title: The spectrum of thyroid disease and risk of new onset atrial fibrillation: a large population cohort study.
abstract: OBJECTIVE
  To examine the risk of atrial fibrillation in relation to the whole spectrum of thyroid function in a large cohort of patients.
  
  
  METHODS
  Population based cohort study of general practice patients identified by linkage of nationwide registries at the individual level.
  
  
  METHODS
  Primary care patients in the city of Copenhagen.
  
  
  METHODS
  Registry data for 586,460 adults who had their thyroid function evaluated for the first time by their general practitioner during 2000-10 and who were without previously recorded thyroid disease or atrial fibrillation.
  
  
  METHODS
  Poisson regression models used to estimate risk of atrial fibrillation by thyroid function.
  
  
  RESULTS
  Of the 586,460 individuals in the study population (mean (SD) age 50.2 (16.9) years, 39% men), 562,461 (96.0%) were euthyroid, 1670 (0.3%) had overt hypothyroidism, 12,087 (2.0%) had subclinical hypothyroidism, 3966 (0.7%) had overt hyperthyroidism, and 6276 (1.0%) had subclinical hyperthyroidism. Compared with the euthyroid individuals, the risk of atrial fibrillation increased with decreasing levels of thyroid stimulating hormone (TSH) from high normal euthyroidism (incidence rate ratio 1.12 (95% CI 1.03 to 1.21)) to subclinical hyperthyroidism with reduced TSH (1.16 (0.99 to 1.36)) and subclinical hyperthyroidism with supressed TSH (1.41 (1.25 to 1.59)). Both overt and subclinical hypothyroidism were associated with a lower risk of atrial fibrillation.
  
  
  CONCLUSIONS
  The risk of atrial fibrillation was closely associated with thyroid activity, with a low risk in overt hypothyroidism, high risk in hyperthyroidism, and a TSH level dependent association with risk of atrial fibrillation across the spectrum of subclinical thyroid disease.
authors.affiliation: Department of Cardiology, Gentofte University Hospital, Hellerup, Denmark. cselmer@gmail.com
authors.forename: Christian
authors.initials: C
authors.lastname: Selmer
authors.forename: Jonas Bjerring
authors.initials: JB
authors.lastname: Olesen
authors.forename: Morten Lock
authors.initials: ML
authors.lastname: Hansen
authors.forename: Jesper
authors.initials: J
authors.lastname: Lindhardsen
authors.forename: Anne-Marie Schjerning
authors.initials: AM
authors.lastname: Olsen
authors.forename: Jesper Clausager
authors.initials: JC
authors.lastname: Madsen
authors.forename: Jens
authors.initials: J
authors.lastname: Faber
authors.forename: Peter Riis
authors.initials: PR
authors.lastname: Hansen
authors.forename: Ole Dyg
authors.initials: OD
authors.lastname: Pedersen
authors.forename: Christian
authors.initials: C
authors.lastname: Torp-Pedersen
authors.forename: Gunnar Hilmar
authors.initials: GH
authors.lastname: Gislason
mesh_terms: D001281:Atrial Fibrillation / Q000453:epidemiology* / Q000209:etiology; D003718:Denmark / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D012042:Registries; D012189:Retrospective Studies; D012307:Risk Factors; D013959:Thyroid Diseases / Q000150:complications*