[Detection of hypertension based on measurements at three occasions in different days and its relationship with obesity in children]

Objective: To analyze the trends in blood pressure (BP) values and the elevated BP based on the measurements at three occasions in different days and its relationship with obesity in children and provide scientific evidence for the identification and prevention of hypertension in children. Methods: A public primary school in Huantai county of Zibo, Shandong province, was selected as the investigation field by using a convenient cluster sampling method. The baseline survey of "Children's Cardiovascular Health Cohort" was carried out from November 2017 to January 2018. All the students with willingness and informed consent in this school were included in the survey, and the valid sample size was 1 505 children (aged 6-11 years). Children with elevated BP at the measurement of the first occasion should had a second measurement 2 weeks later, and a third measurement was given 2 weeks later if BP was still high at the measurement of the second occasion. Hypertension was confirmed if elevated BP was detected in the measurements at all the three occasions in different days. Multivariate linear regression model was used to assess the trend in BP values in children in the measurements at three occasions in different days, Cochran-Armitage trend analysis was used to evaluate the trend of elevated BP, and logistic regression model was used to analyze the relationship of elevated BP with obesity at three occasions in different days. Results: In this study, with the increase of follow-up visits, the BP levels continued to rise (trend P<0.05). The elevated BP rates at three occasions were 15.5%, 4.0% and 1.9%, respectively, showing a significantly downward trend (trend P<0.05). Compared with both normal weight and normal waist circumference, the association between obesity types (general obesity only, abdominal obesity only, and mixed obesity) and elevated BP at three occasions increased (the first occasion: OR=3.62, 95%CI: 2.65-4.96; the second occasion: OR=9.50, 95%CI: 4.95-18.22; and the third occasion: OR=8.94, 95%CI: 3.48-22.96; all P<0.05). Stratified analysis by gender showed similar results. Conclusions: The elevated BP rates based on the measurements at three occasions in different days in children aged 6-11 years showed a significant decrease trend. The association between different types of obesity (especially mixed obesity) and elevated BP in children became stronger gradually with the progress of the follow up.