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

Departments of Renal Medicine and Transplantation, St Georges, University of London, Cranmer Terrace, London SW17 0RE, UK.
Nephrology Dialysis Transplantation (Impact Factor: 3.58). 07/2010; 25(7):2178-87. DOI: 10.1093/ndt/gfp765
Source: PubMed


Equations for estimating glomerular filtration rate (GFR) have not been validated in Sub-Saharan African populations, and data on GFR are few.
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/m(2).
Mean GFR by Ccr was 84.1 ml/min/1.73 m(2); 86.8% of participants had a GFR of >/=60 ml/min/1.73 m(2). Mean MDRD-4 eGFR was 102.3 ml/min/1.73 m(2) (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 m(2)) was close to Ccr. Mean CKD-EPI eGFR was 103.1 ml/min/1.73 m(2), and 89.4 ml/min/1.73 m(2) when the factor for race was omitted. The Cockcroft-Gault equation underestimated GFR compared with Ccr by 9.4 ml/min/1.73 m(2) (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 m(2)/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%.
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.

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    • "The reported high fatality rate associated with CKD in Africa has been attributed to a number of factors including the increasing prevalence of infectious diseases, late referrals of individuals with CKD to specialists, poor prognosis, limited renal replacement therapy, and the lack of agreement on the definition of CKD and standardisation of tests that are currently used for diagnosing the disease [10-13]. With specific reference to CKD diagnosis, the three commonly used estimators of GFR include the Cockcroft-Gault, the Modification of Diet in Renal Disease (MDRD) and the CKD Epidemiology Collaboration (CKD-EPI) equations, and each diagnoses a different subgroup of patients with CKD [11,12,14,15]. The more acclaimed MRDR and CKD-EPI equations apply a correction factor for ethnicity, which may substantially affect the diagnosis of CKD without being necessarily valid in all settings [11,12]. "
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    ABSTRACT: Background Population-based data on the burden of chronic kidney disease (CKD) in sub-Saharan Africa is still very limited. We assessed the prevalence and determinants of CKD, and evaluated the concordance of commonly advocated estimators of glomerular filtration rate (eGFR) in a mixed ancestry population from South Africa. Methods Participants were a population-based sample of adults selected from the Bellville-South community in the metropolitan city of Cape Town. eGFR was based on the Cockroft-Gault (CG), Modification of Diet in Kidney Disease (MDRD) and CKD Epidemiology Collaboration (CKD-EPI) equations (with and without adjustment for ethnicity). Kidney function staging used the Kidney Disease Outcome Quality Initiative (KDOQI) classification. Logistic regressions and kappa statistic were used to investigate determinants of CKD and assess the agreement between different estimators. Results The crude prevalence of CKD stage 3–5 was 14.8% for Cockcroft-Gault, 7.6% and 23.9% respectively for the MDRD with and without ethnicity correction, and 7.4% and 17.3% for the CKD-EPI equations with and without ethnicity correction. The highest agreement between GFR estimators was between MDRD and CKD-EPI equations, both with ethnicity correction, Kappa 0.91 (95% CI: 0.86-0.95), correlation coefficient 0.95 (95% CI: 0.94-0.96). In multivariable logistic regression models, sex, age and known hypertension were consistently associated with CKD stage 3–5 across the 5 estimators. Conclusions The prevalence of CKD stages greater than 3 is the highest reported in Africa. This study provides evidence for support of the CKD-EPI equation for eGFR reporting and CKD classification.
    BMC Nephrology 04/2013; 14(1):75. DOI:10.1186/1471-2369-14-75 · 1.69 Impact Factor
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    • "It has not been validated in black people of other ethnic origin, nor at extremes of body weight [8]. It has recently been shown that the CKD-EPI equation without adjustment for ethnicity is the most useful equation to estimate GFR in a lean Sub-Saharan African population [19] which may share some characteristics with adult SCD populations. Moreover, in a study of one hundred black South Africans, Van Deventer et al. have reported that both the MDRD-v4 [20] and the CKD-EPI [21] equations overestimated GFR when using the ethnicity correction factor as suggested for African-Americans. "
