.
Comparator
There was no separate control group. The primary question compares progression-free survival across CYP2D6 status categories within the treated group; it is not a randomized treatment comparison.
Primary question
How did progression-free survival vary by CYP2D6 status in the two-category analysis? The posted results do not report an answer.
The clinical rationale in the registry describes tamoxifen as hormone therapy intended to block tumor cells' use of estrogen. That rationale explains the treatment choice, but it is not evidence of an outcome in this trial. The record also lists a three-category CYP2D6 progression-free survival outcome among secondary outcomes, along with six-month progression-free status, response, endoxifen concentration by response, and progression-free survival from three months after registration. Results for those outcomes are not reported in the registry record.
3. Trial Design
This was a phase II prospective trial with a single-group model and no masking. Allocation is listed as not applicable, consistent with the absence of a randomized treatment comparison. The registry reports enrollment of 124 and a completed status. The trial start date is 2011-01-07 and the primary completion date is 2020-11-30.
All participants were assigned to the tamoxifen treatment group described in the record. The regimen was oral tamoxifen citrate once daily on days 1-28, repeating every 28 days while disease had not progressed and unacceptable toxicities had not occurred. The registry lists tamoxifen as the drug intervention. It does not report a concurrent placebo or active-treatment control arm.
The primary outcome population is narrower than the overall enrollment description: eligible and treated patients had to have a baseline sample evaluable for CYP2D6 phenotype. The number meeting that outcome-specific description is not reported in the registry record. The record also does not report how many participants started treatment, completed treatment, or contributed evaluable progression-free survival observations.
Progression-free survival was assessed every 3 months for 2 years, then every 6 months up to 5 years. The record defines the event as progression or death, whichever occurred first. RECIST version 1.1 was used to evaluate progression. The planned assessment schedule does not by itself establish how many assessments occurred or how much follow-up was observed for individual participants.
A single-group design can describe outcomes under the study regimen and explore whether those outcomes vary across participant characteristics such as CYP2D6 status. It cannot, by itself, distinguish the effect of treatment from the natural course of disease, other care, or differences between the status groups. The registry record does not report the rationale for the enrollment target, sample-size justification, interim analyses, or a full statistical analysis plan.
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
| Stage | Tamoxifen |
|---|---|
| STARTED | 124 |
| Treated | 122 |
| Eligible and Treated | 113 |
| Eligible and Treated and Had CYP2D6 Score | 85 |
| Eligible and Treated and Had Cycle 3 Edoxifen Evaluation | 63 |
| Eligible and Treated Patients With 3-month Endoxifen and Were Progression-free and Alive at 3 Months | 43 |
| COMPLETED | 1 |
| NOT COMPLETED | 123 |
Reasons for not completing this period:
| Reason | Tamoxifen |
|---|---|
| Disease progression | 77 |
| Adverse Event | 11 |
| Death | 1 |
| Withdrawal by Subject | 7 |
| Physician Decision | 3 |
| Alternative therapy | 9 |
| No documentation that patient went off treatment | 4 |
| Ineligible | 9 |
| Ineligible and never start treatment | 2 |
Analysis population for the primary outcome, as defined in the registry: Eligible and treated patients who had a sample from baseline evaluable for CYP2D6 phenotype
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: Eligible and treated patients are included in this analysis. This is the primary analysis population.
| Characteristic | Unit | Tamoxifen |
|---|---|---|
| Participants analysed | 113 | |
| Age, Continuous | years | 62 (36 to 94) |
| Sex: Female, Male: Female | Participants | 111 |
| Sex: Female, Male: Male | Participants | 2 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 33 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 77 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 3 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 7 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 6 |
| Race (NIH/OMB): White | Participants | 97 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 3 |
| CYP2D6 phenotype: Poor metabolizer | Participants | 2 |
| CYP2D6 phenotype: Intermediate metabolizer | Participants | 27 |
| CYP2D6 phenotype: Normal metabolizer | Participants | 50 |
| CYP2D6 phenotype: Ultra-rapid metabolizer | Participants | 6 |
| CYP2D6 phenotype: Missing | Participants | 28 |
6. Primary Endpoint
The registry lists the primary outcome as Progression-free Survival by CYP2D6 Status in 2 Categories, measured over Assessed every 3 months for 2 years, then every 6 months up to 5 years.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | 95% Confidence Interval |
| Unit | months |
| Endpoint classification | Time-to-Event Analysis |
The primary endpoint is median progression-free survival by CYP2D6 status in two categories. Progression-free survival is the time from registration until progression or death, whichever occurs first. Thus, it combines two kinds of events into one time-to-event outcome; a participant who experiences either event has reached the endpoint.
