Comparison of different equations for estimating glomerular filtration rate for evaluating renal function in people aged 70 years and older

Abstract

Objective To assess the value of different equations for estimating glomerular filtration rate (GFR) for evaluating renal function in people aged 70 years and older. Methods A retrospective study was conducted involving 11 966 elderly people aged 70 years and older, including 5 741 males (48.0%), who underwent routine physical examinations in Beijing Hospital from January 2012 to December 2014 and were followed up for 3 years.Baseline data, including the age, gender, and serum creatinine, were recorded. Results function was assessed using Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI), Modification of Diet in Renal Disease (MDRD) Study, Chinese Modification of Diet in Renal Disease (MDRD) Study, full age spectrum (FAS) equation and Berlin Initiative Study (BIS) equation, respectively.Results The serum creatinine level increased with age in male and female subjects, and the standard deviation also increased with age, indicating greater variability of serum creatinine in the elderly.Of all equations, the FAS and BIS equations had the lowest GFR estimates.The five equations showed good consistency.In males, the Kendall's W coefficient was 0.796 (P = 0.000); the female Kendall's W coefficient was 0.715 (P = 0.000). Based on three ranges of serum creatinine (<88.4 μmol/L, ≥88.4 μmol/L and <132.6 μmol/L, ≥132.6 μmol/L), all patients were divided into three groups.The BIS, MDRD, MDRDc and FAS equations were all consistent in staging CKD at any creatinine level; however, the CKD-EPI equation significantly overestimated renal function at higher levels of serum creatinine.There was no clear age-related trend when each of the five equations was used to calculate the average 3-year eGFR rate. Conclusions The CKD-EPI, MDRD, MDRDc, FAS and BIS equations can be used to assess renal function, but the results vary among different populations.Which equation has the best accuracy for the elderly in China remains inconclusive and further research is urgently needed. Key words: glomerular filtration rate; Aging