Trajectory model of tri-ponderal mass index and the risk of hypertension in Chinese children: A longitudinal cohort study

No previous studies have employed group-based trajectory modeling (GBTM) to investigate the trajectories of tri-ponderal mass index (TMI) in children and its association with the risk of hypertension. This study aims to utilize GBTM to examine the trajectories of TMI and their correlation with the risk of hypertension in Chinese children. A longitudinal cohort study was conducted in Chinese children from 2014 to 2019. Anthropometric measurements and blood pressure readings were recorded annually. TMI was calculated as weight in kilograms divided by height in meters cubed. Blood pressure was determined using a standard mercury sphygmomanometer. The GBTM was used to analyze the trajectory grouping of children's TMI over time. A Cox proportional hazard model was used to evaluate the hypertension risk in different TMI trajectories. The results of TMI group-based trajectory model showed that in the total population, the model was optimal when 5 distinct trajectories in TMI were identified and were labeled as low-decreasing group (n = 5625, 27.0%), moderate-stable group (n = 6932, 33.1%), moderate-increasing group (n = 4628, 22.1%), high-increasing group (n = 2500, 12.1%), and extreme-high increasing group (n = 1171, 5.7%). Compared with the moderate-stable group, the hazard ratio (HR) and 95% confidence interval (CI) of hypertension in low-decreasing group was 0.88 (0.83-0.94), moderate-increasing group (HR = 1.25, 95% CI: 1.18-1.33), high-increasing group (HR = 1.56, 95% CI: 1.46-1.68), and extreme-high increasing group (HR = 1.63, 95% CI: 1.49-1.80) increased the risk of hypertension. There were 5 distinct trajectories of TMI for Chinese children in this longitudinal study. The decrease of TMI level is a protective factor of hypertension in children, while the increase of TMI level is a risk factor of hypertension in children. In addition, children who had a higher increase in TMI level could predict a higher risk of hypertension.