Progression was evaluated using RECIST version 1.1. The registry definition includes appearance of one or more new lesions, unequivocal progression of existing non-target lesions, or at least a 20% increase in the sum of target-lesion diameters relative to the smallest sum on study, including baseline when it is the smallest. The definition also requires an absolute increase of at least 5 mm alongside the relative increase.
Median time-to-event outcomes can describe when half of the relevant population has experienced an event, while accounting for follow-up that may end before every participant has an event. General statistical point: time-to-event endpoints are useful when both the occurrence and timing of an event matter, and when participants can have different follow-up durations. The median alone does not describe the full shape of the outcome distribution or establish why outcomes differ.
The record specifies assessment through a schedule extending up to 5 years, but it does not report the median estimates, confidence intervals, group sizes, or any test of difference. Those primary results are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies a clear primary statistical question: whether median progression-free survival varies across two CYP2D6 status categories among eligible, treated patients with evaluable baseline samples. It does not provide the outcome estimates needed to answer that question. In particular, the record does not report category-specific medians, confidence intervals, a hazard ratio, a p-value, or the number of participants contributing to the primary analysis. The direction and magnitude of any association therefore cannot be determined from the posted results.
Enrollment was 124, but that figure should not be treated as the primary analysis denominator. The endpoint population is described as eligible and treated patients with a baseline sample evaluable for CYP2D6 phenotype. The size of that subset, and the number of participants in each status category, are not reported in the registry record. A difference between total enrollment and an analysis population can arise for many reasons; the record does not specify whether or why any participants were excluded from this endpoint.
The study was single-group, without a randomized comparator. Even if category-specific progression-free survival estimates had been reported, a difference between CYP2D6 groups would be an association within the treated population, not a randomized estimate of a treatment effect. Groups defined by a participant characteristic can differ in other ways, and the registry record does not report adjustment methods or covariates. No causal interpretation of a status-associated difference can be made from the available record.
The endpoint combines progression and death. Consequently, any reported progression-free survival result would describe time until either event rather than progression alone. The record gives a detailed progression definition and an assessment schedule, but it does not report event counts for progression and death separately, censoring information, or the number still under observation at particular times. Such details would help readers understand how the time-to-event estimates were supported.
The record lists six outcome measures and zero analyses. It names secondary outcomes involving progression-free survival in three CYP2D6 categories, progression-free status at 6 months, response, endoxifen concentration by response, and progression-free survival from 3 months post registration. Their results are not reported in the registry record. The absence of posted estimates is not evidence that an outcome was favorable or unfavorable; it means the registry entry does not allow those results to be evaluated.
Safety information is reported separately. In the tamoxifen group, 122 participants were at risk for the serious adverse-event and other adverse-event summaries; 30 were recorded as affected by serious adverse events and 18 by other adverse events. The record also reports 69 deaths and lists several serious adverse-event terms with percentages. These figures describe recorded safety outcomes, but the record does not supply enough detail to establish timing, attribution, event overlap, or causes of death. They do not fill the gap in the primary efficacy results.
In general, confidence intervals convey the statistical precision of an estimate by indicating a range of values compatible with the data under the analysis assumptions. No primary confidence intervals are reported, so the precision of any CYP2D6-specific median cannot be assessed. The completed status and the presence of an endpoint definition do not substitute for the missing numerical outcome results.
9. Statistical Methods Explained
The statistical question is about time to an event, not simply whether a participant did or did not experience progression by the end of follow-up. The endpoint starts at registration and ends at the first of progression or death. The registry states that the outcome is summarized as a median, with a 95% confidence interval, and compared by CYP2D6 status in two categories. The numerical estimates and comparison results are not reported in the registry record.
What does a median time-to-event estimate describe?
General explanation: a median time-to-event estimate is the time by which half of the relevant event-time distribution has experienced the event, according to the statistical method used. It is different from an average because it focuses on the middle of the distribution and can be estimated even when some participants have not yet had an event, provided their partial follow-up is handled appropriately. The registry record does not identify the estimator or provide the data needed to reproduce it.
