title: Neutrophil to lymphocyte ratio and risk of a first episode of stroke in patients with atrial fibrillation: a cohort study.
abstract: BACKGROUND
  The neutrophil to lymphocyte ratio (NLR) is associated with increased risk of cardiovascular morbidity and mortality. We aimed to assess the association between NLR and first episode of stroke in patients with atrial fibrillation.
  
  
  METHODS
  Using the computerized database of the largest HMO in Israel, we identified a cohort of adults, aged 20 years or older, with atrial fibrillation diagnosed before 1 January 2012. Eligible subjects had no prior stroke or TIA, were not on anticoagulants at baseline, and had at least one blood cell count performed in 2011. The cohort (32,912 subjects) was followed for the first event of stroke or TIA until 31 December 2012.
  
  
  RESULTS
  Overall 981 subjects developed stroke during a follow-up of 30,961 person-years (stroke rate, 3.17 per 100 person-years). The incidence rate of stroke increased across NLR quartiles: 2.27, 2.72, 3.26 and 4.54 per 100 person-years, respectively. Cox proportional hazard regression analysis adjusting for the individual CHA2 DS2 -VASc score risk factors showed that, compared with the lowest NLR quartile, the HR for stroke was 1.11 (95% CI, 0.91-1.35), 1.25 (1.03-1.51) and 1.56 (1.29-1.88) for the second, third and highest quartile, respectively. On stratified analysis, NLR refined the risk of stroke across all CHA2 DS2 -VASc score strata. Adding NLR to the CHA2 DS2 -VASc score increased the AUC from 0.627 (95% CI, 0.612-0.643) to 0.635 (0.619-0.651) (P = 0.037).
  
  
  CONCLUSIONS
  The neutrophil to lymphocyte ratio is directly associated with the risk of stroke in patients with atrial fibrillation. Future studies are needed to replicate these findings.
authors.affiliation: Department of Community Medicine and Epidemiology, Carmel Medical Center, Clalit Health Services, and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: W
authors.initials: W
authors.lastname: Saliba
authors.affiliation: Department of Community Medicine and Epidemiology, Carmel Medical Center, Clalit Health Services, and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.
authors.forename: O
authors.initials: O
authors.lastname: Barnett-Griness
authors.affiliation: Internal Medicine C, Ha'emek Medical Center, Afula, Israel.
authors.forename: M
authors.initials: M
authors.lastname: Elias
authors.affiliation: Department of Community Medicine and Epidemiology, Carmel Medical Center, Clalit Health Services, and Bruce Rappaport Faculty of Medicine, Technion-Israel Institute of Technology, Haifa, Israel.|Department of Epidemiology and Disease Prevention, Office of the Chief Physician, Clalit Health Services Headquarters, Tel Aviv, Israel.
authors.forename: G
authors.initials: G
authors.lastname: Rennert
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000925:Anticoagulants / Q000627:therapeutic use; D019540:Area Under Curve; D001281:Atrial Fibrillation / Q000097:blood* / Q000150:complications / Q000188:drug therapy; D015897:Comorbidity; D016208:Databases, Factual; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007557:Israel / Q000453:epidemiology; D007958:Leukocyte Count; D016015:Logistic Models; D018655:Lymphocyte Count; D008297:Male; D008875:Middle Aged; D009504:Neutrophils; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D012306:Risk; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D020521:Stroke / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D055815:Young Adult
chemical_list: D000925:Anticoagulants
keywords: atrial fibrillation; biomarker; clinical prediction rule; inflammation; stroke