Differences in Blood Pressure Levels Among Children by Sociodemographic Status

Melissa Goulding, MS; Robert Goldberg, PhD; Stephenie C. Lemon, PhD

Disclosures

Prev Chronic Dis. 2021;18(9):e88 

In This Article

Discussion

Our study showed prevalence among children aged 8 to 17 years to be 7.2% for elevated BP and 3.8% for hypertensive BP according to 2017 AAP guidelines. Our findings also confirm the important relationship between body weight and BP among children aged 17 years or younger. Children who were classified as overweight or having obesity were more likely to have elevated or hypertensive BP than healthy-weight children. We identified associated sociodemographic differences and found that some, but not all, of these differences were attenuated after accounting for disparities in body weight.[1,8,9] We found higher prevalence estimates of elevated BP in males, older children (16–17 y), non-Latino Black children, and children of lower socioeconomic status. After adjustment for weight status, elevated BP prevalence differences in age, sex, race/ethnicity, and parent/guardian education persisted in these groups. Hypertensive BP was highest among younger children (8–9 y), Mexican America children, and males.

The prevalence of elevated and hypertensive BP observed in our study is higher than previous estimates.[7,8] These earlier estimates were based on previous guidelines where weight distribution skewed the normative tables resulting in higher BPs at lower percentiles and fewer children meeting the elevated and hypertensive percentiles.[18] A previous study that used the 2017 AAP guidelines found a declining trend in hypertensive BP prevalence among children aged 8 to 17 years in NHANES data when comparing data collected in 2005–2008 with data collected in 2013–2016.[1] Focusing on more recent data and not aggregating biennial cycles, we found the prevalence of elevated and hypertensive BP to fluctuate between the study years of 2011 and 2018. However, overlapping confidence intervals suggest these differences were probably due to chance. The prevalence of elevated and hypertensive BPs was highest in the NHANES 2011–2012 cycle and lowest in 2013–2014. Past declining trends may have been misleading by not including the 2011–2012 cycle. Our prevalence estimate of 3.8% suggests that hypertensive BP among children remains an important public health issue and that the Healthy People 2020 goal of reducing this prevalence to 3.2% has thus far not been achieved.[19]

Our study confirmed results of previous studies that showed overweight and obesity to be major risk factors for high BP in children[2–5,7,9,20] and supports changes in the AAP guidelines to the use of BP tables based on children of healthy body weight. In our study, adjustment for weight resulted in the attenuation of prevalence differences in elevated and hypertensive BP across the sociodemographic groups examined, emphasizing the influence of weight on observed disparities in BP. Thus, future studies that examine sociodemographic differences in children's BP levels need to adjust for the child's weight in further stratified or multivariable adjusted regression analyses to more systematically examine differences across any strata under study.

Consistent with the published literature, our findings suggest that in unadjusted estimates male children, children with parent/guardian with lower levels of education, and children from families with low income levels experienced a greater burden of cardiovascular risk because of disproportionate rates of unhealthy body weight.[21] Sex differences in physiologic parameters, such as total cholesterol levels, and health behaviors, such as physical activity levels, have previously been highlighted in relation to childhood obesity and could contribute to the higher unadjusted prevalence of hypertensive BP observed among males.[21] Disparities in the built environment, which affect patterns of physical activity, and access to healthy foods at affordable prices are acknowledged risk factors for children of low socioeconomic status who are overweight and could contribute to the higher unadjusted prevalence of elevated BP observed in children with low levels of parent/guardian education or income.[22,23] Thus, through various weight-related pathways and mediators, weight-related disparities may contribute to disparities in unadjusted prevalence of BP levels across the sociodemographic factors of sex, education, and family income.

The crude racial/ethnic prevalence differences detected in our study underscore the disproportionate burden of elevated BP and unhealthy weight in non-Latino Black communities.[24,25] Numerous factors across socioecological levels have been noted to contribute to disproportionate obesity prevalence across racial/ethnic groups.[24,25] Here again, we see that factors contributing to weight disparities may also contribute to BP-related disparities.[23] Weight-related risk factors can be systematic and range from health care access to safety and opportunity.[26] Beyond describing their existence, more action needs to be taken to disentangle and prevent the factors contributing to these disparities to achieve health equity.

