Secular trends in blood pressure trajectories in Chinese children and adolescents: the impact of changing physical growth.

Abstract

Globally, 80% of cardiovascular disease (CVD) occur in low-income /middle-income countries. High blood pressure (BP), a major risk factor for CVD, has its origins in early-life. We investigated how age trajectories of BP (childhood to late-adolescence) have changed recently in China and the mediating roles of physical growth. Using the longitudinal data on 3785 children from the China Health and Nutrition Survey 1991-2015, we estimated mean BP trajectories (7-18 years) for cohorts born in 1981-1985, 1986-1990, 1991-1995 and 1996-2000 using random effect models. Models were adjusted for BMI and/or height growth to assess their impact on BP trends. BP trajectories shifted upwards across cohorts. Compared with the earliest cohort, mean BP was higher in the latest cohort throughout childhood to late adolescence. For example, the increment in SBP was 4.4 mmHg (95% confidence interval: 2.9-5.8) in boys and 4.0 mmHg (2.6-5.5) in girls at 9 years, narrowed slightly during adolescence, and was 3.0 mmHg (0.7-5.4) and 2.6 mmHg (0.4-4.8) respectively at 17 years. BMI and height trajectories also shifted upwards. The overall increment was greater for height than BMI. When adjusting for physical growth, the increment in BP trajectories reduced (more for height than BMI), but remained in childhood (P < 0.05). The upward shift of BP trajectories among Chinese youths was largely explained by trends in physical growth, especially increasing height. Other early-life factors might have also contributed to the BP trends. Substantial increases in mean BP in children within a short time frame is a public health concern and will affect future CVD, especially in the developing world.