Cluster analysis on longitudinal data of patients with adult-onset asthma

Abstract

Background Previous cluster analyses on asthma are based on cross-sectional data. Aims and objectives To identify phenotypes of adult-onset asthma by using data from baseline (diagnostic) and 12 year follow-up visits. Methods Seinajoki Adult Asthma Study (SAAS) is a 12-year follow-up study of patients with new-onset adult asthma. K-means cluster analysis was performed by using variables from baseline and follow-up visits on 171 patients to identify phenotypes. Results Five clusters were identified. Patients in cluster 1 (n=38) were predominantly non-atopic males with moderate smoking history at baseline. At follow-up 40 % had developed persistent obstruction but the number of patients with uncontrolled asthma (5 %) and rhinitis (10 %) were the lowest. Cluster 2 (n=19) was characterized by older men with heavy smoking history, poor lung function and persistent obstruction at baseline. At follow-up these patients were mostly uncontrolled (84 %) despite use of daily ICS with add-on therapy. Cluster 3 (n=50) was mostly non-smoking females with good lung function at diagnosis/follow-up and well/partially controlled asthma at follow-up. Cluster 4 (n=25) consisted of obese, symptomatic mostly female patients at baseline/follow-up. At follow-up these patients had many comorbidities (40 % psychiatric disease) and were treated with daily ICS and add-on therapy. Cluster 5 (n=39) were mostly atopic, had earliest onset of asthma, highest blood eosinophils and FEV 1 reversibility at diagnosis. At follow-up these patients used lowest ICS dose but 56 % were well-controlled. Conclusions Results can be used to predict outcome of patients with adult-onset asthma and to aid development of personalized therapy.