The association of age, gender and smoking with total IgE and specific IgE

Smoking has been identified as a risk factor for atopy but there are difficulties in interpreting many of the previous studies because the subjects who have been studied have not been representative of the entire population and because there is confounding between gender and smoking.

To investigate the association of age, gender and smoking with total IgE and specific IgE to house dust mite, grass and cat.

A stratified random sample of 20-44 year olds living in three centres in East Anglia and registered with a local general practitioner had blood taken for total immunoglobulin E (IgE) and specific IgE. A smoking history was obtained from a structured interviewer-led questionnaire.

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 with 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 sensitization to grass (odds ratio 0.45; 95% confidence interval 0.28-0.71) and cat (odds ratio 0.47; 0.24-0.94).

Men aged 20-44 years have higher total IgE levels than women of the same age. In young adults smoking explains little of the variation in total IgE and its association with sensitization to common allergens varies between allergens.