Validation of the Health ABC Heart Failure Model for Incident Heart Failure Risk Prediction: The Cardiovascular Health Study Running Title: Validation of the Health ABC HF Model

Background: The recently developed and internally validated Health ABC HF model uses nine routinely available clinical variables to determine incident heart failure risk. In this study, we sought to externally validate the Health ABC HF model. Methods and Results: Observed 5-year incidence of heart failure, defined as first hospitalization for new onset heart failure, was compared with 5-year risk estimates derived from the Health ABC HF model among participants without heart failure at baseline in the Cardiovascular Health Study. During follow-up, 400 of 5335 (7.5%) participants developed heart failure over 5 years vs. 364 (6.8%) predicted by the Health ABC HF model (predicted to observed ratio, 0.90). Observed vs. predicted 5-year heart failure probabilities were 3.2% vs. 2.8%, 9.0% vs. 7.0%, 15.9% vs. 13.7%, and 24.6% vs. 30.8% for the <5%, 5-10%, 10-20%, and >20% 5-year risk categories, respectively. The Hosmer-Lemeshow 2 was 14.72 (d.f.=10; P=0.14) and the C index was 0.74 (95% CI, 0.72-0.76). Calibration and discrimination demonstrated adequate performance across sex and race overall; however risk was underestimated in white men, especially in the 5-10% risk category. Model performance was optimal when participants with normal left ventricular function at baseline were assessed separately. Performance was consistent across age groups. Analyses with death as a competing risk yielded similar results. Conclusions: The Health ABC HF model adequately predicted 5-year heart failure risk in a large community-based study, providing support for the external validity of the model. This tool may be used to identify individuals to target heart failure prevention efforts.