Population-based reference values for kidney function and kidney function decline in 25- to 95-year-old Germans...

Area of Science:

• Nephrology
• Gerontology
• Epidemiology

Background:

• Understanding normal kidney aging is crucial for identifying chronic kidney disease (CKD) risk.
• Estimated glomerular filtration rate (eGFR) using serum creatinine (eGFRcrea) or cystatin C (eGFRcys) are common measures.
• Population-based reference values for eGFR and its decline across a wide age range are limited.

Purpose of the Study:

• To establish age-group-specific reference values for eGFRcrea and eGFRcys.
• To determine population-based reference values for the annual decline in eGFR.
• To aid clinicians in interpreting eGFR values and predicting eGFR decline based on age and risk factors.

Main Methods:

• Analysis of cross-sectional and longitudinal data from four German population-based cohorts (KORA-3, KORA-4, AugUR, DIACORE).
• Inclusion of approximately 12,000 individuals aged 25-95 years with up to five measurements over 25 years.
• Utilized linear mixed models for longitudinal analysis of eGFRcrea and eGFRcys.

Main Results:

• Cross-sectionally, eGFRcrea decreased linearly with age; eGFRcys decreased up to age 60.
• Annual eGFRcrea decline was estimated at -0.80 mL/min/1.73m² for the general population, -0.79 for "healthy" individuals, and -1.20 for individuals with diabetes.
• Reference values and prediction intervals for eGFR and eGFR decline were provided for various subgroups.

Conclusions:

• The study provides essential age-specific reference data for eGFR and eGFR decline.
• These findings support clinicians in assessing kidney function and identifying individuals at higher risk for CKD.
• The established reference values can be used to benchmark individual eGFR against population norms and expected aging trajectories.