Obese Hispanic, White Teens Have Higher Hypertension Risk

Diana Swift

April 11, 2017

The association between hypertension and higher body mass index (BMI) differs markedly between Asian, African-American, Hispanic, and white adolescents, a large, school-based study suggests. The effect of a high BMI on blood pressure was greater in white and Hispanic adolescents than in black and Asian adolescents.

The study, published online April 10 and in the May issue of Pediatrics, suggests obesity contributes differentially to hypertension across these four major US ethical/racial groups. Interestingly, despite having the highest obesity rate, African-American adolescents did not show the exaggerated prevalence of hypertension seen in their obese Hispanic and white counterparts.

"Although an increasing BMI continues to be strongly predictive of an increase in hypertension prevalence across all racial/ethnic groups, it appears to have a smaller impact on African American and Asian populations," Eric L. Cheung, MD, from the Division of Pediatric Nephrology and Hypertension in the Department of Pediatrics at the McGovern Medical School at UTHealth, Houston, and colleagues write.

Previous studies have focused on the independent additive effects of race, ethnicity, and BMI on blood pressure. However, this analysis is the first to study the specific triangulation between race/ethnicity, obesity, and blood pressure across four population groups, the authors explain.

"The prevalence of high blood pressure in teens rises sharply with excessive weight gain, but more so in Hispanic youths compared with other ethnic groups," Joshua A. Samuels, MD, a professor of pediatric nephrology and hypertension at the McGovern Medical School at UTHealth, Houston, told Medscape Medical News. "This knowledge can remind healthcare providers to screen for obesity and measure blood pressure appropriately." Physicians should urge patients to take control of their lifestyle to prevent obesity, especially those with a family history of high blood pressure, he added.

The researchers screened 21,062 adolescents (52% girls) aged 10 to 19 years (mean, 13.8 ± 1.7 years) between 2000 and 2015 at 27 Houston secondary schools as part of the Houston Pediatric and Adolescent Hypertension Program.

The self-reported race/ethnicity composition of the students was 35% Hispanic, 33% non-Hispanic white, 25% African-American, and 7% Asian. In terms of BMI, 18% were overweight and 19% were obese, a percentage similar to that reported for 2011 to 2012 by the National Health and Nutrition Examination Survey.

The researchers determined BMI by height and weight measurement and checked blood pressure three times to diagnose sustained hypertension, according to the National Heart, Lung, and Blood Institute's Fourth Working Group Report criteria.

The researchers found an overall sustained hypertension rate of 2.7%, which was higher than the 1.7% reported in NHANES data for 2009 to 2012. The highest overall hypertension rates were seen in Hispanics (3.1%), followed by African Americans (2.7%), whites (2.6%), and Asians (1.7%; P = .019).

The hypertension rate was higher in boys (3.3%) than girls (2.1%).

Obesity rates were highest among African-American (3.1%) and Hispanic (2.7%) adolescents. But the highest prevalence of sustained hypertension emerged in obese white students (7.4%), compared with obese African-American (4.5%) and obese Asian (4.6%) adolescents.

Among Hispanics, hypertension prevalence was almost six times higher among obese adolescents versus normal weight adolescents. However, at BMIs below the 60th percentile, Hispanic adolescents actually had the lowest predicted prevalence of hypertension of all four racial/ethnic groups.

Although white adolescents exhibited dramatic fourfold increases in blood pressure with obesity, there were far fewer obese non-Hispanic white children with hypertension: 13% compared with 23% of Hispanic students.

Multivariate analysis confirmed BMI as the "categorical factor" in the greater burden of hypertension among obese Hispanic and white participants. In terms of relative risk (RR), the RR for hypertension was 5.81 times higher in obese Hispanic students and 2.17 times higher in overweight Hispanic students compared with those of normal weight. Similarly, obese white adolescents had an increased RR of 4.11, although the RR was 2.29 in their obese African-American peers.

"Although obesity remains the strongest predictor of early hypertension, the strength of this relationship is intensified in Hispanic and white adolescents, whereas it is lessened in African American adolescents," the authors write.

The race/ethnicity factor extends beyond genetics, the authors say. "Differences in culture and social expectations exert influences on health behaviors, environmental exposures, and access to health care. All these factors may affect weight gain and, in turn, [blood pressure]," they write.

As youth-onset cardiovascular disease becomes a growing problem, the findings suggest the need for a flexible approach to BMI interpretation in the United States' diverse population, the authors conclude. They also call for a reliable model for establishing individual risk for childhood hypertension and further studies to address the effect of BMI on diabetes mellitus, dyslipidemia, and obstructive sleep apnea.

The authors have disclosed no relevant financial relationships. This study was supported by the National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health.

Pediatrics. Published online April 10, 2017. Full text

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