Different Asthma Phenotypes in Adult Asthma: Comparison of Allergic Asthma and Nonallergic Asthma

Abstract

Background: Allergen sensitization is a risk factor for the development of bronchial asthma in adults. However, the relationship between allergen sensitization and lung function in asthma patients is not well understood. This study was conducted to evaluate the relationship between sensitized allergens, total serum immunoglobulin E (IgE) level, and lung function in adult asthmatic patients in northern Taiwan.Methods: A total of 266 adult Taiwanese patients diagnosed with asthma between January 2003 and December 2004 were enrolled. Age, sex, duration of asthma, pulmonary function tests, total IgE, eosinophilic cationic protein, and specific IgE of ImmunoCAP were recorded. Allergic was defined as the presence of a specific IgE to 1 or more allergens.Results: There were 161 (60.5%) male and 105 (39.5%) female patients, with a mean age of 60.46 ± 15.40 years. The mean duration of asthma was 13.64 ± 7.35 years. Mite allergens, Dermatophagoides pteronyssinus (48.46%) and Dermatophagoides farina (49.23%), were the most common indoor allergens. We divided the patients into allergic and nonallergic asthma groups: 164 (61.7%) patients had allergic asthma and 102 (38.3%), nonallergic asthma. Patients with allergic asthma were younger, and had a higher total IgE level and better lung function than the nonallergic asthmatics (p＜0.05, respectively). Total serum IgE was correlated to peak expiratory flow (PEF) variability (r=0.3395, p＜0.0001) in asthmatic patients. Among allergic asthmatics, the serum total IgE and PEF variability were higher as the number of positive allergen-specific IgE tests increased.Conclusions: Defining asthma phenotypes as allergic or nonallergic is essential. This study supports the difference between allergic and nonallergic asthma. Patients with allergic asthma were younger and had higher total IgE and better lung function than patients with nonallergic asthma.