Fig. 1
Scattergram plot of eGFR in relation to age for 3837 SCREEN-HF participants. The black line represents the age-related decline in eGFR from 105 ml/min/1.73 m2 at age 40 years to 60 ml/min/1.73 m2 at age 90 years in healthy living potential kidney donors [3]. eGFR values below the black line represent eGFR values below that of a healthy living potential kidney donor of the same age, and correspond to a kidney age that exceeds the chronological age. A 70-year old individual with an eGFR of 60 ml/min/1.73 m2 has an eGFR of a healthy 90-year-old; thus, the kidney age is 20 years older than the chronological age, and the Kidney age - Chronological age Difference (KCD) score is 90–70 = 20 years. Whereas CKD may be defined by eGFR < 60 ml/min/1.73 m2 (green line), age-dependent stepped eGFR criteria of Delanaye et al. [10] define CKD as eGFR < 75 ml/min/1.73 m2 for age < 40 years, < 60 ml/min/1.73 m2 for individuals between 40 and 65 years, and < 45 ml/min/1.73 m2 for age > 65 years (purple line) The red line corresponds to a KCD score of 20 years