Karmaus W, Botezan C
Department of Epidemiology, Michigan State University 48823, USA.
J Epidemiol Community Health. 2002 Mar;56(3):209-17. doi: 10.1136/jech.56.3.209.
To review the "protective" effects of having a higher number of siblings for the risk of atopic eczema, asthma wheezing, hay fever, and allergic sensitisation.
Review of the literature (Medline since 1965 and references).
53 different studies were identified. For eczema, 9 of 11 studies reported an inverse relation with number of siblings; for asthma and wheezing, 21 of 31 reported the inverse association; for hay fever, all 17 studies showed the effect; for allergic sensitisation or immunoglobulin E reactivity 14 of 16 studies supported the "protective" effect of a higher number of siblings. The studies emphasise a "theory" that is based exclusively on epidemiological associations.
Research has not yet answered the question of which causal factors explain the sibling effect. Causal factors must meet two criteria; they must vary with sibship size and they must protect against atopic manifestations. The prevailing "hygiene hypothesis" failed to explain the findings adequately. Alternative explanations include in utero programming or endocrine explanatory models. The epidemiology research into siblings and atopic disorders has entered an intellectually challenging phase. Possessing sufficient knowledge about the causal factors might prevent at least 30% of all cases of asthma, eczema, and hay fever.
探讨兄弟姐妹数量较多对特应性皮炎、哮喘性喘息、花粉症和过敏致敏风险的“保护”作用。
文献回顾（自1965年起的Medline及参考文献）。
共纳入53项不同研究。对于湿疹，11项研究中有9项报告其与兄弟姐妹数量呈负相关；对于哮喘和喘息，31项研究中有21项报告了这种负相关；对于花粉症，所有17项研究均显示出这种效应；对于过敏致敏或免疫球蛋白E反应性，16项研究中有14项支持兄弟姐妹数量较多的“保护”作用。这些研究强调了一种仅基于流行病学关联的“理论”。
研究尚未回答是哪些因果因素导致了兄弟姐妹效应这一问题。因果因素必须满足两个标准：它们必须随同胞数量而变化，并且必须预防特应性表现。流行的“卫生假说”未能充分解释这些发现。其他解释包括子宫内编程或内分泌解释模型。对兄弟姐妹与特应性疾病的流行病学研究已进入一个具有智力挑战性的阶段。了解因果因素可能至少预防30%的哮喘、湿疹和花粉症病例。
