SANTBOISA cohort study protocol: lifestyle, socioeconomic, and environmental factors in paediatric obesity

Paediatric obesity is a major public health concern worldwide. Obesity during childhood or adolescence is associated with an increased risk of obesity and other health problems in adulthood. Studying its determinants is crucial for guiding structural and health promotion interventions. More longitudinal studies are needed to clarify the paediatric obesity paradigm from early ages. This manuscript presents the protocol of the SANTBOISA cohort study. This manuscript presents the protocol of the SANTBOISA cohort study. The study aims to investigate longitudinal changes in children’s BMI z-score and their associations with lifestyle, socioeconomic, perinatal, and environmental factors. SANTBOISA is an observational cohort study of children recruited at ages 3–8 years in Sant Boi de Llobregat (Spain) and followed longitudinally, with the long-term goal of extending follow-up until 18 years of age. By 2024, 2,090 children had already been recruited into the cohort. Data collected include: (1) child sociodemographic characteristics, perinatal variables, lifestyle (diet quality, physical activity, screen time, sleep duration and health-related quality of life), weight status, socioeconomic status and environmental variables; (2) family sociodemographic characteristics and socioeconomic status, parents’ perception of child weight, feeding practices, family lifestyle and weight status. This study will generate evidence on the associations between sociodemographic characteristics, perinatal variables, lifestyle, socioeconomic and environmental factors and the longitudinal change in children’s age- and sex-standardised BMI z-score among children recruited at ages 3–8 years, an area where longitudinal is currently limited. An additional contribution will be the validation and calibration of a questionnaire designed to measure moderate-to-vigorous physical activity. By examining these independent and combined associations over time, the SANTBOISA study will contribute to a deeper understanding of paediatric obesity and its long-term implications. ISRCTN55309740, retrospectively registered on 24/07/2024.