From the Guidelines
A 9-year-old boy at the 99th percentile for body mass index (BMI) is classified as having severe obesity. This classification is based on the definition proposed by the American Heart Association, which states that a BMI ≥99th percentile is considered severe obesity in children and adolescents 1. According to this definition, a BMI at or above the 99th percentile indicates an especially adverse cardiovascular risk factor profile and a high likelihood of tracking of adiposity into adulthood.
The use of percentiles allows for a uniform metric across all ages, enabling comparison of excess weight in children of different ages and sexes. For example, a 9-year-old boy with a BMI at the 99th percentile has a similar excess weight to a 14-year-old boy with a BMI at the 99th percentile, relative to age- and sex-matched peers 1.
Management of severe obesity in children typically involves a comprehensive approach, including:
- Dietary modifications
- Increased physical activity
- Behavioral therapy
- Family involvement
Early intervention is crucial, as childhood obesity often persists into adulthood and increases the risk of developing conditions like type 2 diabetes, hypertension, and cardiovascular disease later in life. The Centers for Disease Control and Prevention (CDC) provides age and sex-specific growth charts to help classify obesity in children, which differs from the classification used for adults 1.
From the Research
Classification of a 9-year-old boy at the 99th percentile for body mass index (BMI)
- A 9-year-old boy at the 99th percentile for BMI is considered to be at a high risk for adverse health outcomes, including dyslipidemia, dysglycemia, and hypertension 2.
- According to the study by 2, significant increases in glycohemoglobin values and prevalence of abnormal values begin at the 99th percentile.
- The American Academy of Pediatrics defines obesity as a BMI at or above the 95th percentile for age and sex 3.
- However, the study by 2 suggests that a judicious approach to screening could include consideration of lipid screening for children beginning at the 80th percentile, but for dysglycemia at the 99th percentile.
- Another study by 4 suggests that a BMI cutoff point at the 99th percentile for age and gender or at 40 kg/m(2) has been suggested for more aggressive treatment of adolescent obesity.
- It is worth noting that the classification of a 9-year-old boy at the 99th percentile for BMI would be considered obese, as it is above the 95th percentile 3, 5.
- The study by 6 defines severe obesity by BMI ≥120% × 95th percentile, but it does not specifically address the 99th percentile.
- Overall, a 9-year-old boy at the 99th percentile for BMI would be considered to be at a high risk for adverse health outcomes and would likely be classified as obese 3, 2, 4.