DIFFERENCES IN PREVALENCE OF CHRONIC KIDNEY DISEASE USING BERLIN INITIATIVE STUDY 1 AND CKD-EPI EQUATIONS IN ELDERY SUBJECTS (ENAH STUDY)

Abstract

Objective: Glomerular filtration rate (GFR) is considered to be the best indicator of renal function in health and disease, and according to the guidelines should be estimated using CKD-Epi equation. CKD-Epi has a limitation when estimating GFR for elderly subjects. Recently, Berlin Initiative Study 1 equation (BIS1) was suggested to be more appropriate for subjects aged 70 or older. Our aim was to analyze differences in estimation GFR and prevalence of CKD when using CKD-Epi and BIS1. Design and method: Data on 2194 adult subjects (random sample of rural population; 383 > = 70 yr, 39.2% male) were analyzed. CKD-Epi and BIS1 were used to estimate eGFR in total group, elderly (> = 70 yr) and younger than 70 yr. Differences between equations were analyzed using chi-square test, kappa inter-rater agreement and Bland-Altman plot analysis. Results: Significant difference in proportion of patients in CKD stages when comparing CKD-Epi vs BIS1 for subjects older than 70 years, p < 0.001 was observed. When estimating GFR with two equations we observed a higher difference in prevalence in elderly subjects for eGFR values < 60 ml/min and > = 60 ml/min than in subjects <70 years (Figure 1). The difference in prevalence between CKD-Epi and BIS1 for older subjects was 22.7%, while for younger 0.008%, p < 0.001 (Figure 1). The agreement between CKD-Epi and BIS1 in older patients was lower than in younger subjects (kappa 0.56 vs kappa 0.67). When analyzing the total population there were more patients in stage 3a CKD using BIS1 equation than using CKD-Epi equation (10.2% vs. 5.8%). A systematic difference was found between the formulas, with BIS1 mean value 8.0 ml/min being lower than that of CKD-Epi (95% limits of agreement: +1.9 to -17.8). Conclusions: Significant difference between CKD-Epi and BIS1 was found. There was a higher difference in CKD prevalence in older subjects and also agreement between two formulas was lower in that subgroup. Our results suggest that specific equation suitable for elderly subjects should be used.