Acute Exacerbation of Asthma Phenotypes and Prognosis Identified by Cluster Analysis

Hospitalized patients for acute asthma exacerbation have more severe asthma, poorer quality of life and an elevated risk of death from asthma. To identify acute exacerbation of asthma phenotypes using cluster analysis and improve our understanding of heterogeneity in patients hospitalized for acute asthma exacerbation. Patients hospitalized for acute exacerbation of asthma between January 2009 to April 2014 have been prospectively and continuously included. Hierarchical cluster analysis was performed by using variables from baseline and follow-up during hospitalization on 825 patients to identify phenotypes. Three clusters were identified. The three most influential variables for cluster assignment were asthma onset time, prehospital OCS use and CRP level within the first 24 hours of hospitalization. Patients in cluster 1 (n=97) were predominantly young, atopic, eosinophilic and with family history of asthma. Cluster 2 (n=526) was characterized by patients with mild, non-early onset and eosinophilic asthma. Cluster 3 (n=202) consisted mostly of severe and OCS required patients with high inflammatory indices (CRP and IL-6), higher risk of lung infection and higher burden of comorbidities. These were treated with the highest amount of systemic steroid and most likely to have been admitted to ICU, mechanical ventilation and death during hospitalization. They experienced the longest hospital length of stay and paid most direct cost for hospitalization. This study identified three distinct phenotypes contributing to hospitalized patients with acute asthma exacerbation. Results can be used to predict outcomes of patients hospitalized for acute asthma exacerbation and to aid in development of personalized and precise treatment.