The WHO Childhood Obesity Surveillance Initiative (COSI) and the CLICK framework

The WHO European Childhood Obesity Surveillance Initiative (COSI) is a well-established system that measures trends in overweight and obesity in over 300,000 primary school aged children from over 40 countries across the WHO European Region. The COSI collects important information related to child anthropometrics, school and family characteristics and child lifestyle behaviors. Major determinants covered by COSI include physical activity, dietary habits and school environments. COSI data has revealed substantial differences in physical activity estimates between countries. However, studies based on COSI data show that 40% of children spend at least two hours watching TV or using electronic devices per day. To prevent increased childhood obesity, policymakers should simultaneously increase opportunities for children to engage in physical activity and act to reduce the amount of time spent on sedentary activities. As children are increasingly online and connected to mobile devices, an emerging concern relates to digital marketing of unhealthy products, which can be effectively targeted at children using advanced persuasive techniques. The WHO CLICK report suggests the need to integrate information such as children's time spent online, device, app and social media usage with outcomes such as child obesity. One future possibility may be to integrate such questions into future COSI questionnaires, which would provide important information at minimal cost and could generate extensive, high quality data. The monitoring and surveillance advocated by the CLICK report is necessary to provide data on whether and how far WHO recommendations in online settings are adopted by governments and public health institutions. The WHO CLICK report acts on consultation with experts to provide a tool to support Member States in monitoring the digital marketing of unhealthy products to children and suggests policy options.