title: Risk of atrial fibrillation and stroke in rheumatoid arthritis: Danish nationwide cohort study.
abstract: OBJECTIVE
  To determine if patients with rheumatoid arthritis have increased risk of atrial fibrillation and stroke.
  
  
  METHODS
  Longitudinal nationwide register based cohort study.
  
  
  METHODS
  Inpatient and outpatient hospital care in Denmark from 1997 to 2009.
  
  
  METHODS
  Entire Danish population aged over 15 years without rheumatoid arthritis, atrial fibrillation, or stroke before 1997. Participants with rheumatoid arthritis were identified by individual level linkage of diagnoses and rheumatoid arthritis treatment.
  
  
  METHODS
  Rates of atrial fibrillation and stroke.
  
  
  RESULTS
  Of 4,182,335 participants included in the cohort, 18,247 were identified as having rheumatoid arthritis during follow-up, with a mean age at disease onset of 59.2 years and a median follow-up of 4.8 years. A total of 156,484 people, including 774 with rheumatoid arthritis, were diagnosed as having atrial fibrillation (age and sex matched event rates of 8.2 per 1000 person years in rheumatoid arthritis patients and 6.0 per 1000 person years in the general population), with an adjusted incidence rate ratio of 1.41 (95% confidence interval 1.31 to 1.51). In addition, 165,343 people, including 718 with rheumatoid arthritis, had a stroke (7.6 per 1000 person years in rheumatoid arthritis and 5.7 per 1000 person years in the general population), with a resultant rate ratio of 1.32 (1.22 to 1.42). For both atrial fibrillation and stroke, relative risks were increased in all strata based on thirds of sex and age, with higher relative risks in younger patients but higher absolute risk differences in older patients.
  
  
  CONCLUSIONS
  Rheumatoid arthritis was associated with an increased incidence of atrial fibrillation and stroke. The novel finding of increased risk of atrial fibrillation in rheumatoid arthritis suggests that this arrhythmia is relevant in cardiovascular risk assessment of these patients.
authors.affiliation: Department of Cardiology, Copenhagen University Hospital Gentofte, 2900 Hellerup, Denmark. jeslin01@geh.regionh.dk
authors.forename: Jesper
authors.initials: J
authors.lastname: Lindhardsen
authors.forename: Ole
authors.initials: O
authors.lastname: Ahlehoff
authors.forename: Gunnar Hilmar
authors.initials: GH
authors.lastname: Gislason
authors.forename: Ole Rintek
authors.initials: OR
authors.lastname: Madsen
authors.forename: Jonas Bjerring
authors.initials: JB
authors.lastname: Olesen
authors.forename: Jesper Hastrup
authors.initials: JH
authors.lastname: Svendsen
authors.forename: Christian
authors.initials: C
authors.lastname: Torp-Pedersen
authors.forename: Peter Riis
authors.initials: PR
authors.lastname: Hansen
mesh_terms: D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000150:complications*; D001281:Atrial Fibrillation / Q000453:epidemiology* / Q000209:etiology; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D020521:Stroke / Q000453:epidemiology* / Q000209:etiology