An analysis of 5 double-blinded, randomized, 12-week asthma trials was undertaken to evaluate pediatric subjects (4 to 11 years; n = 276) who were previously receiving short-acting β₂-agonists alone and subsequently received treatment with placebo. At baseline, all subjects met National Asthma Education and Prevention Program criteria for moderate/severe asthma.

Asthma severity was categorized individually for symptoms, albuterol use, and morning peak expiratory flow and then overall taking into account all three parameters.

Subjects spent the majority of weeks (55%) in the moderate/severe category. Subjects spent approximately 48%, 31%, and 22% of weeks in intermittent, mild, and moderate/severe categories and 57%, 27%, and 15% of weeks, respectively, based on asthma symptoms and albuterol use. Subjects spent approximately 62%, 31%, and 8% of weeks in intermittent/mild, moderate, and severe categories, based on peak expiratory flow; however, >35% of subjects exhibited ≥15 changes in asthma severity classification, based on peak expiratory flow.

Asthma is a disease with varying symptomatology, and pediatric subjects frequently move between severity categories, especially in children with inadequate asthma control. These data also emphasize that asthma severity cannot be determined in many pediatric subjects by discrete, point-in-time assessments of lung function, albuterol use, or asthma symptoms. Failure to recognize this problem may contribute to underestimation of disease severity in pediatric subjects.