乳児湿疹の消長と季節の影響 : 1年に亘る保健所の4ヵ月, 10ヵ月乳児健診の結果  [in Japanese] THE INFLUENCE OF AGEING AND SEASONS ON INFANTILE ECZEMA : A Population-Based Cohort Study of Babies Aged 4 Months and 10 Months  [in Japanese]

【背景・目的】乳児湿疹の住民健診を1年以内に2度おこない, 相互の関連を調べた研究は見あたらないので, これをおこなった. 【方法】大阪府立藤井寺保健所が月2回おこなった4ヵ月健診に1990年9月から1991年8月までの1年にわたりアトピー性皮膚炎のエキスパート皮膚科医1人が参加した. 6ヵ月遅れの同じ乳児の10ヵ月健診に際しても同医師がこれを繰り返した. 全身の皮膚を観察し, 独自の調査票を用いて皮膚症状と掻破痕を評価し, その合計で湿疹の有無を判定した. 湿疹の程度は, 1. 受診不要, 2. 要受診, 3. 要治療の3群に分けた. 各種データは独自のソフトを用いてDEC-7000コンピュータで分析した. 【結果】保健所管轄の人口181994人における1年の健診期間の新生児1775人のうち, 4ヵ月健診には1493人が, 10ヵ月健診には1264人が出席した. 年平均でみると4ヵ月健診では22.0%, 10ヵ月では21.2%に湿疹が認められた. 両方の健診に出席した1264人のうち4ヵ月で22.8%に認められた湿疹のうち10ヵ月まで湿疹が続いたのは9.7%のみで, 13.1%では湿疹がなくなっていた. しかし11.5%に新たに湿疹が生じていた. 4ヵ月と10ヵ月の累積診断率は34.3%に達した. 湿疹の程度は4ヵ月の方が10ヵ月よりも有意に強かった. 月別の診断数は, 両健診ともに期待値との比較で, 4ヵ月健診では2月に有意に高く(OR 1.84, p=0.031), 8月に有意に低かった(OR 0.21, p<0.001). 10ヵ月健診でも2月に有意に高く(OR 2.19, p=0.02), 8月に有意に低かった(OR 0.36, p=0.015). 【結語】生後1年以内の乳児湿疹の皮膚症状は加齢により変化しやすく, また季節の影響を受けやすいと考えられる.

Background : This is probably the first report of a population study on infantile eczema performed for 12 months at two ages of 4 months and 10 months on the same infant group. Methods : The Fujiidera Health Center services the health needs of 181,994 inhabitants of Habikino and Fujiidera cities. Between September 1990 and August 1991,1775 newborns were called for a health check-up performed twice a months when they reached 4 months of age. This was repeated for a year when the infants reached 10 months of age. A total of 1493 4-month old infants and 1264 10-month old infants were examined. An expert dermatologist joined this and performed a complete skin examination throughout the study. The eczematous skin changes were evaluated at 50 different points on the body and scored using an originally made chart. Scratch marks were also evaluated at each area. Based on the scores computed eczema was diagnosed when the total score crossed a threshold number. Based on this the examiner diagnoses were categorized as follows : Degree 1 : no need to visit a doctor, Degree 2 : visit to doctor required, Degree 3 : treatment required. Gender was not considered. The data was analyzed by an originally made software using DEC-7000 computer. Results : Of all the 4-month old Infants examined 329 (22.0%) were initially diagnosed to have eczema while of all the 10-month old infants examined 268 (21.2%) were initially diagnosed to have eczema. Further, out of the 329 4-month old infants initially diagnosed with eczema, 228 were again examined when they were 10-months old. Of this sample ; 123 (9.7%) infants showed continued symptoms of eczema and 165 (13.1%) infants no longer showed signs of eczema. In addition, out of the 976 4-month old infants initially diagnosed without eczema. 145 (11.5%) newly developed eczema at 10 months. Hence the cumulative diagnosis rate of eczema reached 34.3%. Meanwhile the monthly diagnosis number was significantly higher in Feb (OR 1.84, p=0.031) and significantly lower in Aug (OR 0.21, p<0.001) than the expected number calculated from monthly examination number and the annual diagnosis rate at 4 months. This observation was also the case at 10 months (Feb ; OR 2.19, p=0.02, Aug ; OR 0.36, p=0.015) . The degree of eczema was significantly higher (p<0.001. Mann-Whitney ' s U test) at 4 months than 10 months. When this was seen monthly, degree 3 was most prevalent in February-March, while degree 2 was most prevalent in October-January for the 4-month olds. For the 10-month olds, both the degree 3 and degree 2 were quite low throughout the year and only degree 1 showed a monthly change similar to degree 2 plus degree 3 of the 4-month olds. Conclusion : We therefore conclude that eczematous skin manifestations of infantile eczema are easily changeable by age at less than 1 year and are strongly influenced by seasons.