A Study of Limited Heart Monitoring During Non-anthracycline Trastuzumab-based Therapy in Breast Cancer Patients: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Study of Limited Heart Monitoring During Non-anthracycline Trastuzumab-based Therapy in Breast Cancer Patients (NCT03983382), a registered phase not stated study. The primary outcome is Frequency of Cardiac Adverse Events, Defined by a Compositive of Clinical Heart Failure (NYHA Class III or IV) or Cardiac Death..

2. Clinical Question

The clinical question is about the safety and feasibility of reducing the frequency of cardiac monitoring, not about comparing cancer-treatment efficacy. The registry describes the aim as testing whether patients on non-anthracycline trastuzumab therapy can safely be monitored less often than usual. However, the record does not specify the monitoring frequency being tested or provide a like-for-like control group. That limits how directly the posted record can answer whether less frequent monitoring changes cardiac outcomes.

The primary endpoint is a composite: clinical heart failure meeting NYHA Class III or IV, or cardiac death. It is recorded as a count of cardiac adverse events over 12 months from baseline. No primary-endpoint result or analysis is listed, so the registry record does not establish how many such events occurred or how precisely their frequency was estimated.

3. Trial Design

This is a safety and feasibility study registered as NCT03983382. Its title describes limited cardiac monitoring during non-anthracycline trastuzumab-based therapy in breast cancer patients. The official title specifies patients with HER2-positive breast cancer. The sponsor is Memorial Sloan Kettering Cancer Center, and the listed condition is breast cancer.

The registry lists enrollment of 190 and a status of active, not recruiting. The recorded study start is 2019-03-22, and the primary completion date is 2023-09-18. Those dates describe the registry record; they do not establish when any particular participant began or completed follow-up.

The stated purpose is to test whether heart-related side effects can be monitored less often than usual in patients receiving non-anthracycline trastuzumab therapy. Left Ventricular Ejection Fraction is the only intervention listed, classified as a diagnostic test. The actual monitoring schedule, the usual-care schedule, and how monitoring was assigned are not reported in the registry record.

The record does not describe a randomized allocation. It explicitly cautions that this is not a randomized comparison and that the listed arms are not a like-for-like control comparison. The listed arm is titled HER2-Positive Breast Cancer, without a description. Consequently, the registry information does not support treating the arm listing as evidence of two comparable groups or interpreting differences as the effect of a monitoring strategy.

The primary outcome is a count of cardiac adverse events defined by clinical heart failure of NYHA Class III or IV or cardiac death, with a timeframe of 12 months from baseline. Although the registry lists one outcome measure, it lists no analysis. No protocol details, sample-size justification, interim-analysis plan, or statistical analysis plan are reported in the registry record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

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.

6. Primary Endpoint

The registry lists the primary outcome as Frequency of Cardiac Adverse Events, Defined by a Compositive of Clinical Heart Failure (NYHA Class III or IV) or Cardiac Death., measured over 12 months from baseline.

The primary endpoint counts cardiac adverse events defined as a composite of clinical heart failure meeting NYHA Class III or IV or cardiac death. The specified timeframe is 12 months from baseline, and the outcome is expressed as a number of cardiac adverse events rather than a time-to-event measure or a continuous measurement.

A composite endpoint combines more than one type of clinical event under a shared outcome definition. In general, this can capture different serious outcomes relevant to the same clinical question, but the individual components may differ in frequency and clinical meaning. For that reason, an overall composite count does not by itself show which component occurred or how often each component occurred. The registry record does not provide component-specific primary-outcome results.

In general, cardiac outcomes are relevant to a study of cardiac monitoring because the monitoring strategy concerns detection or follow-up of heart-related effects during treatment. The endpoint definition focuses on clinically severe heart failure or cardiac death rather than on a change in an ejection-fraction measurement alone. The record lists Left Ventricular Ejection Fraction as a diagnostic test, but it does not report how measurements were scheduled or used to determine the endpoint.

No result for the primary endpoint is listed, and no analysis is listed. Therefore, its event count, any estimate of its frequency, and the precision of such an estimate are not reported in the registry record. The endpoint definition alone cannot establish the frequency of events or whether the monitoring approach changed their detection.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint is recorded as a count: the number of cardiac adverse events defined by clinical heart failure of NYHA Class III or IV or cardiac death, over 12 months from baseline. The registry identifies the outcome parameter as a number. That description tells readers what type of result was intended, but it does not name an analysis model or specify how the endpoint was summarized. No analysis is listed in the registry record.

What does a count outcome represent?

In general, a count records how many defined events occurred over a specified period or within a specified group. Count data can be analyzed in several ways depending on the study design, exposure time, event definition, and assumptions about the data. For example, an analysis might summarize counts directly or model them while accounting for time at risk. These are general possibilities, not methods identified for this study. The registry record does not state whether the primary outcome was analyzed as a raw count, a rate, a risk, or by another method.

