Prognosis in adult asthma: a national study.

Although one million people consult their general practitioners for asthma each year, data on the prognosis of this disease are scarce, particularly in adults. Mortality was studied among 2547 adult asthmatics attending a national sample of 60 general practices between 1970 and 1976; they were compared with a matched group of non-asthmatic patients. Mortality from all causes was significantly raised in the asthmatic cohort (189 deaths v 112 among controls; relative risk 1.61, 95% confidence interval 1.3 to 2.0), especially in women (92 v 42 deaths; relative risk 2.2 (1.5 to 3.1)), and in the oldest age group (55-59 years). In both sexes the predominant cause of excess mortality was respiratory disease, particularly asthma (25 v 0 deaths) and chronic obstructive airways disease (37 v 4 deaths; relative risk 8.8 (2.8 to 23)). Overall, 94% of the asthmatic cohort survived the mean follow up period of eight years compared with 96% of the controls. In contrast to previous findings, the risk of death due to malignant neoplasms was not significantly reduced overall (34 v 36 deaths), though the risk was significantly reduced among those aged under 45 years (2 v 10 deaths; relative risk 0.2 (0.02 to 0.9)) and there was a significant trend of lowering of relative risk with younger age (p less than 0.01).