Diagnosis of the metabolic syndrome is associated with disproportionately high levels of high-sensitivity C-reactive protein in non-Hispanic black adolescents: an analysis of NHANES 1999-2008

Abstract

Objective: Whereas it is known that the metabolic syndrome (MetS) has a paradoxically lower prevalence in non-Hispanic black adolescents than in non-Hispanic whites or Hispanics, the relative severity of MetS by race/ethnicity is unknown. Inflammation, indicated by high-sensitivity C-reactive protein (hsCRP), is a key factor linking MetS to cardiovascular disease and type 2 diabetes. Our goal was to determine whether elevations of hsCRP vary by race/ethnicity among adolescents with MetS.

Research design and methods: We used the National Health and Nutrition Examination Survey (1999-2008) and evaluated adolescents (age 12-19 years) using a pediatric/adolescent adaptation of the ATP III definition of MetS. We used linear regression to evaluate the interaction between MetS status and ethnicity with respect to hsCRP concentration.

Results: For male and female adolescents, MetS was associated with elevated hsCRP levels compared with adolescents without MetS. However, the elevation in hsCRP between adolescents with and without MetS was greater in non-Hispanic blacks compared with that in non-Hispanic whites (P = 0.04) but not that in Hispanics (P = 0.18). hsCRP concentrations correlated with individual MetS components similarly among all ethnicities. In an evaluation of adolescents diagnosed with MetS, non-Hispanic blacks had higher BMI and more hypertension than other ethnicities but there were no other racial/ethnic differences in the features of MetS.

Conclusions: Non-Hispanic black adolescents have a greater differential in hsCRP between those with and those without MetS than the differential in non-Hispanic whites but not that in Hispanics. Therefore, even though MetS has a low prevalence in non-Hispanic blacks, MetS is a particularly good indicator of inflammation in non-Hispanic black adolescents.

Figure 1

Comparison of hsCRP concentrations by ethnicity. A and B: Adjusted geometric means of hsCRP by sex, ethnicity, and MetS status. Estimated geometric means (95% CIs) for male (A) and female (B) participants among adolescents with (white) and without (gray) MetS, for nonsmokers with a high school degree and an income-to-needs ratio of 2. C: Ratio of adjusted geometic means (95% CIs) of hsCRP values (MetS⁺/MetS⁻) by ethnicity. Male and female subjects were combined because of a lack of an interaction between MetS, ethnicity, and sex (i.e., the ratio of MetS⁺ to MetS⁻ by ethnicity was constant for male and female subjects). For A–C, comparisons between ethnic groups by corresponding MetS status are as follows: *P < 0.05 and **P < 0.01 vs. non–Hispanic whites; #P < 0.05 vs. Hispanics.