Changes in the positive rate of a scratch test with aging obserbed in the same students (A comparison of the data obtained in Shiraoi-cho, Hokkaido, from 1990 to 1993)

Abstract

Changes in positive rate of scratch test with aging were examined, in the same students who had collective physical examination and relevant scrath test in both years of 1990 and 1993 in Shiraoi-cho, Hokkaido. The first graders in the elementary school in 1990 were in the fourth grade in 1993, and those in fourth grade in 1990 were in the first year in junior high school in 1993. In both groups, the positive rate of scrath test was significantly in the years of 1993 compared with the same in 1990. The increase in the positive rate of scrath test with the aging of the students is considered to result from the duration of period during which the students were exposed to allergen.