Crouse, professor of internal medicine (endocrinology/metabolism) and director of the Preventive Cardiology Program at the Wake Forest University Baptist Medical Center, said the study, together with other information presented at the meeting, re-emphasizes the importance of the so-called good cholesterol, high-density lipoprotein (HDL) cholesterol.
"These results suggest that HDL may have a greater import than we have given it," said Crouse, noting the emphasis in recent years on low density lipoprotein (LDL) and triglycerides.
The study involved 842 patients at 49 centers in 19 countries and compared two doses of two statin drugs -- simvastatin and atorvastatin. Both drugs raised HDL, particularly in patients who had an HDL cholesterol below 35 -- which National Cholesterol Education Program classifies as a "major risk factor for coronary heart disease." The effect was more dramatic for simvastatin.
Depending on the drug and the dose, the increase in HDL in patients who started the study with an HDL below 35 ranged from about 7 percent on the higher dose of atorvastatin to 18 percent on the higher dose of simvastatin. The HDL-raising effects of the lower doses of both drugs were in between.
In patients whose HDL cholesterol was above 35, the increases were less dramatic, with simvastatin doing about twice as well as atorvastatin at both doses.
According to the National Cholesterol Education Program, the higher the HDL, the better, and HDL above 60 appears to be protective against heart disease.
"We did not expect to see such dramatic effects of a statin on low HDL, nor did we expect to find that there was a differential effect between simvastatin and atorvastatin," Crouse said.
Patients in the study got one of four treatments: 40 milligrams or 80 milligrams of simvastatin (Zocor, manufactured by Merck & Co., Inc.). or 20 milligrams or 40 milligrams of atorvastatin (Lipitor, manufactured by the Parke Davis division of Warner-Lambert Co., and marketed both by Parke Davis and Pfizer Inc.) Patients took the assigned drug once each evening for 12 weeks.
Crouse and his colleagues also separately analyzed male and female patients and found that in women, the higher dose of simvastatin was significantly better than the higher dose of atorvastatin in raising HDL, but at the lower doses, the two drugs were equivalent.
Among men, the simvastatin was significantly better than the atorvastatin in raising HDL at both doses.
The study also looked at low-density lipoprotein (LDL) cholesterol and found both drugs substantially reduced LDL, regardless of dose. Both drugs also reduced triglycerides to a similar extent. (The lower the LDL, the lower the risk of coronary heart disease, according to the National Cholesterol Education Program, a national coalition of medical groups.)
"The observation that simvastatin beneficially raises low HDL while lowering LDL should make this finding attractive to physicians for the lipid-altering properties that collectively lower cardiovascular risk," Crouse said.
All patients were put on a low-fat diet four weeks before the drug trial began.
"It has not yet been established that increasing HDL cholesterol by itself reduces the risk of coronary events," Crouse said, but statistics show that as HDL goes up, the incidence of coronary heart disease decreases.
Other studies have shown that each point (milligram per deciliter) increase in HDL corresponds to a 2 to 3 percent reduction in the risk of developing coronary artery disease.
Crouse added, "If HDL is important, then factors that raise HDL may be important."
According to industry sources, the cholesterol-lowering market is now valued at $7.5 billion annually.