title: Psoriasis and the risk of pneumonia: a population-based study.
abstract: BACKGROUND
  Psoriasis is a prevalent autoimmune disorder. Various studies have reported on the relationship between psoriasis and chronic diseases but very few have explored the association between psoriasis and subsequent acute infection. This retrospective cohort study aimed to compare the risk of pneumonia between subjects with and those without psoriasis.
  
  
  METHODS
  The medical records of 14,022 patients with psoriasis and 14,022 without psoriasis were obtained from the Taiwan Longitudinal Health Insurance Database 2000. Each patient was followed-up for a three-year period. Cox proportional hazard regressions were performed to compare difference of subsequent pneumonia incidence between subjects with and those without psoriasis.
  
  
  RESULTS
  There were 206 (1.47%) subjects with psoriasis and 138 (0.98%) without psoriasis hospitalized for pneumonia. By Cox proportional hazard regressions analysis, the HR (hazard ratio) of pneumonia requiring hospitalization for patients with psoriasis was 1.50 (95% confidence interval [CI]: 1.21-1.86) compared to patients without psoriasis. The adjusted HR was 1.40 (95% CI: 1.12-1.73). The adjusted HR of pneumonia hospitalization for subjects with mild and severe psoriasis was 1.36 (95% CI: 1.09-1.70) and 1.68 (95% CI: 1.12-2.52), respectively, compared to those without psoriasis.
  
  
  CONCLUSIONS
  Patients with psoriasis have significantly higher incidence of pneumonia compared to those without psoriasis.
authors.affiliation: Graduate Institute of Life Science, National Defense Medical Center, Taipei, Taiwan; Sleep Research Center, Taipei Medical University Hospital, Taipei, Taiwan.
authors.forename: Li-Ting
authors.initials: LT
authors.lastname: Kao
authors.affiliation: Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Cha-Ze
authors.initials: CZ
authors.lastname: Lee
authors.affiliation: Department of Urology, National Taiwan University Hospital and College of Medicine, Taipei, Taiwan.
authors.forename: Shih-Ping
authors.initials: SP
authors.lastname: Liu
authors.affiliation: Division of Gastroenterology, Department of Internal Medicine, Cathay General Hospital, Taipei, Taiwan; School of Health Care Administration, Taipei Medical University, Taipei, Taiwan.
authors.forename: Ming-Chieh
authors.initials: MC
authors.lastname: Tsai
authors.affiliation: Sleep Research Center, Taipei Medical University Hospital, Taipei, Taiwan; School of Health Care Administration, Taipei Medical University, Taipei, Taiwan.
authors.forename: Herng-Ching
authors.initials: HC
authors.lastname: Lin
mesh_terms: D000328:Adult; D015331:Cohort Studies; D005260:Female; D006760:Hospitalization; D006801:Humans; D008297:Male; D008875:Middle Aged; D011014:Pneumonia / Q000453:epidemiology*; D011565:Psoriasis / Q000150:complications* / Q000453:epidemiology; D012189:Retrospective Studies; D012306:Risk; D013624:Taiwan / Q000453:epidemiology; D055815:Young Adult