Joint Trajectories of Lifestyle Indicators and Their Associations with Blood Pressure among Chinese Middle School Students

Lifestyle behaviors, defined as a combination of dietary behavior, physical activity (PA), screen time (ST), and sleep duration indicators, are strongly associated with blood pressure (BP) in students. Our aim was to characterize the joint trajectories of lifestyle behaviors among middle school students and evaluate their association with BP. Data were obtained from the monitoring dataset on common diseases and health factors among students in Jiading District, Shanghai, China, conducted from 2019 to 2023. Lifestyle behavior data were collected annually from middle school students aged 12-18 years through questionnaires covering dietary behavior score, PA, ST, and sleep duration. Students' BP was measured in 2023. Joint trajectories of lifestyle behaviors were determined using group-based multi-trajectory modeling. Associations between lifestyle trajectories and students' BP were examined using multiple linear regression and modified Poisson regression. A total of 1378 middle school students (759 [58.98%] boys, median age 14.36 years [IQR: 13<middle dot>30-13.28]) with lifestyle behaviors data assessed at least three times were included, and they were categorized into four joint lifestyle trajectories as follows: "remain unhealthy with low PA and increasing ST" (n = 141, 10.46%), "remain unhealthy with only low PA" (n = 305, 22.63%), "change towards unhealthy with decreasing sleep duration" (n = 776, 57.57%), and "relatively healthy" (n = 126, 9.35%). After adjusting for important confounders, the "remain unhealthy with low PA and increasing ST" group was associated with higher diastolic BP (DBP) [beta: 3.49, 95% CI: 0.55-6.44] and higher mean arterial pressure (MAP) [beta: 3.19, 95% CI: 0.37-6.01] in students compared with the "relatively healthy" group. Additionally, compared with the "relatively healthy" group, students in the "remain unhealthy with low PA and increasing ST" group had a 1.12-fold increase in the risk of hypertension (risk ratios: 1.12, 95% CI: 1.03-1.24). All trend p values in DBP, MAP, and hypertension from the "relatively healthy" group to the "remain unhealthy with low PA and increasing ST" group were less than 0.05. Four distinct lifestyle trajectories were identified among middle school students. Students who remained in the "unhealthy with low PA and increasing ST" lifestyle trajectory were associated with later elevations in BP.