High total serum IgE level at diagnosis was associated with a progressive decline in lung function in asthmatic patients with allergic bronchopulmonary mycosis

Abstract Background Allergic bronchopulmonary mycosis (ABPM), including allergic bronchopulmonary aspergillosis (ABPA), is an immune-mediated lung disease characterized by high serum total IgE and eosinophilia. The serum total IgE level is a well-established diagnostic and monitoring marker for ABPM/ABPA; however, its prognostic significance has not been fully elucidated. In particular, whether serum total IgE level at diagnosis is associated with subsequent longitudinal decline in lung function is unknown. Here we evaluated whether serum total IgE level at diagnosis is predictive of lung function decline and disease exacerbation in ABPA/ABPM. Methods We retrospectively analyzed 39 patients diagnosed with ABPA/ABPM from April 2022 through February 2025. Clinical data, lung function, exacerbation rates (no./y), and treatment were assessed at diagnosis, 1 y afterward, and at final follow-up (mean, 4.7 y). Patients were classified according to IgE level at 1 y (dichotomized to ≥ 50% IgE reduction and < 50% IgE reduction). Results During the study period, 100% of patients received inhaled corticosteroid, 56% received systemic corticosteroids, and 23% received antifungal therapy, but none was treated with any biologic. The exacerbation rate was correlated with serum IgE level at diagnosis ( p = 0.026, r = 0.36) but not with eosinophilia. The serum IgE level at diagnosis was inversely correlated with change in percent vital capacity ( P = 0.0015, r = –0.68), percent forced vital capacity (%FVC; P = 0.009, r = –0.70), and percent forced expiratory volume in 1 s (%FEV 1 ; P = 0.038, r = – 0.48). Exacerbation rates at 1 y after diagnosis ( p = 0.03) and final follow-up ( p = 0.011) were lower in the IgE-decreased group than IgE-unchanged/increased group. The three patients with chronic pulmonary fibrosis were the only patients who showed consistently high serum total IgE levels and low pulmonary function (%FVC and %FEV₁) at diagnosis, as confirmed by computed tomography. In contrast, high-attenuation mucus, bronchiectasis, and mucus plugging showed no consistent relationship between serum total IgE levels and pulmonary function. Conclusion High serum IgE levels at diagnosis may predict a decline in lung function and increased exacerbation risk in patients with ABPA/ABPM. Management of serum IgE levels may mitigate ABPA/ABPM exacerbation and help preserve pulmonary function.