title: Epidemiology and comorbidities of psoriasis patients in a national database in Taiwan.
abstract: BACKGROUND
  Recent findings in psoriasis research have shown that psoriasis is frequently associated with systemic comorbidities.
  
  
  OBJECTIVE
  This study aims to describe the epidemiology of psoriasis and the prevalence of comorbidities in patients with psoriasis in Taiwan.
  
  
  METHODS
  Patients who had at least one outpatient visit or admission with ICD-9-CM diagnosis code 696.0-1 in the Taiwan National Health Insurance (NHI) claims database during 2006 were identified as psoriasis cases. The cases were further classified into moderate to severe psoriasis (sPsO) for those who had previously received systemic therapy during the study period and mild psoriasis (mPsO) for those who had not. The cases were matched in a 1:4 ratio with controls from a sample cohort of 997,771 enrolees representative of the Taiwan population. Matching variables included age, gender and residential area. Prevalence of comorbidities was assessed using prevalence relative risk (RR) based upon a Cox proportional regression model.
  
  
  RESULTS
  51,800 psoriasis cases were identified (prevalence=0.235%; mean age=46.4±18.6; male:female=1.6:1) and 17.5% of cases were sPsO type. Psoriasis was associated with a significantly increased prevalence ratio (RR; [95% confidence interval]) for hypertension (1.51; [1.47, 1.56]), diabetes (1.64; [1.58, 1.70]), hyperglyceridaemia (1.61; [1.54, 1.68]), heart disease (1.32; [1.26, 1.37]), hepatitis B viral infection (1.73; [1.47, 2.04]), hepatitis C viral infection (2.02; [1.67, 2.44]), rheumatoid arthritis (3.02; [2.68, 3.41]), systemic lupus erythematosus (6.16; [4.70, 8.09]), vitiligo (5.94; [3.79, 9.31]), pemphigoid (14.75; [5.00, 43.50]), pemphigus (41.81; [12.41, 140.90]), alopecia areata (4.71; [2.98, 7.45]), lip, oral cavity and pharynx cancer (1.49; [1.22, 1.80]), digestive organs and peritoneum cancer (1.57; [1.41, 1.74]), depression (1.50; [1.39, 1.61]), fatty liver (2.27; [1.90, 2.71]), chronic airways obstruction (1.47; [1.34, 1.61]), sleep disorder (3.89; [2.26, 6.71]), asthma (1.29; [1.18, 1.40]), and allergic rhinitis (1.25; [1.18, 1.33]). Conversely, psoriasis was not associated with an increased risk of Crohn's disease.
  
  
  CONCLUSIONS
  Psoriasis was associated with a significantly increased risk of comorbidities, especially for those patients with moderate to severe disease. These health associations should be taken into consideration when evaluating the burdens of psoriasis and designing effective treatment plans.
authors.affiliation: Department of Dermatology, College of Medicine, National Taiwan University, and National Taiwan University Hospital, Taipei, Taiwan.
authors.forename: Tsen-Fang
authors.initials: TF
authors.lastname: Tsai
authors.forename: Ting-Shun
authors.initials: TS
authors.lastname: Wang
authors.forename: Sheng-Tzu
authors.initials: ST
authors.lastname: Hung
authors.forename: Phiona I-Ching
authors.initials: PI
authors.lastname: Tsai
authors.forename: Brad
authors.initials: B
authors.lastname: Schenkel
authors.forename: Mingliang
authors.initials: M
authors.lastname: Zhang
authors.forename: Chao-Hsiun
authors.initials: CH
authors.lastname: Tang
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000553:Ambulatory Care / Q000706:statistics & numerical data; D016022:Case-Control Studies; D015897:Comorbidity; D019992:Databases as Topic / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009313:National Health Programs / Q000706:statistics & numerical data; D010343:Patient Admission / Q000706:statistics & numerical data; D015995:Prevalence; D016016:Proportional Hazards Models; D011565:Psoriasis / Q000175:diagnosis / Q000188:drug therapy / Q000453:epidemiology*; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D017678:Sex Distribution; D013624:Taiwan / Q000453:epidemiology; D055815:Young Adult