School-based surveillance on visit-to-visit blood pressure variability and high blood pressure in children and adolescents.

Background: The predictive importance of visit-to-visit blood pressure variability (VVV) for high blood pressure (HBP) in a pediatric population has been largely unsettled. We aimed to evaluate it based on Health Promotion Program for Children and Adolescents (HPPCA), a school-based surveillance conducted from 2012 to 2018 in Suzhou, China.

Methods: A total of 330,618 participants had BP measurement in 2018 and ≥ 3 BP records during 2012-2017, were recruited from HPPCA. Absolute BP values (in mmHg) were converted into age-, sex- and height- normalized z-scores. VVV was expressed as standard deviation (SD), coefficient of variation (CV) or average real variability (ARV) of BP z-scores during 2012-2017. Logistic regression models were used to assess the associations between VVV and HBP in 2018.

Results: In 2018, 42,554 (12.87%) subjects were defined as HBP. VVV, except for SBP-CV and DBP-CV, was significantly higher in the HBP group than normotensives group. After adjusting for covariates including mean BP values from 2012 to 2017, SBP-SD, SBP-ARV, DBP-SD and DBP-ARV, increased the risk of HBP by 5.70 [95% confidence interval (95% CI) 5.54-5.87], 4.10 (95% CI 4.01-4.20), 4.70 (95% CI 4.50-4.90) and 3.39 (95% CI 3.28-3.50) times, respectively. Notably, SBP-SD significantly improved risk discrimination of HBP based on other risk variables (c-statistics, net reclassification index and integrated discrimination improvement significantly increased).

Conclusions: Higher SD or ARV of BP, was independently related with higher probability of HBP in Chinese pediatric population. SBP-SD could be potentially helpful for detecting HBP. Future researches investigating the predictive value of VVV are warrant.