A longitudinal study of serum IgE in a community cohort: Correlations with age, sex, smoking, and atopic status

Abstract

A number of factors, including age, sex, smoking habits, and atopic status have been reported in cross-sectional studies to influence levels of serum IgE. We have examined the effects of these variables on serum IgE in a community population cohort of 1109 subjects during a longitudinal study in which two serum samples were obtained 8 years apart from each subject. For the entire cohort, mean serum IgE level changed little during the follow-up period (28.9 versus 26.0 IU/ml). Most of the decreases were observed in children and young adults. Subjects more than the age of 35 years demonstrated no systematic change in serum IgE levels. By the end of follow-up (when there were few subjects still less than 16 years of age), significant relationships of IgE to age could no longer be demonstrated in nonatopic subjects. Also, in the nonatopic subjects of this cohort, there were no significant differences in IgE levels between the sexes. Among atopic subjects, there was a clear tendency for IgE to decrease with age, with atopic women more than 35 years of age demonstrating greater declines in IgE levels during follow-up than men of comparable age. The IgE levels in atopic male subjects were significantly higher than in atopic female subjects after the age of 35 years. Smoking was associated with an elevation in serum IgE. In this cohort, the smoking effect appeared to be limited to male subjects. Among allergen skin test negative subjects at the start of the study, IgE levels >1 SD above the group mean were predictive of the subsequent development of allergic skin test reactivity. Although these findings confirm many findings from cross-sectional studies, they provide additional information concerning the epidemiology of IgE in the general population.