Daily Dose: High Normal Body Weight in Youths & Hypertension

Patient Care brings primary care clinicians a lot of medical news every day—it’s easy to miss an important study. The Daily Dose provides a concise summary of one of the website's leading stories you may not have seen.

On March 14, 2023, we reported on a study published in JAMA Network Open that examined the risk of hypertension (HTN) associated with high normal body mass index (BMI) for age and different weight trajectories in children and adolescents aged 3-17 years.

The study

Researchers analyzed the electronic health records of 801 019 youth who were members of Kaiser Permanente in Southern California between 2008 and 2015, with a follow-up of 5 years. Using the US Centers for Disease Control and Prevention growth charts, investigators divided average BMI into low (5th-39th percentile), medium (40th-59th percentiles), and high (60th – 84th percentiles) to provide insight into the risk of HTN at a weight below the threshold for overweight. Youths were categorized as underweight (BMI for age <5th percentile), low normal weight (≥5th to <40th percentile), medium normal weight (≥40th to <60th percentiles), high normal weight (≥60th to <85th percentiles), overweight (≥85th to <95th percentiles), moderately obese (≥95th to <97th percentiles), and severely obese (≥97th percentile).

Overall, the median age of the study cohort was 9.4 years, 51.1% were girls, and 53.4% were Hispanic. Over the 5-year follow-up, researchers identified 24 969 youths with incident HTN (incidence rate [IR] 6.97 per 1000 person-years; 95% CI, 6.89-7.06). The IRs per 1000 person-years were higher among boys (8.49; 95% CI, 8.36-8.63) than girls (5.52; 95% CI, 5.42-5.63), higher among youths with a state-subsidized health plan (7.91; 95% CI, 7.72-8.11) than those without (6.70; 95% CI, 6.61-6.80), and were highest among White (7.20; 95% CI, 7.02-7.38) and Hispanic youths (7.19; 95% CI, 7.08-7.32) compared with other youths (IRs ranged from 5.71 to 6.40).

Compared with participants with a baseline BMI for age in the medium range (40th-59th percentile), the adjusted hazard ratio (aHR) for HTN within a maximum of 5 years was 1.26 (95% CI, 1.20-1.33) for youths in the high range (60th-84th percentiles) if they maintained their BMI for age. The aHR was 4.94 (95% CI, 4.72-5.18) in participants with a baseline BMI for age in the ≥97th percentile (severely obese) who maintained their body weight.

With every 1-unit annual increase in the distance to the median BMI for age, the aHR increased by 1.04 (95% CI, 1.04-1.05), according to the study results. Weight gain increased the risk associated with baseline BMI for age in the ≥97th percentile with an aHR of 1.04 (95% CI, 1.04-1.05) per 1-unit annual increase in the distance to the median BMI for age.

Note from authors

"The results of this cohort study indicate a strong association between body weight and the risk of hypertension. A high normal body weight in children, ranging from the 60th to the 84th percentile of BMI for age, was associated with increased hypertension risk. Furthermore, the risk of hypertension increased as additional weight gain occurred over time. Under this evidence, further research should reevaluate the current wide range of body weight considered normal and related health risks of high normal weight."

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