Childhood Obesity Surveillance Initiative (COSI) in Poland: Implementation of Two Rounds of the Study in the Context of International Methodological Assumptions.

Nowadays, childhood obesity is one of the key health problems in European countries. This article presents a study that is part of the World Health Organization (WHO) Childhood Obesity Surveillance Initiative (COSI) implemented in the WHO European Region since 2007. The main goal of the study is to monitor obesity in early school-aged children. The methodology of the study, the thematic scope of research tools, the organisational principles and the development of research carried out in Poland in the context of existing international assumptions are presented. In Poland, two rounds of the study were financed by the National Health Program, in cooperation with the WHO Office in Poland. The first study was carried out from November to December 2016 on a group of 3,408 children aged 8 years from 135 schools and 2,298 parents, in 9 voivodeships in Poland. The second round was carried out in the last quarter of 2018 in 12 voivodeships. A group of 2691 pupils aged 8 years from the 2nd grade of 140 primary schools in Poland and 2450 parents were examined. Data on body mass index distribution and lifestyle-related behaviours of children and their families were collected. Poland is the first country where blood pressure was measured in all participants of the COSI study. Considering the growing obesity epidemic, reliable monitoring of overweight and obesity in early childhood and the study of determinants of this phenomenon should be a priority for public health. The results obtained from this type of research are a reference point for the design and implementation of accurate prevention initiatives in this age group.