Three phenotypes of adult-onset asthma.

RATIONALE: Adult-onset asthma differs from childhood-onset asthma in many respects. It is more heterogeneous, often severe and frequently associated with loss of lung function. To identify underlying mechanisms of adult-onset asthma and to capture predictors of disease progression, detailed characterization and phenotyping is necessary. OBJECTIVES: To characterize adult-onset asthma and identify subphenotypes of adult-onset asthma. METHODS: A cohort of 200 patients with adult-onset (>18 year) asthma (age 54 (26-75) year) was recruited from one academic and three nonacademic pulmonary outpatient clinics in Amsterdam, the Netherlands. These patients were fully characterized with respect to clinical, functional and inflammatory markers. After data reduction, K-means nonhierarchical cluster analysis was performed to identify clusters of adult-onset asthma. MEASUREMENTS AND MAIN RESULTS: Patients with adult-onset asthma were predominately female (61%) and nonatopic (55%). Within this group of patients were identified three clusters of adult-onset asthma. Cluster 1 (n = 69) consisted of patients with severe eosinophilic inflammation-predominant asthma and persistent airflow limitation despite high-intensity anti-inflammatory treatment, with relatively low symptom scores. The second cluster was characterized by obese women with frequent symptoms, high healthcare utilization and low sputum eosinophils. The third cluster consisted of patients with mild-to-moderate, well-controlled asthma with normal lung function and low inflammatory markers. Repeatability accuracy was 98.2%. CONCLUSIONS: Amongst patients with adult-onset asthma, three subphenotypes can be identified with distinct clinical and inflammatory characteristics. These subphenotypes help to understand the underlying pathobiology and provide clinicians with directions for personalized management.

Non-atopic males with adult onset asthma are at risk of persistent airflow limitation.

BACKGROUND: Patients with asthma have on average a more rapid decline in FEV (1) as compared with the general population. Recent cluster analysis has revealed different asthma phenotypes that can be distinguished by age of onset and reversibility of airflow limitation. OBJECTIVE: This study aimed at detecting risk factors associated with persistent airflow limitation in patients with the adult onset asthma phenotype. METHODS: We recruited 88 patients with adult onset (≥ 18 years) asthma from an academic pulmonary outpatient clinic in the Netherlands. The associations of age, age of asthma onset, asthma duration, gender, race, atopy, smoking pack-years, BMI, use of oral corticosteroids with post-bronchodilator FEV (1) /FVC were investigated. RESULTS: Multiple linear regression analysis showed an association of absence of atopy (r = -0.27, B = -0.26, P = 0.01) and male gender (r = 0.31, B = 0.30, P = 0.004) with post-bronchodilator FEV (1) /FVC. Multiple logistic regression analysis showed that male patients were 10.8 (CI: 2.6-45.2) times the odds than women to have an FEV (1) /FVC < 0.7, and non-atopic patients were 5.2 (CI: 1.3-20.3) times the odds to have an FEV (1) /FVC < 0.7 than atopic patients. CONCLUSIONS AND CLINICAL RELEVANCE: We conclude that in patients with adult onset asthma, male gender and absence of atopy are associated with persistent airflow limitation. This might suggest that amongst patients with adult onset asthma, non-atopic male patients are at increased risk of accelerated decline in lung function.