In general, count models often rely on assumptions about how much observations vary around their average. Over-dispersion means the observed variation is greater than a model's assumptions allow. If present, it can make uncertainty appear too small when a model does not account for it. This is a general consideration for count outcomes; the record does not identify a count model or report any assessment of over-dispersion.

Why is the composite definition important?

The endpoint combines clinical heart failure of NYHA Class III or IV and cardiac death. In general, a composite can bring several outcomes into one measure, but the interpretation depends on which components occurred and how they contribute to the total. A count for the combined endpoint cannot reveal the component-specific pattern unless those component counts are also reported. The registry record does not provide primary-endpoint component counts or a result for the composite.

The timeframe, 12 months from baseline, defines the period associated with the endpoint. In general, interpretation of an event count also depends on whether participants have comparable observation time and how events after loss to follow-up are handled. The record does not report follow-up completeness, censoring rules, or missing-data procedures. It therefore does not support a more detailed account of how the time window was applied in analysis.

What can confidence intervals and tests tell readers?

In general, a confidence interval gives a range of estimates compatible with the observed data and the method's assumptions. Its width conveys precision: a narrower interval indicates greater precision than a wider interval, all else being equal. A statistical test addresses compatibility between data and a specified null hypothesis under its assumptions. Neither an interval nor a test can correct a poorly matched comparison or an incomplete outcome definition. No confidence interval, test statistic, or p-value for the primary endpoint is listed in this record.

The registry describes no randomized comparison and cautions that the listed arms are not a like-for-like control comparison. In general, random allocation can support causal comparisons by balancing factors between groups on average, while a nonrandomized comparison can be affected by differences in who receives each approach. Here, the allocation method and a usable comparator are not reported. This means the registry information does not establish a method for estimating the effect of limited monitoring relative to usual monitoring.

How should planning calculations be understood?

The planning assumptions describe an illustration based on a stated fraction of the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. For time-to-event illustrations, the stated quantity is the total number of events; for other outcomes, it is participants per arm. These are planning conventions, not observed trial results. The registry record does not report a trial-specific sample-size justification. It also lists no primary-outcome analysis from which an observed effect could be interpreted, so planning illustrations cannot be treated as evidence of observed power or as a result of the study.

More generally, a planning calculation estimates what study size or event information might be needed under chosen assumptions. Its output depends on the assumed effect, variability, design, and error rates. It does not establish that the planned assumptions were met, that the study achieved a particular level of power, or that a clinical effect was observed. The registry record does not report an analysis plan describing how such planning assumptions relate to the actual study conduct.

Finally, no multiplicity adjustment, interim-analysis approach, analysis population, or missing-data method is specified. Those details can influence how estimates and uncertainty should be interpreted. Without them, statistical interpretation should remain limited to the endpoint definition and the adverse-event counts that are explicitly recorded.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists one primary outcome measure and no analyses. It does not report a multiplicity plan, such as how inference would be handled if several outcomes, timepoints, or subgroup analyses were tested. In general, multiplicity arises when multiple statistical questions are considered; without an analysis plan, it is not possible to determine which comparisons were intended to support a primary conclusion or whether any adjustment was planned.

Missing-data procedures are not reported in the registry record. The record does not state how participants without complete follow-up, missing cardiac assessments, or uncertain event status were handled. In general, missing outcome information can affect both the estimated event frequency and the uncertainty around it, especially if the likelihood of missingness is related to health status or monitoring. That is a general concern, not a claim about what occurred in this study.

The analysis populations are also not reported. Enrollment is listed as 190, but the registry does not state how many participants were included in a primary-outcome analysis, whether all enrolled participants were followed for the full timeframe, or how eligibility for analysis was defined. Enrollment should not be treated as the analyzed population without those details.

No interim-analysis plan or stopping rule is reported. The status is active, not recruiting, but that status does not describe an interim statistical review. Taken together, the absence of analysis-population, missing-data, multiplicity, and interim-analysis details limits assessment of how the primary outcome would have been analyzed and how robust any resulting inference would be.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: death nos (0.5%).

The serious-adverse-event summary lists a count of 1 with 190 at risk in the HER2-Positive Breast Cancer group. The other-adverse-event summary lists a count of 8 with 190 at risk. The record also lists 1 death and identifies Death NOS at 0.5% among the top serious terms. These are registry safety-summary figures; no further analysis or explanation of event attribution is reported.

These counts should be kept distinct from the primary endpoint. The primary endpoint is defined as clinical heart failure of NYHA Class III or IV or cardiac death within 12 months from baseline. The safety summary does not identify whether the listed death was cardiac, whether it met the primary endpoint definition, or whether the other listed events overlap with the endpoint. It is not possible to infer that relationship from the registry record.

In general, a safety count is easier to interpret when the record defines the event category, time window, event-versus-participant counting method, and relationship to treatment. Those details are not all. The listed counts do not by themselves establish comparative safety because no like-for-like control comparison is available in the registry record.

