Trends in asthma therapy in the United States: 1965-1992

Many recent studies indicate an increasing morbidity and mortality of asthma in the past two decades. This study uses data from the National Disease and Therapeutic Index (NDTI) to document and analyze trends in drug therapy for asthma in the United States from 1965 through 1992.

The NDTI maintains a continuous rotating national sampling of approximately 1% of US physicians in office-based practice proportionately representative of practicing generalists and specialists who report issuance of drugs in treatment by diagnosis for all patient encounters for a period of two days every 3 months. Annual summaries of five demographic categories and 14 drug categories, characterizing the asthma patient-physician encounters as percent of visits for the 28-year period of 1965 through 1992 are analyzed and characterized.

Physician visits for asthma treatment have shifted somewhat from generalists to specialists in internal medicine and pediatrics. Allergists treat a significant proportion of the asthmatic population. Most patients are seen in the office. There has been no significant change in rates of inpatient visits. Age distribution of the population of patient visits for asthma has been stable, but there is a steady drop in ratio of males to females. Since the mid-1970s, inhaled adrenergic bronchodilator prescriptions have been issued at a markedly increasing rate. Concurrently, issuance of xanthines and oral adrenergic drugs also rose dramatically but then decreased beginning in the mid-1980s. Corticosteroids are used in 15% to 20% of visits, but only recently has the inhaled route of administration shown prominence. Allergen immunotherapy for asthma has decreased more than 10-fold. Cromolyn is prescribed infrequently.

Major changes have occurred in drug treatment by physicians for asthma in the US since 1965. Bronchodilating drugs predominate, and they are being prescribed in more effective forms at a generally increasing rate. Corticosteroid use has increased at a slower rate and in smaller proportion of patient-visits, while allergen immunotherapy has dramatically declined. The male-to-female ratio of asthmatic patients who visit doctors for treatment appears to be decreasing.