Reproducibility and stability of severe asthma research program (SARP) clinical cluster phenotypes in SARP3

Background: The SARP1/2 cluster analysis identified 5 clinical asthma phenotypes that reflect inflammatory mechanisms: a spectrum of early onset allergic asthma (Clusters 1,2,4), late onset severe asthma (Cluster 3) and severe asthma with COPD characteristics (Cluster 5). Aims: Evaluate reproducibility and stability of SARP1/2 clinical cluster phenotypes in SARP3, a 3-year longitudinal cohort enriched for severe asthma. Methods: SARP3 subjects > 12 years old (n= 594) were assigned to SARP1/2 clusters using 11 variables and compared to the SARP1/2 cohort (n=1176). Subjects in both SARP1/2 and SARP3 (n=68) were assigned to clusters twice using unique SARP1/2 and 3 data. Results: The SARP3 cohort is skewed toward severe asthma clusters 3(16%), 4(15%) and 5(19%). SARP3 subjects are older with longer disease duration (p Conclusions: All five SARP1/2 clinical cluster phenotypes are reproducible in SARP3 with a shift toward more severe clusters (3,4,5). In a subset of SARP subjects with longitudinal data there was heterogeneity in the progression of disease severity that was associated with changes in baseline lung function. These results suggest that a clinical approach guided by monitoring of lung function could identify patients at risk for disease progression.