A 15-YEAR FOLLOW-UP-STUDY OF VENTILATORY FUNCTION IN ADULTS WITH ASTHMA

Background Although the prevalence of asthma and morbidity related to asthma are increasing, little is known about the natural history of lu ng function in adults with this disease. Methods We used data from a l ongitudinal epidemiologic study of the general population in a Danish city, the Copenhagen City Heart Study, to analyze changes over time in the forced expiratory volume in one second (FEV1) in adults with self -reported asthma and adults without asthma. The study was conducted be tween 1976 and 1994; for each patient, three measurements of lung func tion were obtained over a 15-year period. The final data set consisted of measurements from 17,506 subjects (8136 men and 9370 women), of wh om 1095 had asthma. Results Among subjects who participated in all thr ee evaluations, the unadjusted decline in FEV1 among subjects with ast hma was 38 mi per year, as compared with 22 mi per year in those witho ut asthma. The decline in FEV1 normalized for height (FEV1 divided by the square of the height in meters) was greater among the subjects wit h asthma than among those without the disease (P<0.001). Among both me n and women, and among both smokers and nonsmokers, subjects with asth ma had greater declines in FEV1 over time than those without asthma (P <0.001). At the age of 60 years, a 175-cm-tall nonsmoking man without asthma had an average FEV1 of 3.05 liters, as compared with 1.99 liter s for a man of similar age and height who smoked and had asthma. Concl usions In a sample of the general population, people who identified th emselves as having asthma had substantially greater declines in FEV1 o ver time than those who did not, (N Engl J Med 1998;339:1194-200.) (C) 1998, Massachusetts Medical Society.