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2014
Journal Article
Titel
Prevalence and phenotypic characteristics of severe adult-onset asthma in the U-Biopred cohort
Titel Supplements
Abstract
Abstract
Rationale: A recent study has shown that severe adult-onset asthma is a distinct clinical phenotype, characterized by absence of atopy, nasal polyposis, higher FeNO, persistent eosinophilic airway inflammation and higher blood neutrophil counts [Amelink et al, JACI 2013]. The aim of the present study was to assess the prevalence and phenotypic characteristics of adult-onset disease amongst patients with severe asthma. Methods: This was a cross-sectional analysis of the U-BIOPRED severe asthma cohort. Patients were recruited from tertiary pulmonary outpatient clinics. Asthma diagnosis was confirmed by a history of typical symptoms and one of the following criteria: reversibility in FEV1 of >=12% and 200ml after 400mcg inhaled salbutamol OR airway hyper-responsiveness (PC20 <8 mg/ml) OR diurnal PEF variation OR a decrease in FEV1 of 12% within four weeks after treatment tapering. A diagnosis of severe asthma was based on international IMI-criteria (Bel et al. Thorax 2011). All patients had either uncontrolled asthma as defined by the GINA guidelines AND/OR two or more severe exacerbations in the past 12 months, despite the use of maximal doses of inhaled corticosteroids and long-acting beta-2-agonists. Patients were classified as severe adult-onset asthma (asthma diagnosed >18 years) or as severe childhood-onset asthma. (Ex)smokers (143 patients, 37.1%) were included. Clinical and functional characteristics and inflammatory markers were collected and independent T-test, Mann Whitney U test and Chi-square test were used for group comparisons. Univariate and multivariate logistic regression analyses were performed to determine factors associated with severe adult-onset asthma. Results: 216 out of 385 (56.1%) patients with severe asthma had adult-onset disease. Compared with patients with severe childhood-onset asthma, patients with severe adult-onset asthma had higher prevalence of male gender (43% vs 30%, p=0.01), were heavier smokers (8.3 (0-108) vs 2.9 (0-67.5) pack-years, p<0.001), had higher FeNO levels (geometric-mean±gsd 29±2.3 vs 23±2.1ppb, p =0.018), higher rate of positive reversibility test (20±19.2 vs 15%±14.8, p=0.02), and higher blood and sputum eosinophil counts (geometric-mean±gsd 3.27%±0.04 vs 2.11%±0.98, p<0.001; 14% (0-74.15) vs 6.4% (0-58.0), p<0.001). Multiple logistic regression analysis showed that a higher number of pack-years and higher blood eosinophil counts were independently associated with adult-onset of the disease (Table 1). Conclusions: These results show that more than half of patients with severe asthma in tertiary care have adult-onset asthma. A higher number of pack-years and higher blood and sputum eosinophil counts are independently associated with severe adult-onset asthma. This suggests a distinct phenotype, characterized by eosinophilia and/or positive smoking history.
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