Clinical Epidemiology of Asthma in An HMO

BACKGROUND: Asthma is the second most common chronic respiratory disorder seen by physicians in outpatients, and in 1988 was estimated to be the primary or secondary cause of 9.3 percent of all physician office visits for ambulatory medical care in the United States. Reports citing increased asthma morbidity and mortality in this country and abroad have intensified interest in this disorder. Investigations into possible explanations for these increases, however, have been hampered by the lack of good longitudinal data on the incidence, prevalence, and health care utilization associated with asthma, and by the lack of generally accepted diagnostic criteria for defining the disease. DESIGN NARRATIVE: Use of the Kaiser-Permanente Northwest Region data base allowed an examination of the secular trends in the prevalence and incidence of physician-diagnosed asthma and asthma-like disorders in inpatient and outpatient populations over a 20 year period, health care utilization and temporal changes in utilization patterns for asthma, and the natural history of asthma in selected subpopulations. Demographic factors examined were limited to age and sex. The study completion date listed in this record was obtained from the "End Date" entered in the Protocol Registration and Results System (PRS) record.