The Nutrition Debate #255: “Risk Prediction with triglycerides…”

Virtually everyone who has blood taken at the doctor’s office these days gets a standard “lipid panel.” The cholesterol test. Your doctor gets assayed values for Total Cholesterol (TC) and High-density lipoproteins (HDL), the so-called “good” cholesterol, and more recently a value for non-HDL cholesterol in lieu of very low density lipoproteins. It also has a related measurement, serum triglycerides, a fat molecule circulating in your blood. In addition to these measurements, the lipid panel also reports on low density lipoproteins (LDL), a calculated value using the Friedewald formula (LDL=TC-HDL-TG/5).

Your doctor will use the Total Cholesterol, if it’s over 200mg/dL, to try to persuade you to take a statin drug. Statins effectively lower LDL cholesterol, known as the “bad” cholesterol, and therefore lower TC. (TC=HDL+LDL+TG/5). This is a dubious benefit for virtually everyone except those with coronary artery disease (CAD). In patients with existing coronary artery disease, statins are indicated for secondary prevention, to prevent a heart attack.

Most lipid panels also include a ratio, Total Cholesterol to triglycerides (TC/TG), as a cardiovascular “risk indicator.” Doctors use this to evaluate the risk of cardiovascular events such as heart attack (Myocardial Infarction or MI), stroke, and death, among other outcomes. In The Nutrition Debate #27, I presented the case that “the strongest predictor of a heart attack” is the ratio of triglycerides to HDL cholesterol, or TG/HDL. That column, written three years ago, applies to the general “healthy” population and has proved to be one of the most popular I have written. It’s also one of my editor’s favorites.

A more recent study, published in Clinical research in cardiology: official journal of the German Cardiac Society, provides a fresh look at “Risk prediction with triglycerides in patients with stable coronary disease on statin treatment.” The aim of this prospective study was “to analyze the role of fasting and postprandial triglycerides (TG) as risk modifiers in patients with coronary artery disease (CAD).” The trial used standardized measurements of oral triglyceride and glucose tolerance in 514 patients with stable CAD, confirmed by angiography, 95% of whom were treated with a statin.

After 48 months follow-up, using both fasting and postprandial measurements and primary outcomes of cardiovascular death and hospitalizations, the researchers sought to determine if either fasting and/or postprandial serum triglycerides were a risk indicator and could predict the primary outcome. The results were surprising – indeed, startling, in my opinion.

“CONCLUSIONS: Fasting serum triglycerides >150 mg/dL independently predict cardiovascular events in patients with coronary artery disease on guideline-recommended medication [statin drugs]. Assessment of postprandial TG does not improve risk prediction compared to fasting TG in these patients.”

The RESULTS were unequivocal. For fasting TG >150 vs. <106 mg/dL, the hazard ratio (HR) was 1.79. Translation: If you have CAD and are taking a statin, and your triglycerides are over 150 mg/dL, you have an ~80% greater chance of dying or being hospitalized for CAD over 4 years than if your triglycerides are <106/mg/dL.

The analysis then concluded, “Risk prediction by TG was independent of traditional risk factors, medication, glucose metabolism, [and] LDL- and HDL-cholesterol. Total cholesterol [and] LDL- and HDL-cholesterol concentrations were not associated with the primary outcome [cardiovascular death and hospitalizations].”

MY TAKEAWAY: If you have been diagnosed with coronary artery disease (CAD), your doctor will surely prescribe a statin, the guideline-recommended medication, and you should take it. But remember that your fasting serum triglycerides are an independent risk factor. Fortunately, they are also a modifiable risk factor, which is to say, one that YOU can change. But there’s no magic bullet. Prescriptions for Niacin and fibrates work for some people, and may be indicated for very high TGs, but the best way to lower your fasting serum triglycerides and to keep them low  is with Omega 3 fatty acids (2g fish oil/day) (http://www.nlm.nih.gov/medlineplus/druginfo/natural/993.html) and lowering the carbs in your diet.

Your doctor is not likely to have seen this research from the German Cardiac Society. My intrepid editor found it for me.  Besides, fasting serum triglycerides from 150- 199 mg/dL are currently regarded as “borderline” in the medical guidelines, so your doctor will likely says something inane like, “We’ll have to watch that,” or “Cut back on your drinking.” But remember, the hazard ratio for “primary outcomes” for TGs above 150 mg/dL was 1.79. Do you want to become a statistic?

Take a look at The Nutrition Debate #68, “Triglycerides, Fish Oil and Sardines,” to see my n=1 odyssey with triglycerides. I started out “borderline,” but my most recent TGs have been 51, 55, 34, 49, 47, 58, 54, 56, 65, 53, 31, 38, 52, 49, 50 and 34.