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ICD Code: 493. Asthma



ICD Code: 493. Article Review
Title: Stafford RS et al; "National Trends in Asthma Visits and Asthma Pharmacotherapy, 1978-2002." Journal of Allergy and Clinical Immunology; V.111; No.4; 4/03; p729
      STUDY DESIGN: Using 1978-2002 data from the National Disease and Therapeutic Index (NDTI), this study documents 25-year trends in asthma office visits and pharmacotherapy, with a focus on the use of controller and reliever medications. Data were extracted from the NDTI, a continuing physician survey conducted by IMS HEALTH (Plymouth Meeting, PA). The NDTI provides nationally representative diagnostic and prescribing information on patients treated by office-based physicians in the continental U.S. Physicians provide information on each patient encounter during their data collection periods. Most of these asthma visits occur in outpatient settings. In 2002, 89% were office visits, 6% were hospital visits, 4% were telephone calls, and 1% were nursing home visits. The percentage of visits for which each drug class was prescribed was calculated by dividing the total number of times that the drug class was reported in a calendar year by the estimated number of national visits for asthma for that year.
      PHYSICIAN VISIT TRENDS: There was a doubling in the estimated national number of annual visits by patients diagnosed with asthma between 1978 (8.5 million visits) and 1990 (17.7 million visits). The number of asthma visits then stabilized at a mean of 16 million between 1991 and 2002. In relation to U.S. population estimates, the number of asthma visits increased from 4 to 7 per 100 people between 1980 and 1990; it has remained at 6 ever since. Between 1978 and 2002, the proportion of first visits increased by more than 10%, accounting for 1 in 4 asthma visits in 2002.
      PHYSICIAN SPECIALTY: Across the study period, allergists, general/family practitioners, internists, and pediatricians represent the four specialties that primarily treat patients with asthma. The percentage of visits to allergists decreased by more than half (from 28% in 1978 to 12% in 2002), whereas the percentage of visits to general/family practitioners declined from 30% to 25%. Over time, asthma treatment has shifted to internists and pediatricians; the percentage of visits increased from 24% to 30% for internists and from 14% to 27% for pediatricians. More detailed specialty information available after 1990 illustrates that a stable proportion of care has been provided by all primary care physicians, including general internists (43% in 2002), whereas pulmonologists have consistently provided a modest share of visits (11% in 2002).
      PRESCRIPTION PATTERNS: The aggregate prescription rate for long-term controllers increased continuously between 1978 and 2002. In 2001, controllers were reported in 83% of visits, higher for the first time than the rate for relievers (80%). This differential between controller use and reliever use widened in 2002 (81% versus 72%). Increases in the prescription rates of controllers reflect a rise in the use of inhaled corticosteroids, long-acting beta-2-agonists, and more recently, leukotriene modifiers. Aggregate prescription rates for relievers increased from 1978 (58%) through 1993 (102%), reflecting multiple relievers per patient, but have since declined. The decline between 1994 and 2002 in reliever medication use resulted from decreased short-acting oral beta-2-agonist and systemic corticosteroid use and from stabilized use of short-acting inhaled beta-2-agonists.
      In 1978, inhaled corticosteroids and short-acting inhaled beta-2-agonists were both prescribed in 8% of visits, resulting in a 100% ratio of the use of inhaled corticosteroids to the use of short-acting inhaled beta-2-agonists (C:B ratio). This ratio quickly dropped to 30% by 1983 and remained below 30% for the following 6 years, primarily because of markedly increased prescription rates of short-acting inhaled beta-2-agonists. Beginning in 1989, the C:B ratio consistently increased, reaching 92% in 2002.
      Before 1990, xanthines dominated the treatment of asthma. However, after a sizable increase from 40% in 1978 to 63% in 1984, xanthine use dropped to just 2% in 2002.
      From 1978 to 1989, the average number of medications per patient increased from 1.7 to 2.0. Since 1989, this figure has been stable at 2.0 medications per patient, despite the increasing number of medications and classes available for treatment.
      LONG-TERM CONTROL: The proportion of annual total asthma visits for which an inhaled corticosteroid is prescribed remained constant (about 8%) from 1978 to 1988 and then began rising; it reached 48% in 2002. Beclomethasone is the inhaled corticosteroid that has been on the market for the longest time; its prescription rates remained consistent at about 10% through 1998, but its use has declined in the last 4 years (1% in 2002) as additional inhaled steroids have become available. Between 1988 and 1997, increasing aggregate use of inhaled steroids reflected small increases in beclomethasone use, the entry of flunisolide, and increasing use of triamcinolone (4% in 1989 to 15% in 1997). Fluticasone, released in 1996, has been the most frequently prescribed inhaled corticosteroid since 1998 (20% in 2002). The formulated combination of fluticasone and salmeterol (a long-acting beta-2-agonist) was reported in 20% of asthma visits in 2002, its second year on the market. Use of budesonide increased from 2% in 1998, its first year on the market, to 8% in 2002.
      Although they are prescribed relatively infrequently, the use of cromones (mostly cromolyn, but rarely nedocromil) had increased from 2% of visits in 1978 to 9% of visits in 1995; it has since declined to under 1% of visits in 2002.
      Long-acting beta-2-agonists (i.e., salmeterol and formoterol) and leukotriene modifiers (i.e., montelukast, zafirlukast, and zileuton) are relatively new therapeutic options. In their first years on the market, long-acting beta-2-agonists (1994) and leukotriene modifiers (1997) were each reported in 7% of asthma visits. The use of these single-entity long-acting beta-2-agonists peaked at 15% in 2000 and has since declined to 9% in 2002. This decline during the past 2 years has coincided with the entry and increasing use of the combination formulation of salmeterol and fluticasone. Leukotriene modifier use has increased steadily, reaching 24% in 2002. After entering the market in 1998, montelukast (20% of visits in 2002) has been prescribed more frequently than zafirlukast (2%) and zileuton (under 1%).
      QUICK-RELIEF MEDICATIONS: Prescription rates for the four medication classes of asthma relievers have been stable or declining, with the exception of short-acting inhaled beta-2-agonists, the rates for which increased markedly from 8% in 1978 to 56% in 1991 and then remained constant at 58% to 62% before a recent decline beginning in 1999. Albuterol dominates prescriptions for short-acting inhaled beta-2-agonists. Prescription rates for short-acting oral beta-2-agonists have declined continuously from 30% in 1978 to 3% in 2002. The use of systemic corticosteroids has remained relatively constant at about 20%, with some indications of a decline beginning in 1999. Beginning in 1987, anticholinergics (predominantly ipratropium) have been prescribed in only 2% to 4% of asthma visits, with little variation.
      DISCUSSION: Although many factors could account for the apparent plateau in the annual number of asthma visits noted in the 1990s and the continuing favorable evolution in asthma pharmacotherapy, published guidelines on asthma management likely have contributed to these patterns.

Search Criteria: Text - Journal of Allergy and Clinical Immunology; V.111; No.4; 4/03; p729