Phenotypic characteristics of asthmatic patients with distal airways obstruction

Abstract

<bold>Background:</bold> Asthma is being recognized as a complex clinical syndrome, rather than a specific disease entity. Evidence is accumulating to support the concept that airways dysfunction and inflammation in the distal airway region of the lung may be contributing to distinct asthmatic patient phenotypes. <bold>Aim:</bold> Compare the characteristics associated to proximal and distal airway phenotype among asthmatics. <bold>Methods:</bold> Retrospective study between 2016 and 2019. In asthmatics, distal airway obstruction (DAO = Group 1) was defined by FEV1/FVC>70%,FEV1>80% and DEM 25-75 <predicted value -1.64 RSD (residual standard deviation). Proximal airway obstruction(PAO =Group 2) was defined by FEV1/FVC<70% and FEV1<80% of predicted value. PAO and DAO asthmatics were compared for clinical, biological, morphological and evolution parameters. <bold>Results:</bold> Among 69 asthmatics, 38 and 31were respectively included in DAO and PAO groups. There was no difference between the two groups in sex ratio, mean age;body mass index and active smoking. Allergic asthma was noted 52% and 46% of DAO and PAO respectively. A family history of atopy was present in48% and 23% of G1 and G2 patients respectively (p=0.03). A personal history of atopy was noted in 64% and 34% of DAO and PAO respectively (p=0.014). PAO was associated with more severe asthma than that observed in DAO group (32%vs10%;p=0.026). Well controlled asthma was founded in DAO group(71%vs25%;p<0.0001). <bold>Conclusion:</bold> Asthma associated to DAO is predominantly linked to atopic characteristics, and less severe than PAO asthma. These results suggest that DAO asthma may constitute a relevant asthma phenotype Medium and long term clinical implications and the impact on treatment need to be evaluated.