Pre-dialysis chronic kidney disease progression over 4 years in the context of the Public Health System in Brazil: is ethnicity a factor?

Introduction: The prevalence of chronic kidney disease (CKD) significantly increased, and populations with high social vulnerability tend to have worse CKD progression. Objective: To evaluate the impact of ethnicity on the control of pre-dialytic CKD in a Brazilian Unified Health System interdisciplinary outpatient clinic. Material and Methods: Data of 1,992 CKD patients were retrospectively collected from August/2010 to December/2014. Patients referred by primary health care, >18 years, ≥ two consultations were included. Sociodemographic data were collected upon admission; clinical and laboratory data were obtained at each consultation. Patients were divided into groups according to skin colour (self-identified). A descriptive analysis was performed; variables were compared using ANOVA, chi-square or Mann-Whitney U tests. Variables associated with the delta of the estimated glomerular filtration rate (eGFR) were evaluated using linear regression, adjusting for confounding variables. Results: 25.1% were black, 34.4% brown, and 40.5% white. Approximately 51.2% had income ≤ two minimum wages, 84.8% had low level education, 14.0% were illiterate. Black patients were younger and had lower education level; they had higher systolic blood pressure, total cholesterol, high-density lipoproteins, intact parathyroid hormone; their haemoglobin and vitamin D were lower. The median annual eGFR loss was 0 (P25 −6.70, P75 +8.76), 36.5% had rapid eGFR loss (>5 ml/min/year). Only use of angiotensin-converting enzyme inhibitors and low proteinuria were determined as significant for the outcome (RR: 0.92, CI: 0.010–0.684, p=0.02; RR: 0.8, CI: 0.998-0.999, p=0.001). Conclusion: Ethnicity did not impact CKD progression, even though black patients presented clinical and sociodemographic characteristics associated with worse disease progression.