WHO European Childhood Obesity Surveillance Initiative (COSI)

Now in its 4th round of data collection, the WHO European Childhood Obesity Surveillance Initiative (COSI) is established in 35 Member States of the WHO European Region, with the number of countries growing with each data collection round.

Participating countries in COSI measure trends in overweight and obesity among primary school children aged 6–9 years in order to understand the progress of the epidemic in this population group, gain intercountry comparisons within the European Region and inform action to reverse the trend.

COSI is a unique system that provides a large data set, with at least 250 000 children in the Region, based on nationally representative samples and standardized weight and height measurements. The children are measured and studied on the basis of a common protocol and approach. The first data collection took place during the 2007–2008 school year, the second round during the 2009–2010 school year, the third round during the 2012–2013 school year and the fourth round started with the 2015–2016 school year.

COSI was set up in response to the WHO European Ministerial Conference on Counteracting Obesity, held in Istanbul, Turkey, in 2006. Member States recognized the need for a harmonized surveillance system among primary school children to inform policy development in the area of combating the emerging obesity epidemic in the European Region. The importance of, and political commitment to, the surveillance system was reinforced in the Vienna Declaration on Nutrition and Noncommunicable Diseases in the Context of Health 2020, adopted in 2013, and the European Food and Nutrition Action Plan 2015–2020, adopted in 2014.

Since its launch in 2007, COSI has already made a difference by informing policy initiatives and the public health response to the obesity epidemic in the Region. Furthermore, the COSI data collected has resulted in 7 international scientific publications, with more in preparation, 1 international report, and more than 15 national publications and 25 national reports based on the previous three data collection rounds.

COSI sign-up and data collection process

All countries within the European Region are encouraged to sign up for COSI.

Prior to the introduction of COSI in a Member State, the country identifies an institute with responsibility for the overall national coordination and management and assigns a principal investigator as the institute’s authorized representative. The institute then signs a collaborative agreement with the WHO Regional Office for Europe, defining the roles and responsibilities of the participating country and of the Regional Office, including data release and publication policies, principles, terms and procedures.

The COSI system is simple to implement and does not consume many resources. It does not aim to replace the existing health, anthropometric and dietary surveillance systems of countries or those being planned. On the contrary, the COSI approach has a strong potential to be integrated into existing systems, where possible. The COSI protocol and manual of procedures allow each participating country to develop a system that fits its local circumstances.

WHO support for the 2015–2016 data collection round

The Regional Office introduced an additional tool for online data collection for the 2015–2016 round in response to the growing number of participating countries. This database management system, called OpenClinica, is custom prepared for each interested country to facilitate the process. Data can be entered directly online during data collection or afterwards from the information collected on paper.
In addition, the Regional Office provides technical support in implementing COSI, with assistance in sampling, equipment and training, and continues to organize COSI network meetings every year. Most recently, the 9th meeting was held in June 2016 in Saint Petersburg, Russian Federation. The next meeting is planned for February 2017 in Malta.