title: Serum cystatin C level, kidney disease markers, and incidence of age-related macular degeneration: the Beaver Dam Eye Study.
abstract: OBJECTIVE
  To examine the associations of the serum cystatin C level and chronic kidney disease with the incidence of age-related macular degeneration (AMD) over 15 years.
  
  
  METHODS
  In this population-based cohort study of 4926 individuals aged 43 to 86 years at baseline, 3779 participated in 1 or more follow-up examinations. Age-related macular degeneration was determined by grading photographs of the macula. Individuals were defined as having mild or moderate to severe chronic kidney disease based on a value of more than 45 mL/min/1.73 m(2) to 60 mL/min/1.73 m(2) or less and 45 mL/min/1.73 m(2) or less, respectively, according to the Modification of Diet in Renal Disease Study equation.
  
  
  RESULTS
  While controlling for age and other risk factors, the level of serum cystatin C at baseline was associated with the incidence of early AMD (odds ratio per log standard deviation [95% confidence interval], 1.16 [1.01-1.35]) and exudative AMD (1.42 [1.03-1.96]) but not geographic atrophy (0.89 [0.56-1.41]) or progression of AMD (1.02 [0.88-1.18]). Mild chronic kidney disease was associated with the 15-year cumulative incidence of early AMD (odds ratio per log standard deviation, 1.36 [95% confidence interval, 1.00-1.86]) but not the incidence of other AMD end points.
  
  
  CONCLUSIONS
  There is a relationship between the level of serum cystatin C and chronic kidney disease with the incidence of AMD. The underlying biological processes remain to be determined.
authors.affiliation: Department of Ophthalmology and Visual Sciences, University of Wisconsin School of Medicine and Public Health, 610 N Walnut St, Room 417 WARF, Madison, WI 53726-2336, USA. kleinr@epi.ophth.wisc.edu
authors.forename: Ronald
authors.initials: R
authors.lastname: Klein
authors.forename: Michael D
authors.initials: MD
authors.lastname: Knudtson
authors.forename: Kristine E
authors.initials: KE
authors.lastname: Lee
authors.forename: Barbara E K
authors.initials: BE
authors.lastname: Klein
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood*; D001806:Blood Urea Nitrogen; D055316:Cystatin C / Q000097:blood*; D018450:Disease Progression; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D015994:Incidence; D007676:Kidney Failure, Chronic / Q000097:blood*; D008268:Macular Degeneration / Q000097:blood* / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D011507:Proteinuria; D012307:Risk Factors; D014922:Wisconsin / Q000453:epidemiology
chemical_list: D015415:Biomarkers; D055316:Cystatin C