The association between triglycerides and incident cardiovascular disease: What is "optimal"?

Elevated triglycerides (TGs) are associated with increased risk of cardiovascular disease (CVD), but the best way to both measure TGs and assess TG-related risk remains unknown.

The objective of the study was to evaluate the association between TGs and CVD and determine whether the average of a series of TG measurements is more predictive of CVD risk than a single TG measurement.

We examined 15,792 study participants, aged 40-65 years, free of CVD from the Atherosclerosis Risk in Communities and Framingham Offspring studies, using fasting TG measurements across multiple examinations over time. With up to 10 years of follow-up, we assessed time-to-first CVD event, as well as a composite of myocardial infarction, stroke, or cardiovascular death.

Compared with a single TG measurement, average TGs over time had greater discrimination for CVD risk (C-statistic, 0.60 vs 0.57). Risk for CVD increased as average TGs rose until an inflection point of ~100 mg/dL in men and ~200 mg/dL in women, above which this risk association plateaued. The relationship between average TGs and CVD remained statistically significant in multivariable modeling adjusting for low-density lipoprotein cholesterol, and interactions were found by sex and high-density lipoprotein cholesterol level.

The average of several TG readings provides incremental improvements for the prediction of CVD relative to a single TG measurement. Regardless of the method of measurement, higher TGs were associated with increased CVD risk, even at levels previously considered "optimal" (<150 mg/dL).