In this trial, the event is a composite of progression or death. An estimate therefore concerns the time to either event under the endpoint definition, not the time to progression in isolation. Progression was evaluated under RECIST version 1.1, using new lesions, unequivocal progression of non-target lesions, or the specified increase in target-lesion diameter. The record states that the relative increase must also meet an absolute increase threshold. These criteria define what counts as progression, but they do not reveal how many events occurred or when.
Why is a confidence interval relevant?
General explanation: a confidence interval communicates uncertainty around an estimated quantity. A narrower interval indicates greater statistical precision under the method's assumptions, while a wider interval indicates less precision. It does not guarantee that the interval contains the true value, and it does not address biases caused by study design or measurement. Although the registry identifies a 95% confidence interval as the dispersion measure for the primary endpoint, no interval limits are posted. Precision cannot therefore be judged.
For time-to-event data, participants may have different follow-up lengths, and some may leave observation before experiencing the endpoint. General explanation: such observations are commonly handled as censored, meaning that the event time is known only to exceed the participant's observed follow-up. The validity of time-to-event estimates depends on assumptions about censoring and the analysis approach. The registry record does not report censoring counts, reasons for censoring, the estimator used, or diagnostic checks, so those aspects cannot be assessed.
What does the CYP2D6 grouping contribute?
The primary outcome is organized by CYP2D6 status in two categories, while a secondary outcome uses three categories. General explanation: grouping a biomarker or phenotype can make comparisons easier to present, but results depend on how the groups are defined and how participants are classified. The registry record does not specify the category definitions or the number of participants in each category. It also does not report whether status was determined by a particular assay or how uncertain or unavailable classifications were handled.
A comparison within a single treated group can identify a pattern of outcomes associated with status, if results are available. It does not establish that CYP2D6 status caused a difference in progression-free survival. The groups were not assigned at random, and the registry does not report covariate adjustment or other methods intended to address differences between groups. No treatment-by-status comparison against a control group is possible in this single-group design.
What can be concluded from the reported analysis information?
The registry lists zero analyses. It names the primary and secondary outcome measures but does not provide analysis estimates for them. The registry record does not report a statistical test, a hazard ratio, or a p-value for the primary question. The information is therefore insufficient to evaluate the size, precision, or statistical evidence for a CYP2D6-associated difference.
The record describes a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It states that the effect to detect is a specified fraction of the observed effect; for time-to-event planning, the reported quantity is the total number of events. Such sample-size calculations are planning illustrations, not observed power and not trial outcomes. The observed effect and numerical planning results are not reported in the registry record. The registry also does not report the trial's own sample-size justification, so the planning assumptions should not be mistaken for the original design rationale.
General explanation: over-dispersion refers to variability greater than a statistical model expects. When it is present, model-based standard errors and tests can be too optimistic if the extra variability is ignored. The posted primary endpoint is time-to-event, and the registry does not report an over-dispersion model or a model-based analysis. No claim about whether over-dispersion was assessed or relevant can be made from this record.
Similarly, general statistical concepts such as proportional hazards, competing risks, or alternative estimators may matter in analyses of time-to-event outcomes, but the registry record does not state that any particular method was used. Naming a possible method would not establish that it was part of this trial's analysis. The appropriate reading is limited to the endpoint definition, the planned summary measure, the assessment schedule, and the fact that numerical results are not posted.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists six outcome measures: the primary progression-free survival outcome by CYP2D6 status in two categories, and secondary measures covering a three-category status analysis, progression-free status at 6 months, response, endoxifen concentration by response, and progression-free survival from 3 months post registration. The record lists zero analyses and does not report numerical results for these outcomes.
When a study evaluates multiple outcomes or multiple subgroup comparisons, general statistical explanation is that the chance of finding at least one apparently notable result can increase if each is assessed independently without accounting for the number of analyses. Methods for addressing multiplicity may include a prespecified hierarchy or adjustment, but the registry record does not report whether any strategy was planned or used. It is also not reported in the registry record whether these outcomes were prioritized in a particular order or whether any analyses were exploratory.
Missing-data methods are not reported in the registry record. The primary endpoint population requires an evaluable baseline sample for CYP2D6 phenotype, but the record does not state how many samples were unavailable or unevaluable, how such cases were handled, or whether missing follow-up information was addressed with a specified method. The number of participants with endpoint data and the distribution across status categories are also not reported.
