Abstract 14284: A Clinical Risk Score Predicting Heart Failure and Cardiomyopathy After Adjuvant Trastuzumab Therapy for Breast Cancer
Introduction: Adjuvant trastuzumab improves survival for HER2+ breast cancers. However, trastuzumab, independently and in combination with anthracyclines, increases the risk of heart failure and/or cardiomyopathy (HF/CM), particularly in older patients. Clinical risk stratification tools would be useful to guide monitoring and treatment decisions regarding choice of chemotherapy.
Methods: We used the linked SEER - Medicare database to study older women with stage I-III breast cancer who were treated with adjuvant trastuzumab +/- chemotherapy following surgery. Major exclusion criteria included pre-existing HF/CM or other cancers. The study outcome was HF/CM within 3 years of adjuvant therapy as identified by ICD-9 codes. We divided the study sample into derivation and validation cohorts. In the derivation cohort, we estimated a Cox proportional hazards model, and we used significant risk factors to construct a risk score. Risk scores were then calculated for each subject in the validation cohort, and the risk of HF/CM was classified into low, medium, and high strata.
Results: In the full cohort of 1,664 women, ages 67 to 94, 318 (19.1%) developed HF or CM during 3 years of follow up. The risk score model included the following risk factors: concurrent chemotherapy (anthracycline regimen vs. non-anthracycline regimen vs. none), age, and history of coronary artery disease, atrial fibrillation or flutter, diabetes, hypertension, and renal failure. Individual risk score totals ranged from 0 to 9. The risk score allowed classification of 3-yr HF/CM risk in the validation cohort from low (0-3 points) at 16%, to medium (4-5 points) at 26%, to high (6-9 points) at 39% (see Table).
Conclusion: This risk score can stratify patients for risk of HF/CM after adjuvant trastuzumab therapy. While limited by use of administrative data, this approach demonstrates proof-of-concept that a clinically useful risk score can be developed in the future using primary clinical data.
- © 2013 by American Heart Association, Inc.