Supplementary Material for: Serum Total Immunoglobulin E Is a Surrogate of Atopy in Adult-Onset Asthma: A Longitudinal Study

<b><i>Background:</i></b> Studies have shown that serum total immunoglobulin E (IgE) levels are higher in asthmatics. However, the role of the serum total IgE level, independently from atopy, in adult asthma is not understood. We studied the associations between serum total IgE, the number of sensitizations and the sum of specific IgEs and new-onset asthma using longitudinal data from the European Community Respiratory Health Survey. <b><i>Methods:</i></b> Serum total and specific IgE to 4 common inhalant allergens were measured at baseline in 9,175 participants, with a follow-up of 9 years. Individuals with asthma history and/or asthma symptoms were excluded. Atopy was defined as the presence of at least one specific IgE ≥0.35 kU/l. Total and specific IgEs were regressed against new-onset asthma using multivariate logistic regression with a random intercept for the study centre. <b><i>Results:</i></b> Two hundred and ninety-seven participants had developed asthma during follow-up (incidence rate 5.7 per 1,000 person-years). A 10% higher level of total IgE was associated with a 12% increased risk of new-onset asthma (p = 0.005). However, after adjustment for the number of positive specific IgEs [odds ratio (OR) for multiple sensitization 1.74, 95% confidence interval (CI) 1.05–2.88] and the sum of allergen-specific IgEs (OR 1.18, 95% CI 1.00–1.40), the association between total IgE and asthma disappeared (OR 1.00, 95% CI 0.91–1.10). Seventeen percent of new-onset asthma cases could be attributed to atopy, and this estimate was not largely modified when the total IgE level was simultaneously taken into account. <b><i>Conclusions:</i></b> After taking into account the number and intensity of 4 specific IgEs, the serum total IgE level was not associated with new-onset asthma in adults.

<b><i>研究背景：</i></b> 已有研究显示，哮喘患者的血清总免疫球蛋白E（total immunoglobulin E, IgE）水平更高。然而，在不考虑特应性（atopy）的情况下，血清总IgE水平在成人哮喘中的独立作用尚未明确。本研究依托欧洲社区呼吸健康调查（European Community Respiratory Health Survey）的纵向数据，探讨了血清总IgE、致敏原数量、特异性IgE总和与新发哮喘之间的关联。<b><i>研究方法：</i></b> 本研究共纳入9175名受试者，在基线时检测其针对4种常见吸入性变应原的血清总IgE及特异性IgE水平，并进行了为期9年的随访。排除既往有哮喘病史或存在哮喘症状的受试者。特应性定义为至少存在1种特异性IgE≥0.35 kU/l。以研究中心为随机截距项，采用多因素logistic回归分析总IgE及特异性IgE与新发哮喘的关联。<b><i>研究结果：</i></b> 随访期间共有297名受试者新发哮喘，发病率为5.7例/1000人年。血清总IgE每升高10%，新发哮喘的风险增加12%（p=0.005）。然而，在校正致敏原阳性数量[多重致敏的比值比（odds ratio, OR）为1.74，95%置信区间（confidence interval, CI）为1.05~2.88]及变应原特异性IgE总和（OR=1.18，95%CI：1.00~1.40）后，总IgE与哮喘的关联消失（OR=1.00，95%CI：0.91~1.10）。17%的新发哮喘病例可归因于特应性，同时纳入血清总IgE水平后，该估计值未发生显著改变。<b><i>研究结论：</i></b> 在考虑4种特异性IgE的数量及强度后，血清总IgE水平与成人新发哮喘无显著关联。