Prevalence of reduced eGFR in European adults using KDIGO and age-adapted eGFR thresholds

The current definition for chronic kidney disease (CKD) does not account for age-related kidney function decline. Age-adapted CKD definitions have been suggested, but their impact on the estimates of reduced kidney function prevalence remains unclear. We aimed to compare the prevalence of reduced estimated glomerular filtration rate (eGFR) in European adults using the KDIGO eGFR threshold and three age-adapted eGFR thresholds.

This cross-sectional study included data collected after 1999 from nine general population-based studies from seven European countries. eGFR was calculated using the European Kidney Function Consortium equation. Prevalence of reduced eGFR was estimated over age using four eGFR thresholds: the KDIGO eGFR threshold (eGFR <60 mL/min/1.73 m2), the categorical age-adapted eGFR threshold (eGFR <75 mL/min/1.73 m2 if aged <40 years, eGFR <60 mL/min/1.73 m2 if aged 40-65 years, eGFR <45 mL/min/1.73 m2 if aged >65 years), and two novel continuous age- and sex-adapted eGFR thresholds based on the 5th and 2.5th percentile of eGFR in healthy individuals.

We used data from over 2.5 million European adults (46% men). Among those under 40 years, the KDIGO threshold provided the lowest average prevalence estimate (<1%), followed by the categorical age-adapted threshold (3%) and the 2.5th and 5th continuous age- and sex-adapted thresholds (4% and 7%). In adults over 65 years, the 2.5th continuous age- and sex-adapted threshold (10%) estimated the lowest prevalence, followed by the 5th continuous age- and sex-adapted threshold (15%), categorical age-adapted threshold (19%) and KDIGO threshold (45%).

Using age-adapted eGFR thresholds would likely cause a shift in the prevalence of reduced kidney function. However, the association between these novel age-adapted thresholds and clinical outcomes needs to be established before considering their incorporation into the definition of CKD.