To the Editor
Elevated blood pressure (BP) in childhood is associated with short‐term risk of target organ damage,1 as well as long‐term risk of subclinical cardiovascular diseases (CVDs) and premature mortality in adulthood.2 The US National High Blood Pressure Education Program Working Group recommended BP measurements in children aged 3 years or older in routine health examinations to early identify and control elevated BP in children.3 Although two previous publications using National Health and Nutrition Examination Survey (NHANES) data demonstrated that the prevalence of elevated BP slightly decreased in the United States from 1999 to 2012,4, 5 its trend in recent years is unknown. Thus, we aimed to estimate the most recent prevalence of elevated BP and the trends in children in the United States from 1999–2000 to 2013–2014.
Methods
Data were obtained from NHANES conducted in 2013–2014.5 NHANES selects a representative of the US civilian, noninstitutionalized population using a complex and multistage probability sampling design. Participants and their parents provided written informed consent. This survey received the approval from the ethics review board of the National Center for Health Statistics.
High BP was defined as systolic BP/diastolic BP ≥95th percentile references by sex, age, and height (based on the 2000 Centers for Disease Control and Prevention [CDC] growth charts), while high‐normal BP was defined as systolic BP ≥90th percentile but <95th percentile or systolic BP/diastolic BP ≥120/80 mm Hg based on the fourth report on the diagnosis, evaluation, and treatment of high blood pressure in children and adolescents.3 Overweight and obesity were defined using the 2000 CDC growth charts.
The Complex Samples module in SPSS 13.0 (SPSS Inc, Chicago, IL) was used for data analyses, with adjustment for weights to account for stratification and clustering in NHANES. Complex Samples logistical analysis was used to examine the trends in prevalence of high‐normal BP and high BP from 1999–2000 to 2013–2014. P<.05 was considered statistically significant without multiple testing adjustment.
Results
A total of 1796 US children aged 8 to 17 years in 2013–2014 were included in the present study. In 2013–2014, 1.1% had high BP and 6.5% had high‐normal BP. Boys had a higher prevalence of normal BP than girls (boys 8.4% vs girls 4.5%, P=.007), while there was no statistical significance for prevalence of high BP (boys 1.5% vs girls 0.7%, P=.121). Older children had a higher prevalence of high‐normal BP than young children (13–17 years vs 8–12 years: 9.4% vs 3.5%, P=.003) but they had a similar prevalence of high BP (1.5% vs 0.7%, P=.147). In addition, overweight and obese children had a higher prevalence of high‐normal BP (P<.001) and high BP (P=.049) than children with normal weight. However, we did not find any difference between race/ethnic subgroups.
Between 1999–2000 and 2013–2014, the prevalence of high BP decreased in the total children, as well as in boys and girls, respectively (all P<.05, Figure A) although the prevalence of high‐normal BP leveled off over time (Figure B). Compared with 1999–2000, the prevalence of high BP declined by 63.3%, 54.5%, and 74.1%, in the total children and boys and girls, respectively, in 2013–2014.
Figure 1.
Trends in (A) high blood pressure (BP) and (B) high‐normal BP in US children, 1999–2014.
Discussion
To our knowledge this is the first study to report the most recent prevalence of elevated BP in US children based on NHNAES data in 2013–2014. In the present study we found that high BP decreased significantly in US children from 1999–2000 to 2013–2014, with only 1.1% of US children having high BP in 2013–2014. These findings are exciting, although the exact reasons are unclear. The recent evidence has demonstrated that the decreased trends in high BP in US children might be the result of improvements in dietary factors,5 as well as the increase in physical activity and decrease in sedentary behavior. However, the decreased trends cannot be attributable to obesity and sodium intake, which are still much higher than expected.5 Further studies should consider which factors have led to the decreased trends in high BP in US children over time.
Author Contributions
Dr Xi had full access to all data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: Dr Xi. Acquisition, analysis, and interpretation of data: all authors. Drafting of the manuscript: Drs Ma and Xi. Critical revision of the manuscript for important intellectual content: Dr Xi. Statistical analysis: Dr Xi. Study supervision: Dr Xi.
Conflict of Interest
None reported.
Funding/Support
This study was supported by the Young Scholars Program of Shandong University (2015WLJH51). We thank the National Center for Health Statistics of the US Centers for Disease Control and Prevention for sharing the NHANES data.
Role of the Funder/Sponsor
The funding sources had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.
References
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