The primary prevention of asthma in children study: Design of a multifaceted prevention program Childhood asthma, a chronic disease of the airways, is predominantly newly diagnosed in infants and small children. Asthma is the main cause of school absence (1, 2), involves high costs and is known to reduce the quality of life of children and their parents. During the last decades there has been a substantial increase in the prevalence of asthma worldwide (3, 4), which emphasizes the need to prevent its development. It is generally thought that genetic as well as environmental factors are involved in the devel- opment of asthma (5, 6). Because it is not yet possible to influence the genetic factors, preven- tion programs should focus on influencing the environmental factors. There are reasons to believe that the first signs of sensitization occur already in the prenatal stage by the interaction between the maternal environment and the foetus (7). Therefore, it is important to start interven- tion in the prenatal stage. Several primary prevention studies are being performed, and are still in progress. In most primary prevention studies only one (8–10) intervention was tested whereas in others two single interventions with or Kuiper S, Maas T, van Schayck CP, Muris JWM, Scho¨nberger HJAM, Dompeling E, Gijsbers B, van Weel C, Andre´ Knottnerus J on behalf of the PREVASC group. The primary prevention of asthma in children study: Design of a multifaceted prevention program. PediatrAllergyImmunol2005:16:321–331. Ó2005BlackwellMunksgaard The PREVASC study addresses the primary prevention of asthma in infants and small children. The objective of this study is to investigate whether a multifaceted prenatally started intervention strategy in high- risk infants leads to a decrease in the occurrence of (severe) asthma and whether a refinement of the prevention strategy leads to an increase in the adherence to the prevention program. The primary prevention program includes house dust mite impermeable bed coverings, educa- tion on breast feeding, hypoallergenic feeding, timing of introduction of solid food and smoking cessation. A total of 888 infants were prenatally included. By the time of inclusion the mothers were 3–7 months preg- nant. About 27 infants were excluded from the study and 18 dropped out. Of the remaining 843 infants 535 had a first-degree familial pre- disposition of asthma (high-risk group), whereas a reference group of 308 (162 boys) infants was not predisposed for asthma in the first-degree (low-risk group). To evaluate the (cost-)effectiveness of the preventive intervention, 222 (118 boys) infants of the high-risk group allocated to the intervention group and 221 (112 boys) allocated to a control group are followed up. The low-risk infants served as controls to evaluate the predictive value of high risk (first-degree familial predisposition of asthma). The infants are followed from the prenatal stage until they reach the age of 6 yr. The remaining 92 high-risk infants were included in an optimized randomized-clinical adherence trial (RCAT). Of these 92 infants, 45 (20 boys) were allocated to an intervention group and 47 (24 boys) to a control group. Until now all infants have been followed for at least 1 yr. Sandra Kuiper 1 , Tanja Maas 1 , Constant P. van Schayck 1 , Jean W. M. Muris 1 , Huub J. A. M. Schçnberger 1 , Edward Dompeling 2 , Barbara Gijsbers 1 , Chris van Weel 3 and J. AndrØ Knottnerus 1 on behalf of the PREVASC group 1 Department of General Practice, Care and Public Health Research Institute, University of Maastricht, Maastricht, 2 Department of Pediatrics, Care and Public Health Research Institute, University Hospital Maastricht, Maastricht, 3 Department of General Practice, University Medical Centre Nijmegen, Nijmegen, The Netherlands Key words: asthma; allergen avoidance; infants; house dust mite; multifaceted primary prevention; randomized-controlled trial Sandra Kuiper, Department of General Practice, Care and Public Health Research Institute, University of Maastricht, PO Box 616, 6200 MD Maastricht, The Netherlands Tel.: +31 43 388 21 84 Fax: +31 43 361 93 44 E-mail: sandra.kuiper@hag.unimaas.nl Accepted 21 February 2005 Pediatr Allergy Immunol 2005: 16: 321–331 Copyright Ó 2005 Blackwell Munksgaard PEDIATRIC ALLERGY AND IMMUNOLOGY DOI: 10.1111/j.1399-3038.2005.00278.x 321