Canadian Centre for Health and Safety in Agriculture & Department of Medicine, University of Saskatchewan, Saskatoon, SK, Canada.
BMC Pulm Med. 2012 Sep 12;12:56. doi: 10.1186/1471-2466-12-56.
The association between endotoxin exposure and asthma is complex and has been associated with rural living. We examined the relationship between domestic endotoxin and asthma or wheeze among rural school-aged children (6-18 years) and assessed the interaction between endotoxin and other characteristics with these outcomes.
Between 2005 and 2007 we conducted a case-control study of children 6-18 years in the rural region of Humboldt, Canada. Cases (n = 102) reported doctor-diagnosed asthma or wheeze in the past year. Controls (n = 208) were randomly selected from children without asthma or wheeze. Data were collected to ascertain symptoms, asthma history and indoor environmental exposures (questionnaire), endotoxin (dust collection from the play area floor and child's mattress), and tobacco smoke exposure (saliva collection). Statistical testing was completed using multiple logistic regression to account for potential confounders and to assess interaction between risk factors. A stratified analysis was also completed to examine the effect of personal history of allergy.
Among children aged 6-12 years, mattress endotoxin concentration (EU/mg) and load (EU/m2) were inversely associated with being a case [odds ratio (OR) = 0.44, 95% confidence interval (CI) = 0.20-0.98; and OR = 0.38, 95% CI = 0.20-0.75, respectively]. These associations were not observed in older children or with play area endotoxin.
Our results suggest that endotoxin exposure might be protective for asthma or wheeze. The protective effect is found in younger school-aged, non-allergic children. These results may help explain the inconsistencies in previous studies and suggest that the protective effects of endotoxin in the prevention of atopy and asthma or wheeze are most effective earlier in life.
内毒素暴露与哮喘之间的关系复杂，并与农村生活有关。我们研究了农村学龄儿童（6-18 岁）家中内毒素与哮喘或喘息之间的关系，并评估了内毒素与其他特征与这些结果之间的相互作用。
在 2005 年至 2007 年期间，我们在加拿大洪堡农村地区进行了一项 6-18 岁儿童的病例对照研究。病例（n=102）报告过去一年中被医生诊断患有哮喘或喘息。对照组（n=208）是从没有哮喘或喘息的儿童中随机选择的。收集数据以确定症状、哮喘病史和室内环境暴露（问卷调查）、内毒素（从游乐区地板和儿童床垫上收集灰尘）和烟草烟雾暴露（唾液收集）。使用多因素逻辑回归完成统计检验，以说明潜在的混杂因素，并评估危险因素之间的相互作用。还进行了分层分析，以检验过敏个人史的影响。
在 6-12 岁的儿童中，床垫内毒素浓度（EU/mg）和负荷（EU/m2）与病例呈负相关[比值比（OR）=0.44，95%置信区间（CI）=0.20-0.98；和 OR=0.38，95% CI=0.20-0.75]。这些关联在年龄较大的儿童或游乐区内毒素中均未观察到。
我们的结果表明，内毒素暴露可能对哮喘或喘息有保护作用。这种保护作用在年龄较小的学龄、非过敏儿童中发现。这些结果可能有助于解释先前研究中的不一致，并表明内毒素在预防特应性和哮喘或喘息方面的保护作用在生命早期最为有效。
