Comparison of formulas for calculating estimated glomerular filtration rate and its diagnostic thresholds for chronic kidney disease in older adults: a cross-sectional study

Abstract

Objective To evaluate and compare the CKD-EPI, BIS1 and MDRD formulas and diagnostic thresholds of 45 and 60 ml/min/1.73m2 in older patients. Method A cross-sectional, descriptive, analytical observational study was conducted. Patients aged ≥65 years treated at a referral outpatient clinic between January 2020 and June 2022, were assessed. Patients with only one creatinine level or with transient GFR abnormalities were excluded. Results The GFR estimates using the CKD-EPI formula were higher than both the BIS1 and MDRD formulas in patient groups aged 65-74 years and 75-84 years. In the group of patients aged 85-94 years, the CKD-EPI showed no difference when compared with the MDRD, yielding higher estimates only compared with the BIS1. Greater dispersion was found between the CKD-EPI and BIS1, showing less agreement between these formulas, as confirmed by the Kappa test (76.7%), while there was almost perfect agreement between the CKD-EPI and MDRD. Conclusion The BIS1 formula showed stronger correlation of the decrease in eGFR with advancing age, reflecting the physiological renal aging process and serving as a potentially useful tool for estimating GFR in older adults. The formula can help provide a more accurate diagnosis of CKD and aid planning of interventions to slow the progression of CKD and predict the risk of mortality from cardiovascular diseases.