title: Long-term variability of inflammatory markers and associated factors in a population-based cohort.
abstract: OBJECTIVE
  To investigate long-term variability in serum high-sensitivity C-reactive protein (CRP) and interleukin-6 (IL-6) and to determine associated risk factors for high-risk inflammatory profiles.
  
  
  METHODS
  Prospective population-based cohort study.
  
  
  METHODS
  Participants (N = 1,443) of the Epidemiology of Hearing Loss Study and the Beaver Dam Eye Study, two population-based prospective studies of aging in the same cohort.
  
  
  METHODS
  In participants aged 43 to 79 at the initial examination (1988-1990), serum high-sensitivity CRP was measured from three time-points (1988-1990, 1998-2000, 2009-2010), and serum IL-6 was measured from two (1998-2000, 2009-2010).
  
  
  RESULTS
  When IL-6 levels were categorized into tertiles, 50.8% of participants were in the same group 10 years later (weighted kappa (κ) = 0.34). When CRP was categorized into three risk groups, 53.4% of participants were in the same group 10 years later (κ = 0.36), and 32.4% were in the same group at all three examinations (κ = 0.27). IL-6 increased from a geometric mean of 1.54 pg/L to 1.78 pg/L over 10 years, whereas CRP increased from a geometric mean of 1.67 mg/L to 2.25 mg/L over 10 years and then decreased to 1.93 mg/L over the next 10 years. These 10-year decreases in CRP were not observed in those not reporting statin use. Factors associated with long-term higher levels of IL-6 and CRP were older age (IL-6), obesity, smoking, lower physical activity (IL-6), lower high-density lipoprotein cholesterol (IL-6), and a history of statin (non)use (CRP).
  
  
  CONCLUSIONS
  Inflammatory marker levels tracked over the long term into older age with within-person increases were observed. Several potentially modifiable risk factors were associated with long-term higher levels of inflammatory markers.
authors.affiliation: Department of Population Health Sciences, University of Wisconsin, Madison, Wisconsin 53726, USA. snash@wisc.edu
authors.forename: Scott D
authors.initials: SD
authors.lastname: Nash
authors.forename: Karen J
authors.initials: KJ
authors.lastname: Cruickshanks
authors.forename: Ronald
authors.initials: R
authors.lastname: Klein
authors.forename: Barbara E K
authors.initials: BE
authors.lastname: Klein
authors.forename: F Javier
authors.initials: FJ
authors.lastname: Nieto
authors.forename: Rick
authors.initials: R
authors.lastname: Chappell
authors.forename: Carla R
authors.initials: CR
authors.lastname: Schubert
authors.forename: Michael Y
authors.initials: MY
authors.lastname: Tsai
mesh_terms: D000328:Adult; D000368:Aged; D002097:C-Reactive Protein / Q000032:analysis*; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D034381:Hearing Loss / Q000097:blood / Q000453:epidemiology; D006801:Humans; D007249:Inflammation / Q000097:blood* / Q000175:diagnosis* / Q000453:epidemiology; D018836:Inflammation Mediators / Q000097:blood*; D015850:Interleukin-6 / Q000097:blood*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D011446:Prospective Studies; D012307:Risk Factors
chemical_list: D018836:Inflammation Mediators; D015850:Interleukin-6; D002097:C-Reactive Protein
keywords: aging; inflammation; long-term variability
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