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.