By Karla Gale

NEW YORK (Reuters Health) Oct 27 - Apolipoprotein B (apoB) appears to represent a better index of risk than does low-density lipoprotein cholesterol (LDLC) level, investigators report in the November 11th issue of Circulation: Journal of the American Heart Association.

"Our study showed that patients who had a high triglyceride level and a high apoB were the ones more likely to have high blood sugar, more insulin resistance, more inflammation, and more prothrombogenic factors," co-author Dr. Allan D. Sniderman told Reuters Health.

Dr. Sniderman, at Royal Victoria Hospital in Montreal, and members of the Insulin Resistance Atherosclerosis Study (IRAS) group analyzed data from 1522 subjects, ages 49 to 69 years old. "Hyper-LDLC" was defined as levels of 130 mg/dL or higher, and "hyper-apoB" 99 mg/dL or higher.

Approximately 10% of subjects met the definition for elevated LDLC but not for apoB, and another 10% had elevated apoB in the presence of normal LDLC. After combining these two groups, the authors note, 19% of the cohort would have a different treatment recommendation if apoB were used to guide treatment instead of LDLC.

According to their findings, "normo-LDLC hyper-apoB individuals have significantly lower mean age, HDL cholesterol, and LDL particle size and higher body mass index, waist circumference, triglycerides, fasting insulin, 2-hour insulin, and plasminogen activator inhibit-1 values than the hyper-LDLC normo-apoB group."

"Our hypothesis is that these data relate back to fatty acid metabolism," Dr. Sniderman said. "It patients have excess energy intake, it is difficult for adipose tissue to store fatty acids," which in turn increases cardiovascular risk.

Dr. Sniderman suggests two choices for assessing patients at risk. In his own practice, he measures apoB as part of a routine panel.

An alternative, he said, is that when patients present with high triglyceride levels or a low HDL, measuring apoB would "produce a more complete estimate of patient risk and potential for benefit" from statin treatment.

Circulation 2003.