By Dr. Geoffrey Modest
So, no great surprise, but it seems that cardiometabolic risk factors track the degree of obesity in children and young adults (see N Engl J Med 2015;373:1307-17). A cross-sectional analysis of overweight and obese kids/young adults (age 3-19) in the National Health and Nutrition Examination Survey from 1999-2012 looked at measured height and weight, along with an array of cardiometabolic risk factors (lipids, A1c, etc.), assessing the relationship over different obesity levels.
Background (from the CDC):
- Childhood obesity (defined as BMI >95th %ile) has more than doubled in children and quadrupled in adolescents in past 30 years: % of children aged 6-11 in the US who were obese increased from 7% in 1980 to 18% in 2012; for adolescents 12-19yo, it increased from 5% to 21%.
- In 2012 >1/3 of children and adolescents were overweight or obese
- Despite recent declines in obesity prevalence in preschool-aged kids, obesity is still way too prevalent: overall for those 2-19 yo, the prevalence “has remained fairly stable at about 17% and affects about 12.7 million children and adolescents for the past decade”, though the prevalence in those 2-5 yo has decreased significantly from 13.9% in 2003-4 to 8.4% in 2011-2, at which time the prevalence was 17.7% in 6-11 yo and 20.5% in 12-19 yo; the prevalence was highest in Hispanics (22.4%) and non-Hispanic blacks (20.2%) vs non-Hispanic whites (14.1%)
Details of study:
- 8579 individuals (53.7% white, 16.5% black, 24.0% Hispanic; 52% male) with BMI>85th %ile, of whom 46.9% were overweight (BMI 85-95th%), 36.4% had class I obesity (95-120% of the 95th %ile), 11.9% had class II obesity (120-140% of the 95th %ile or BMI≥35), and 4.8% had class III obesity (≥140% of the 95th %ile, or BMI≥40).
Results, as progress from overweight to class I to class II to class III obesity:
- LDL: 94.6, 98.4, 98.2, 96.5 (p=0.131, non-significant)
- HDL: 49.4, 46.7, 43.5, 41.3 (p<0.001)
- Systolic BP: 108.5, 111.0, 112.6,116.2 (p<0.001)
- Diastolic BP 57.0, 58.8, 58.7, 64.5 (p<0.001)
- Fasting triglycerides: 91.0, 113.2, 113.3, 143.2 (p<0.001)
- Glycohemoglobin 5.15, 5.20, 5.30, 5.37 (p<0.001)
- Fasting glucose: 93.2, 95.1, 96.7, 96.5 (p=0.001)
- And, overall, these risk factors did have a sex difference: males did worse. In fact, the only significant ones for females were: HDL, systolic/diastolic BP, glycohemoglobin and glucose; and for each of these, the prevalence in males was much higher.
So, although this study tracked only the surrogate markers of cardiometabolic parameters (not so likely to have cardiac clinical events at this age…..), this study is important because:
- Obesity in kids tracks with obesity in adults
- This study, vs older ones, looks at levels of obesity and differences in risk factors, showing a graded response overall: the worse the obesity, the worse the risk factors. And, this study, I think, justifies subdividing obesity in kids into different levels (since there are differences in attributable cardiometabolic risks), as is done with adults.
- And, though clinical events are the gold standard, autopsy studies have shown that there are fatty streaks in pretty much everyone aged 15-34; and there are advanced atherosclerotic lesions in 2% of men/0% of women aged 15-19 and 20% of men/8% of women aged 30-34. So, actual disease does begin early and, per usual, is seems better to deal with risk factors early on, before clinical disease manifests itself….
Also, for prior blog on the relationship between pediatric obesity and increased left ventricular mass from the Bogalusa Heart Study, see https://stg-blogs.bmj.com/bmjebmspotlight/2015/01/25/primary-care-corner-with-geoffrey-modest-md-obesity-and-left-ventricular-mass-in-kids/