Introduction: Between 1988-94 and 2007-10, total cholesterol (TC), non-HDL-C, HDL-C, LDL-C, and triglycerides (TG) showed favorable trends in US youth. We tested the hypotheses that these favorable trends continued in the more recent period 2003-14 and that favorable trends were also seen in apolipoprotein B (apoB).
Methods: We analyzed cross-sectional data in 15,712 youths aged 6-19 years from 6 NHANES surveys: 2003-04, 2005-06, 2007-08, 2009-10, 2011-12, and 2013-14. We applied survey weights to generate US population-level estimates and used multivariate linear regression to test for time-dependent trends in lipid levels, separately by sex and age group (6-11 vs. 12-19 years). Fasting LDL-C, TG and apoB were available only at ages ≥12 years; pubertal stage was not available.
Results: See Figure. TC and non-HDL-C generally showed significant decreasing linear trends in mean levels and favorable linear trends in the prevalence of ideal versus adverse levels, but these improvements were smaller and not significant in 12-19 year-old females. Conversely, HDL-C generally showed an unfavorable downward trend over time, a finding that reached borderline significance in 12-19 year-old females (β=-0.3 mg/dL per year, p=0.054), and the prevalence of HDL-C <40 mg/dL increased significantly in this group (β=0.6%, p=0.02). Despite the unfavorable HDL-C trend, TG showed significant favorable linear trends in mean levels and patterns of ideal versus adverse levels in both male and female 12-19 year-olds. LDL-C and apoB showed neutral to favorable patterns, with significant linear trends for an increase in the prevalence of LDL-C<110 mg/dL (β=0.5%, p=0.02) and a decrease in the prevalence of apoB ≥110 mg/dL (β=-0.9%, p=0.03) for 12-19 year-old females.
Conclusions: Favorable trends in lipids were generally seen in US youth from 2003-14, with a notable exception for HDL-C. It will be important to understand factors contributing to these trends.