title: Family history of psoriasis, stressful life events, and recent infectious disease are risk factors for a first episode of acute guttate psoriasis: results of a case-control study.
abstract: BACKGROUND
  The association of guttate psoriasis with streptococcal pharyngitis is well accepted. The association of other risk factors is less well defined.
  
  
  OBJECTIVE
  We attempted to provide an estimate of the risk for guttate psoriasis associated with a recent infectious disease and to explore other potential risk factors, including family history of psoriasis and psychologic stress.
  
  
  METHODS
  This was a case-control study. Cases were patients with a first diagnosis ever of acute guttate psoriasis, made by a dermatologist. Controls were patients newly diagnosed as having dermatologic conditions other than psoriasis and seen in the same outpatient services as the cases. Inclusion of cases and controls was restricted to patients older than 16 years. The Holmes and Rahe Social Readjustment Rating Scale was used to assess stressful life events during the 6 months before diagnosis. A total of 73 cases (median age, 26 years) and 430 controls (median age, 28 years) were included in the analysis.
  
  
  RESULTS
  A family history of psoriasis was strongly associated with guttate psoriasis, the multivariate odds ratio being 7.0 (95% confidence interval, 3.7-13.5) for subjects who reported a history of the disease in parents or siblings. Stressful life events were also associated with guttate psoriasis. The multivariate odds ratio was 1.7 (95% confidence interval, 0.8-3.6) for subjects scoring 41 to 100 and 2.6 (95% confidence interval, 1.3-5.2) for those scoring more than 100 on the Holmes and Rahe Scale. The risk increased with the reported history of any infectious disease. The analysis of specific diagnoses documented a high and significant association with acute pharyngitis, the adjusted odds ratio being 7.8 (95% confidence interval, 1.8-32.5).
  
  
  CONCLUSIONS
  The study confirmed that recent pharyngeal infection is a risk factor for guttate psoriasis. It also documented the strong association between guttate psoriasis and a family history of psoriasis. Finally, the study added evidence to the belief that stressful life events may represent risk factors for the onset of psoriasis. By relying on the clinical diagnosis we possibly underestimate the association of guttate psoriasis with infection.
authors.affiliation: Clinica Dermatologica, Università degli Studi de Milano-Bicocca, Ospedale Riuniti de Bergamo, Bergamo, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Naldi
authors.forename: L
authors.initials: L
authors.lastname: Peli
authors.forename: F
authors.initials: F
authors.lastname: Parazzini
authors.forename: C F
authors.initials: CF
authors.lastname: Carrel
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010612:Pharyngitis / Q000150:complications*; D011565:Psoriasis / Q000209:etiology* / Q000235:genetics; D012307:Risk Factors; D013290:Streptococcal Infections / Q000150:complications*; D013315:Stress, Psychological