THE ASSOCIATION OF AGE, GENDER AND SMOKING WITH TOTAL IGE AND SPECIFIC IGE

Background Smoking has been identified as a risk factor for atopy but there are difficulties in interpreting many of the previous studies be cause the subjects who have been studied have not been representative of the entire population and because there is confounding between gend er and smoking. Objective To investigate the association of age, gende r and smoking with total IgE and specific IgE to house dust mite, gras s and cat. Methods A stratified random sample of 20-44 year olds livin g in three centres in East Anglia and registered with a local general practitioner had blood taken for total immunoglobulin E (IgE) and spec ific IgE. A smoking history was obtained from a structured interviewer -led questionnaire. Results Among non-smokers geometric mean total IgE was higher in men than women but unrelated to age. Smoking explained less than 1% of the variation in total IgE. Smoking was associated wit h an increased risk of sensitization to house dust mite (odds ratio 1. 59; 95% confidence interval 1.02-2.48) but a decreased risk of sensiti zation to grass (odds ratio 0.45; 95% confidence interval 0.28-0.71) a nd cat (odds ratio 0.7; 0.24-0.94). Conclusion Men aged 20-44 years ha ve higher total IgE levels than women of the same age. In young adults smoking explains little of the variation in total IgE and its associa tion with sensitization to common allergens varies between allergens.