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

The record supports a limited description of the study: it was intended to assess the safety and feasibility of less frequent cardiac monitoring during non-anthracycline trastuzumab-based therapy in patients with HER2-positive breast cancer. It specifies a primary composite endpoint of clinical heart failure of NYHA Class III or IV or cardiac death, measured as a count over 12 months from baseline. It also lists serious and other adverse-event counts for the HER2-Positive Breast Cancer group.

The record does not report the primary endpoint result or any analysis. It therefore does not show the frequency of the defined composite outcome, the precision of an estimate, or whether outcomes differed under limited versus usual monitoring. The listed adverse-event and death figures do not answer those questions because their relationship to the primary endpoint is not described and there is no like-for-like control comparison.

In general, a study result is interpreted in light of its design, outcome definition, analysis population, missing data, and uncertainty. The registry cautions that the study is not a randomized comparison and that the listed arms are not comparable controls. The monitoring schedules and allocation method are not reported. Thus, the record does not provide a basis for attributing differences in outcomes to monitoring frequency, even if a difference were reported elsewhere.

Nor does the registry information establish that a particular monitoring schedule is safe or unsafe. The study purpose is not itself a finding, and enrollment or study status is not an outcome result. The status active, not recruiting and the listed primary completion date do not supply missing analyses. The appropriate conclusion from this record is that the research question and endpoint are documented, but the primary result and the evidence needed for a comparative interpretation are not reported in the registry record.

13. Why This Trial Matters Statistically

This study raises a statistical question about how monitoring frequency can be evaluated when the outcome of interest is a relatively specific composite of serious cardiac events. The endpoint combines clinical heart failure of NYHA Class III or IV with cardiac death and uses a defined timeframe of 12 months from baseline. Statistical interpretation depends not only on the endpoint definition but also on how events are counted, how completely they are ascertained, and how comparisons are structured.

The registry's caution about the comparison is especially important. It states that the study is not a randomized comparison and that the listed arms are not a like-for-like control comparison. Without a suitable comparator and a reported allocation method, an observed event count alone would not establish the effect of a monitoring strategy. This is a general lesson in clinical biostatistics: outcome data and causal evidence are not interchangeable.

The record also illustrates why an endpoint definition is not a result. A clearly described composite can identify the question researchers intended to address, but readers still need the observed outcome, an analysis, and measures of uncertainty to judge what the data support. Here, no primary-outcome analysis is listed, and the record does not report component-specific results, analysis populations, or missing-data handling.

Finally, safety summaries need careful separation from primary efficacy or safety analyses. The serious-event, other-event, and death entries are useful descriptive registry information, but the record does not connect them to the primary composite or a comparative estimate. For statistical readers, the distinction between study purpose, endpoint, descriptive counts, and analyzed evidence is central to a restrained interpretation.

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 registry record leaves key design details unspecified. It does not report the limited-monitoring schedule, the usual-monitoring schedule, or how participants were assigned to any monitoring approach. It explicitly states that this was not a randomized comparison and that the listed arms are not a like-for-like control comparison. The arm description is blank, so the listed HER2-Positive Breast Cancer group does not clarify the comparison structure.

The primary endpoint is defined, but its result and analysis are absent. The record lists no analysis, no component-specific outcome counts, and no estimate of event frequency or precision. The adverse-event summary does not establish whether its death count is cardiac or whether the events overlap with the primary composite.

Other information needed to assess the outcome is also not reported: analysis populations, follow-up completeness, event ascertainment procedures, missing-data handling, multiplicity, interim analyses, and the statistical analysis plan. The registry lists enrollment of 190, but does not say how many participants contributed data to the primary outcome or how many had complete follow-up.

The record's status and dates provide administrative context but do not resolve these limitations. The study is active, not recruiting, with a primary completion date of 2023-09-18, yet no primary analysis is listed. No trial-specific sample-size justification is reported. These omissions prevent assessment of the precision, robustness, and comparative meaning of a primary endpoint result from the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: A Study of Limited Heart Monitoring During Non-anthracycline Trastuzumab-based Therapy in Breast Cancer Patients — NCT03983382.
• Registry record last updated 2026-05-15; status last verified 2026-05.
• Results first posted 2024-10-28.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

NCT03983382 is a safety and feasibility study of limited cardiac monitoring during non-anthracycline trastuzumab-based therapy in patients with HER2-positive breast cancer. The sponsor is Memorial Sloan Kettering Cancer Center. The registry lists enrollment of 190, a start date of 2019-03-22, a primary completion date of 2023-09-18, and status active, not recruiting.

The primary endpoint is the count of clinical heart failure of NYHA Class III or IV or cardiac death within 12 months from baseline. Left Ventricular Ejection Fraction is listed as a diagnostic test. The registry cautions that this is not a randomized comparison and that the listed arms are not a like-for-like control comparison.

The safety summary lists 1 serious event and 8 other events with 190 at risk, along with 1 death and Death NOS at 0.5% among the top serious terms. No primary-outcome analysis is listed. The monitoring schedules, analysis populations, and missing-data methods are not reported in the registry record.