title: Association of White Blood Cell Count and Differential with the Incidence of Atrial Fibrillation: The Atherosclerosis Risk in Communities (ARIC) Study.
abstract: BACKGROUND
  Although inflammation is involved in the development of atrial fibrillation (AF), the association of white blood cell (WBC) count and differential with AF has not been thoroughly examined in large cohorts with extended follow-up.
  
  
  METHODS
  We studied 14,500 men and women (25% blacks, 55% women, mean age 54) free of AF at baseline (1987-89) from the Atherosclerosis Risk in Communities (ARIC) study, a community-based cohort in the United States. Incident AF cases through 2010 were identified from study electrocardiograms, hospital discharge records and death certificates. Multivariable Cox proportional hazards regression was used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for AF associated with WBC count and differential.
  
  
  RESULTS
  Over a median follow-up time of 21.5 years for the entire cohort, 1928 participants had incident AF. Higher total WBC count was associated with higher AF risk independent of AF risk factors and potential confounders (HR 1.09, 95% CI 1.04-1.15 per 1-standard deviation [SD] increase). Higher neutrophil and monocyte counts were positively associated with AF risk, while an inverse association was identified between lymphocyte count and AF (multivariable adjusted HRs 1.16, 95% CI 1.09-1.23; 1.05, 95% CI 1.00-1.11; 0.91, 95% CI 0.86-0.97 per 1-SD, respectively). No significant association was identified between eosinophils or basophils and AF.
  
  
  CONCLUSIONS
  High total WBC, neutrophil, and monocyte counts were each associated with higher AF risk while lymphocyte count was inversely associated with AF risk. Systemic inflammation may underlie this association and requires further investigation for strategies to prevent AF.
authors: Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, Minnesota, United States of America.
authors: Jeffrey R
authors: JR
authors: Misialek
authors: Cardiovascular Division, Department of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota, United States of America.
authors: Wobo
authors: W
authors: Bekwelem
authors: Cardiovascular Division, Department of Medicine, University of Minnesota Medical School, Minneapolis, Minnesota, United States of America.
authors: Lin Y
authors: LY
authors: Chen
authors: Department of Epidemiology, UNC Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, United States of America.
authors: Laura R
authors: LR
authors: Loehr
authors: Division of Medicine, John Hopkins University School of Medicine, Baltimore, Maryland, United States of America; Department of Epidemiology, John Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
authors: Sunil K
authors: SK
authors: Agarwal
authors: Epidemiological Cardiology Research Center (EPICARE), Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America; Department of Epidemiology and Prevention, Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America; Department of Internal Medicine (Cardiology Section), Wake Forest School of Medicine, Winston-Salem, North Carolina, United States of America.
authors: Elsayed Z
authors: EZ
authors: Soliman
authors: Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, Minnesota, United States of America.
authors: Faye L
authors: FL
authors: Norby
authors: Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, Minnesota, United States of America.
authors: Alvaro
authors: A
authors: Alonso
mesh_terms: D050197:Atherosclerosis / Q000097:blood* / Q000150:complications / Q000453:epidemiology*; D001281:Atrial Fibrillation / Q000097:blood* / Q000453:epidemiology* / Q000209:etiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D014481:United States / Q000453:epidemiology