A hierarchical Bayesian tri-variate analysis on factors associated with anthropometric measures in a large sample of children and adolescents: the CASPIAN-IV study

Background: This study aimed to assess determinants of anthropometric measures in a nationally representative sample of Iranian children and adolescents. Methods: This nationwide study was conducted among 13,280 students, aged 6-18 years, who were randomly selected from 30 provinces in Iran. Anthropometric measures were determined by calibrated instruments. Demographic and socio-economic (SES) variables, lifestyle behaviors, family history of chronic disease and prenatal factors were studied, as well. A hierarchical Bayesian tri-variate analysis was used to assess the factors associated with obesity measures of the body mass index (BMI), waist-to-height ratio (WHtR) and wrist circumference (WrC). Results: The results showed that the BMI was associated with SES score, family history of obesity, family history of diabetes mellitus, physical inactivity, screen time, duration of sleep, breakfast consumption, birth weight, breast-feeding, junk food and place of residence (urban-rural). All these factors were also significantly associated with WrC except for consumption of junk food. Many of these factors had a partial but significant relationship with WHtR. Conclusions: Various factors contribute to obesity. Preventive and educational programs on manageable factors such as increasing physical activity, eating breakfast and limiting TV or screen time could be helpful in controlling obesity in schoolchildren and reducing associated complications.