In our study, racial/ethnic disparities in prevalence of elevated and hypertensive BP remained after adjusting for weight status. This indicates that factors other than body weight contribute to racial/ethnic disparities in children's BP and that other pathways to less than optimal BP levels may begin in childhood. One such pathway is psychosocial stress, which has been extensively studied in adult populations.[27] Empirical investigation of pathways (obesity-related and other) to racial/ethnic disparities in elevated BP prevalence is warranted as are interventional and policy-based efforts designed to narrow these differences and lower children's risk of subsequent cardiovascular disease. Weight disparities did not fully explain observed differences in elevated BP prevalence by sex in our study. In adult populations, sex-related BP differences are well established,[28] and our findings suggest that the pathways to these sex-related BP differences may begin in childhood.

The differences we found in prevalence estimates of elevated and hypertensive BP in relation to age may be due in part to increased BP variability among young children[29] and in the use of percentile-based definitions for children aged 8 to 12 years compared with static cutoffs for children aged 13 to 17 years.[30] Additionally, prevalence differences detected across age groups could be due to changes in BP associated with puberty and to the intersection of these changes with age, sex, and race/ethnicity. Further understanding is needed about how levels of BP disorders differ, and long-term follow-up data on BP levels among children are needed.

Our study highlights opportunities for reduction of elevated and hypertensive BP levels among US children. Efforts focusing on increased equity in access to care through policy changes to combat obesity in racially/ethnically and socioeconomically diverse populations should be expanded. Specific focus and efforts directed at systematic change to improve social determinants of health are also needed. Efforts to understand the causes of racial/ethnic and socioeconomic disparities and to reduce them could have short- and long-term benefits through improvements in children's health and long-term prevention into adulthood.[31] Given the well-known tracking of BP into the adult years and the strong association between elevated BP and cardiovascular and other chronic diseases, particular focus on preventing the large number of males with elevated BP from progressing to hypertension is warranted.[32] Further research and risk reduction approaches should be directed to expanding BP screening in national samples of young children to improve our understanding of childhood hypertensive BP and reduce the risk of chronic diseases associated with hypertension later in life. Clinicians should be aware of socioeconomic disparities and the role of overweight highlighted in our study.

Strengths of the present study come from its use of contemporary nationally representative data and current BP screening guidelines. Although assessing subgroup differences in children's elevated and hypertensive BP may be difficult because of low case counts, we were able to combine the 4 most recent NHANES data cycles to obtain contemporary estimates across sociodemographic groups. The data analyzed in our study were collected by trained professionals who used standardized methods under controlled conditions and with quality control measures. This is important because collecting accurate BP measurements among children can be challenging.[5]

Our study also has limitations. Despite the strengths inherent in the use of NHANES data, the study was limited by the data collected in that survey. Although declining response rates are of concern, NHANES has taken steps to mitigate the potential for nonresponse bias.[13] Blood pressure measurements were limited to a single occasion rather than a series on 3 occasions, as is necessary for clinical diagnosis. However, previous childhood hypertension studies also used readings from a single occasion, including those providing national prevalence estimates.[1,5] No single measure accurately reflects socioeconomic status, and we were unable to evaluate food insecurity as a marker of socioeconomic status, or low birthweight as a potential confounder, because NHANES assesses these measures only in children aged 16 years or older. Data on other important, potentially confounding variables, including family history of hypertension, chronic kidney disease, and chronic sleep disturbance were not available.

Elevated and hypertensive BP affects US children disproportionately in various sociodemographic groups, and body weight influences these health disparities. The burden of this cardiovascular risk is higher in children who are male, non-Latino Black, or of low socioeconomic status. Age, sex, and race/ethnicity may influence BP independently of weight status. Efforts are needed to better understand and intervene on the mechanisms through which these factors interact with BP in children. Obesity and hypertension are preventable disorders that potentially cause lifelong harm. Continued and amplified efforts are needed related to elevated and hypertensive BP among children aimed at lowering the prevalence, decreasing disparities, and ultimately achieving health equity.

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