Factors Associated With Overuse of Inhaled b-Agonists and Underuse of Inhaled Corticosteroids

Methods: We examined baseline data from a longitudinal survey of adult patients with asthma. The setting was a consortium of 15 national managed care organizations serving 11 large employers. Baseline surveys were completed by 6612 health plan enrollees at least 18 years old who had had at least 2 visits with a diagnostic code for asthma in the preceding 2 years. The main outcome measures were the overuse of inhaled b-agonists and the underuse of inhaled corticosteroids. Independent variables were patient and process of care factors. Results: Among patients with moderate or severe asthma, 16% of users of inhaled b-agonists reported overuse (.8 puffs per day on days of use), and 64% of users of inhaled corticosteroids reported underuse (use on #4 days/wk or #4 puffs per day). Overuse of inhaled b-agonists was most strongly associated with concomitant treatment with inhaled corticosteroids or anticholinergic agents, increased asthma symptom severity, problems in obtaining asthma medication, and male sex. Underuse of inhaled corticosteroids was associated with nonwhite race, younger age (18 to 34 years), lower use of inhaled b-agonist, lower symptom severity, and not possessing a peak flow meter. Rates of misuse of medication also varied by speciality of the patient’s provider (generalist, allergist, or pulmonologist). Conclusions: Overuse of inhaled b-agonists may be caused by symptom severity, while underusers of corticosteroids may interrupt use as symptoms abate. This study demonstrated an important opportunity to improve medication use among patients with asthma. Arch Intern Med. 1999;159:2697-2704