Pediatric Pulmonology, Supplement 26:225–228 (2004) The Role of Allergen Avoidance in Primary and Secondary Prevention Angela Simpson, MD and Adnan Custovic, MD, PhD The strong association between allergic sensitisation and childhood asthma raises the question of whether reducing exposure to allergens from before birth can re- duce sensitisation and whether this has any effect on the development of allergic disease. The primary prevention studies are, by design, long term and will take many years to report the definitive findings. We here describe the studies in progress which have published results of clini- cal outcomes, focussing on studies of inhalant allergens (summarised in Table 1). ISLE OF WIGHT STUDY This was the first study to implement an intervention designed to reduce exposure to inhalant allergens as part of a primary prevention programme in 120 in high-risk children (58 active and 62 control) [1–3]. The interven- tion comprised combined avoidance of food and dust mite allergens to age 9 months. Acaricides were applied to carpets and upholstered furniture, and infants in both groups slept on polyvinyl-covered mattresses with vented head area. Lactating mothers were asked to avoid dairy, eggs, wheat, fish, soya and nuts, and these foods were not introduced into the infant’s diet until after 9 months of age. Infants who were not breast fed were given a soy- based hydrolysed formula. Levels of Der p 1 at 9 months were significantly lower levels in the active compared to the control group, but even after the intervention the levels were still higher than the baseline levels seen in most other studies [1]. Follow up of all 120 children was achieved at age 1, 2, 4 and 8 years. A reduction in sensitisation and in wheeze was reported at age 1 year, but at ages 2 and 4 years differences in respiratory symptoms failed to reach statistical significance. At age 8 years, sensitisation to mite was reduced by more than 50% in the active group, despite only modest reductions in mite allergen levels. In the multivariate analysis, the active group were signifi- cantly less likely to have current wheeze (aOR 0.26, 95% CI 0.07–0.96, p ¼ 0.04), nocturnal cough (aOR 0.22, 95% CI 0.06–0.83, p ¼ 0.02), wheeze with bronchial hyper- responsiveness (aOR 0.11, 95%CI 0.01–1.02, p ¼ 0.05) and atopy (aOR 0.21 95% CI 0.07–0.62). CANADIAN PRIMARY PREVENTION STUDY (CAPPS) Children at high risk of allergic disease were recruited antenatally, and 497 of the 545 randomised subjects were reviewed at age 1 year [4]. The multifaceted intervention included measures to reduce exposure to inhalant and food allergens. Mite allergens were significantly reduced in the parental bed throughout the study. For the child’s mattress, levels were low in both groups after birth. Despite advice, there was no reduction in the use of carpets, with a similar reluctance to part with the family pet. At age 1 year, the authors assigned children as having possible or probable asthma based on an a priori standard of frequency and duration of episodes of symptoms and asthma medication usage. Another clinical outcome was rhinitis without colds. Using these descriptions, there was a significant reduction in probable asthma and in rhinitis in the active group. SPACE The Study on the Prevention of Allergy in Children in Europe recruited new born children from Austria, Germany and the UK [5]. In total, 696 high-risk children were included in the 3 centres. The intervention was directed towards both inhalant and food allergens. Mite From the North West Lung Centre, Wythenshawe Hospital, Manchester, UK. Address correspondance and reprint requests to Prof. Adnan Custovic, North West Lung Centre, Wythenshawe Hospital, Southmoor Road, Manchester M23 9LT, UK. E-mail: a.custovic@man.ac.uk ß 2004 Wiley-Liss, Inc. DOI 10.1002/ppul.70113