Effect of age upon airway obstruction and reversibility in adult patients with asthma

Objective: In a cross-sectional study we evaluated the effect of aging (separately from that of duration of disease) on airway obstruction and reversibility by comparing two groups of non-smoker patients with asthma. Methods: We compared two groups of patients: group A, which had 50 subjects (8 men and 42 women) aged 59.7 ± 4.6 years (mean ± SD), and group B, comprised of 51 subjects (19 men and 32 women) who were 35.7 ± 7.4 years old. The groups were selected because of comparable baseline degree of obstruction (FEV₁% of predicted, 67.8 ± 20.3 in group A; 73.0 ± 19.6 in group B, NS) and duration of the disease (14.0 ± 11.7 years vs 11.2 ± 9.1, NS). Spirometric examination, with a bronchodilator test, was performed and subjects not reaching 85% of predicted were submitted to a 4-week course of inhaled steroids. Results: Although a higher number of subjects from group B responded to the acute bronchodilator test (p < 0.001), the maximum response achievable with treatment (steroid or bronchodilator) (ΔFEV₁ expressed as the percent of predicted) was not statistically different between groups (12.0 ± 17.5 vs 16.0 ± 23.9). The mean FEV₁ attainable after treatment (ΔFEV₁%PT) was significantly lower in the older group (p = 0.0006). Within groups, the baseline FEV₁% did not correlate with age; it was inversely correlated with the duration of the disease (p < 0.03 and p < 0.01, respectively). In both groups ΔFEV₁ was inversely related with the baseline FEV₁, whereas FEV₁%PT was correlated with the duration of the disease, with a slope nearly doubled in group B (p < 0.001). Conclusions: Both the process of aging and the prolonged exposure to disease effects are important factors in determining the functional characteristics of chronic asthma: In particular, aging is associated not only with a reduced acute responsiveness to bronchodilators, but also with a reduced slope of the duration-FEV₁%PT relationship that suggests a slowing of the rate of loss of reversibility of uncertain biological meaning.