Indoor Allergens And Asthma

我们的哮喘研究项目包括暴露评估和预防两部分，重点关注暴露于常见室内过敏原与哮喘患病率和发病率之间的关系。全国住房铅和过敏原调查(NSLAH)是一项对国家住房中地板和床垫灰尘中的过敏原类型和水平的研究，是第一项提供美国人口过敏原暴露估计的研究。它涵盖了全国75个初级抽样单位的831个家庭。主要终点是测量尘螨、蟑螂、猫、狗、鼠、鼠和真菌过敏原水平，以及从调查家庭的一系列地点收集的灰尘样本中的内毒素。对老鼠过敏原的分析结果表明，82%的美国家庭有可检测到的老鼠过敏原水平，35%的家庭有1.6微克老鼠过敏原/克灰尘的水平，这一水平与老鼠过敏原敏感率的增加有关。在也患有活动性哮喘的过敏性个体中，暴露于1.6微克老鼠过敏原/克粉尘中会增加出现哮喘症状的几率。哮喘患者没有报告有过敏反应，当他们在家中暴露在高水平的老鼠变应原中时，没有增加出现症状的几率。在那些没有过敏的人中，家庭暴露于内毒素已经成为哮喘发展和严重程度的一个重要因素。我们之前从NSLAH报道，家庭内毒素浓度增加是确诊哮喘患病率增加、过去一年哮喘症状、目前使用哮喘药物和喘息的危险因素。由于限制内毒素暴露的重要性，特别是在哮喘患者中，几项研究评估了室内灰尘中的内毒素浓度或家庭表面内毒素负荷的预测因子。总体而言，这些研究局限于特定的地理区域、人口群体或住房类型；大多数研究局限于家庭房间地板灰尘或床上用品。由于这些研究的目标范围和对一两个城市的关注，出现了一些相互矛盾的结论，提出了这些结论是否具有普遍性的问题。NSLAH提供了机会，在代表美国人口的全国样本中调查住房内毒素污染的预测因素。5个采样点的加权几何平均内毒素浓度范围为18.7至80.5个内毒素单位(EU)/mg，内毒素负荷范围为4,160至19,500 EU/m2。家庭水库粉尘中内毒素的增加主要与贫困、人口、宠物、家庭清洁和地理环境有关。我们还与CDC/NCHS的研究人员合作，实施NHANES 2005-2006年的过敏原和哮喘部分。我们收集了卧室粉尘、测量的总IgE和过敏原特异性IgE，并评估了美国约9000人的哮喘和过敏患病率和发病率。对这些大型数据集的分析将使我们能够1)估计全国室内过敏原和内毒素暴露的流行率，2)估计全国对室内、室外和食物过敏原过敏的流行率，3)估计包括哮喘在内的过敏性疾病在全国范围内的流行率，4)调查过敏原和内毒素暴露、过敏性敏化和包括哮喘在内的过敏性疾病之间的复杂关系。在分析IgE水平以估计全国过敏性致敏流行率时，发现总IgE值的中位数男性高于女性；非西班牙裔黑人和墨西哥裔美国人高于非西班牙裔白人；那些受教育程度低于12年级、贫困加剧、血清可替宁水平更高、体重指数更高的人；以及至少1项特异性IgE结果阳性的人。8.8%的人报告了目前的哮喘。哮喘的患病率因年龄、种族/民族、性别、贫困、血清可替宁水平和体型而有显著差异。过敏性个体的哮喘患病率高于非过敏性个体。哮喘组总IgE水平的几何均值显著高于非哮喘组。在6岁及以上的美国人群中，血清总IgE水平与医生诊断的当前哮喘有关，但仅限于有过敏症的人。在美国人口中，血清胆固醇和过敏之间的关系在种族之间也存在差异，非西班牙裔黑人过敏的几率随着非高密度脂蛋白水平的增加而降低。这种关系在任何其他种族群体(即非西班牙裔白人和墨西哥裔美国人)中都不显著。在考虑哮喘时，患有哮喘的人的总胆固醇和非高密度脂蛋白胆固醇低于没有哮喘的人；然而，这种关系主要见于墨西哥裔美国人，而不是非西班牙裔群体。

Our asthma research program involves both exposure assessment and prevention components, and focuses on the relationship between exposure to common indoor allergens and asthma prevalence and morbidity. The National Survey of Lead and Allergens in Housing (NSLAH), a study of allergen types and levels in floor and bedding dust in the nations housing, is the first study to provide estimates of allergen exposure in the U.S. population. It encompasses 831 homes in 75 primary sampling units located throughout the country. The major endpoints are measurements of dust mite, cockroach, cat, dog, mouse, rat and fungal allergen levels, and endotoxin in dust samples collected from an array of sites in the surveyed homes. Results from analysis of mouse allergens indicate that 82% of U.S. homes have detectable levels of mouse allergen with 35% of homes having levels >1.6 microgram mouse allergen/gram dust a level associated with increased mouse allergen sensitization rates. In allergic individuals who also have active asthma, defined as having doctor-diagnosed asthma and asthma symptoms in the preceding 12 months, being exposed to levels of mouse allergen >1.6 microgram mouse allergen/gram dust increased the odds of having asthma symptoms. Asthmatic individuals, who did not report having allergies, did not have increased odds of having symptoms when exposed to elevated mouse allergen levels in their homes. Household exposure to endotoxin has emerged as an important factor in the development and severity of asthma in those who do not have allergies. We previously reported from NSLAH that increasing concentration of endotoxin in homes was a risk factor for increased prevalence of diagnosed asthma, asthma symptoms in the past year, current use of asthma medications, and wheezing. Because of the importance of limiting endotoxin exposures, particularly