School and child participation rates in COSI-Ireland, pre- and post-COVID-19 pandemic

BACKGROUND: The Childhood Obesity Surveillance Initiative (COSI) is a World Health Organisation (WHO) project established in 2008 to routinely measure trends in overweight and obesity among primary school children in over 40 European countries. This study compares school and child participation rates for COSI-Ireland Round 6 (R6), conducted October 2022 - March 2023, to Round 5 (R5), conducted in 2018, pre-COVID-19. METHODS: Sentinel schools (n = 187) invited to partake in all previous Irish COSI rounds were again invited by letter and follow-up telephone calls to participate in R6. These schools remain a representative sample of all primary schools in Ireland, including DEIS (Delivering Equality of Opportunity in Schools) schools. Consent was obtained at three levels: school, parent, and child. Parents of children in one randomly selected class of 1st, 2nd, 5th, and 6th classes of each consenting school were invited to participate by letter. Verbal assent was obtained from each child with parental consent before being measured. RESULTS: School participation in R6 decreased slightly compared to R5; 65% (n = 121/187) and 73% (n = 135/185), respectively. In total, 79% (n = 33/42) of DEIS schools consented to partake in R6, substantially higher than non-DEIS school participation of 61% (n = 88/145). The R6 DEIS school response rate was also similar to R5 (81%; n = 21/26), despite an increase in the number of DEIS schools following reclassification in 2022. The examination rate of the total cohort in R6 was 55.5% (n = 5,180/9,337), in line with R5 (57.6%). The number of children examined was similar across classes, with slightly more girls (54%) than boys (46%). CONCLUSIONS: Despite the challenges posed by COVID-19 in conducting this research, COSI-Ireland R6 school participation was well preserved, notably in DEIS schools, demonstrating their commitment to equity in obesity trends. Child examination rates were also remarkably well-maintained relative to the preceding pre-pandemic round. KEY MESSAGES: • COSI-Ireland R6 findings will allow for continued monitoring of obesity in primary school children and inter-European country comparison. • COSI-Ireland R6 findings will inform programme planning and evaluation to address childhood overweight and obesity.