title: The epidemiology of extra-articular manifestations in ankylosing spondylitis: a population-based matched cohort study.
abstract: OBJECTIVE
  To assess the incidence and risks of common extra-articular manifestations (EAMs), that is, acute anterior uveitis (AAU), psoriasis and inflammatory bowel disease (IBD), in patients with ankylosing spondylitis (AS) compared with population-based controls.
  
  
  METHODS
  All incident patients with AS (n=4101) from the UK Clinical Practice Research Datalink (1987-2012) were matched with up to seven control subjects without AS by year of birth, sex and practice (n=28,591). Incidence rates, cumulative incidence rates and adjusted (adj) HRs for the development of EAMs were calculated, with time-dependent adjustments for age, sex, comorbidity and medication use.
  
  
  RESULTS
  At diagnosis of AS, the proportion of patients with an EAM was 11.4% for AAU, 4.4% for psoriasis and 3.7% for IBD. Incidence rates of EAMs were 8.9/1000 person-years for AAU, 3.4/1000 person-years for psoriasis and 2.4 /1000 person-years for IBD in AS. The 20-year cumulative incidence was 24.5%, 10.1% and 7.5%, respectively. Risks of EAMs were 1.5-fold to 16-fold increased versus controls, with an adj HR of 15.5 (95% CI 11.6 to 20.7) for AAU, adj HR of 1.5 (95% CI 1.1 to 1.9) for psoriasis and adj HR of 3.3 (95% CI 2.3 to 4.8) for IBD. For psoriasis and IBD, the highest risks were found in the 1st years after diagnosis, while developing AAU continued to be increased also 10 years after diagnosis of AS.
  
  
  CONCLUSIONS
  The risk of, in particular AAU, but also of psoriasis and IBD, is significantly increased in patients with AS compared with controls. Hazard patterns are different for each of the EAMs.
authors.affiliation: Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht, The Netherlands Division of Rheumatology, Department of Medicine, Maastricht University Medical Center, Maastricht, The Netherlands Care and Public Health Research Institute (CAPHRI), Maastricht University, Maastricht, The Netherlands.
authors.forename: Carmen
authors.initials: C
authors.lastname: Stolwijk
authors.affiliation: Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht, The Netherlands Division of Rheumatology, Department of Medicine, Maastricht University Medical Center, Maastricht, The Netherlands Care and Public Health Research Institute (CAPHRI), Maastricht University, Maastricht, The Netherlands.
authors.forename: Ivette
authors.initials: I
authors.lastname: Essers
authors.affiliation: Division of Rheumatology, Department of Medicine, Maastricht University Medical Center, Maastricht, The Netherlands Care and Public Health Research Institute (CAPHRI), Maastricht University, Maastricht, The Netherlands.
authors.forename: Astrid
authors.initials: A
authors.lastname: van Tubergen
authors.affiliation: Division of Rheumatology, Department of Medicine, Maastricht University Medical Center, Maastricht, The Netherlands Care and Public Health Research Institute (CAPHRI), Maastricht University, Maastricht, The Netherlands.
authors.forename: Annelies
authors.initials: A
authors.lastname: Boonen
authors.affiliation: Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht, The Netherlands.
authors.forename: Marloes T
authors.initials: MT
authors.lastname: Bazelier
authors.affiliation: Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht, The Netherlands.
authors.forename: Marie L
authors.initials: ML
authors.lastname: De Bruin
authors.affiliation: Division of Pharmacoepidemiology and Clinical Pharmacology, Utrecht Institute for Pharmaceutical Sciences, Utrecht, The Netherlands Care and Public Health Research Institute (CAPHRI), Maastricht University, Maastricht, The Netherlands Department of Clinical Pharmacy and Toxicology, Maastricht University Medical Centre, Maastricht, The Netherlands MRC Lifecourse Epidemiology Unit, Southampton General Hospital, Southampton, UK.
authors.forename: Frank
authors.initials: F
authors.lastname: de Vries
mesh_terms: D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D015994:Incidence; D015212:Inflammatory Bowel Diseases / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D011565:Psoriasis / Q000453:epidemiology*; D012189:Retrospective Studies; D012307:Risk Factors; D013167:Spondylitis, Ankylosing / Q000150:complications* / Q000453:epidemiology; D006113:United Kingdom / Q000453:epidemiology; D014606:Uveitis, Anterior / Q000453:epidemiology*; D055815:Young Adult
keywords: epidemiology; inflammatory bowel disease; psoriasis; uveitis