Common measures of asthma severity lack association for describing its clinical course

To address the problems of increasing asthma morbidity and mortality rates, reliable severity measures must be identified. Accordingly, we compared three measures and their relationship to beclomethasone compliance.

Three clinical measures (symptom scores, morning peak expiratory flow rates, and number of as needed albuterol inhalations with Nebulizer Chronologs [Forefront Technologies, Inc., Lakewood, Colo.]) were assessed daily in 13 adults with asthma for 8.9 +/- 2.1 weeks. The relationships among these three variables were analyzed in terms of Pearson correlation coefficients. These were evaluated for each of the three possible pairs of the three clinical measures for each of the 13 patients. The relationship between inhaled beclomethasone compliance and the pairwise correlations was studied with the use of nonparametric statistical procedures.

In four of the 13 patients, no pairwise correlations between any of the three severity measures were observed. The peak expiratory flow rate-symptom score relationship was observed in eight patients, whereas peak expiratory flow rate-albuterol use and albuterol use-symptom score correlations were each seen in four patients. Mean beclomethasone compliance was 64% and was greatest in those patients whose albuterol use increased concurrently with symptom scores (94% vs 50%, p = 0.02).

The commonly used measures of asthma severity, symptom scores, peak flow rate, and beta-agonist use may not be interchangeable in describing the clinical course. Patients whose beta-agonist use is driven by symptoms tend to be more compliant with use of inhaled corticosteroids.