Open Access Study protocol

Early detection and counselling intervention of asthma symptoms in preschool children: study design of a cluster randomised controlled trial

Esther Hafkamp-de Groen12*, Ashna D Mohangoo123, Johan C de Jongste4, Johannes C van der Wouden5, Henriëtte A Moll4, Vincent WV Jaddoe146, Albert Hofman6, Harry J de Koning2 and Hein Raat2

Author Affiliations

1 The Generation R Study Group, Erasmus MC, Rotterdam, The Netherlands

2 Department of Public Health, Erasmus MC, Rotterdam, The Netherlands

3 TNO Quality of Life, Netherlands Organisation for Applied Scientific Research, Department Prevention and Care, Leiden, The Netherlands

4 Department of Paediatrics, Erasmus MC-Sophia Children's Hospital, Rotterdam, The Netherlands

5 Department of General Practice, Erasmus MC, Rotterdam, The Netherlands

6 Department of Epidemiology, Erasmus MC, Rotterdam, The Netherlands

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BMC Public Health 2010, 10:555  doi:10.1186/1471-2458-10-555

Published: 15 September 2010



Prevention of childhood asthma is an important public health objective. This study evaluates the effectiveness of early detection of preschool children with asthma symptoms, followed by a counselling intervention at preventive child health centres. Early detection and counselling is expected to reduce the prevalence of asthma symptoms and improve health-related quality of life at age 6 years.


This cluster randomised controlled trial was embedded within the Rotterdam population-based prospective cohort study Generation R in which 7893 children (born between April 2002 and January 2006) participated in the postnatal phase. Sixteen child health centres are involved, randomised into 8 intervention and 8 control centres. Since June 2005, an early detection tool has been applied at age 14, 24, 36 and 45 months at the intervention centres. Children who met the intervention criteria received counselling intervention (personal advice to parents to prevent smoke exposure of the child, and/or referral to the general practitioner or asthma nurse). The primary outcome was asthma diagnosis at age 6 years. Secondary outcomes included frequency and severity of asthma symptoms, health-related quality of life, fractional exhaled nitric oxide and airway resistance at age 6 years. Analysis was according to the intention-to-treat principle. Data collection will be completed end 2011.


This study among preschool children provides insight into the effectiveness of early detection of asthma symptoms followed by a counselling intervention at preventive child health centres.

Trial registration

Current Controlled Trials ISRCTN15790308.