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

Background: The association of guttate psoriasis with streptococcal pharyng itis is well accepted. The association of other risk factors is less well d efined. Objective: We attempted to provide an estimate of the risk for guttate psor iasis associated with a recent infectious disease and to explore other pote ntial risk factors, including family history of psoriasis and psychologic s tress. Methods: This was a case-control study Cases were patients with a first dia gnosis ever of acute guttate psoriasis, made by a dermatologist. Controls w ere patients newly diagnosed as having dermatologic conditions other than p soriasis and seen in the same outpatient sen ices as the cases. Inclusion o f cases and controls was restricted to patients older than 16 years. The Ho lmes and Rahe Social Readjustment Rating Scale was used to assess stressful life events during the 6 months before diagnosis. A total of 73 cases (med ian 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 psoriasi s. The multivariate odds ratio was 1.7 (95% confidence interval, 0.8-3.6) f or subjects scoring 41 to 100 and 2.6 (95% confidence interval, 1.3-5.2) fo r those scoring more than 100 on the Holmes and Rahe Scale. The risk increa sed with the reported history of any infectious disease. The analysis of sp ecific diagnoses documented a high and significant association with acute p haryngitis, the adjusted odds ratio being 7.8 (95% confidence interval, 1.8 -32.5). Conclusion: The study confirmed that recent pharyngeal infection is a risk factor for guttate psoriasis. It also documented the strong association bet ween 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 w e possibly underestimate the association of guttate psoriasis with infectio n.