Increasing Total Serum IgE, Allergic Bronchopulmonary Aspergillosis, and Lung Function in Cystic Fibrosis

BACKGROUND: Allergic bronchopulmonary aspergillosis (ABPA) is a hypersensitivity disorder contributing to lung disease in cystic fibrosis (CF) and challenging to diagnose. OBJECTIVE: This study analyzed the predictive value of increasing total IgE (t-IgE) levels in a CF cohort alongside with clinical and serologic data. METHODS: A total of 387 children and young adults were followed from 2000 to 2006 and retrospectively classified into 6 groups. Patients with t-IgE levels < 95th percentile and without specific Aspergillus fumigatus (Af)-IgE were classified as "Naive," those with Af-specific IgE (Af-sIgE) as "Sensitized." Patients with elevated t-IgE at entrance and Af-sIgE were labeled "Former ABPA," and those without, as "High t-IgE." Patients whose t-IgE values started normal and exceeded the 95th percentile during the study were labeled either "ABPA at risk" if Af-sIgE-positive or "Rising t-IgE" if not. Courses of t-IgE over time were divided into episodes with increasing IgE (Delta IgE) and related to pulmonary outcome. RESULTS: A total of 125 patients were classified Naive (32%), 64 Sensitized (17%), 49 ABPA at risk (13%), 32 Rising t-IgE (8%), 102 Former ABPA (26%), and 15 High t-IgE (4%). A total of 874 Delta IgE episodes were accompanied by forced expiratory volume in 1 second (FEV1) declines (r = -0.21, P<.0001). Steroid treatment of severest Delta IgE episodes resulted in improved long-term pulmonary outcomes (P<.01). This FEV1 preservation effect was only detectable if t-IgE levels at least doubled within 3 months and exceeded the 95th age-specific percentile (P<.05). CONCLUSIONS: Delta IgE obtained from the course of t-IgE levels may be helpful in diagnosing treatment requiring ABPA and predicts the effect of systemic steroid treatment on pulmonary outcome. (C) 2017 American Academy of Allergy, Asthma & Immunology