Abstract
Central obesity is associated with a higher risk of hypertension. This study aimed to analyze waist circumference (WC) trajectories and discover their association with blood pressure and the risk of hypertension. The data were obtained from the China Health and Nutrition Survey (CHNS), with a sample of 11,885 adults aged 18 or older. Trajectory groups of WC were identified by group-based trajectory modeling. Three trajectory groups were identified in males: "normal-stable group" (group 1), "normal-increase to central obesity group" (group 2), and "central obesity-slight decrease group" (group 3). There were also three identified in females: "normal-increase to central obesity group" (group 1), "normal-stable group" (group 2), and "central obesity-increase group" (group 3). For males, compared with group 1, systolic blood pressure (SBP) and diastolic blood pressure (DBP) increased by 2.47 mmHg and 2.13 mmHg, respectively, in group 2, and by 3.07 mmHg and 2.54 mmHg, respectively, in group 3. The adjusted hazard ratios (HR) and 95% confidence interval (95% CI) of hypertension in groups 2 and 3 were 1.16 (1.06-1.28) and 1.29 (1.10-1.50), respectively. For females, compared with group 2, SBP and DBP increased by 1.69 mmHg and 1.68 mmHg, respectively, in group 1, and by 4.96 mmHg and 2.77 mmHg, respectively, in group 3. The HR and 95% CI of hypertension in groups 2 and 3 were 1.21 (1.07-1.36) and 1.52(1.17-1.99), respectively. We found that the WC trajectory was a risk factor for hypertension and elevated blood pressure independent of basal WC. Increased risk of hypertension was nonlinearly associated with annual WC increase.