Smoking habit is still fairly common among asthmatics. So far, the impact of smoke on severe asthma burden has not been specifically investigated. We aimed to estimate the frequency of smoking habit among severe asthma patients, their clinical features, and the impact of smoke on asthma outcomes. The Severe Asthma Network in Italy (SANI) registry was analyzed. Demographic, clinical, and functional features of smokers, never and former smokers were compared. Data from 1194 patients were explored. Smokers were younger, with a lower asthma onset age. Atopy, BMI and respiratory/systemic comorbidities were equally distributed. In former smokers pre- and post-FEV1/FVC was significantly lower; no other significant differences were detected. Similar findings were confirmed when stratifying the former smokers by pack-years and length of smoking cessation. Among former smokers, lymphocytes and neutrophils were higher in the <15 years of smoking cessation group. Blood eosinophils were comparable in never and former smokers. When clustering the population by blood eosinophils, no significant differences in pulmonary function and exacerbations were observed. Our data suggest that a personal smoking history has a relatively low impact on disease burden. It remarks the importance of smoking cessation as a main intervention, particularly in severe asthma.
Keywords: Severe Asthma Network in Italy; cigarette smoking; eosinophils; lung function; severe asthma.