Overestimation of glomerular filtration rate by creatinine‐based equation in heart failure patients is predicted by a novel scoring system

Aims Creatinine‐based estimated glomerular filtration rate (eGFRcre) has been shown to overestimate the glomerular filtration rate (GFR) when it is compared with cystatin C‐based estimated GFR (eGFRcys) in older people. We investigated clinical determinants of GFR overestimation by eGFRcre and developed a score for prediction of GFR overestimation (OE) in heart failure patients. Methods We retrospectively examined 244 Japanese heart failure patients (aged 72.2 ± 13.1 years; 48% women) who had no known extrarenal factors that affect serum cystatin C concentration. eGFR OE by eGFRcre was defined as eGFRcre being ≥120% of cystatin C‐based eGFR. Results The proportion of heart failure patients with OE was 14.3%. Patients with OE were older, had lower body weight and total skeletal muscle mass than those in patients without OE. Laboratory examinations showed that hemoglobin concentration was lower, and the ratio of blood urea nitrogen‐to‐creatinine was higher in patients with OE than in patients without OE. In multivariate regression analysis, body weight (