A Multi-state Model for Analysing Transitions between Body Mass Index Categories During Childhood - Generation XXI Birth Cohort Study

Abstract

Prevalence of overweight and obesity in young children has risen dramatically in the last decades in most developed countries. Childhood overweight and obesity are known to have immediate and long-term health consequences and are now recognized important public health concerns. We used a Markov 4-state model with states defined by four body mass index (BMI) categories (underweight, normal weight, overweight, and obese) to study the rates of transition of children aged 4 to 10 years to higher or lower BMI categories. This model was also used to study the relation of explanatory variables to their transition rates. The participants consisted of 4887 children from Generation XXI birth cohort, Porto – Portugal, with anthropometric evaluation at the age 4 and at least in one of the subsequent follow up waves. Children who were normal weight are more likely to move to higher BMI categories than lower categories; whereas overweight children attained similar rates of transition to the two adjacent categories. The influence of maternal age and education, type of delivery, sex and birth weight on childhood overweight or obesity was evaluated, but statistical significant results were only observed for sex and maternal education on the progressive transitions.