Haematological profile of chronic kidney disease in a mixed-ancestry South African population: a cross-sectional study

Objectives The objectives were to characterise the haematological profile of screen-detected chronic kidney disease (CKD) participants and to correlate the complete blood count measures with the commonly advocated kidney function estimators. Methods The current cross-sectional study used data, collected between February 2015 and November 2016, of 1564 adults of mixed-ancestry, who participated in the Cape Town Vascular and Metabolic Health study. Kidney function was estimated using the Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations. CKD was defined as estimated glomerular filtration rate (eGFR) <60mL/min/1.73m(2), and anaemia as haemoglobin level <13.5g/dL (men) and <12g/dL (women). Results Based on the MDRD and CKD-EPI equations, the crude prevalence of CKD was 6% and 3%. Irrespective of the equation used, median red blood cell (RBC) indices were consistently lower in those with CKD compared with those without CKD (all p<0.0001). Despite not showing any significant difference in total white blood cell (WBC) count between the two groups, the number of lymphocytes were lower (p=0.0001and p<0.0001 for MDRD and CKD-EPI, respectively) and neutrophil count (both p<0.0297) and the ratio of lymphocytes to neutrophil (both p<0.0001) higher in the CKD group compared with those without CKD; with the remaining WBC indices similar in the two groups. The platelet count was similar in both groups. Of the screen-detected CKD participants, 45.5% (MDRD) and 57.8% (CKD-EPI) were anaemic, with the prevalence increasing with increasing severity of CKD, from 37.2% (stage 3) to 82.4% (stages 4-5). Furthermore, CKD-EPI-estimated kidney function, but not MDRD, was positively associated with RBC indices. Conclusion Though it remains unclear whether common kidney function estimators provide accurate estimates of CKD in Africans, the correlation of their estimates with deteriorating RBC profile, suggests that advocated estimators, to some extent approximate kidney function in African populations.