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）是一项关于全国住房地板和床上灰尘中过敏原类型和水平的研究，是第一个提供美国人口中过敏原暴露估计的研究。它包括全国75个主要抽样单位的831个家庭。主要终点是测量尘螨，蟑螂，猫，狗，小鼠，大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粉尘样本中的内毒素。小鼠过敏原分析的结果表明，82%的美国家庭有可检测到的小鼠过敏原水平，35%的家庭有1.6微克/克灰尘的小鼠过敏原水平，这一水平与小鼠过敏原致敏率增加有关。在同时患有活动性哮喘的过敏个体中（定义为在过去12个月内有医生诊断的哮喘和哮喘症状），暴露于小鼠过敏原水平bbb1.6微克小鼠过敏原/克灰尘中会增加出现哮喘症状的几率。没有报告过敏的哮喘患者，在家中暴露于小鼠过敏原水平升高时，出现症状的几率并没有增加。家庭暴露于内毒素已成为一个重要的因素，在那些没有过敏的哮喘的发展和严重程度。我们之前从NSLAH报道，家庭内毒素浓度的增加是哮喘诊断患病率增加的一个危险因素，过去一年的哮喘症状，目前哮喘药物的使用和喘息。由于限制内毒素暴露的重要性，特别是在哮喘患者中，一些研究已经评估了室内灰尘中内毒素浓度或室内表面内毒素负荷的预测因子。一般来说，这些研究局限于一个特定的地理区域、人口群体或住房类型；大多数都局限于家庭活动室的地板灰尘或床上用品。由于这些研究的目标范围和重点是一两个城市，因此出现了一些相互矛盾的调查结果，使人怀疑这些调查结果是否可以普遍化。NSLAH提供了在全国范围内调查住房内毒素污染预测因子的机会，该样本旨在代表美国人口。5个采样点的加权几何平均内毒素浓度范围为18.7 ~ 80.5 EU/ mg，内毒素负荷范围为4160 ~ 19500 EU/m2。家庭储尘中内毒素的增加主要与贫困、人、宠物、家庭清洁度和地理位置有关。我们还与CDC/NCHS的调查人员合作，实施了NHANES 2005-2006的过敏原和哮喘部分。我们收集了卧室灰尘，测量了总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。对这个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患病率，2)估计全国对室内，室外和食物过敏原过敏的患病率，3)估计全国包括哮喘在内的过敏性疾病的患病率。4)探讨过敏原与内毒素暴露、过敏性致敏与哮喘等变应性疾病之间的复杂关系。在分析IgE水平以估计全国过敏致敏率时，发现男性总IgE值的中位数高于女性；非西班牙裔黑人和墨西哥裔美国人的比例高于非西班牙裔白人；对于那些受教育程度低于12年级、贫困程度增加、血清可替宁水平较高和体重指数较高的人；以及至少有1项特异性IgE阳性的患者。目前有8.8%的人口报告患有哮喘。哮喘患病率因年龄、种族/民族、性别、贫困、血清可替宁水平和体型而有显著差异。过敏人群的哮喘患病率高于非过敏人群。哮喘组总IgE水平几何平均值明显高于非哮喘组。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，但仅在过敏人群中。在美国人群中，血清胆固醇与过敏之间的关系也存在种族差异，非西班牙裔黑人的非高密度脂蛋白胆固醇水平升高，过敏几率降低。这种关系在任何其他种族（即非西班牙裔白人和墨西哥裔美国人）中都不显著。当考虑哮喘时，哮喘患者的总胆固醇和非高密度脂蛋白胆固醇低于无哮喘患者；然而，这种关系主要见于墨西哥裔美国人，而非西班牙裔美国人。

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.