Epidemiology of atopy patch tests with food and inhalant allergens in an unselected population of children

Abstract

Atopy patch test (APT) has been used as a diagnostic tool in patients with suspected food or inhalant allergy. This study assessed the prevalence of positive APT with food or inhalant allergens in an unselected population of schoolchildren. We also evaluated the link between positive APT reactions and skin-prick tests (SPT) for food and inhalant allergens, circulating eosinophils and histamine skin reactivity. We studied an unselected population of 380 children aged 9 or 13 yr living in Rome, Italy. APTs were carried out with food (native or standardized) and inhalant allergens. All the children also underwent skin-prick testing with five common inhalant and four food allergens. We also measured eosinophil cell counts and histamine skin reactivity. The prevalence of positive APT reactions for foods in unselected children ranged between 4% and 11% for hen's egg, tomato, and wheat flour and was similar for both age groups studied. The prevalence of positive APT for milk was significantly lower in children aged 13 than in children aged 9 (p = 0.013). No concordance emerged between positive APT and SPT for foods. Conversely, APT and SPT for inhalant allergens yielded statistically significant concordance (p < 0.001). APT produces positive reactions for food or inhalant allergens in a significant number of subjects in the general population of schoolchildren. Age influences the prevalence of positive APTs with cow's milk to some extent. Inhalant allergens probably induce a positive APT reaction through an immunoglobulin E-linked process, while food allergens probably do not.

Prevalence and cumulative incidence of food hyper‐sensitivity in the first 10 years of life

“…In this cohort, 2 of 588 (0.34%) children were sensitized to egg. Ronchetti et al . reported egg sensitization of 0% in 6‐ to 9‐year‐olds in Italy and 1% in 13‐year‐olds.…”

Value of the Atopy Patch Test in the Diagnosis of Food Allergy in Children with Gastrointestinal Symptoms

“…The atopy patch test is a relatively new diagnostic method used in allergology [14,15]. Most of the studies on the atopy patch test estimated their utility in diagnosis of allergy to milk, egg, soy and wheat in atopic dermatitis [16][17][18][19][20][21][22]. Only scarce studies evaluated the utility of aPT in allergy with gastrointestinal symptoms [23][24][25][26]29].…”

“…for a long time, based on the pioneer studies on atopy patch tests, it has been thought that the positive result of the test is caused by a skin reaction to pollen allergens in patients with atopic dermatitis and only recently has it been recognized that food allergens have also dominated works in the literature for a long time on atopic patch tests in patients with atopic dermatitis [6][7][8]. The early opinion that a skin patch test is an eczematous reaction in patients with eczema and that the result of that test in patients without atopic dermatitis may only be negative has not been confirmed [20]. In recent years, a greater attention has begun to be paid to the IgE--independent mechanism, since it has turned out to be very frequent and even predominant in the case of symptoms in the gastrointestinal system.…”

“…a number of papers dealing with the utility of the food atopy patch test in food allergy in infants and children with atopic dermatitis has been published [16][17][18][19][20] but only a few have estimated the utility of these test in children with gastrointestinal symptoms [23][24][25][26][27]. The continuous search for new methods with high specificity and sensitivity is aimed at the introduction of necessary elimination diets but also at the avoidance of unnecessarily wide restrictive diets.…”

Scientific Opinion on the evaluation of allergenic foods and food ingredients for labelling purposes

“…In young children (up to three years), the prevalence of positive SPTs to eggs ranged from 1.4 % (Venter et al, 2008) in the UK to 5.2 % (Julge et al, 2001) in Estonia. Lower sensitisation rates were reported for older children, ranging from zero (Julge et al, 2001;Ronchetti et al, 2008) to 2.8 % (Schafer et al, 1999) (Ro et al, 2012), and, for adults, between 0.4 % and 1.9 % (Schafer et al, 2001), except in Hungary, where 7.3 to 11.1 % of adult subjects were sensitised to egg yolk as assessed by positive SPT (Bakos et al, 2006). Higher sensitisation rates were observed when specific IgE levels were used for diagnosis.…”