The influence of smoking on asthma in the real-life

Asthmatic smokers have reduced quality of life and need frequent specialist visits/hospitalization. Smoking habit represents for asthmatics a higher risk for comorbidities and lung function impairment. The impact of cigarette smoking on asthmatics should be addressed to evaluate the related risk factors.

This real-life observational study evaluated demographic, clinical/functional, and biological parameters of 521 asthmatic patients stratified as never (0 PY), light (1-10 PY), and heavy smokers (>10PY).

The heavy smokers with asthma were more frequently older, male, overweight, and non-allergic than other asthmatics. Although similar ICS dose and severity among groups, heavy smokers had more significant airflow limitation (FEV₁/FVC = 0.65 ± 0.10, p < 0.01; FEV₁%pred = 79.20 ± 21.20, p < 0.01), air trapping (RV %pred. = 135.6 ± 44.8, p < 0.05; RV/TLC = 0.48 ± 0.12, p < 0.05), and fixed airflow obstruction (post-bronchodilation FEV₁/FVC = 0.66 ± 0.10; p = 0.01) than never and light smokers with asthma. Heavy smokers also demonstrated reduced blood eosinophils (p < 0.05) and FeNO (p < 0.01), increased frequency of type-2 low inflammation and LABA/LAMA use but had less frequently persistent rhinitis and chronic rhinosinusitis with nasal polyposis. Heavy smokers showed higher prevalence of paraseptal/bullous emphysema and arterial hypertension. Considering the risk analysis, heavy smokers showed less chance to have allergy (OR = 0.5), persistent rhinitis (OR = 0.6), chronic rhinosinusitis with nasal polyposis (OR = 0.3), or high FeNO (OR = 0.4), but they were prone to develop fixed airflow obstruction (post-bronchodilation FEV1%pred<80%, OR = 2.0, and post-bronchodilation FEV1/FVC≤0.70, OR = 2.0).

Heavy smokers had more severe obstructive impairments than light and never smokers with similar ICS dose, showing a steroid insensitivity, but displayed less allergy with low FeNO and blood eosinophil count, thus being a definite phenotype.