WASHINGTON -- Boosting "good" cholesterol does not protect against heart attacks and strokes, according to an eagerly awaited study that was abruptly stopped when the outcome became clear, officials said Thursday.
The federally funded study of more than 3,400 U.S. adults at high risk for heart attacks and strokes was halted 18 months early after researchers realized that the drug niacin failed to cut the risk -- as was hoped and suggested by many earlier, smaller studies, officials said. In fact, niacin appeared to increase study participants' risk for one particular type of stroke.
The findings are a major blow to what had been one of the most promising hopes for reducing the toll from cardiovascular disease, which kills about 800,000 Americans each year, making it the leading cause of death in the United States.
"Seeking new and improved ways to manage cholesterol levels is vital," Susan Shurin, acting director of the National Heart, Lung and Blood Institute, which funded the $52.7 million study, said in a statement. "Although we did not see the expected clinical benefits, we have answered an important scientific question."
Heart attacks and strokes have been dropping, in part by cutting "bad" LDL cholesterol, which can clog arteries. Many researchers hoped that the next big advance would come from a new generation of drugs that boost "good" HDL cholesterol, which is thought to clear LDL. A large body of research had found that people with low HDL levels were more likely to be stricken by heart attacks and strokes.
Doubts about the HDL-hiking hypothesis began to emerge, however, when the HDL-raising drug fenofibrate failed in 2005 to cut heart attacks and strokes among diabetics. Another study the following year found a different HDL-raising drug, torcetrapib, actually increased the risk. But researchers held out hope that niacin might be beneficial.
To put that strategy to the first rigorous test, researchers launched the AIM-HIGH study involving 3,414 people with a history of heart disease. All were taking the statin Zocor to keep their LDL levels low but remained at high risk because they had low HDL and high triglycerides.
The subjects took either a high-dose, extended-release version of niacin known as Niaspan or a placebo. Some also took another cholesterol-lowering drug called Zetia. HDL levels rose and triglycerides dropped among those taking niacin, which is also known as vitamin B3. But an independent panel of experts monitoring the experiment terminated it April 25, after just 32 months of follow-up, when it concluded that those taking niacin were no less likely to have a heart attack or stroke.
The federally funded study of more than 3,400 U.S. adults at high risk for heart attacks and strokes was halted 18 months early after researchers realized that the drug niacin failed to cut the risk -- as was hoped and suggested by many earlier, smaller studies, officials said. In fact, niacin appeared to increase study participants' risk for one particular type of stroke.
The findings are a major blow to what had been one of the most promising hopes for reducing the toll from cardiovascular disease, which kills about 800,000 Americans each year, making it the leading cause of death in the United States.
"Seeking new and improved ways to manage cholesterol levels is vital," Susan Shurin, acting director of the National Heart, Lung and Blood Institute, which funded the $52.7 million study, said in a statement. "Although we did not see the expected clinical benefits, we have answered an important scientific question."
Heart attacks and strokes have been dropping, in part by cutting "bad" LDL cholesterol, which can clog arteries. Many researchers hoped that the next big advance would come from a new generation of drugs that boost "good" HDL cholesterol, which is thought to clear LDL. A large body of research had found that people with low HDL levels were more likely to be stricken by heart attacks and strokes.
Doubts about the HDL-hiking hypothesis began to emerge, however, when the HDL-raising drug fenofibrate failed in 2005 to cut heart attacks and strokes among diabetics. Another study the following year found a different HDL-raising drug, torcetrapib, actually increased the risk. But researchers held out hope that niacin might be beneficial.
To put that strategy to the first rigorous test, researchers launched the AIM-HIGH study involving 3,414 people with a history of heart disease. All were taking the statin Zocor to keep their LDL levels low but remained at high risk because they had low HDL and high triglycerides.
The subjects took either a high-dose, extended-release version of niacin known as Niaspan or a placebo. Some also took another cholesterol-lowering drug called Zetia. HDL levels rose and triglycerides dropped among those taking niacin, which is also known as vitamin B3. But an independent panel of experts monitoring the experiment terminated it April 25, after just 32 months of follow-up, when it concluded that those taking niacin were no less likely to have a heart attack or stroke.
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