Background and aims: Severe asthma is burdened by frequent exacerbations and use of oral corticosteroids (OCS) which worsen patients’ health and increase healthcare spending. Aim of this study was to assess the clinical and economic effect of adding mepolizumab (MEP) for the treatment of these patients. Methods: Patients >18 years old, referred to 8 asthma clinics, starting MEP between May 2017 and December 2018, were enrolled and followed-up for 12 months. Information in the 12 months before mepolizumab were collected retrospectively. The evaluation parameters included: OCS use, number of exacerbations/hospitalizations, concomitant therapies, comorbidity, and annual number of working days lost due to the disease. The primary objective w...