Differences between asthma–COPD overlap syndrome and adult-onset asthma

Differences between asthma–COPD overlap syndrome (ACOS) and adult-onset asthma are poorly understood. This study aimed to evaluate these differences in a clinical cohort of patients with adult-onset asthma, as a part of the Seinäjoki Adult Asthma Study (SAAS).188 patients were diagnosed with adult-onset asthma and re-evaluated 12 years after diagnosis. They were divided into three groups based on smoking history and post bronchodilator spirometry values: 1) never- and ex-smokers with 1)/forced vital capacity (FVC) ≥0.7) patients with ≥10 pack-years; and 3) ACOS patients with ≥10 pack-years and FEV1/FVC ACOS patients had lower diffusing capacity (DLCO/VA 86% predicted versus 98 or 96% predicted; pversus 3.60 or 3.85×109 L−1; p=0.008), and higher IL-6 levels (2.88 versus 1.52 or 2.10 pg·mL−1, pThis study shows distinct differences in diffusing capacity, blood neutrophil and IL-6 levels, bronchial reversibility, lung function and comorbidities between ACOS and adult-onset asthma. The present findings should be considered in the comprehensive assessment of adult asthma patients.