Simplifying cardiovascular risk estimation using resting heart rate

Elevated resting heart rate (RHR) is a known, independent cardiovascular (CV) risk factor, but is not included in risk estimation systems, including Systematic COronary Risk Evaluation (SCORE). We aimed to derive risk estimation systems including RHR as an extra variable and assess the value of this addition. The National FINRISK study (including 14 997 men and 15 861 women) was used to derive two formulas for estimation of 10 year risk of CV disease (CVD) mortality. The first formula contained current SCORE variables-total cholesterol, systolic blood pressure, smoking, age and gender. Inclusion of RHR resulted in only minor improvements in discrimination, based on both area under receiver operating characteristic curve (AUROC, men: 0.840 from 0.838, P = 0.5038; women: 0.87 from 0.865, P = 0.0522) and net reclassification index (NRI). The second, simplified formula contained only, age, smoking, gender, and body mass index. Addition of RHR to this simplified formula resulted in a statistically significant and meaningful improvement in AUROC (men: 0.819 from 0.812, P = 0.037; women: 0.862 from 0.827, P = 0.023) and NRI (0.05). Calibration also improved. A simple chart for estimating 10 year risk of fatal CVD including RHR is presented. Addition of RHR to formulas already containing lipid and blood pressure measures does not appreciably improve risk estimation. However, inclusion of RHR in simple systems, which can potentially enhance cost-effectiveness and accessibility of risk estimation, is useful.