Atopy in asthmatic children attending a tertiary hospital in Pretoria

Abstract

RATIONALE: Asthma is said to be an atopic condition and the presence of atopy is regarded as a surrogate marker for determining asthma in a young child with chronic respiratory symptoms. However some local community findings have brought into question the association between allergy and asthma. The primary aim of this study was to document the prevalence and nature of allergy sensitivities in a group of asthmatic children attending a tertiary hospital in Pretoria, South Africa: (i) to compare them to a group of matched non-atopic children; and (ii) to compare them for co-morbid conditions present in the asthmatic children. METHODS: A random sample of 100 children attending the asthma clinic at Pretoria Academic Hospital was included after obtaining parental consent and patient assent. An age- and sex-matched control group of 50 non-atopic children was included. Standard allergen extracts (Alk Abelló) with negative and positive controls were administered to all children. Reactions were positive if the wheal was 3 mm greater than the negative control at 10 minutes (for inhalants) and the cut-points of Sporik were used to determine positive food reactions. All atopic children had asthma confirmed by airway hyper-responsiveness on spirometry. RESULTS: 45 asthmatic children had a positive skinprick test (SPT). Sixteen per cent of control children had a positive SPT. The most common inhalant allergen was Bermuda grass (22%). Peanut allergy was documented in 9% of the patients. CONCLUSIONS: Atopy (positive SPT and known disease) was demonstrated in only 45% of asthmatic children. This is less than many reported international studies and suggests that asthma must be associated with other environmental exposures in some areas of the world, including ours.