Qiu R, et al. - This study entailed characterization of patients treated in hospital for an acute exacerbation of asthma, with a focus on clinical and inflammatory features. Four clusters were defined. Airflow obstruction and a neutrophilic, eosinophilic or mixed inflammation were the parameters used to differentiate clusters during recovery from an exacerbation of asthma. During an exacerbation, eosinophilic inflammation was detected in smoking and non-smoking asthmatics.