Children and adolescents whose body weight is in the upper limit of the normal are 26% more likely to develop hypertension within five years, according to the findings of a new research published online March 14, 2023, in JAMA Network Open.^1,2

This trial designed as a retrospective cohort study included 801,019 children and adolescents aged 3 to 17 years, who were treated at Kaiser Permanente in the southern part of the state of California in the United States between 2008 and 2015. The age of the participants was a median of 9.4 years. More than half (51.1%) were girls. The aim of the research was to assess the risk of hypertension associated with high normal body mass index (BMI) for age and different weight trajectories. Based on the baseline BMI for age, the normal body weight was categorized as low (5th-39th percentile), medium (40th-59th percentile) and high (60th-84th percentile). Participants with BMI for age <5th percentile were considered as underweight, while those with BMI of ≥85th to <95th percentiles were categorized as overweight, ≥95th to <97th percentiles as moderately obese and ≥97th percentile as severely obese.

Results showed that a total of 24,969 study subjects developed incident hypertension over the follow up period of 5 years with incidence rate (IR) of 6.97 per 1000 person-years. Boys were more likely to develop hypertension vs girls with incidence rates of 8.49 and 5.52, respectively. The incidence rate of hypertension was noted to be higher among those who were on a state-subsidized health plan (7.91) compared to participants who were not on such a plan (6.70).

Compared to the participants in the medium normal weight category (40th-59th percentile), the risk of hypertension was increased 26% among those in the high normal weight group i.e., between the 60th and 84th percentiles of BMI with adjusted hazard ratio (aHR) of 1.26 if they maintained their BMI for age. Among those with severe obesity (baseline BMI ≥97th percentile), whose weight remained stable, the aHR was 4.94.

With every unit increase in BMI per year, the risk of hypertension increased by 4% with an aHR of 1.04. “The risk associated with weight change was higher in youths living with low to high normal weight and overweight than in youths living with severe obesity.”

Having a body weight within the expected range for age may lull one into a false sense of security because this study has shown that children and adolescents with a body weight in the upper limit of the normal were also at a higher risk of developing hypertension as were those who had severe obesity. Any additional weight gain further increased the risk of hypertension. “Our results suggest that the current range of normal weight from the 5th to 84th percentiles of BMI for age in children may be too wide and requires re-evaluation with regard to health risks”, noted the authors.

Reference

1. Koebnick C, et al. Association of high normal body weight in youths with risk of hypertension. JAMA Netw Open. 2023 Mar 1;6(3):e231987. doi: 10.1001/jamanetworkopen.2023.1987.
2. Kaiser Permanente Press release, March 14, 2023. Available at: https://about.kaiserpermanente.org/health-and-wellness/health-research/news/extra-pounds-put-kids-at-higher-risk-for-hypertension. Accessed on March 15, 2023.