Ambulatory care visits for asthma: United States, 1993-94.

OBJECTIVE This report describes ambulatory visits for asthma in the United States across three ambulatory care settings. The primary focus is on visits to office-based physicians. METHODS The data sources include the National Ambulatory Medical Care Survey (NAMCS), a national probability survey of visits to office-based physicians in the United States, and the National Hospital Ambulatory Medical Care Survey (NHAMCS), a national probability survey of visits to hospital emergency and outpatient departments in the United States. Most estimates presented are annual averages for the 2-year period, 1993-94. Visits for asthma are defined as those for which asthma was the first-listed diagnosis. A trend analysis compares office visit data collected in 1993-94 to data in the 1980-81 NAMCS. RESULTS There was an average annual estimate of 13.7 million ambulatory care visits for asthma in 1993-94, an annual rate of 53.4 visits per 1,000 persons. Four-fifth of ambulatory care utilization for asthma was conducted in physician offices. Relative utilization of office-based physicians was less for adolescent and black patients. The office visit rate for asthma increased 50 percent between 1980-81 and 1993-94. During 1993-94, use of office visits for asthma averaged 43 visits per 1,000 persons of 11 million office visits per year. The office visit rate in the Northeast was almost 2.5 times that in the South, although the prevalence of asthma was similar among regions. There were 5.8 return asthma visits for every new problem encounter. More than 40 percent of asthma visits had one or two comorbidities, mostly other respiratory conditions. Spirometry was used in 28 percent of asthma visits by new patients. Bronchodilators and anti-inflammatory agents were the most common medications prescribed. The use of corticosteroids and beta2-adrenergic agonists, either alone or in combination, increased substantially since 1980-81. The rate of utilization of methylxanthines decreased 61 percent between 1980-81 and 1993-94. CONCLUSIONS The patient populations receiving care for asthma vary depending on the ambulatory care setting. Patients relying on hospital outpatient care for chronic asthma conditions may receive differential treatment and have different outcomes compared with patients of office-based physicians. For office-based ambulatory care, visits for asthma have increased substantially since 1980. Medication is the primary method of treatment with an increasing use of anti-inflammatory agents. The preferred bronchodilator has changed from methylxanthines to beta2-adrenergic agonists.