Abstract
BACKGROUND: Cross-sectional studies have reported a lower prevalence of sensitization in older adults, but few longitudinal studies have examined whether this is an aging or a year-of-birth cohort effect. OBJECTIVE: We sought to assess changes in sensitization and total IgE levels in a cohort of European adults as they aged over a 20-year period. METHODS: Levels of serum specific IgE to common aeroallergens (house dust mite, cat, and grass) and total IgE levels were measured in 3206 adults from 25 centers in the European Community Respiratory Health Survey on 3 occasions over 20 years. Changes in sensitization and total IgE levels were analyzed by using regression analysis corrected for potential differences in laboratory equipment and by using inverse sampling probability weights to account for nonresponse. RESULTS: Over the 20-year follow-up, the prevalence of sensitization to at least 1 of the 3 allergens decreased from 29.4% to 24.8% (-4.6%; 95% CI, -7.0% to -2.1%). The prevalence of sensitization to house dust mite (-4.3%; 95% CI, -6.0% to -2.6%) and cat (-2.1%; 95% CI, -3.6% to -0.7%) decreased more than sensitization to grass (-0.6%; 95% CI, -2.5% to 1.3%). Age-specific prevalence of sensitization to house dust mite and cat did not differ between year-of-birth cohorts, but sensitization to grass was most prevalent in the most recent ones. Overall, total IgE levels decreased significantly (geometric mean ratio, 0.63; 95% CI, 0.58-0.68) at all ages in all year-of-birth cohorts. CONCLUSION: Aging was associated with lower levels of sensitization, especially to house dust mite and cat, after the age of 20 years.