title: Determination of the best method to estimate glomerular filtration rate from serum creatinine in adult patients with sickle cell disease: a prospective observational cohort study.
abstract: BACKGROUND
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Service de Médecine Interne, centre de référence des syndromes drépanocytaires majeurs, Faculté de médecine Paris Descartes et Assistance publique – Hôpitaux de Paris, Hôpital Européen Georges Pompidou, Cedex 15, Paris 75908, France.
authors.forename: Jean-Benoît
authors.initials: JB
authors.lastname: Arlet
authors.forename: Jean-Antoine
authors.initials: JA
authors.lastname: Ribeil
authors.forename: Gilles
authors.initials: G
authors.lastname: Chatellier
authors.forename: Dominique
authors.initials: D
authors.lastname: Eladari
authors.forename: Sophie
authors.initials: S
authors.lastname: De Seigneux
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Souberbielle
authors.forename: Gérard
authors.initials: G
authors.lastname: Friedlander
authors.forename: Marianne
authors.initials: M
authors.lastname: de Montalembert
authors.forename: Jacques
authors.initials: J
authors.lastname: Pouchot
authors.forename: Dominique
authors.initials: D
authors.lastname: Prié
authors.forename: Marie
authors.initials: M
authors.lastname: Courbebaisse
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000465:Algorithms; D000755:Anemia, Sickle Cell / Q000097:blood* / Q000150:complications / Q000175:diagnosis*; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D003404:Creatinine / Q000097:blood*; D003936:Diagnosis, Computer-Assisted / Q000379:methods; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007674:Kidney Diseases / Q000097:blood* / Q000175:diagnosis* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D015415:Biomarkers; D003404:Creatinine