Transition patterns of weight status: A cohort study of Chinese school-age children

Abstract

Background: Childhood overweight and obesity are increasing public concerns. However, little is known about the transition patterns of childhood weight status, especially in developing countries. In this study, we aimed to evaluate patterns of change in weight status and the risk factors among Chinese school-age children.

Methods: This retrospective cohort study included 2,334 children aged 6 years with complete 5-year (2012-2017) physical examination data in Minhang District, Shanghai. A time-homogeneous three-state Markov model was fit to the longitudinal data with dynamic outcomes (normal weight, overweight, and obesity).

Results: According to the Markov model, 42.3% of school-age children who were initially overweight transitioned to another weight status within 1 year, with 24.8% (95% confidence interval [CI]: 23.1, 27.0) transitioning to normal weight and 17.5% (95% CI: 15.9, 19.3) becoming obese. In contrast, children who were initially normal weight (92.9% [95% CI: 92.3, 93.5]) or obese (83.1% [95% CI: 81.1, 84.8]) tended to maintain their initial weight status. Male sex, semi-urban area, absence of late adiposity rebound, lower annual height increments, higher annual weight increments, and higher initial body mass index were significantly associated with a higher risk of developing or maintaining overweight and obesity (p < 0.05).

Conclusions: The weight status of Chinese school-age children is more likely to change among those who are initially overweight than in those who are initially obese. Interventions to promote healthy weight status may be more effective if key groups are targeted, such as overweight and pre-school-age children.

Keywords: childhood obesity; cohort study; multistate model; transition probability; weight status.

Figure 1

Hazard ratios and 95% confidence intervals for intensities of transition (A) from normal weight to overweight; (B) from overweight to normal weight; (C) from overweight to obesity; and (D) from obesity to overweight. BMI, body mass index.