Apolipoprotein B, oxidized low-density lipoprotein, and LDL particle size in predicting the incidence of metabolic syndrome: the Cardiovascular Risk in Young Finns study.

OBJECTIVE: To test whether serum apolipoprotein B (apoB) and low-density lipoprotein (LDL) particle characteristics (oxidation and mean particle size) predict the incidence of metabolic syndrome (MetS).

METHODS: The 6-year follow-up study included 1429 adults (baseline mean age 31.5). Lipids, apoB, and apoA1 were measured at baseline in 2001. LDL oxidation was measured with monoclonal antibody-based enzyme-linked immunosorbent assay (oxLDL-prot) and with a method measuring oxidized lipids in LDL (oxLDL-lipids). Mean LDL particle size was calculated from proton nuclear magnetic resonance spectroscopy data.

RESULTS: Increased concentrations of both oxLDL-measures were associated with increased apoB levels but not with LDL particle size. The odds ratios (95% confidence intervals) for MetS incidence during a 6-year follow up by quartiles of apoB were 2.0 (1.0-3.8) for the second quartile, 3.1 (1.7-5.7) for the third quartile, and 4.2 (2.3-7.6) for the fourth quartile. This association remained after adjusting for age, sex, body mass index, homeostasis model assessment for insulin resistance, C-reactive protein, smoking, LDL cholesterol, oxidized LDL measures (p ≤ 0.01) in addition to risk factors comprising the MetS (p = 0.03). OxLDL-prot and oxLDL-lipids levels were not independently associated with incident MetS after adjusting for apoB. Mean LDL particle size was not associated with the incidence of MetS.

CONCLUSION: ApoB is associated with increased risk of MetS incidence. We found no clear evidence to suggest that increased LDL oxidation or small mean LDL particle size would facilitate the development of MetS.