Characteristics of phenotypes of elderly patients with asthma.

Background: The characteristics of phenotypes of elderly patients with asthma are unknown. The aim of this study was to classify these phenotypes using lung function tests and images from high-resolution computed tomography (HRCT), and to identify associations between clinical characteristics and phenotypes.
Methods: A cross-sectional study was conducted in 165 elderly patients (>65 years of age) who underwent a multidimensional assessment of clinical and functional status and comorbidity. The patients were divided into three phenotypes: (1) asthma-predominant, (2) asthma-obstructive airway disease (OAD) overlap without emphysema, and (3) asthma-OAD overlap with emphysema (asthma-emphysema overlap) based on chest HRCT. A receiver operating characteristic (ROC) curve was constructed to evaluate the cutoff for differentiating between the two OAD phenotypes. Multivariate analysis was also used to distinguish between these two phenotypes.
Results: The phenotypes were asthma-predominant in 48 patients (29%), asthma-OAD without emphysema in 36 (22%), and asthma-emphysema in 81 (49%). Patients with asthma-emphysema were more frequent smokers. In multivariate analysis, smoking status (odds ratio 2.92: 95% CI 1.21-7.00, P = 0.03) and % predicted FEV1 ≤70% (odds ratio 3.18: 95% CI 1.13-8.92, P = 0.03) differed significantly between the asthma-emphysema and asthma-OAD without emphysema phenotypes.
Conclusions: Half of elderly patients with asthma are characterized by asthma-emphysema overlap. Our results showed that elderly patients with asthma who are smokers and have moderate or severe OAD are also likely to have emphysema.
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