Analysis: Blood-Fat Test Better With Food?

By ED SUSMAN

New studies suggest that changing the timing for measuring blood fats may provide better information about future heart disease risk — the test might be more accurate if the patient being tested has had a meal.

Almost all doctors now tell patients to have their blood cholesterol and other fats checked after fasting for at least eight hours. But two new studies to be published in the Journal of the American Medical Association Wednesday suggest that non-fasting levels of triglycerides, in fact, are better predictors of heart disease.

These studies may change the way doctors collect information on blood fats, said Paul Ridker, professor of medicine at Brigham and Women’s Hospital/Harvard medical School in Boston, the senior author of one of the two studies.

Certainly, our findings suggest that it is going to be much more clinically convenient to be able to take non-fasting reading of blood lipids, Ridker told United Press International.

Most patients are told to report for blood testing after fasting, Ridker said, not for any biological reason but for historical reasons. Previously, in order to determine levels of different types of cholesterol, it was necessary to get a fasting reading of triglycerides. But now cholesterol fractions are derived directly and have been for the last decade, he explained.

What’s more, getting the fasting reading of triglycerides may actually have skewed data and diluted the role that triglycerides play as a risk factor for heart disease, Ridker said. While he studied the role of non-fasting triglycerides just in women, researchers in Denmark found a similarly strong relationship for women and a significant relationship between non-fasting triglycerides and heart disease in men.

If our findings are confirmed, clinical care may be simplified by using non-fasting lipid profiles for atherosclerosis risk predication, said Borge Nordestgaard at Herlev University Hospital in Copenhagen.

Nordestgaard and colleagues studied outcomes in about 14,000 Danish men and women over a 28-year period. They found that the higher the levels of triglycerides, the greater the risk of heart attacks, ischemic heart disease — illness caused by blood vessels being blocked through the process known as atherosclerosis — and death.

We were unaware of the Danish study when we were doing our work. It is gratifying to see that we have similar results, Ridker told UPI. Triglycerides had been suspected of being a risk factor for heart disease based on fasting measurements but, in truth, we spend more of our day in a non-fasting state. The figures on non-fasting triglycerides appear to make triglyceride levels a stronger predictor of heart disease.

Ridker and associates reviewed data collected in the Women’s Health Study that included more than 25,000 participants. Of them about 20,000 women had fasting triglyceride levels and about 5,000 women had data on non-fasting triglycerides. The researchers found that the fasting figures showed little relevance to later outcomes, but the non-fasting triglyceride levels were predictive — independent of other risk factors — of future cardiovascular events.

We believe that we now can add non-fasting triglyceride levels to family history and levels of C-reactive protein — a measure of inflammation — to other traditional risk factors such as total cholesterol, high-density lipoprotein (HDL) cholesterol and low density lipoprotein cholesterol to get a more accurate picture of a patient’s future cardiovascular risk, Ridker said.

He said that the studies reported in the journal do not change recommendations that patients keep triglycerides levels below 150 milligrams per deciliter.

In an editorial that accompanied the JAMA articles, Patrick McBride, professor of medicine at the University of Wisconsin-Madison, said the discussion of when to test for triglycerides does not override the decision on when to treat patients.

For clinicians, it is important to recognize that when triglyceride levels are between 150 and 1000 mg/dL, the risk for atherosclerosis-related events is significantly increased, he wrote. Therefore, it is important to aggressively and comprehensively treat patients with dyslipidemias that includes high levels of triglycerides, low levels of HDL-cholesterol, and the presence of small LDL-cholesterol particles, using both lifestyle change and medications if necessary.

Ridker said that, in addition to the way triglyceride levels are used by doctors in formulating treatment plans, the measurement of triglycerides may play a major role in determining how clinical trials are performed and whether trials that have triglyceride levels as endpoints need to be re-evaluated.