Increase in sensitization to common airborne allergens among adults - two population-based studies 15years apart.

Katja Warm,Eva Rönmark,Bo Lundbäck,Anne Lindberg

doi:10.1186/1710-1492-9-20

Abstract

BackgroundStudies on time trends of allergic sensitization among adults are rare. The aim of the study was to compare the prevalence of allergic sensitization to common airborne allergens among adults 15 years apart and to identify risk factors for allergic sensitization.MethodsClinical examinations including skin prick test (SPT) and structured interviews were performed in two random population samples in 1994 and 2009. Furthermore, specific IgE was analyzed in 2009. SPT data were available for 483 subjects in 1994 and for 463 subjects in 2009 in ages 20–60 years. Specific IgE was analyzed in 692 subjects in ages 20–79 years.ResultsSensitization to cat (16% to 26%, p < 0.001), dog (13% to 25%, p < 0.001), birch (13% to 18%, p = 0.031) and timothy (12% to 21%, p < 0.001), based on SPT, increased significantly from 1994 to 2009. Sensitization to any positive SPT increased from 35% to 39%, p = 0.13.The proportion of having ≥3 positive SPT reactions increased from 40% to 56%, p = 0.002. The sensitization pattern yielded similar results based on specific IgE. Risk factors for allergic sensitization were having a family history of allergy (OR 3.1, 95% CI 2.0-4.8 for any positive SPT; OR 2.7, 95% CI 1.8-4.0 for any elevated IgE) and urban living (OR 1.7, 95% CI 1.0-2.7; OR 1.5, 95% CI 1.0-2.4).ConclusionsThe prevalence of allergic sensitization to major airborne allergens as well as multi-sensitization increased significantly between the study years. Young age, a family history of allergy and urban living were significant risk factors for allergic sensitization.

Highlights

Studies on time trends of allergic sensitization among adults are rare
The prevalence of any positive skin prick test (SPT) increased from 34.6% to 39.3% (34.8-43.8%), not significantly (p = 0.13)
Sensitization to mites and moulds was uncommon both years (Figure 1; Table 2). In both surveys a positive SPT to any allergen was most common in the youngest age group, 20–29 years (55.3%; 60.7%, p = 0.58) and lowest in the oldest age group, 50–60 years (26.2%; 28.6% p = 0.61)

Summary

Introduction

Studies on time trends of allergic sensitization among adults are rare. In contrast to studies among children, few studies based on objective clinical methods have analyzed time trends in prevalence of allergic sensitization among adults. Studies performed during the 1990s have reported an increasing prevalence of sensitization [1,2,3]. It is not clear if this trend of an increase is continuing. Recent studies among children and adolescents suggest that the earlier reported increase in prevalence of allergic sensitization over several decades might have levelled off [4,5], while others report an on-going increase [6,7]. Trends in prevalence of sensitization to specific allergens have been sparsely studied among both children and adults. Gene-environment interactions are of importance [13]

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