Cardiotoxicity diagnoses and inpatient outcomes in principal breast cancer hospitalizations: National Inpatient Sample, 2018–2023.

Abstract

e24036 Background: Cardiotoxicity diagnoses are increasingly recognized among patients with cancer, yet national data describing their association with inpatient severity, mortality, and resource utilization during breast cancer hospitalizations remains limited. Methods: A retrospective cross-sectional analysis of the 2018–2023 National Inpatient Sample was performed. Adult hospitalizations with a principal diagnosis of breast cancer (ICD-10-CM C50*) were included. Cardiotoxicity was defined by the presence of myocarditis (I40*), cardiomyopathy or heart failure (I42*/I50*), or arrhythmia (I47–I49*) in any diagnosis position. Outcomes included in-hospital mortality (primary), shock (R57*), mechanical ventilation (ICD-10-PCS 5A1935Z/5A1945Z/5A1955Z), extreme APR-DRG severity, length of stay (LOS), and hospitalization cost. Costs were derived using hospital-specific cost-to-charge ratios. National estimates accounted for NIS stratification, clustering, and discharge-level weighting. Multivariable survey-weighted logistic and linear regression models compared outcomes by cardiotoxicity status, adjusting for age, sex, year, race, payer, ZIP-code income quartile, elective admission, and hospital teaching status and region. Sensitivity analyses restricted cardiotoxicity to secondary diagnosis positions (DX2–DX40). Results: Among 32,672 unweighted principal breast cancer hospitalizations (weighted N = 163,360), cardiotoxicity was present in 11.7% (weighted n = 19,050). Crude mortality was higher among hospitalizations with cardiotoxicity compared with those without (6.77% vs 2.93%), as were shock (1.55% vs 0.45%) and mechanical ventilation (1.68% vs 0.59%). In adjusted analyses, cardiotoxicity was independently associated with increased odds of extreme severity (OR 2.92, 95% CI 2.29–3.71), in-hospital mortality (OR 1.54, 95% CI 1.28–1.85), shock (OR 2.65, 95% CI 1.74–4.05), and mechanical ventilation (OR 2.69, 95% CI 1.88–3.87). Cardiotoxicity was also associated with longer LOS (+1.11 days, 95% CI 0.86–1.36) and higher adjusted hospitalization cost (+$1,714, 95% CI $642–$2,786). Associations persisted in sensitivity analyses restricted to secondary diagnoses, including mortality (OR 2.41, 95% CI 2.08–2.78) and mechanical ventilation (OR 2.87, 95% CI 2.15–3.82). Conclusions: In nationally representative hospitalization-level data, cardiotoxicity diagnoses were common among principal breast cancer admissions and were independently associated with greater inpatient severity, mortality, critical care utilization, LOS, and costs. These findings identify cardiotoxicity as a high-risk inpatient phenotype with important implications for resource utilization and inpatient care pathways.