title: Serum concentration of cystatin C and risk of end-stage renal disease in diabetes.
abstract: OBJECTIVE
  Patients with diabetes have a high risk of end-stage renal disease (ESRD). We examined whether prediction of this outcome, according to chronic kidney disease (CKD) staging by creatinine-based estimates of the glomerular filtration rate (eGFRcreat), is improved by further staging with serum cystatin C-based estimates (eGFRcyst).
  
  
  METHODS
  Patients with diabetes in CKD stages 1-3 were selected from three cohorts: two from Joslin Diabetes Center, one with type 1 diabetes (N = 364) and one with type 2 diabetes (N = 402), and the third from the Finnish Diabetic Nephropathy (FinnDiane) Study of type 1 (N = 399). Baseline serum concentrations of creatinine and cystatin C were measured in all patients. Follow-up averaged 8-10 years and onsets of ESRD (n = 246) and death unrelated to ESRD (n = 159) were ascertained.
  
  
  RESULTS
  Although CKD staging by eGFRcyst was concordant with that by eGFRcreat for 62% of Joslin patients and 73% of FinnDiane patients, those given a higher stage by eGFRcyst than eGFRcreat had a significantly higher risk of ESRD than those with concordant staging in all three cohorts (hazard ratio 2.3 [95% CI 1.8-3.1]). Similarly, patients at a lower stage by eGFRcyst than by eGFRcreat had a lower risk than those with concordant staging (0.30 [0.13-0.68]). Deaths unrelated to ESRD followed the same pattern, but differences were not as large.
  
  
  CONCLUSIONS
  In patients with diabetes, CKD staging based on eGFRcyst significantly improves ESRD risk stratification based on eGFRcreat. This conclusion can be generalized to patients with type 1 and type 2 diabetes and to diabetic patients in the U.S. and Finland.
authors.affiliation: Research and Clinic Divisions, Joslin Diabetes Center, Harvard Medical School, Boston, MA, USA. andrzej.krolewski@joslin.harvard.edu
authors.forename: Andrzej S
authors.initials: AS
authors.lastname: Krolewski
authors.forename: James H
authors.initials: JH
authors.lastname: Warram
authors.forename: Carol
authors.initials: C
authors.lastname: Forsblom
authors.forename: Adam M
authors.initials: AM
authors.lastname: Smiles
authors.forename: Lena
authors.initials: L
authors.lastname: Thorn
authors.forename: Jan
authors.initials: J
authors.lastname: Skupien
authors.forename: Valma
authors.initials: V
authors.lastname: Harjutsalo
authors.forename: Robert
authors.initials: R
authors.lastname: Stanton
authors.forename: John H
authors.initials: JH
authors.lastname: Eckfeldt
authors.forename: Lesley A
authors.initials: LA
authors.lastname: Inker
authors.forename: Per-Henrik
authors.initials: PH
authors.lastname: Groop
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D003404:Creatinine / Q000097:blood; D055316:Cystatin C / Q000097:blood*; D003928:Diabetic Nephropathies / Q000097:blood / Q000453:epidemiology; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000453:epidemiology*; D008297:Male; D055815:Young Adult
chemical_list: D055316:Cystatin C; D003404:Creatinine