[Mortality and fatal risk factors in 1075 outpatients treated for asthma]

Mortality and markers of risk of death from asthma were studied among 1,075 astmathics attending a chest clinic in Copenhagen between 1974 and 1990; they were compared with a sex- and age-matched group of non-asthmatic patients. Both groups comprised 425 males (mean age 37 yrs (SD 15)) and 650 females (mean age 39 yrs (SD 16)) and the mean follow up period was 8.6 yrs (SD 4.2). Mortality from all causes was significantly increased in the asthmatic subjects (93 deaths) compared to the control group (41 deaths); relative risk (RR) 2.4, (95% confidence interval (CI) 1.6 to 3.4). The predominant cause of excess mortality was obstructive pulmonary disease, that is, status asthmaticus (14 vs. 0 deaths, RR 8.2) and chronic asthma (19 vs. 0 deaths, RR 8.3). Mortality analysis employing the multiple regression model of Cox revealed that age, pack-years of smoking, eosinophilia, level of FEV1% pred and degree of reversibility in FEV1 were significant predictors of death from asthma. In subjects with eosinophilia (> 0.45 mia/l), the risk of dying from asthma was 7.4 (CI 2.8-19.7) greater than in those without eosinophilia. Compared to subjects with 15-24% reversibility in FEV1, the subjects with 25-49% and > 50% reversibility had a 2.7 and 7.0 higher risk of death from asthma, respectively. Mortality was significantly increased in asthmatics compared to matched controls, primarily due to death from acute and chronic asthma. Furthermore, the present findings suggest that eosinophilia and pronounced increase in FEV1 following bronchodilator are strong markers of subsequent risk of death from asthma.