The record does not describe the analysis populations beyond the primary population definition, nor does it state whether all treated participants or only a subset were used for secondary outcomes. Interim analyses and a complete statistical plan are not reported in the registry record. Without these details, it is not possible to assess whether analysis choices were prespecified, how missing observations affected estimates, or how the multiple outcome questions were interpreted.
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 |
|---|---|---|---|
| Tamoxifen | 30 | 122 | 24.6% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Tamoxifen | 69 of 124 |
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 |
|---|---|
| Tamoxifen | 18 of 122 |
Most frequent serious adverse event terms
| Event term | Organ system | Tamoxifen |
|---|---|---|
| Lymphocyte count decreased | Investigations | 4 of 122 |
| Back pain | Musculoskeletal and connective tissue disorders | 4 of 122 |
| Bone pain | Musculoskeletal and connective tissue disorders | 4 of 122 |
| Hypertriglyceridemia | Metabolism and nutrition disorders | 3 of 122 |
| Arthralgia | Musculoskeletal and connective tissue disorders | 3 of 122 |
| Dyspnea | Respiratory, thoracic and mediastinal disorders | 3 of 122 |
| Hypertension | Vascular disorders | 3 of 122 |
| Fatigue | General disorders | 2 of 122 |
| Aspartate aminotransferase increased | Investigations | 2 of 122 |
| Thromboembolic event | Vascular disorders | 2 of 122 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Tamoxifen |
|---|---|---|
| Fatigue | General disorders | 18 of 122 |
| Back pain | Musculoskeletal and connective tissue disorders | 17 of 122 |
| Nausea | Gastrointestinal disorders | 14 of 122 |
| Hot flashes | Vascular disorders | 11 of 122 |
| Anemia | Blood and lymphatic system disorders | 10 of 122 |
| Constipation | Gastrointestinal disorders | 9 of 122 |
| Vomiting | Gastrointestinal disorders | 9 of 122 |
| Hypertension | Vascular disorders | 9 of 122 |
| Edema limbs | General disorders | 8 of 122 |
| Aspartate aminotransferase increased | Investigations | 8 of 122 |
Serious events with the highest arm-level rate: lymphocyte count decreased (3.3%), back pain (3.3%), bone pain (3.3%), hypertriglyceridemia (2.5%), arthralgia (2.5%).
The registry reports safety counts for the tamoxifen group. The number at risk was 122 for both serious adverse events and other adverse events. Thirty participants were recorded as affected by serious adverse events, and 18 were recorded as affected by other adverse events. The registry also records 69 deaths. These are distinct reported safety counts; the death figure should not be interpreted as the number of deaths caused by tamoxifen.
The listed serious adverse-event terms include lymphocyte count decreased, back pain, and bone pain, each reported as 3.3%, and hypertriglyceridemia, arthralgia, and dyspnea, each reported as 2.5%. These are the terms identified among the top serious events in the record. The registry does not report their timing, duration, severity grading details, relationship to treatment, or whether participants experienced more than one listed event.
General explanation: an at-risk denominator describes the group used for a safety summary, while the affected count describes participants recorded with an event under that summary. Such counts do not by themselves establish causation or compare safety against another treatment. There is no control group in this trial, and the registry does not report enough detail to make causal attribution. The safety figures therefore describe recorded events in the treated group, not a comparative estimate of treatment-related risk.
12. What the Result Does, and Does Not, Mean
The registry record documents a phase II study of single-agent tamoxifen in metastatic or recurrent breast cancer and defines a primary question about progression-free survival by CYP2D6 status. It also specifies how progression was defined and how often assessments were planned. These details clarify what the investigators intended to measure.
The posted information does not provide the primary outcome estimates. There are no reported CYP2D6-category medians, confidence intervals, or statistical comparison results. As a result, the record does not show whether the groups had similar or different progression-free survival, how large any difference might have been, or how precisely it was estimated. It also does not report results for the named secondary outcomes.
The registry's completed status does not indicate the direction or success of the findings. Nor does a defined endpoint, a planned schedule, or a sample-size planning assumption substitute for observed outcome data. The record reports enrollment of 124, but the primary analysis population is restricted to eligible, treated patients with an evaluable baseline sample; its size is not reported.
