Improvements in small airway dysfunction and respiratory symptoms following tezepelumab for severe asthma

Background Small airway dysfunction (SAD) is a key feature of severe asthma, contributing to poor symptom control and exacerbations. Tezepelumab has demonstrated efficacy in reducing exacerbations and improving lung function, but its specific effects on SAD remain underexplored. We aimed to assess changes in SAD among patients initiating tezepelumab. Methods A prospective observational study was carried out among patients with severe asthma treated with tezepelumab in a tertiary centre. SAD was assessed at baseline and 6 months using impulse oscillometry (IOS) and spirometry. We focused on frequency dependence of resistance ( R 5–20 ) and the area under the reactance curve (AX) to define SAD, with pathological cut-offs >0.1 kPa·L −1 ·s −1 and >1.0 kPa·L −1 , respectively. Paired analyses were used to compare changes over time. Results 34 patients were included (median age 60 years, 74% females, 21% biologic-experienced) with a median follow-up of 183 days. There were significant improvements from baseline to follow-up in forced expiratory volume in 1 s (FEV 1 ) (median 1.73 versus 1.97 L, p=0.001), mid-expiratory flow at 25–75% of forced vital capacity (FVC) (median 1.26 versus 1.73 L·s −1 , p=0.002), R 5−20 (median 0.16 versus 0.08 kPa·L −1 ·s −1 , p