LucKi Birth Cohort Study: rationale and design.

BACKGROUND: Infancy and childhood are characterized by rapid growth and development, which largely determine health status and well-being across the lifespan. Identification of modifiable risk factors and prognostic factors in critical periods of life will contribute to the development of effective prevention and intervention strategies. The LucKi Birth Cohort Study was designed and started in 2006 to follow children from birth into adulthood on a wide range of determinants, disorders, and diseases. During preschool and school years, the primary focus is on the etiology and prognosis of atopic diseases (eczema, asthma, and hay fever) and overweight/obesity. METHODS/DESIGN: LucKi is an ongoing, dynamic, prospective birth cohort study, embedded in the Child and Youth Health Care (CYHC) practice of the 'Westelijke Mijnstreek' (a region in the southeast of the Netherlands). Recruitment (1-2 weeks after birth) and follow-up (until 19 years) coincide with routine CYHC contact moments, during which the child's physical and psychosocial development is closely monitored, and anthropometrics are measured repeatedly in a standardised way. Information gathered through CYHC is complemented with repeated parental questionnaires, and information from existing registries of pharmacy, hospital and/or general practice. Since the start already more than 5,000 children were included in LucKi shortly after birth, reaching an average participation rate of ~65 %. DISCUSSION: The LucKi Birth Cohort Study provides a framework in which children are followed from birth into adulthood. Embedding LucKi in CYHC simplifies implementation, leads to low maintenance costs and high participation rates, and facilitates direct implementation of study results into CYHC practice. Furthermore, LucKi provides opportunities to initiate new (experimental) studies and/or to establish biobanking in (part of) the cohort, and contributes relevant information on determinants and health outcomes to policy and decision makers. Cohort details can be found on www.birthcohorts.net .

Trends in wheeze in Dutch school children and the role of medication use.

BACKGROUND: While the prevalence of childhood wheeze continues to increase in many countries, decreasing trends have also been reported. This may be explained by increased use of asthma medication, which effectively suppresses wheeze symptoms. In this study we investigated trends in wheeze in Dutch school children between 1989 and 2005, and their association with medication use. METHODS: In five repeated cross-sectional surveys between 1989 and 2005, parents of all 5- to 6-year-old and 8- to 11-year-old children eligible for a routine physical examination were asked to complete a questionnaire on their child's respiratory health. We identified all children for whom a questionnaire was completed in two successive surveys. Children were grouped according to birth year and classified into one out of four wheeze categories: "no wheeze," "discontinued wheeze," "continued wheeze," or "new-onset wheeze." RESULTS: In total, 3,339 children, born in 1983 (N = 670), 1988 (N = 607), 1992 (N = 980), and 1995 (N = 1,082), participated twice. Over the study period, the proportion of children with "no wheeze" increased from 73.8% to 86.1% (Ptrend < 0.001), while the proportion of children with "discontinued" and "continued" wheeze decreased from 13.2% to 6.3% (Ptrend < 0.001) and from 8.8% to 3.1% (Ptrend < 0.001), respectively. Medication use was consistently associated only with the presence of wheeze symptoms and this association did not change over time (Pbirth year × medication use > 0.05 for all wheeze categories). CONCLUSION: An increasing trend of Dutch school children with "no wheeze," and decreasing trends of children with "discontinued" and "continued" wheeze between 1989 and 2005 could not be explained by (increased) medication use. This suggests that wheeze prevalence is not masked by medication use, but is truly declining.