Epidemiologic studies have demonstrated that elderly patients with fixed airflow obstruction can be affected by asthma or chronic obstructive pulmonary disease (COPD).

We studied 49 consecutive elderly outpatients, presenting fixed airflow obstruction, by clinical history (smoking), pulmonary function tests, blood gas analysis, and induced sputum.

The age was not different in patients with COPD (n=28) and asthma (n=21) (70.2±3.9 years vs. 69.6±3.7 years), also the degree of fixed airflow obstruction was similar (FEV₁: 58.3±1.5% vs. 59.0±1.4% of predicted). Patients with asthma had significantly more eosinophils in peripheral blood (0.43±0.05×10⁻³μL vs. 0.27±0.1×10⁻³μL, P<0.0001), and in induced sputum (5.0% [(p25th and p75th) 5.0–6.0%] vs. 1.0% [(p25th and p75th) 0.01–1.0%]; P<0.0001), as well as serum ECP (18.6±4.9ng/mL vs. 7.7±4.7ng/mL, P<0.0001) and ECP in the induced sputum (31.6±2.9ng/mL vs. 5.6±4.9ng/mL, P<0.0001). Finally, in induced sputum the eosinophils EG₂⁺ were higher in patients with asthma than in patients with COPD (40.5 [(p25th and p75th) 39.3–44.3] MFI vs. 3.9 [(p25th and p75th) 0–11.4] MFI, P<0.0001). They also had significantly higher diffusing capacity, and a greater reversibility to steroids, after 14-day course of therapy, whereas the reversibility to 400μg of salbutamol was similar.

Despite similar fixed airflow obstruction, elderly patients with asthma have distinct characteristics compared with patients with COPD.