Family history of psoriasis and recent infectious disease are risk factors for the first episode of acute guttate psoriasis

Abstract

Background Psoriasis is a heterogeneous disease in its clinical expression. Both geneticand environmental factors are thought to contribute to the pathogenesis. The association ofguttate psoriasis with streptococcal pharyngitis is well accepted. The association of otherrisk factors is less well-defined.Objectives The aim of this study was to estimate the risk for guttate psoriasis with recentinfections and to explore other potential risk factors like family history of psoriasis.Patients and methods This was a case-control study. Cases were patients with the firstdiagnosis ever of acute guttate psoriasis. Controls were patients newly diagnosed as havingdermatologic conditions other than psoriasis and seen in the same outpatient services as thecases. Inclusion of cases and controls was restricted to patients up to 18 years of age. Atotal 35 cases (median age, 8 years) and 150 controls (median age, 12½ years) wereincluded in the analysis.Results A significant difference was observed for a family history of psoriasis. 45.7% ofpatients with guttate psoriasis gave a family history of psoriasis in their first-degreerelatives. The risk of psoriasis was also increased in subjects who reported a history of arecent infectious episode. The analysis by individual diagnosis pointed to acute pharyngitisas the disease with the strongest association. Twenty-seven patients (77.1%) gave a historyof sore throat preceding the onset of guttate psoriasis. All of them had a throat swabperformed, of these 20 had normal flora cultured. Only 6 had a positive culture and in thesecases Lancefield group C ß-hemolytic streptococci were isolated. ASO titer was raised in21 (60%) patients of guttate psoriasis .Conclusion The study confirmed that recent pharyngeal infection is a risk factor for guttatepsoriasis. It also documented the strong association between guttate psoriasis and a familyhistory of psoriasis