Lifetime incidence risk of Alopecia Areata estimated at 2.1 percent by Rochester Epidemiology Project, 1990–2009

Alopecia Areata (AA) is characterized by patchy, nonscarring, autoimmune-mediated hair loss, although many aspects of AA pathogenesis are unknown (Gilhar et al., 2012). The scalp is most commonly involved in clinically treated AA, but any hair-bearing surface of the body may be affected (Wasserman et al., 2007). Males and females of any age and hair color can have AA (Finner, 2011; Kyriakis et al., 2009). According to the First National Health and Nutrition Examination Survey conducted in the early 1970s, AA is fairly common; it was estimated to affect about 2 of every 1,000 people in the United States (Safavi, 1992). Dermatologists encounter AA in 0.7% to 4.0% of their patient populations (Price, 1991; Sharma et al., 1996; Tan et al., 2002). A previous study reported by Mayo Clinic and National Institutes of Health (Safavi et al., 1995) showed that the overall incidence of AA in Olmsted County, Minnesota, was 20.2 per 100,000 person-years from 1975 through 1989. A similar incidence rate for both sexes with a lifetime risk of 1.7% was observed.