Current guideline criteria for mild asthma are based on symptomatology or rescue use which are quite broad, suggesting that they may not define a distinct group of patients. Furthermore, the results of a recent study suggested that patients with mild persistent asthma may not require regular maintenance treatment with an inhaled corticosteroid (ICS).1.
This analysis evaluated subjects (n=85) previously receiving short-acting beta2-agonists alone from two completed 12-wk trials in which subjects received placebo. Subjects were initially stratified by baseline PEF ≥80% or <80% predicted and further stratified by symptoms and/or albuterol use on ≤2 days/wk, 3-6 days/wk or 7 days/wk.
For subjects with PEF ≥80% and symptoms/albuterol use on ≤2 days/wk, the majority of weeks (78%) were spent in the intermittent or mild categories. However, for subjects with PEF ≥80% and symptoms/albuterol use on 3-6 days/wk, subjects who could be guideline-classified as having mild persistent asthma, approximately 54% of weeks were spent in the moderate or severe categories. In addition, for subjects with PEF ≥80% and daily symptoms or albuterol use (i.e., the type of subject often recruited into mild asthma studies1), 77% of weeks were spent in the moderate category. Furthermore, when only those pts with PEF <80% and symptoms/albuterol use on ≤2 days/wk were considered, approximately 67% of weeks were spent in the moderate or severe categories.
This analysis clearly demonstrates that asthma severity cannot be determined in many patients by discrete, point-in-time assessments of lung function, albuterol use or symptoms. More importantly, these observations suggest that the current classification system for persistent asthma needs to be re-evaluated as many patients who meet current guideline criteria for mild persistent asthma would appear to be more appropriately classified as having moderate or severe disease.
Using current guidelines to define mild asthma may underestimate the true severity of the underlying disease. In light of recent publications, this underestimation may lead to inadequate therapy for patients with mild asthma. 1. Boushey, et al. NEJM 2005;352:1519-28.
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