Department of Preventive Medicine and Public Health, Faculty of Medicine, Fukuoka University, Fukuoka, Japan.
BMC Public Health. 2011 Jul 14;11:561. doi: 10.1186/1471-2458-11-561.
Although an inverse relationship between number of siblings and likelihood of allergic disorders has been shown in many epidemiological studies, the biological mechanism underlying this phenomenon has not yet been identified. There is no epidemiological research regarding the sibling effect on allergic disorders in Japanese adults. The current cross-sectional study examined the relationship between number of siblings and prevalence of allergic disorders among adult women in Japan.
Subjects were 1745 pregnant women. This study was based on questionnaire data. The definitions of wheeze and asthma were based on criteria from the European Community Respiratory Health Survey whereas those of eczema and rhinoconjunctivitis were based on criteria from the International Study of Asthma and Allergies in Childhood. Adjustment was made for age, region of residence, pack-years of smoking, secondhand smoke exposure at home and at work, family history of asthma, atopic eczema, and allergic rhinitis, household income, and education.
The prevalence values of wheeze, asthma, eczema, and rhinoconjunctivitis in the past 12 months were 10.4%, 5.5%, 13.0%, and 25.9%, respectively. A significant inverse exposure-response relationship was observed between the number of older siblings and rhinoconjunctivitis, but not wheeze, asthma, or eczema (P for trend=0.03); however, the adjusted odds ratio (OR) for having 2 or more older siblings was not significant although the adjusted OR for having 1 older sibling was statistically significant (adjusted OR=0.71 [95% CI: 0.56-0.91]). Number of total siblings and number of younger siblings were not related to wheeze, asthma, eczema, or rhinoconjunctivitis.
This study found a significant inverse relationship between the number of older siblings and the prevalence of rhinoconjunctivitis among pregnant Japanese women. Our findings are likely to support the intrauterine programming hypothesis; however, we could not rule out the hygiene hypothesis.
尽管许多流行病学研究表明兄弟姐妹数量与过敏疾病的发生几率呈反比关系，但这一现象背后的生物学机制尚未得到明确。目前尚无关于日本成年人兄弟姐妹对过敏疾病影响的流行病学研究。本横断面研究调查了日本成年女性中兄弟姐妹数量与过敏疾病患病率之间的关系。
研究对象为 1745 名孕妇。本研究基于问卷调查数据。喘息和哮喘的定义基于欧洲社区呼吸健康调查的标准，而湿疹和鼻结膜炎的定义则基于儿童过敏和哮喘国际研究的标准。调整因素包括年龄、居住地区、吸烟包年数、家庭和工作环境中的二手烟暴露、哮喘家族史、特应性皮炎和过敏性鼻炎家族史、家庭收入和教育程度。
过去 12 个月喘息、哮喘、湿疹和鼻结膜炎的患病率分别为 10.4%、5.5%、13.0%和 25.9%。随着年龄较大的兄弟姐妹数量的增加，鼻结膜炎的患病率呈显著负相关趋势，但喘息、哮喘或湿疹无此趋势（趋势检验 P=0.03）；然而，调整后的 OR 对于有 2 个或更多年龄较大的兄弟姐妹虽有统计学意义，但无显著意义（调整 OR=0.71[95%CI：0.56-0.91]）。总的兄弟姐妹数量和年龄较小的兄弟姐妹数量与喘息、哮喘、湿疹或鼻结膜炎均无显著相关性。
本研究发现日本孕妇中年龄较大的兄弟姐妹数量与鼻结膜炎的患病率呈显著负相关。我们的研究结果可能支持宫内编程假说，但不能排除卫生假说。
