Weight transitions and psychosocial factors: A longitudinal cohort study of Finnish primary school children with overweight.

For targeted prevention and treatment of childhood obesity, primary health care needs methods to identify children potentially developing obesity. The objectives of this study were to examine transitions across weight categories and their association with psychosocial family- and school-related factors, data on which were retrieved from health records. This longitudinal cohort study comprised 507 Finnish children with overweight, identified from a random sample of 2000 sixth graders in Helsinki in 2013. We applied Markov multistate models to analyze the transition rates over six primary school years between BMI SDS categories of normal weight, overweight and obesity, as assessed by Finnish BMI-for-age reference, and to examine relations between transition rates and family- and school-related factors. Among 3116 pairs of consecutive growth measurements from 225 girls and 282 boys aged 6-14, 719 transitions from weight category to another occurred. The highest 1-year probabilities were 0.76 for girls to stay in overweight and 0.80 for boys to stay in obesity. Transitions from normal weight to overweight and from obesity to overweight were more probable than vice versa. Transitions from overweight into obesity were among girls associated with older age (HR 2.63) and divorced or single parents (HR 2.29), as well as among boys with experiences of crises (HR 2.40) and being bullied (HR 1.66). Factors identifiable in school health care and associated with the probability of transition towards obesity should be considered when planning individual support and intervention programs.