For years now, everyone's attention has been on the "bad" cholesterol — LDL, or low-density lipoprotein cholesterol. The goals were to get it below 130 milligrams per deciliter (mg/dL), then 100, and now, for high-risk patients, down to the 70 mg/dL range.
Often lost in the shuffle has been the "good" cholesterol — HDL, or high-density lipoprotein cholesterol. HDL particles act as good scavengers to take away fat from arterial walls before it becomes imbedded into plaque.
Risk of heart attack declines 1% to 3% for every 1% increase in HDL. But the treatments available to raise HDL have been overshadowed by statins and their dramatic ability to lower LDL. Now, however, as more and more people get their LDL way down, interest in raising HDL is growing. Moderate to intense physical exercise (as advised by your doctor) and one to two alcoholic beverages per day can increase HDL a little.
New drugs to raise HDL appeared promising. But clinical trials have questioned their safety. Also it’s not clear how much extra benefit you actually get by raising your HDL if your LDL is ideal.
The two main classes of existing drugs are "fibrates" and niacin and related compounds. The best known fibrates are fenofibrate (Tricor) and gemfibrozil (Lopid). Both are available as generic medicines.
Pooled data on gemfibrozil and other fibrates show they lower total cholesterol by about 25 mg/dL, LDL cholesterol by about 12 mg/dL, and triglycerides by about 70 mg/dL. HDL goes up by a little more than 4 mg/dL. Together, these effects lead to a reduction in risk of cardiac problems of about 25% from fibrates.
The most common side effects are abdominal discomfort, gas and diarrhea. Rashes are also common. Less common problems include liver and muscle damage. Muscle damage is more likely to occur when a person takes both a fibrate and a statin.
Niacin lowers LDL by about 21 mg/dL, and raises HDL by nearly 7 mg/dL on average. Side effects are common, though, particularly with older preparations of niacin. Most people taking the "immediate release" forms of niacin get flushing, versus only about 25% of patients taking newer preparations in which there is "sustained release" of the drug. Gastrointestinal symptoms, skin, muscle and liver problems are other major side effects. Similar to fibrates, muscle damage is more likely to occur when a person takes both niacin and a statin.
These relatively high rates of side effects tell you why doctors have loved pushing statins to reduce LDL for the last decade — hardly anyone has side effects, and both patient and doctor can point to lower and lower LDL results.
The bottom line on HDL: A low level is associated with higher heart disease risk. Raising it with more exercise is the best approach. However, until we have clear evidence that drug therapy to raise HDL improves outcomes, just adding more drugs to get a higher number doesn't always make sense.
Thomas H. Lee, M.D. is the chief executive officer for Partners Community HealthCare Inc. He is a professor of medicine at Harvard Medical School. He is an internist and cardiologist at Brigham and Women's Hospital. Dr. Lee is the chairman of the Cardiovascular Measurement Assessment Panel of the National Committee for Quality Assurance.