Quantification of atopy, lung function and airway hypersensitivity in adults

Abstract

BackgroundStudies in children have shown that concentration of specific serum IgE (sIgE) and size of skin tests to inhalant allergens better predict wheezing and reduced lung function than the information on presence or absence of atopy. However, very few studies in adults have investigated the relationship of quantitative atopy with lung function and airway hyperresponsiveness (AHR).ObjectiveTo determine the association between lung function and AHR and quantitative atopy in a large sample of adults from the UK.MethodsFEV1 and FVC (% predicted) were measured using spirometry and airway responsiveness by methacholine challenge (5-breath dosimeter protocol) in 983 subjects (random sample of 800 parents of children enrolled in a population-based birth cohort enriched with 183 patients with physician-diagnosed asthma). Atopic status was assessed by skin prick tests (SPT) and measurement of sIgE (common inhalant allergens). We also measured indoor allergen exposure in subjects' homes.ResultsSpirometry was completed by 792 subjects and 626 underwent methacholine challenge, with 100 (16.0%) having AHR (dose-response slope>25). Using sIgE as a continuous variable in a multiple linear regression analysis, we found that increasing levels of sIgE to mite, cat and dog were significantly associated with lower FEV1 (mite p = 0.001, cat p = 0.0001, dog p = 2.95 × 10-8). Similar findings were observed when using the size of wheal on skin testing as a continuous variable, with significantly poorer lung function with increasing skin test size (mite p = 8.23 × 10-8, cat p = 3.93 × 10-10, dog p = 3.03 × 10-15, grass p = 2.95 × 10-9). The association between quantitative atopy with lung function and AHR remained unchanged when we repeated the analyses amongst subjects defined as sensitised using standard definitions (sIgE>0.35 kUa/l, SPT-3 mm>negative control).ConclusionsIn the studied population, lung function decreased and AHR increased with increasing sIgE levels or SPT wheal diameter to inhalant allergens, suggesting that atopy may not be a dichotomous outcome influencing lung function and AHR.

Sensitization pattern affects the asthma risk in Finnish adult population

“…The comparisons of demographic data or SPT results between asthma and control groups were performed by conditional logistic regression and were reported as odds ratios (OR) with 95% confidence intervals. We formed four categories based on the number of SPTpositive reactions (0; 1-2; 3-5; [6][7][8][9][10][11][12][13][14][15][16][17]. Models between all skin prick test results and asthma were also tested for the following 14 potential confounding factors: smoking, allergic rhinitis, nasal polyps, education level, training, occupation field, childhood background in farm/countryside, previous/current exposure to dogs/cats, and parental asthma/allergy.…”

Allergy in severe asthma

“…The sum of the levels of specific IgE antibodies (or the summative size of SPT wheals) to inhalant allergens is a better predictor of the onset, presence, persistence and severity of childhood asthma than the mere presence of a 'positive allergy test' (15)(16)(17). The clinical importance of 'quantitative atopic sensitization' has been confirmed in subsequent studies in adult asthma (18). It is now recognized that quantification of atopic sensitization in early life among young children with wheezing is one of the best discriminators to identify those who are at high risk of subsequent development of persistent asthma (19).…”

“…Significantly, more patients with STRA are polysensitized and have food allergy. Perhaps the most important distinctive feature of STRA becomes apparent when atopic sensitization is quantified (18,59). Patients with severe asthma have a much higher allergic burden (51, 60) suggesting that atopic sensitization plays a critical role in the development, progression and persistence of paediatric severe disease.…”

Food allergies in developing and emerging economies: need for comprehensive data on prevalence rates

“…Peer-reviewed data of prevalence rates is however very limited. Acknowledgement of the paucity of data on food allergies has resulted in the formation of the Platform of Food Allergens a discussion forum of various professionals to address the issue [64]. …”