A Prospective, Clinical Study on Asymptomatic Sensitisation and Development of Allergic Rhinitis: High Negative Predictive Value of Allergological Testing

Abstract

Background: Asymptomatic aeroallergen sensitisation affects approximately 10% of Western adolescents and is an established risk factor for the development of respiratory allergy. The reported incidence is 2–20% annually. Previous studies are based on out-seasonal symptom recollection or selected populations, conferring bias towards higher incidence rates. Objective: The aim was to determine the incidence of onset of symptoms among clinically well-characterised asymptomatic, sensitised subjects compared with controls, and to evaluate the predictive values of common allergological tests. Methods: We performed a prospective, clinical, non-interventional, 2-year follow-up study on subjects (identified by population screening) with seasonal allergic birch or grass pollen rhinitis (n = 52), asymptomatic sensitisation to grass or birch (AS, n = 52) or non-atopic, healthy control subjects (n = 39). Experimental allergen susceptibility was assessed at inclusion and at follow-up by skin prick test, conjunctival challenge, intradermal late-phase reaction and measurement of specific IgE. Participants completed in-seasonal symptom and medication diaries during 2 subsequent seasons. Results: We observed an annual incidence rate of 5% for the onset of symptoms in the AS group (healthy control group 0%). At baseline, the AS group displayed intermediate experimental allergen susceptibility. Subjects developing symptoms had higher levels of specific IgE and larger late-phase reaction than those persistently asymptomatic. However, the positive predictive values were low (14–27%) in contrast to the negative predictive values (95–100%). Conclusion: In a well-characterised young population, asymptomatic aeroallergen sensitisation conferred a low risk for onset of symptoms during the 2-year follow-up. Persistent asymptomatic phenotype could be accurately predicted by negative results from simple allergological testing.

They Tell Me I’m Allergic to Ragweed

“…Although the observations in this article are similar to observations made by practicing allergists on a daily basis, surprisingly, there are relatively few published accounts documenting sensitization and symptom development [1,2] . For example, the observation that sensitization to hen's egg is associated with future aeroallergen sensitization and clinical allergy in young children is often made in clinical practice, but there are very few studies, e.g.…”

“…With the increased accessibility to IgE testing, allergists often see persons with positive specific IgE results and are asked to interpret the clinical significance of these tests. In the current era of evidence-based medicine, it is important to have scientific data to support clinical recommendations.The article by Bodtger et al [1] in this issue of International Archives of Allergy and Immunology begins to provide some systematic information on this topic. The authors followed 52 skin test-positive subjects (birch and/or grass) who had rhinitis symptoms and 52 similarly skin test-positive subjects who had no rhinitis symptoms.…”

“…The present study provides evidence that sensitization to pollen is predictive of future allergy symptoms. As the article by Bodtger et al [1] states: 'there is little relevant literature on the predictive capacity of skin testing'. It has been said that 'all physicians conduct research on a daily basis.…”

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“…The combination of non-occupational predictors included in the model accounts for more than half of the new cases and, thus, is better than SPT alone (PPV 14-49%) [27,28]. Intrinsic factors such as parental disease 4.0 (2.3-6.9) 1.5 (0.9-2.6) H: never versus ever having had occupational high risk exposure history or SPT seem to be at least as important for allergic rhinitis as modifiable ones.…”