Bacharier LB, Strunk RC, Mauger D, White D, Lemanske RF Jr, Sorkness CA. Am J Resp Crit Care Med. 2004;170:426–432
Purpose of the Study.
To determine if lung-function measures are consistent with levels of asthma severity as defined by the National Asthma Education and Prevention Program/Expert Panel Report 2 guidelines.
Children (n = 219) aged 5 to 18 years (mean age: 10.1 ± 3.4 years) with asthma attending 2 academic medical center subspecialty clinics for routine evaluation of asthma.
Parents completed questionnaires regarding asthma medication use and symptom frequency. Children performed spirometry. Symptom frequency (daytime, nighttime, and exertional) was used to classify severity of asthma according to the National Asthma Education and Prevention Program/Expert Panel Report 2 guidelines. Asthma severity was also categorized by medication use suggested in the guidelines. For inhaled corticosteroid (ICS) use, the average daily microgram dose actually taken was classified as low, medium, or high based on the guidelines. Patients receiving low-dose ICS or another controller medication (leukotriene receptor antagonists, cromolyn, nedocromil, or theophylline) alone were assigned mild persistent asthma status. Patients receiving low-dose ICS plus 1 additional controller medication or a medium dose of an ICS alone were classified as moderate persistent. The use of moderate-dose ICS with additional controller medication, the use of high-dose ICS, or the use of >2 controller medications resulted in a classification of severe persistent asthma (Table 1).
Patients tended to report very good levels of asthma symptom control, with 68.1% of patients being classified as intermittent or mild persistent based on symptom frequency. However, because the majority of patients were receiving controller therapy, the distribution of severity assignments was shifted toward more severe disease when medication use alone was considered.
The authors concluded that in children, asthma severity classified by symptom frequency and medication usage does not correlate with forced expiratory volume in 1 second (FEV1) categories defined by National Asthma Education and Prevention Program guidelines. FEV1 is generally normal even in severe persistent childhood asthma.
As the authors’ noted, “classification of asthma severity is complex and is influenced by the variability of disease severity within a patient over time as well as being confounded by current asthma treatment.” Rather than trying to hit the moving target of asthma severity classification, I believe it is preferable to focus on achieving good asthma control, defined by normal and/or personal-best spirometry and rare need for albuterol. If assignment to a severity category is still desired, this can be based on the amount of medication required to achieve good asthma control.