BACKGROUND: Research is limited on physicians' compliance with recent clinical guidelines for asthma treatment. OBJECTIVE: Our purpose was to investigate the relationships among clinical guidelines, asthma pharmacotherapy, and office-based visits through use of nationally representative data. METHODS: Nationally representative data on prescribing patterns by office-based US physicians were extracted from the National Disease and Therapeutic Index. We tracked 1978-2002 trends in the frequency of asthma visits and patterns of asthma pharmacotherapy, focusing on the use of controller and reliever medications. RESULTS: The estimated annual number of asthma visits in the United States increased continuously from 1978 through 1990 (18 million visits); since 1990, it has remained relatively stable. Controller medication use increased 8-fold between 1978 and 2002, inhaled corticosteroids manifesting the biggest increases. The use of reliever medications, particularly short-acting oral beta(2)-agonists, decreased modestly over this period. The aggregate use of controllers (83% of visits) superseded that of relievers (80%) for the first time in 2001. Improved appropriateness of asthma pharmacotherapy was also suggested by an increase in the controller-to-reliever ratio, which reached 92% in 2002. Xanthines, which once dominated asthma therapy (63% of visits in 1978), were used in only 2% of visits in 2002. More recent drug entrants have been adopted rapidly, single-entity long-acting inhaled beta(2)-agonists being used in 9% of visits and leukotriene modifiers in 24% of visits in 2002. CONCLUSION: Asthma pharmacotherapy has changed extensively in the past 25 years. Practices over the last decade are increasingly consistent with evidence-based guidelines. These changes in medication use might have contributed to the lack of a recent increase in asthma visits.

Warwick, A. B., K. Haver, et al. (1998). "Homozygous sickle cell disease and cystic fibrosis in an adolescent." Pediatr Pulmonol 26(3): 224-7.

Haver, K., C. Gerard, et al. (1997). "Neutral endopeptidase activity in newborn and adult rabbit tracheas." Eur Respir J 10(8): 1844-9.

Neutral endopeptidase (NEP, E.C. 3.4.24.11), a widely distributed ectoenzyme, cleaves and inactivates a variety of biologically active peptides, including the tachykinin, substance P (SP). This study was undertaken to determine whether the modulation of SP airway smooth muscle contraction by NEP is age-dependent. We studied the contractile response of isolated tracheal rings from newborn and 120 day old New Zealand white rabbits. We measured NEP activity and determined immunoreactive NEP content in tracheal membrane preparations. NEP activity was then localized histochemically in sections of rabbit tracheas. In the presence of the NEP inhibitor, SCH 32615, the contractile response of isolated tracheal rings to SP was increased both in the newborn and 120 day old rabbits. However, the increase was greatest in the newborn animals. NEP activity in tracheal membrane preparations increased fivefold between the newborn and 120 day old rabbits. Western blot analysis also revealed a significant increase in the immunoreactive NEP content of these tracheal membrane preparations between the newborn and 120 day old rabbits. NEP activity, localized histochemically, was most intense in the epithelial region of the newborn animals, with a shift of activity to the subepithelial region with age. The prominent epithelial localization of neutral endopeptidase in the tracheas of these 1 day old rabbits, which we have shown to have relatively low neutral endopeptidase activity, suggests that the location of neutral endopeptidase in the airway, including proximity to relevant substance P receptors, may be critical to its function.