Clinical phenotypes of patients hospitalized for an asthma exacerbation: prognostic implications.

BACKGROUND: Hospitalization due to acute asthma exacerbation (AE) is a highly detrimental situation requiring critical management to prevent further deterioration, including mechanical ventilation, intensive care unit (ICU) admission, and death. However, patients hospitalized for AEs are highly heterogeneous and remain largely unexplored.

OBJECTIVE: Identify clinical and inflammatory phenotypes of AE requiring hospitalization associated with in-hospital outcomes.

METHODS: We performed a hierarchical cluster analysis of 825 consecutively recruited patients hospitalized for AEs. Logistic regressions were conducted to quantify the independent associations of the identified phenotypes with in-hospital outcomes. Decision tree analysis was developed to predict cluster assignment.

RESULTS: We identified three clusters of patients, which had significantly different characteristics associated with in-hospital adverse outcomes. Cluster 1 (n=526, 63.8%) was a late-onset phenotype, cluster 2 (n=97, 11.8%) was an early-onset phenotype, and cluster 3 (n=202, 24.5%) was a phenotype with fewer eosinophils and more comorbidities. Clusters 2 and 3 had an elevated risk of death (RRadj 18.10 and 19.17, respectively) and mechanical ventilation (RRadj 2.56 and 5.71, respectively) than did cluster 1. Individuals in cluster 3 had an extended length of hospital stay (11 days), increased hospitalization direct costs (13,481.57 Chinese Yuan[CNY]), and a higher risk of ICU admission (RRadj 2.14) than individuals in clusters 1 and 2. The decision tree assigned 90.8% of the participants correctly.

CONCLUSIONS: We identified three phenotypes with differential clinical and inflammatory characteristics associated with in-hospital adverse outcomes. These new phenotypes might have important and clinically relevant implications for the management of patients hospitalized for AEs.