A unique asthma phenotype characterized by frequent asthma exacerbations

RATIONALE: The impact of asthma exacerbations on classifying asthma severity has not yet been defined. METHODS: Charts were reviewed of children age 5-18 years, seen in clinic within the prior year, presenting to National Jewish triage for an acute asthma exacerbation. RESULTS: 34 patients, mean (±SD) age 10.2±3.6 years (53% male; 50% Caucasian), were analyzed. 88% used inhaled corticosteroids (mean daily dose 565±314 mcg); 62% used a long-acting beta2-agonist; 12% used montelukast; and 6% were oral corticosteroid-dependent. All but 1 had a history of a prior ER visit; hospitalization in 76%; intubation in 9%; and ICU admission in 20% for asthma. They required a mean of 3.0 corticosteroid bursts/year; over half had ≥3 exacerbations/year. 15 and 85% were moderate and severe persistent asthmatics, respectively, by the Global Initiative for Asthma Guidelines classification. However, only 18% reported nocturnal symptoms >twice/month, 41% had symptoms >once/week, and the mean best FEV1 was 101.6±18.2% predicted. Variable degrees of exacerbation were found as 24, 47, and 29% presented with mild, moderate, and severe asthma exacerbations, respectively, based on the NAEPP classification; with a mean FEV1 of 70.6 ± 18.8% predicted. One third were hospitalized. CONCLUSION: These moderate and severe persistent asthmatics have normal pulmonary function between exacerbations, and many reported mild symptoms. The frequency of exacerbations most commonly increased their level of severity, despite controller therapy. This population may represent a unique phenotype of asthmatics prone to exacerbations while maintaining normal spirometric lung function. Other markers are needed to identify the instability of their disease.