Phenotypes & Prognosis of Acute Asthma Exacerbations Identified

More severe asthma, poorer quality of life symptoms, and an elevated risk of death from the disease are prevalent in patients hospitalized with acute asthma exacerbation.

Due to this staggering statistic, a team of investigators decided to use cluster analysis to improve the understanding of heterogeneity in patients hospitalized for acute asthma exacerbation by identifying acute exacerbation of asthma phenotypes.

In an analysis presented at the American Academy of Allergy, Asthma & Immunology (AAAAI) 2019 Annual Meeting in San Francisco, CA, this week, asthmatic patients who were hospitalized due to acute exacerbations between January 2009 to April 2014 were prospectively and continuously assessed. By using variables from baseline and follow-up during hospitalization on 825 patients, hierarchical cluster analysis was performed to identify phenotypes.

In their the results, investigators identified 3 clusters. Asthma onset time, prehospital OCS use, and CRP level within the first 24 hours of hospitalization included the 3 most influential variables for cluster assignment.

In cluster 1 (n= 97), patients were predominantly young, atopic, eosinophilic, and with family history of asthma. In cluster 2 (n= 526), patients were characterized by mild, non-early onset and eosinophilic asthma. In cluster 3 (n= 202), patients mostly consisted of severe and OCS required patients with high inflammatory indices (CRP and IL-6), higher risk of lung infection, and higher burden of comorbidities.

The highest amount of systemic steroid was used to treat these patients, who were likely to have been admitted to ICU, administered mechanical ventilation, and/or died during hospitalization. These patients also paid the most direct cost for hospitalization and had the longest hospital length stay.

From their results, investigators identified 3 distinct phenotypes that contribute to hospitalized patients with acute asthma exacerbation. With these phenotypes, physicians can better predict outcomes of patients hospitalized for acute asthma exacerbation and shepherd the development of personalized and precise treatment.

In a previous study, a team of investigators identified traits that predict future asthma attack. They included (in order of most impactful to least):

• History of prior attacks
• Depression
• Vocal cord dysfunction
• Inhaler device polypharmacy
• Obstructive sleep apnea
• Systemic inflammation
• Eosinophilic airway inflammation
• Being underweight
• Anxiety
• Upper airway disease

Since these traits predict future attacks, Vanessa McDonald, lead study author behind the identified 10 treatable traits, noted that they are considered highly clinically important.

In severe asthma, common traits were allergic sensitization, upper‐airway disease, airflow limitation, eosinophilic inflammation, and frequent exacerbation.

Among the 10 traits found to predict exacerbation risk, the traits found to correlate the strongest with risks of depression, inhaler device polypharmacy, vocal cord dysfunction, and obstructive sleep apnea.

"We report the higher burden experienced by patients with severe asthma compared to non-severe and importantly identify which treatable traits are predictive of future asthma attacks,” McDonald said at the time. “This highlights the usefulness of the treatable traits approach in severe asthma and identifies important targets for treatment.”

This study, “Acute Exacerbation of Asthma Phenotypes and Prognosis Identified by Cluster Analysis,” was published online in The Journal of Allergy and Clinical Immunology.