Abstract
BackgroundAllergy and Aspergillus hypersensitivity (AH) were shown to be associated with severe symptoms or worse lung function in COPD patients. The prevalence of elevated total IgE (T-IgE) and its association with clinical symptoms and lung function in COPD have not been studied. The prevalence of AH and its correlation with clinical characteristics in a COPD cohort of larger sample size is also lacking.Methods273 patients with COPD were evaluated by respiratory symptoms, blood test, chest HRCT, lung function, serum detection of T-IgE and Aspergillus specific IgE. Patients with T-IgE ≥ 1000 KU/L were further investigated for allergic bronchopulmonary aspergillosis (ABPA).ResultsThe prevalence of elevated T-IgE and AH in patients with COPD was 47.3% and 15.0%, respectively. Eight patients (2.9%) met the diagnostic criteria for ABPA. Compared with the normal T-IgE group, patients with elevated T-IgE had a longer history of dyspnea (p < 0.01), an earlier onset of dyspnea after chronic cough/expectoration (p < 0.01), and were more likely to wheeze (p < 0.01). They also showed worse lung functions and more severe GOLD staging (p < 0.01). Analysis of the clinical data in male patients with smoking as the risk factor showed the same results. To evaluate the clinical characteristics of COPD with AH, patients with elevated T-IgE were further divided into subgroups with and without AH. When compared with the normal T-IgE group, both the two subgroups showed longer history of dyspnea (p < 0.01), an earlier onset of dyspnea (p < 0.01) and a worse status of lung function (p < 0.05). Correlation analysis demonstrated that T-IgE was correlated positively with the time length of dyspnea (r = 0.401, p < 0.001), and the ratio of duration of dyspnea to that of chronic cough/expectoration (r = 0.59, p < 0.001), but negatively with FEV1/FVC% (r = −0.194, p = 0.001), and FEV1%predicted (r = −0.219, p < 0.001).ConclusionsThere was a high prevalence of elevated serum T-IgE and AH in patients with COPD. Serum T-IgE level was correlated with symptoms such as dyspnea and impairment of lung function. Allergens other than Aspergillus may have similar effects on disease expression or progression of COPD.
Highlights
Allergy and Aspergillus hypersensitivity (AH) were shown to be associated with severe symptoms or worse lung function in Chronic obstructive pulmonary disease (COPD) patients
The results demonstrated that the prevalence of elevated serum T-Immunoglobulin E (IgE) was 47.3% (129/273) in patients with COPD, implying that even among COPD patients without obvious atopy, hypersensitive inflammation of the lower airways may exist, probably representing the real proportion of the allergic phenotype in patients with COPD, a much higher prevalence as compared to those reported by Jamieson et al [2] and Bafadhel et al [5]
Our study showed that the prevalence of Aspergillus sensitization in patients with COPD was 15%, similar to that reported by Bafadhel et al, but higher than that by Agarwal et al Besides the different study subjects, different methods to determine Aspergillus sensitization may be a main reason for the discrepancy, because detection of specific IgE has been shown to be more sensitive than Skin prick test (SPT) to identify Aspergillus sensitization [12,21,22]
Summary
Allergy and Aspergillus hypersensitivity (AH) were shown to be associated with severe symptoms or worse lung function in COPD patients. The prevalence of elevated total IgE (T-IgE) and its association with clinical symptoms and lung function in COPD have not been studied. A recent study by Jamieson et al [2] showed that there was an “allergic phenotype” of COPD, which accounted for 21% or 30% by allergy history (doctor-diagnosed hay fever or allergic symptoms) or allergy testing (increased allergen-specific IgE) in two cohorts. Patients with the allergic phenotype of COPD had more and severe respiratory symptoms and frequent exacerbations, no significant difference in lung function compared to the non-allergic phenotype [2]. The prevalence of Aspergillus hypersensitivity (AH) and allergic bronchopulmonary aspergillosis (ABPA) in asthma was 28% and 12.9% respectively in one study [3]. More recently Bafadhel et al [5] demonstrated that AH was present in 13% of COPD subjects and was associated with worse lung function
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