Lai Peggy S, Sheehan William J, Gaffin Jonathan M, Petty Carter R, Coull Brent A, Gold Diane R, Phipatanakul Wanda
Division of Pulmonary and Critical Care, Massachusetts General Hospital, Boston, MA; Harvard Medical School, Boston, MA.
Harvard Medical School, Boston, MA; Boston Children's Hospital, Brigham and Women's Hospital, Boston, MA.
Chest. 2015 Nov;148(5):1251-1258. doi: 10.1378/chest.15-0098.
Endotoxin exposure is associated with airway inflammation. Children spend 6 to 8 h/d in school, yet the effect of school-specific endotoxin exposure on asthma morbidity is not well understood.
In this longitudinal cohort study, 248 students with asthma, from 38 inner-city schools, underwent baseline phenotyping and follow-up. Clinical outcomes were evaluated throughout the academic school year and linked to classroom-specific dust and air endotoxin levels as well as home dust endotoxin levels. The primary outcome was maximum asthma symptom-days per 2-week period.
Classrooms had higher settled dust endotoxin levels compared with homes (14.3 endotoxin unit/mg vs 11.3 endotoxin unit/mg; P = .02). Airborne endotoxin levels exceeding recommended occupational exposure limits for adults were recorded in 22.0% of classrooms. Classroom air endotoxin levels were independently associated with increased maximum symptom-days in children with nonatopic asthma, but not in those with atopic asthma (interaction P = .03). Adjusting for home exposures, classroom endotoxin exposure was independently associated with a dose-dependent increase in asthma symptom-days for children with nonatopic asthma (adjusted incidence rate ratio, 1.16 [95% CI, 1.03-1.31]; P = .02). In these subjects, maximum symptom-days increased by 1.3 days for each 14-day period when comparing students in classrooms with the lowest endotoxin levels compared with average measured levels.
Inner-city children with asthma are exposed to high levels of airborne endotoxin at school, resulting in increased asthma symptoms in children with nonatopic asthma. Mitigation of school-related exposures may represent a strategy to decrease asthma morbidity in this population.
ClinicalTrials.gov; No.: NCT01756391; URL: www.clinicaltrials.gov.
接触内毒素与气道炎症相关。儿童每天在学校度过6至8小时，但学校特定环境下内毒素暴露对哮喘发病率的影响尚不清楚。
在这项纵向队列研究中，来自38所市中心学校的248名哮喘学生接受了基线表型分析和随访。在整个学年评估临床结局，并将其与教室特定灰尘和空气中的内毒素水平以及家庭灰尘内毒素水平相关联。主要结局是每2周期间哮喘症状最严重的天数。
与家庭相比，教室中沉降灰尘内毒素水平更高（14.3内毒素单位/毫克对11.3内毒素单位/毫克；P = 0.02）。22.0%的教室记录到空气中内毒素水平超过成人推荐职业暴露限值。教室空气中内毒素水平与非特应性哮喘儿童症状最严重天数增加独立相关，但与特应性哮喘儿童无关（交互作用P = 0.03）。调整家庭暴露因素后，教室中的内毒素暴露与非特应性哮喘儿童哮喘症状天数呈剂量依赖性增加独立相关（调整后的发病率比，1.16 [95%CI，1.03 - 1.31]；P = 0.02）。在这些受试者中，将内毒素水平最低的教室中的学生与平均测量水平的学生相比，每14天期间症状最严重天数增加1.3天。
市中心患哮喘的儿童在学校接触高水平的空气中内毒素，导致非特应性哮喘儿童哮喘症状增加。减轻与学校相关的暴露可能是降低该人群哮喘发病率的一种策略。
ClinicalTrials.gov；编号：NCT01756391；网址：www.clinicaltrials.gov。
