Duration of Asthma and Physiologic Outcomes in Elderly Nonsmokers

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Abstract
Airway and alveolar inflammation have been described in asthma. Prolonged inflammation may lead to airway remodeling, which can result in physiologic abnormalities. Elderly lifetime nonsmokers are an ideal population in which to examine the consequences of longstanding asthma. To test the hypothesis that airflow limitation and hyperinflation are associated with the duration of asthma, we evaluated airflow and lung volumes in a cohort of elderly asthmatic individuals. All subjects were > 60 yr of age and were lifetime nonsmokers (n = 75). Patients with asthma of long duration (LDA; n = 38) had asthma for >/= 26 yr (median = 40.0 yr); patients with asthma of short duration (SDA; n = 37) had asthma for < 26 yr (median = 9 yr). Patients with LDA had a significantly lower FEV(1)% predicted than did those with SDA (59.5 +/- 2.6% versus 73.8 +/- 3.1% [mean +/- SEM], respectively; p < 0.007). Regression analysis demonstrated that duration of asthma was inversely associated with FEV(1)% predicted (r = 0.264, p < 0.03). After bronchodilator administration, the patients with LDA continued to show airflow obstruction (FEV(1)% predicted = 65.4 +/- 2.9). Only 18% of patients with LDA attained a normal postbronchodilator FEV(1), whereas 50% of those with SDA were able to do so (p < 0.003). The FRC% predicted was significantly higher in subjects with LDA than in those with SDA (142.9 +/- 5.6 versus 124.1 +/- 4.4, respectively, p < 0.01). Multiple regression analysis revealed an association between FRC and duration of asthma that was independent of the degree of airflow limitation. These data suggest that the duration of asthma is associated with the degree of airflow limitation and hyperinflation. Moreover, these abnormalities can become irreversible over time, and may reflect distal airway and/or parenchymal changes as well as proximal airway remodeling.

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