Aim and objective: Persistent Airflow Limitation (PAL) has been reported to characterize an asthma phenotype more prone to loss control. However, whether severe asthmatics (SA) with PAL are defined by specific features has not been fully yet clarified. We aimed to see if SA with PAL can be clustered in a peculiar clinical, functional and laboratory profile.

Methods: Forty-two uncontrolled SA were included in this cross-sectional study. Two cohorts were distinguished depending on the presence of PAL (i.e. FEV1/FVC post bd <70%). Functional (FEV1% pred.; R5-R20), clinical (ACT score, subjects with ?1 exacerbation/year) and biological endpoints (blood eosinophils; Fraction of exhaled Nitric Oxide - FeNO) were collected. Data series were expressed as median and interquartile range (IQR).

Results: PAL (n.25) and non-PAL SA (n.17) features are resumed in Table. Median FEV1% in PAL was 56%±23 versus 78.5%±20 in non-PAL (p=0.0034). Median R5-R20 in the PAL group was supportive of Small Airway Disease - SAD (defined as R5-R20 >0.07) conversely from non-PAL: 0.21±0.32 versus 0.06±0.05 (p=0.0002). No significant correlations were found for clinical and biological data.

 
Conclusion: Study findings show that SA with PAL present a peculiar phenotype characterized by more impared lung function and significant involvement of distal lungs. It can be speculated that the challenge in achieving optimal control in SA with PAL might be related to SAD.