Incidence of alopecia areata in Olmsted County, Minnesota, 1975 through 1989.

OBJECTIVE: To assess the incidence and natural history of alopecia areata (AA) among unselected patients from a community.

DESIGN: We conducted a retrospective population-based descriptive study of AA among residents of Olmsted County, Minnesota, for the period from 1975 through 1989.

MATERIAL AND METHODS: After identifying 292 Olmsted County residents first diagnosed with AA during the 15-year study period, we reviewed their complete (inpatient and outpatient) medical records in the community and statistically analyzed the effects of gender and age-group.

RESULTS: The overall incidence of AA was 20.2 per 100,000 person-years and did not change with time. Rates were similar in the two genders and over all ages, and lifetime risk was estimated at 1.7%. Eighty-seven percent of patients were examined by a dermatologist who diagnosed AA, and 29% of cases were confirmed by biopsy. Most patients had mild or moderate disease, but alopecia totalis or universalis developed at some point during the clinical course in 21 patients.

CONCLUSION: This study of the incidence and natural history of AA in a community shows that this disorder is fairly common and can be seen at all ages. Although spontaneous resolution is expected in most patients, a small but significant proportion of cases (probably approximately 7%) may evolve into severe and chronic hair loss, which may be psychosocially devastating for affected persons.