title: Apolipoprotein E and kidney function in older adults.
abstract: BACKGROUND
  Previous studies suggest that the ε4 and ε2 alleles of apolipoprotein E (APOE) may be associated with decreased and increased risks of CKD, respectively, but there are limited data in older adults. We evaluated the associations of apolipoprotein E alleles with kidney function among older adults in the cardiovascular health study (CHS).
  
  
  METHODS
  Caucasian participants had APOE allelic analysis and serum creatinine and cystatin C measured at baseline (n = 3,844 for cross sectional analysis) and in follow up (n = 3,226 for longitudinal analysis). APOE variation was evaluated as an additive model with number of ε2, ε3 and ε4 alleles. GFR was estimated using the CKD epidemiology equation (eGFRcreat) and the cystatin C demographic equation (eGFRcys). The primary outcome was CKD defined by eGFR < 60 ml/min/1.73 m2. The secondary outcome was rapid progression defined by annual loss of eGFR > 3 ml/min/1.73 m2.
  
  
  RESULTS
  Mean eGFRcreat was 72 ml/min/1.73 m2 (25% CKD). Compared with the ε3 allele, the APOE ε4 allele was associated with reduced risk of CKD by eGFRcreat: unadjusted odds ratio (OR) and 95% confidence interval (CI) 0.79 (0.67 - 0.93) per allele, fully adjusted OR (95% CI) 0.80 (0.68 - 0.96) per allele. Results were consistent using eGFRcys. There was no association of the ε2 allele with CKD or between the apolipoprotein E gene with rapid progression.
  
  
  CONCLUSIONS
  The apolipoprotein ε4 allele was associated with lower odds of CKD in elderly Caucasian individuals. Future research should confirm these findings in other races and explore mechanisms to explain these results.
authors.affiliation: Division of Nephrology, Department of Medicine, Tufts Medical Center, Boston, MA 02111, USA.
authors.forename: Rebecca Kurnik
authors.initials: RK
authors.lastname: Seshasai
authors.forename: Ronit
authors.initials: R
authors.lastname: Katz
authors.forename: Ian H
authors.initials: IH
authors.lastname: de Boer
authors.forename: David
authors.initials: D
authors.lastname: Siscovick
authors.forename: Michael G
authors.initials: MG
authors.lastname: Shlipak
authors.forename: Dena E
authors.initials: DE
authors.lastname: Rifkin
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Sarnak
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000483:Alleles; D001057:Apolipoproteins E / Q000235:genetics*; D016001:Confidence Intervals; D003404:Creatinine / Q000097:blood; D003430:Cross-Sectional Studies; D055316:Cystatin C / Q000097:blood; D018450:Disease Progression; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000502:physiology*; D008297:Male; D016017:Odds Ratio; D051436:Renal Insufficiency, Chronic / Q000097:blood / Q000235:genetics* / Q000503:physiopathology*; D012307:Risk Factors; D044465:White People / Q000235:genetics
chemical_list: D001057:Apolipoproteins E; D055316:Cystatin C; D003404:Creatinine