Allergen sensitisation in asthmatic children: consecutive case series
TF Leung, AM Li, G Ha
Department of Paediatrics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong
OBJECTIVE. To investigate the pattern of sensitisation to aero-allergens and food allergens among asthmatic children in Hong Kong, and to investigate any correlation between atopy and the severity of asthma.
DESIGN. Consecutive case series.
SETTING. Paediatric out-patient clinic of a university teaching hospital, Hong Kong.
PARTICIPANTS. Two hundred and four consecutive children with physician-diagnosed asthma who attended from January 1999 through June 2000.
MAIN OUTCOME MEASURES. Demographic data, questionnaire assessment of asthma control, spirometric evaluation, response to skin prick testing, eosinophil count, and total serum immunoglobulin E concentration.
RESULTS. The median patient age was 8.2 years (range, 5.7-11.3 years), and the median 1-second forced expiratory volume was 95% of the predicted value. The median absolute eosinophil count in the peripheral blood was 0.48 x 109 /L and the ratio of total serum immunoglobulin E to the age-adjusted upper limit of the normal range was 2.7. Atopy, as defined by at least one positive response to skin prick testing, was found in 170 (83.3%) of the 204 patients. House dust mites were the most commonly sensitised aero-allergen (n=167; 81.9%). Sensitisation to food allergens was found in 47 (23.0%) of the patients. The self-reported frequency of asthmatic attacks was associated with a positive response to skin prick testing with animal allergens (P for trend = 0.001), whereas spirometric indices correlated with the degree of atopy and the presence of in vivo cockroach-specific immunoglobulin E.
CONCLUSION. Sensitisation to indoor aero-allergens, as determined by skin prick testing, is prevalent among Chinese children with mild-to-moderate asthma, whereas sensitisation to food allergens is not. The severity of asthma is correlated with skin prick test responses to pet and cockroach allergens.
Hong Kong Med J 2000;6:355-60
Key words: Allergens; Asthma; Child; IgE/blood; Skin tests; Spirometry