Risk prediction model for heart failure and cardiomyopathy after adjuvant trastuzumab therapy for breast cancer

Background: adjuvant trastuzumab improves survival for women with human epidermal growth factor receptor 2-positive breast cancer,but increases risk for heart failure (hf) and cardiomyopathy (cm). however,clinical trials may underestimate hf/cm risk because they enroll younger subjects with fewer cardiac risk factors. we sought to develop a clinical risk score that identifies older women with breast cancer who are at higher risk of hf or cm after trastuzumab.methods and results: using the surveillance,epidemiology and end results (seer)-medicare database,we identified women with breast cancer who received adjuvant trastuzumab. using a split-sample design,we used a proportional hazards model to identify candidate predictors of hf/cm in a derivation cohort. a risk score was constructed using regression coefficients,and hf/cm rates were calculated in the validation cohort. the sample consisted of 1664 older women (mean age 73.6 years) with 3-year hf/cm rate of 19.1%. a risk score consisting of age,adjuvant chemotherapy,coronary artery disease,atrial fibrillation or flutter,diabetes mellitus,hypertension,and renal failure was able to classify hf/cm risk into low (0 to 3 points),medium (4 to 5 points),and high (≥6 points) risk strata with 3-year rates of 16.2%,26.0%,and 39.5%,respectively.conclusions: a 7-factor risk score was able to stratify 3-year risk of hf/cm after trastuzumab between the lowest and highest risk groups by more than 2-fold in a medicare population. these findings will inform future research aimed at further developing a clinical risk score for hf/cm for breast cancer patients of all ages.