Background
Blood pressure (BP) is expected to have increased over time in children in most countries due to the increasing prevalence of childhood obesity worldwide. However, data on secular trends in BP at the population level in children and adolescents are scarce, and trends remain unclear in most countries. We therefore conducted a systematic review of studies assessing secular trends in BP in children and adolescents.
Methods
We conducted a systematic search using MEDLINE, CINHAL, EMBASE databases and Web of science, supplemented by searches in Google Scholar and manual searches of bibliographies of key retrieved articles. We included studies reporting mean levels of BP or the prevalence of elevated BP on at least two different points in time, involving children and adolescents 0 to 19 years old, targeting a defined geographic region, using a cross-sectional design with population- or school-based sampling. Two reviewers independently extracted data using a standardized data collection form.
Results
Out of 1739 citations screened, we identified 18 studies including 2,042,470 participants examined between 1963 and 2012. 13 studies were conducted in high-income countries (USA, Canada, Ireland, Germany, Austria, Greece, Russia, South Korea, Japan, Taiwan), 5 in middle-income countries (Turkey, Seychelles, China) and none in low-income countries. 13 studies were school-based and 5 were population-based. The median number of participants per study was 8,401 (range: 780 to 1,010,153). The prevalence of overweight or obesity increased in 16 studies, decreased in 1 study, and trends differed by sex in 1 study. Blood pressure decreased over time in 13 studies, increased in 4, and did not change in 1. Conclusion
While almost all studies showed an increase in overweight and obesity, a majority of studies showed a secular decrease in blood pressure in children and adolescents. Our findings suggest that secular trends in blood pressure do not mirror secular trends in overweight. This implies that other factors mitigate the effect of overweight on blood pressure in children and adolescents.