Eosinophilia is associated with increased all-cause mortality after a follow-up of 30 years in a general population sample

We investigated whether allergy is associated with increased all-cause mortality. Two allergy markers, peripheral blood eosinophilia (greater than or equal to 275 eosinophilic cells per mm(3)) and positive skin tests (sum score greater than or equal to 3), were available for 5,383 subjects of a cohort study on asthma and chronic obstructive pulmonary disease in general population samples of Vlagtwedde and Vlaardingen, the Netherlands, in 1965-1972. During 30 years of follow-up, 1,135 subjects died. In a Cox regression analysis, eosinophilia was associated with an increased risk (relative risk = 1.4; 95% confidence interval = 1.2-1.7) of all-cause mortality, independent of gender, age, smoking habits, percentage predicted forced expiratory volume in 1 second (FEV1 % predicted), and positive skin tests at the start of the study. Subjects with positive skin tests had only an increased risk of all-cause mortality in the subgroup of subjects with FEV1 <80% of predicted (relative risk = 1.7; 95% confidence interval = 1.0-2.8). These results remained essentially unchanged after exclusion of subjects with asthma. We conclude that eosinophilia is associated with increased all-cause mortality. An increased number of peripheral blood eosinophils may reflect an increased inflammatory response, resulting in tissue injury. It is possible that the association between a low FEV1 % predicted and all-cause mortality is partly mediated by an atopic constitution.