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 (> or =275 eosinophilic cells per mm3) and positive skin tests (sum score > or =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.