Assessment of GFR by four methods in adults in Ashanti, Ghana: the need for an eGFR equation for lean African populations

Abstract

Background. Equations for estimating glomerular filtration rate (GFR) have not been validated in Sub-Saharan African populations, and data on GFR are few.Methods. GFR by creatinine clearance (Ccr) using 24-hour urine collections and estimated GFR (eGFR) using the four-variable Modification of Diet in Renal Disease (MDRD-4)[creatinine calibrated to isotope dilution mass spectrometry (IDMS) standard], Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Cockcroft–Gault equations were obtained in Ghanaians aged 40–75. The population comprised 1013 inhabitants in 12 villages; 944 provided a serum creatinine and two 24-hour urines. The mean weight was 54.4 kg; mean body mass index was 21.1 kg/m2.Results. Mean GFR by Ccr was 84.1 ml/min/1.73 m2; 86.8% of participants had a GFR of ≥60 ml/min/1.73 m2. Mean MDRD-4 eGFR was 102.3 ml/min/1.73 m2 (difference vs. Ccr, 18.2: 95% CI: 16.8–19.5); when the factor for black race was omitted, the value (mean 84.6 ml/min/1.73 m2) was close to Ccr. Mean CKD-EPI eGFR was 103.1 ml/min/1.73 m2, and 89.4 ml/min/1.73 m2 when the factor for race was omitted. The Cockcroft–Gault equation underestimated GFR compared with Ccr by 9.4 ml/min/1.73 m2 (CI: 8.3–10.6); particularly in older age groups. GFR by Ccr, and eGFR by MDRD-4, CKD-EPI and Cockcroft–Gault showed falls with age: MDRD-4 5.5, Ccr 7.7, CKD-EPI 8.8 and Cockcroft–Gault 11.0 ml/min/1.73 m2/10 years. The percentage of individuals identified with CKD stages 3–5 depended on the method used: MDRD-4 1.6% (7.2 % without factor for black race; CKD-EPI 1.7% (4.7% without factor for black race), Ccr 13.2% and Cockcroft–Gault 21.0%.Conclusions. Mean eGFR by both MDRD-4 and CKD-EPI was considerably higher than GFR by Ccr and Cockcroft–Gault, a difference that may be attributable to leanness. MDRD-4 appeared to underestimate the fall in GFR with age compared with the three other measurements; the fall with CKD-EPI without the adjustment for race was the closest to that of Ccr. An equation tailored specifically to the needs of the lean populations of Africa is urgently needed. For the present, the CKD-EPI equation without the adjustment for black race appears to be the most useful.

Are the Creatinine-Based Equations Accurate to Estimate Glomerular Filtration Rate in African American Populations?

“…This is also indirectly suggested by the difference in weight observed between the trials (mean weight of 69.5 kg in South Africans versus 84.1 kg in African Americans in the MDRD study) (8,14). The same results have also been found in Ghanaian populations even if GFR was only estimated by creatinine clearance (and not measured GFR) (11). From the same South African cohort, inaccuracy of the CKD-EPI study equation has also been recently demonstrated by the CKD-EPI group (31).…”

“…Eventually, we need additional trials to better estimate GFR in African subjects. This is a necessary step to better assess the real prevalence of CKD in these populations in which prevention is preponderant in health politics because of low economic resources (11,44).…”

Implication of CKD-EPI Equation to Estimate Glomerular Filtration Rate in Chinese Patients with Chronic Kidney Disease

“…A separate large collaborative group of data was used to design and verify the new equation. It has been validated in nonrenal disease of middle-aged people, 15 renal transplant recipients, 16 polycystic kidney disease patients, 17 Australian, 18 African, 19 and some Asian populations. 20 The CKD-EPI equation more appropriately categorized individuals with respect to long-term clinical risk compared with the MDRD study equation, suggesting improved clinical usefulness in this middle-aged population.…”

CKD-EPI is a Better Tool for Detecting Renal Dysfunction in Hypertensive Pregnancy: A Case-Control Study in Ghana

“…Smith et al [26] who assessed renal impairments in pregnancy complicated by renal disease or preeclampsia, suggested that in all situations, the MDRD-4 equation substantially underestimates eGFR during pregnancy and cannot be recommended for use in clinical practice. Additionally, in a Ghanaian study Eastwood et al [27] proposed for the use of the CKD-EPI equation in assessing GFR in blacks because it was suggested as an outstanding equation when dealing with black subjects. Although, Silva Junior assessed renal function using 4 different equations, they reported that the CKD-EPI-Creatinine Cystatin C equation was a more sensitive equation to detect renal loss as it could identify 9% of their study population as having renal impairment as compared to the others that averaged 2%.…”