among asthmatic individuals, several studies have evaluated the predictors of endotoxin concentration in house dust or endotoxin loading of surfaces in homes. In general, these studies have been confined to a particular geographic area, demographic group, or type of housing; and most have been limited to either the family room floor dust or bedding. Because of the targeted scope of these studies and the focus on one or two municipalities, some contradictory findings have emerged, raising the question as to the generalizability of the findings. The NSLAH provided the opportunity to investigate the predictors of endotoxin contamination in housing in a nationwide sample designed to represent the U.S. population. Weighted geometric mean endotoxin concentration ranged from 18.7 to 80.5 endotoxin units (EU)/mg for the five sampling locations, and endotoxin load ranged from 4,160 to 19,500 EU/m2. Increased endotoxin in household reservoir dust is principally associated with poverty, people, pets, household cleanliness, and geography. We have also worked with investigators at the CDC/NCHS to implement the allergen and asthma component of NHANES 2005-2006. We collected bedroom dust, measured total and allergen-specific IgE and assessed asthma and allergy prevalence and morbidity in approximately 9000 individuals in the U.S. Analysis of this large dataset will allow us to 1) estimate nationwide prevalence of indoor allergen and endotoxin exposures, 2) estimate nationwide prevalence of allergic sensitization to indoor, outdoor and food allergens, 3) estimate nationwide prevalence of allergic diseases including asthma, and 4) investigate the complex relationships between allergen and endotoxin exposures, allergic sensitization and allergic diseases including asthma. In analysis of IgE levels to estimate nationwide prevalence of allergic sensitization, median total IgE values were found to be higher for males than for females; for non-Hispanic Blacks and Mexican-Americans than for non-Hispanic whites; for those with less than a 12th grade education, increased poverty, higher serum cotinine levels, and higher body mass indices; and for those with at least 1 positive specific IgE result. Current asthma was reported by 8.8% of the population. The prevalence of asthma differed significantly by age, race/ethnicity, sex, poverty, serum cotinine level, and body size. The prevalence of asthma was higher among allergic than non-allergic individuals. The geometric mean for total IgE level was significantly higher among asthmatics than non-asthmatics. Among the US population 6 years and older, total serum IgE levels were associated with doctor-diagnosed current asthma but only among persons who had allergies. There are also differences between racial groups in the relationship between serum cholesterol and allergy in the US population with non-Hispanic blacks having a reduced odds of allergy with increasing levels of non-HDL Cholesterol. This relationship was not significant in any other racial group (i.e., non-Hispanic whites and Mexican Americans). When considering asthma, Total Cholesterol and non-HDL Cholesterol were lower in those with current asthma than in those without current asthma; however this relationship is primarily seen in Mexican Americans and not in non-Hispanic groups.