Prevalence of Alopecia Areata in the First National Health and Nutrition Examination Survey

To the Editor.—  No estimates of the incidence or prevalence of alopecia areata (AA) have been published. The First National Health and Nutrition Examination Survey (NHANES-I), conducted from 1971 through 1974, contained a dermatologic examination of 20 749 individuals in a probability sample of the US population. This communication presents the prevalence of AA as estimated from the findings of NHANES-I.

Materials and Methods.—  The survey design and methods of NHANES-I have been well described by the National Center for Health Statistics (NCHS).^1,2 The examiner's diagnosis of AA could be recorded in four places on the survey form as follows: (1) "significant dermatological diagnosis" (limit of three); (2) a finding on the scalp; (3) a finding on the face; or (4) a finding on the nail.Using a published table of upper- and lower-bound factors based on the Poisson distribution,³ 95% confidence intervals (CIs) for total prevalence and