title: Sarcoidosis in patients with psoriasis: a population-based cohort study.
abstract: OBJECTIVE
  Psoriasis is a chronic inflammatory disease characterized by a systemic immunological response which is mainly driven by activated T helper (Th) 1 and Th17 lymphocytes. Like psoriasis, sarcoidosis is a chronic inflammatory disorder with Th1/Th17-driven inflammation. Therefore, we investigated the risk of sarcoidosis in patients with psoriasis compared to the background population in a nationwide cohort.
  
  
  METHODS
  The study included the entire Danish population aged ≥10 years followed from 1st January 1997 until diagnosis of sarcoidosis, death or 31st December 2011. Patients with a history of psoriasis and/or sarcoidosis at baseline were excluded. Information on comorbidity and concomitant medication was identified by individual-level linkage of administrative registers. Incidence rates of sarcoidosis were calculated and adjusted hazard ratios (HRs) were estimated by multivariable Cox regression models adjusted for age, gender, comorbidity, medications and socioeconomic status.
  
  
  RESULTS
  A total of 6,043,518 subjects were eligible for analysis. In the study period 70,125 patients with new-onset psoriasis, including 11,834 patients with severe psoriasis, were identified. The overall incidence rates of sarcoidosis were 1.18, 2.22, and 4.06 per 10,000 person-years for the reference population (9,717 cases), mild psoriasis (78 cases) and severe psoriasis (22 cases), respectively. Compared to the reference population, the age- and gender-adjusted HRs for sarcoidosis were increased in patients with psoriasis with HR 1.49 (95% confidence interval [CI] 1.18-1.87) and HR 2.51 (CI 1.64-3.85) for those with mild and severe disease, respectively.
  
  
  CONCLUSIONS
  In this nationwide cohort, psoriasis was associated with a disease severity-dependent increased risk of sarcoidosis.
authors.affiliation: Department of Cardiology, Gentofte Hospital University of Copenhagen, Hellerup, Denmark.
authors.forename: Usman
authors.initials: U
authors.lastname: Khalid
authors.affiliation: Department of Cardiology, Gentofte Hospital University of Copenhagen, Hellerup, Denmark; Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark; National Institute of Public Health, University of Southren Denmark, Copenhagen, Denmark.
authors.forename: Gunnar Hilmar
authors.initials: GH
authors.lastname: Gislason
authors.affiliation: Department of Cardiology, Gentofte Hospital University of Copenhagen, Hellerup, Denmark; Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Peter Riis
authors.initials: PR
authors.lastname: Hansen
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D006801:Humans; D011565:Psoriasis / Q000150:complications*; D012306:Risk; D012507:Sarcoidosis / Q000150:complications* / Q000453:epidemiology; D055815:Young Adult