Dallas, - For the first time a statin drug has been shown to reduce the risk of type 2 diabetes, according to a study published in today's Circulation: Journal of the American Heart Association.
In a second study, the same drug, pravastatin - a cholesterol-lowering drug from a class of medications known collectively as "statins" - was also shown to reduce the risk of stroke.
"This is significant because it is the first time that treatment with a statin has been shown to have an impact on the development of diabetes," says Allan Gaw, M.D., Ph.D., the senior author of the first study.
Gaw's team analyzed data from the West of Scotland Coronary Prevention Study, or WOSCOPS, which was designed to determine pravastatin's effectiveness in preventing a first heart attack in people with high cholesterol. They found that those given pravastatin had a 30 percent reduced risk of developing diabetes.
"Diabetes is a serious health problem and a major risk factor for developing cardiovascular disease," says Gaw, director of the Clinical Trials Unit at Glasgow Royal Infirmary, a teaching hospital of the University of Glasgow in Scotland. "While great strides have been made in the care and management of patients, there is relatively little we can do medically to prevent the development of diabetes."
He and his colleagues used WOSCOPS data from 5,974 men, ages 45 to 64, to examine the effect of pravastatin on the development of diabetes. Among the men, 153, or 2.6 percent, developed the disease. The 30 percent risk reduction for diabetes that they found among pravastatin users was eye-catching. However, because of the relatively few men who developed the disease, further large, randomized studies are needed to confirm the finding, Gaw says.
"Also, we need to do some more basic science work to unravel the precise mechanism for this interesting and potentially very important finding," he adds.
A significant and unanswered question from both studies is whether the pravastatin findings apply to all drugs in the statin family.
"It really depends on the underlying mechanism," Gaw says. "If it is simply due to cholesterol or triglyceride reduction, then all statins may be expected to share this effect. If, however, it is related to some specific property of pravastatin, the mechanism may be unique to that drug."
In the second study, pravastatin was shown to reduce the risk of stroke by 22 percent in people who had already suffered a heart attack or the severe chest pain known as angina.
"It is very clear that lipid lowering with pravastatin reduces the stroke rate in patients with documented coronary disease, and you see this effect in all patients, regardless of such factors as gender and blood pressure," says Robert P. Byington, Ph.D., the lead author on the paper.
Byington and his colleagues pooled data from WOSCOPS with that from CARE (Cholesterol and Recurrent Events) and LIPID (Long-term Intervention with Pravastatin in Ischemic Disease) trial, two studies that tested pravastatin's effectiveness in stopping a heart attack in people who already had one or who had been hospitalized with severe chest pain. CARE was conducted in the United States and Canada; LIPID was carried out in Australia and New Zealand.
The series of studies using combined data from the three pravastatin trials is known as the Prospective Pravastatin Pooling Project. Pooling data from the three independent studies, which had similar designs, statistically strengthened the validity of the researchers' findings.
The three studies totaled 19,768 patients; half received pravastatin and half got placebo. In all, 598 participants, or 3 percent of the total, suffered a stroke within five years after joining a study.
For the Pooling Project overall, pravastatin recipients had a 20 percent reduced risk of stroke compared to those receiving placebo. When risk reduction was considered for each study separately, results were slightly different: Among the heart attack survivors in CARE and LIPID, the risk was reduced 22 percent. Risk reduction among the high-cholesterol patients of the WOSCOPS trial was 11 percent.
"Among the people in CARE and LIPID, regardless of what kind of patient we had - older or younger, male or female, moderate or high cholesterol - they benefited from being on pravastatin in terms of having a reduced level of stroke," says Byington, who is professor of public health science at Wake Forest University School of Medicine in Winston-Salem, N.C.
"Even people who were on blood-pressure lowering drugs or aspirin - two treatments used to prevent stroke - demonstrated a reduction in stroke with pravastatin," he adds.
Byington suggests the difference in stroke reduction between WOSCOPS participants and those in the other two studies lies in the seriousness of their condition. "The CARE and LIPID patients were markedly sicker, and they were at higher risk for stroke," he says.
Co-authors with Dr. Byington are Barry R. Davis, M.D., Ph.D.; Jonathan F. Plehn, M.D.; Harvey D. White, D.Sc.; Jennifer Baker, M.Sc., M.B.; Stuart M. Cobbe, M.D.; and James Shepherd, M.D.
Co-authors with Dr. Gaw are Dilys J. Freeman, Ph.D.; John Norrie, M.Sc.; Naveed Sattar, Ph.D.; R. Dermot G. Neely, M.D.; Stuart M. Cobbe, M.D.; Ian Ford, Ph.D.; Christopher Isles, M.D.; A. Ross Lorimer, M.D.; Peter W. Macfarlane, Ph.D.; James H. McKillop, M.D.; Christopher J. Packard, Ph.D.; and James Shepherd, Ph.D.
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