COSI Portugal

Obesity in children is an important health concern, accelerating throughout the world with particular alarming trends in Europe. A comprehensive and detailed assessment of the magnitude of this public health problem was imperative to stimulate adequate political response and the need was recognized for standardized European-wide harmonized surveillance systems on which policy development within the WHO European Region could be based.

As a follow-up to this recommendation, the Nutrition and Food Security Programme of WHO/Europe established the European Childhood Obesity Surveillance System (COSI) in 2007, and Portugal was one of the 13 countries who have joined this initiative.

COSI/WHO Europe is an ongoing, systematic process of collection, analysis, interpretation and dissemination of descriptive information for monitoring excess body weight. The system aims to measure trends in overweight and obesity in children aged 6-10 year-old every three years, in order to have a correct understanding of the progress of the epidemic, to reverse the epidemic but also allowing inter- country comparisons within the WHO European Region.

The implementation of a simple, standardized, harmonized and sustainable surveillance system was important to fill the current gap in longitudinal information on nutritional status, tackle and monitor the obesity epidemic in children and identify groups at risk as well as can be merged with other protocols to evaluate the impact of obesity preventive interventions in school settings. Therefore, a robust monitoring system that covers similar age groups with standardized methods of surveillance and research was needed.

In Portugal, this system has been conducted by the National Institute of Health Doutor Ricardo Jorge and the Directorate General of Health and implemented by the Regional Health Authorities (ARS) in all seven Portuguese Regions: North; Centre; Lisbon and Tagus Valley; Alentejo; Algarve; Azores and Madeira.

CEIDSS is the technical supporting organization  and data manager of COSI Portugal. Working directly with the Institutions of the Ministry of Health of Portugal as well as with the COSI European team, CEIDSS provides  each round COSI training to 200 examiners, provides technical and equipment support for the project. It is also responsible for the Data management:  processing, management and validation of Databases of COSI Portugal.

The first data collection took place in the school year 2007/2008, where 13 European countries participated, namely: Belgium, Bulgaria, Cyprus, Czech Republic, Ireland, Italy, Latvia, Lithuania, Malta, Norway, Portugal, Slovenia and Sweden. The results from the first round showed a prevalence of overweight (including obesity) children ranged from 19 to 49% in boys and from 18% to 43% in girls in the European region, according to the WHO criteria. The first round of the COSI Portugal analyzed data from 3765 children aged 6-8-year-old from 181 primary schools. According to WHO criteria 37,9% were overweight and 15,3% were obese with higher prevalence was shown in boys than in girls.

In the second round of the study (2009/2010), four new countries joined the COSI/WHO Europe: Greece, Hungary, Macedonia and Spain. At Round 2, the prevalence of overweight (including obesity; WHO definitions) ranged from 18% to 57% among boys and from 18% to 50% among girls; 6 − 31% of boys and 5 − 21% of girls were obese. Southern European countries had the highest overweight prevalence. The highest significant decrease in overweight prevalence was observed in Italy, Portugal and Slovenia and the highest significant increase in Latvia and Norway. 4064 children from 176 primary school participated in the 2nd round of COSI Portugal. Prevalence of childhood overweight was 35,6% and childhood obesity was 14,6%, again higher in boys.

The third round of the COSI/WHO Europe (2012/2013) had 21 countries participating (four new joined: Albania, Romania, Moldavia and Turkey). In this round COSI Portugal 2013 measured 5935 children aged 6 (30%), 7 (44,6%) and 8 years old (25,4%). 196 primary school participated from the 7 Portuguese regions. According to WHO criteria the prevalence of overweight and obesity in these children has decreased in this 5-year period. 31,6% of children were overweight and 13,9% were obese. On the other hand, thinness decreased between 2008 (1,0%) and 2010 (0,8%) but has tripled in 2013 (2,7%). COSI/WHO Europe is the largest European study of the World Health Organization, where more than 160 000 children already participating. The WHO European Region is now launching the 4th round (2015/2016), with 31 countries participating including the newly joined countries: Austria, Croatia, Denmark, Estonia, Poland and Kazakhstan.

COSI Portugal is in the fourth round (2015/2016), attended by 31 countries, including those who joined for the first time: Austria, Croatia, Denmark, Estonia, Poland and Kazakhstan. In this round COSI Portugal 2016 measured 6745 children aged 6 (27,1%), 7 (49,4%) and 8 years old (23,6%). 230 primary school participated from the 7 Portuguese regions. According to WHO criteria the prevalence of overweight and obesity in these children has decreased over the years, and this is the result of many factors, including food education, work carried out by health and education professionals. 30,7% of children were overweight and 11,7% were obese. On the other hand, thinness decreased between 2008 (1,0%) and 2010 (0,8%) tripled in 2013 (2,7%) and decreased again in 2016 (0,9%). COSI/WHO Europe is the largest European study of the World Health Organization, where more than 160 000 children already participating.

In this round COSI Portugal 2019 measured 7210 children (48,9% girls and 51,1% boys). 228 primary school participated from the 7 Portuguese regions. According to WHO criteria the prevalence of overweight and obesity in these children has decreased over the years, and this is the result of many factors, including food education, work carried out by health and education professionals. Between 2008 and 2019, Portugal has consistently shown a downward trend in the prevalence of overweight and childhood obesity. From 2008 to 2019, there was an 8,3% reduction in the prevalence of overweight (37,9% to 29,6%) and childhood obesity from 15,3% in 2008 to 12,0% in 2019.

The 6th COSI Portugal round, held during the 2021/2022 school year, evaluated 6205 children (50.0% girls) in the 226 participating primary schools. According to the WHO criteria for assessing nutritional status, the prevalence of childhood obesity has been decreasing over the last few years as a result of many factors, namely the nutritional education work carried out by health and education professionals. However, the results of the 6th round seem to contradict this trend observed from the first round (2008) to the previous round (2019), with an increase of 2.2 percentage points (pp) in the prevalence of excess weight in children. , from 2019 to 2022 (2019: 29.7% to 2022: 31.9%) and +1.6 pp of childhood obesity (2019: 11.9% to 2022: 13.5%). In addition to monitoring the prevalence of overweight and childhood obesity, the 6th round of the COSI study exceptionally included a study (COSI/COVID-19) assessing the impact of the SARS-CoV-2/COVID-19 pandemic in nutritional status and behaviors associated with the lifestyle of school-age children.

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