Asthma Phenotypes Defined From Parameters Obtained During Recovery From a Hospital-Treated Exacerbation

Asthma is a heterogeneous disease with diverse clinical manifestations and inflammatory pathologies that is punctuated by exacerbations.

To describe the clinical and inflammatory characteristics of patients with asthma treated in hospital for an acute exacerbation.

Data from 320 adult patients receiving treatment for an acute exacerbation of asthma were obtained. In 218 patients with complete data, we used the Ward hierarchical clustering to obtain clusters. Pulmonary function, blood cell counts, sputum cell counts, serum IgE levels, and fractional exhaled nitric oxide were measured on hospital admission. We selected 13 variables with which we performed the Ward minimum-variance hierarchical clustering.

Four clusters were defined. Clusters 1 (24.5%) and 3 (36.7%) were characterized by predominantly female patients with asthma with sputum neutrophilia, with cluster 1 associated with a small degree of airflow obstruction and early-onset asthma and cluster 3 with a moderate degree of reduction in FEV₁. Clusters 2 (22.0%) and 4 (16.5%) were associated with high sputum eosinophilia and severe airflow obstruction. Cluster 4 was made exclusively of male smoking subjects, whereas cluster 2 was made up of predominantly female nonsmoking subjects with the worst FEV₁, forced expiratory flow at 25% to 75% of forced vital capacity (% predicted), and partial pressure of oxygen in arterial blood on admission. There were no differences between clusters in terms of atopy, serum IgE, prevalence of nasal disease, dose of maintenance inhaled corticosteroids, or oral/systemic corticosteroid use and asthma exacerbations.

The clusters during recovery from an exacerbation of asthma were distinguished by airflow obstruction and a neutrophilic, eosinophilic, or mixed inflammation. Eosinophilic inflammation was found in smoking and nonsmoking patients with asthma during an exacerbation.