Which fasting triglyceride levels best reflect coronary risk? Evidence from the Turkish Adult Risk Factor Study

Abstract

Background: Association between raised low-density lipoprotein cholesterol (LDL-C) levels and high risk for coronary heart disease (CHD) is well established and taken into account in guidelines on coronary prevention.

Hypothesis: The relationship between risk for coronary heart disease (CHD) and the levels of fasting plasma triglycerides was studied in the cohort of the Turkish Adult Risk Factor Study, a representative random sample of an adult population.

Methods: In 829 men and 907 women aged > or =27 years (mean 48.5+/-11), plasma lipids and lipoproteins were measured by the enzymatic dry method in the postabsorptive state. A sample of values was validated in a reference laboratory. Apoliprotein (apo) A-I and B were measured by the turbidimetric immunoassay using commercial kits in part of the cohort. Blood pressure and anthropometric measurements were made. Criteria for the diagnosis of CHD were based on history, cardiovascular examination, and Minnesota coding of resting electrocardiograms. Coronary heart disease was diagnosed in about 7% of the subjects. Participants were divided into four categories depending on their triglyceride levels: I = < 100 mg/dl (282 men, 400 women), II = 100-139 mg/dl (204 men, 228 women), III = 140-212 mg/dl (188 men, 180 women), and IV = > or = 212 mg/dl (155 men, 99 women).

Results: After adjustment for age, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol, smoking, and body mass index by logistic regression analysis, and after assigning the CHD risk of 1 to Category I, the relative risk for men and women combined rose to 1.42 in Category III (p<0.045) while it diminished to 0.94 in Category IV (p = 0.79). In women, the odds ratio (OR) rose gradually up to 1.78 (p< 0.025) in Category III, only to decline in Category IV. The OR in men was slightly, insignificantly, and equally elevated in Categories III and IV. Patients with CHD in Category III were not distinguished from those in Category IV by the studied risk parameters. It was suggested that high risk for CHD--particularly in subjects with slightly elevated or normal cholesterol levels-is often not reflected by extreme increases of fasting triglycerides but best by modest elevations (140-212 mg/dl), which serve better as a marker of triglyceride-rich lipoprotein particles. This knowledge may prove to be of value in population screening and individual risk assessment.