MORTALITY AND MARKERS OF RISK OF ASTHMA DEATH AMONG 1,075 OUTPATIENTSWITH ASTHMA

Background: According to national health statistics, mortality rates f or asthma have been increasing steadily over the past decades. Mortali ty and markers of risk of death from asthma were studied among asthmat ics attending a chest clinic in Copenhagen between 1974 and 1990. Meth ods: The study group consisted of 1,075 asthmatics in whom the diagnos is of asthma had been verified by objective/paraclinical criteria; the y were compared with a sex- and age-matched group of nonasthmatic pati ents. Both groups of subjects comprised 425 men (mean age, 37.3 years [SD 15.2]) and 650 women (mean age, 38.5 years [SD 16.0]), and the mea n follow-up period was 8.6 years (SD 4.2) in both asthmatics and contr ols. Results: Mortality from all causes was significantly increased in the asthmatic subjects (93 deaths) compared with the control group (4 1 deaths); relative risk [RR], 2.4; 95% confidence interval [CI], 1.6 to 3.4). The predominant cause of excess mortality was obstructive pul monary disease, that is, status asthmaticus (14 vs 0 deaths, RR 8.2) a nd COPD not classified as status asthmaticus (19 vs 0 deaths, RR 8.3). Overall, 91% of the asthmatic cohort survived the mean follow-up peri od of almost 9 years compared with 96% of the controls. Mortality anal ysis employing the multiple regression model of Cox revealed that age, pack-years of smoking, eosinophilia, level of FEV(1) percent predicte d, and degree of reversibility in FEV(1) were significant predictors o f death from asthma, whereas no association was found between previous hospital admissions for asthma and subsequent death from asthma. In s ubjects with eosinophilia (>0.45 mia [10(9)/L]), the risk of dying fro m asthma was 7.4 (CI 2.8 to 19.7) greater than in those without eosino philia. Compared with subjects with 15 to 24% reversibility in FEV(1), the subjects with 25 to 49% and >50% reversibility had a 2.7 and 7.0 higher risk of death from asthma, respectively. Conclusion: Mortality was significantly increased in asthmatics compared with matched contro ls, primarily because of death from acute and chronic asthma. Furtherm ore, the present findings suggest that eosinophilia and pronounced inc rease in FEV(1) after bronchodilator are strong markers of subsequent risk of death from asthma.