TY - JOUR T1 - Site of psoriasis (scalp or intergluteal/perianal), ⩾3 affected sites, and nail dystrophy predicted psoriatic arthritis in incident psoriasis JF - Evidence Based Medicine JO - Evid Based Med SP - 185 LP - 185 DO - 10.1136/ebm.14.6.185 VL - 14 IS - 6 A2 - , Y1 - 2009/12/01 UR - http://ebm.bmj.com/content/14/6/185.abstract N2 - In patients with psoriasis, what are the clinical predictors for psoriatic arthritis?Design:incidence cohort study with ⩽30 years of follow-up (20 936 person-years).Setting:Olmsted County, Minnesota, USA.Patients:1593 patients who were 18–98 years of age (mean age 43 y, 50% women), had a first diagnosis of psoriasis (plaque psoriasis 79%, guttate psoriasis 8.2%, sebopsoriasis 5.4%, and pustular psoriasis 3.3%), and did not have psoriatic arthritis at baseline.Prognostic factors:demographics, type of psoriasis, site of psoriasis, number of affected sites, and nail dystrophy.Outcomes:psoriatic arthritis, defined as a score ⩾3 on the following CASPAR criteria: (1) current psoriasis (2 points) or personal or family history of psoriasis; (2) nail dystrophy, such as onycholysis, pitting, or hyperkeratosis; (3) negative RF; … ER -