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    ABSTRACT: Sickle cell disease (SCD) leads to tissue hypoxia resulting in chronic organ dysfunction including SCD associated nephropathy. The goal of our study was to determine the best equation to estimate glomerular filtration rate (GFR) in SCD adult patients. We conducted a prospective observational cohort study. Since 2007, all adult SCD patients in steady state, followed in two medical departments, have had their GFR measured using iohexol plasma clearance (gold standard). The Cockcroft-Gault, MDRD-v4, CKP-EPI and finally, MDRD and CKD-EPI equations without adjustment for ethnicity were tested to estimate GFR from serum creatinine. Estimated GFRs were compared to measured GFRs according to the graphical Bland and Altman method. Sixty-four SCD patients (16 men, median age 27.5 years [range 18.0-67.5], 41 with SS-genotype were studied. They were Sub-Saharan Africa and French West Indies natives and predominantly lean (median body mass index: 22 kg/m2 [16-33]). Hyperfiltration (defined as measured GFR >110 mL/min/1.73 m2) was detected in 53.1% of patients. Urinary albumin/creatinine ratio was higher in patients with hyperfiltration than in patients with normal GFR (4.05 mg/mmol [0.14-60] versus 0.4 mg/mmol [0.7-81], p = 0.01). The CKD-EPI equation without adjustment for ethnicity had both the lowest bias and the greatest precision. Differences between estimated GFRs using the CKP-EPI equation and measured GFRs decreased with increasing GFR values, whereas it increased with the Cockcroft-Gault and MDRD-v4 equations. We confirm that SCD patients have a high rate of glomerular hyperfiltration, which is frequently associated with microalbuminuria or macroalbuminuria. In non-Afro-American SCD patients, the best method for estimating GFR from serum creatinine is the CKD-EPI equation without adjustment for ethnicity. This equation is particularly accurate to estimate high GFR values, including glomerular hyperfiltration, and thus should be recommended to screen SCD adult patients at high risk for SCD nephropathy.
    BMC Nephrology 08/2012; 13(1):83. DOI:10.1186/1471-2369-13-83 · 1.69 Impact Factor
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    ABSTRACT: Premesse La formula CKD-EPI (Chronic Kidney Disease Epidemiology Collaboration) è stata proposta in sostituzione della MDRD (Modification of Diet in Renal Disease) per stimare la velocità di filtrazione glomerulare (eGFR) nella pratica medica quotidiana. Scopo di questo studio è stato di valutare la comparabilità tra le due formule e di determinare l’effetto dell’applicazione della CKD-EPI sulla riclassificazione dei pazienti negli stadi della malattia renale cronica (CKD), in due vaste popolazioni di 186.575 e 28.349 pazienti ambulatoriali tra 20–70 anni, afferenti ai laboratori di riferimento per l’area di Monza e la Provincia di Lodi e la cui creatinina è stata rispettivamente determinata con due diversi metodi tracciabili IDSM. Metodi I valori della creatinina sierica, ottenuti utilizzando rispettivamente un metodo enzimatico e uno cinetico al picrato alcalino secondo Jaffè tra l’1 agosto del 2009 e l’1 agosto del 2010, sono stati ricavati dal database dei laboratori. La comparabilità tra i valori di eGFR stimati con le due formule è stata valutata mediante il metodo di Bland e Altman. Abbiamo anche confrontato la prevalenza della CKD nei singoli stadi ottenuta applicando ciascuna formula sui dati sia generali sia stratificati per età, sesso e valori di eGFR. Risultati Nessuna differenza tra la CKD-EPI e la MDRD per valori di eGFR <60 mL/min/1,73 m2, mentre per valori superiori la MDRD sottostima in modo consistente la GFR con entrambi i metodi analitici. La prevalenza di CKD allo stadio 2 era segnatamente più bassa con la CKD-EPI (22,1% vs 43,2% della MDRD e con il metodo enzimatico e 33,7% vs 52% della MDRD con il metodo Jaffè) cosÌ come la prevalenza di CKD allo stadio 3 (4,2% vs 5,2% della MDRD e con il metodo enzimatico e 3,2% vs 4,6% con il metodo Jaffè). Conclusioni L’applicazione della formula CKD-EPI rispetto alla MDRD determina una stima di GFR più elevata e una più bassa prevalenza di CKD negli stadi iniziali indipendenti dal metodo di misura della creatininemia. Queste differenze sembrano più rilevanti specialmente nelle donne, nella fascia di età fra 20–30 anni e per livelli di eGFR con la MDRD fra 30–59 mL/min/1,73 m2.
    Rivista Italiana della Medicina di Laboratorio 03/2012; 8(1). DOI:10.1007/s13631-011-0040-5
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