Even if a difference between CYP2D6 categories were available, this single-group trial would describe an association among treated participants, not a randomized comparison of tamoxifen with another treatment. Differences between status groups could reflect other characteristics, and the registry does not report adjustment methods. The study design cannot on its own establish that CYP2D6 status caused an outcome difference or quantify a treatment effect relative to a control.
The safety counts provide a separate description of events in the tamoxifen group, but they do not establish that treatment caused those events. Overall, the record offers the design and endpoint definitions needed to understand the research question, but not the numerical efficacy results required to answer it.
13. Why This Trial Matters Statistically
Statistically, the trial is notable for asking a biomarker-related question within a prospective treatment study: whether progression-free survival varies by CYP2D6 status among patients receiving single-agent tamoxifen. The endpoint is time-to-event and the registry specifies both its event definition and its assessment schedule. These features make the intended relationship understandable without turning the study into a randomized comparison.
The design also illustrates why the distinction between an overall enrollment figure and an outcome-specific analysis population matters. Enrollment is reported as 124, whereas the primary outcome requires treatment and a baseline sample evaluable for CYP2D6 phenotype. Since the size and composition of that subset are not reported, readers cannot assess how much information supports the primary question or whether the status groups were balanced.
The record is statistically incomplete for interpretation: it lists the outcomes but no analyses. Without the estimates and uncertainty measures, the central association cannot be evaluated. This is a useful reminder that a well-described endpoint and a completed trial status do not communicate the result. Registry entries are most informative when outcome definitions, analysis populations, estimates, and precision are all available together.
The single-group design sets an important boundary on what the study can establish. A status-associated pattern could be descriptive or hypothesis-generating, but it would not isolate a treatment effect against a control. A careful statistical reading therefore separates the biological question, the observed outcome (not reported), and the causal claim the design could support. In this record, the first is clear, the second is unavailable, and the third is not established by the design.
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 primary limitation for interpreting outcomes is that numerical efficacy results are not reported in the registry record. The record gives no category-specific progression-free survival medians, confidence intervals, analysis denominators, or comparison statistics. The same absence applies to the listed secondary outcomes. Thus, it is not possible to evaluate effect size, precision, or consistency across outcomes.
The trial had a single-group design and no randomized control arm. It cannot provide a like-for-like comparison of tamoxifen against another treatment. The primary comparison is across CYP2D6 status categories within the treated group, but the category definitions and group sizes are not reported. Differences between groups may be associated with characteristics other than CYP2D6 status, and adjustment methods are not reported.
The primary endpoint population requires eligible and treated patients with a baseline sample evaluable for CYP2D6 phenotype, while the total enrollment is 124. The number included in the endpoint analysis and the reasons for any unavailable or unevaluable data are not reported. Handling of missing endpoint data, censoring, and participants without adequate follow-up is also not reported.
The record specifies RECIST version 1.1 and a progression definition, but does not provide separate counts for progression and death, event timing, or follow-up completeness. It lists 0 analyses and does not report interim analyses, multiplicity methods, a detailed statistical plan, or the trial's sample-size justification. Safety counts are available, but attribution, timing, and overlap among events are not described. These gaps limit both efficacy interpretation and a detailed assessment of safety context.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Tamoxifen Citrate in Treating Patients With Metastatic or Recurrent Breast Cancer — NCT01124695.
- Registry record last updated 2023-06-29; status last verified 2023-06.
- Results first posted 2023-03-14.
- 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
NCT01124695 is a completed phase II prospective, single-group, unmasked trial sponsored by ECOG-ACRIN Cancer Research Group. It enrolled 124 participants with metastatic or recurrent breast cancer and evaluated single-agent oral tamoxifen citrate. The regimen was once daily on days 1-28, repeating every 28 days while disease had not progressed and unacceptable toxicities had not occurred.
The primary outcome was median progression-free survival by CYP2D6 status in two categories among eligible, treated patients with a baseline sample evaluable for CYP2D6 phenotype. Progression or death, whichever occurred first, defined the endpoint, with progression assessed under RECIST version 1.1. The registry lists six outcome measures and 0 analyses; primary and secondary numerical results are not reported in the registry record.
The record reports safety counts for the tamoxifen group, including 30 affected by serious adverse events, 18 affected by other adverse events, and 69 deaths, with 122 at risk for each adverse-event summary. The design has no randomized control group, and the registry record does not establish causal attribution for safety events or report a comparative treatment effect.