Glomerular filtration rate estimated by the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation in type 1 diabetes based on genomic ancestry

BACKGROUND: Black individuals have a great risk of developing chronic kidney disease (CKD) that is associated with high morbimortality, so it is important to classify them into the correct renal function group. Some equations used to estimate glomerular filtration rate (eGFR) divide patients only into two categories: African Americans and non-African Americans. The CKD-EPI equation was tested only in African Americans, and not Black patients from other regions, and takes into consideration self-reported color-race instead of genomic ancestry (GA) to determine the use of the ethnic correction factor. So far, this equation has not been evaluated in admixed populations, such as the Brazilian, using the percentage of GA to decide to apply the correction factor. The purpose of our study was to compare, in patients with type 1 diabetes (T1D), the eGFR calculated without the use of the correction factor, with the values obtained using the correction factor in patients presenting 50% or more of African GA. METHODS: This cross-sectional, multicenter study enrolled 1279 patients from all geographic regions of Brazil. The CKD-EPI equation was used and CKD was defined as eGFR < 60 ml/min. GA were inferred using a panel of 46 AIM-INDEL, afterwards patients presenting an African GA ≥ 50% were selected. RESULTS: Initially, all patients with African GA ≥ 50% (n = 85) were considered as non-African Americans when calculating the eGFR and afterwards the ethnic correction factor was applied to recalculate the eGFR. CKD was present in 23 patients and 56.5% of them were redefined as having normal renal function after using the correction factor, mainly women [11 of the 13 patients (84.6%)], with GFR between 52–59.3 ml/min. CONCLUSIONS: More than half of the patients in the study were reclassified to a normal renal function group, showing that GA may be an important tool to decide between the use of the ethnic correction factor in the CKD-EPI equation in a highly admixed population of patients with T1D. A large-scale study involving GA and eGFR in comparison to reference methods should be conducted to better establish whether or not the ethnic correction factor should be used in highly admixed populations.