An extensive survey of the incidence of acne vulgaris in Switzerland was made by Bloch.1 His series included 2,136 female subjects aged from 6 to 18 years and 2,055 male subjects aged from 6 to 19 years. Since a similar survey of a large group was not available in the American literature, it was decided to make one. Our survey includes 2,052 subjects, 872 male and 1,180 female, between the ages of 5 and 22 years.
Since it was desirable to compare the results of our survey with those of Bloch and because he has provided a classification of the severity of acne that is relatively quantitative, his classification has been adhered to.
The following grades of acne were distinguished by Bloch: —, no efflorescence, no acne; ±, under 5 comedones; +, from 5 to 20 comedones; ++, from 20 to 50 comedones, or inflammatory acne with papules and pustules,
HINRICHSEN J, IVY AC. INCIDENCE IN THE CHICAGO REGION OF ACNE VULGARIS. Arch Derm Syphilol. 1938;37(6):975–982. doi:10.1001/archderm.1938.01480120041006
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