Around a third of all heart attacks and strokes can be avoided in people at risk of vascular disease by using statin drugs to lower blood cholesterol levels � irrespective of the person�s age or sex, and even if their cholesterol levels do not seem high. That�s the conclusion of UK researchers who have just completed the world�s largest randomised trial on cholesterol-lowering therapy.
Unveiling the key findings today (Tuesday 13 November) at the American Heart Association�s Scientific Sessions 2001, lead researcher Professor Rory Collins said: �This is a stunning result, with massive public health implications. We�ve found that cholesterol-lowering treatment can protect a far wider range of people than was previously thought, and that it can prevent strokes as well as heart attacks.�
The MRC/BHF Heart Protection Study (HPS) involved 20,000 volunteers aged 40-80 years who were at high risk of coronary heart disease, but for whom there was substantial uncertainty about the balance of benefits and safety of cholesterol-lowering therapy. It specifically targeted groups of patients in which there was little direct evidence of benefit � including women, the over 70s, people with diabetes, those with non-coronary vascular disease, and those with average or below-average cholesterol levels. Volunteers were allocated either 40mg daily simvastatin as cholesterol-lowering therapy, or matching dummy tablets. Study treatment and follow-up continued for an average of five and a half years in 69 UK hospitals.
The funding of �21 million (US $32 million) was provided by the UK�s Medical Research Council (MRC), the British Heart Foundation (BHF), and the pharmaceutical companies Merck & Co. Inc. and Roche Vitamins Ltd. The study was, however, designed, conducted and analysed entirely independently of all funding sources by the Clinical Trial Service Unit of Oxford University. It started in 1994 and ended only last month.
Summary of major findings
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- Cholesterol-lowering with statin treatment reduces the risk of heart attacks and of strokes by at least one-third, as well as reducing the need for arterial surgery, angioplasty and amputations.
- Reductions of at least one-third in these �major vascular� events were found in a very wide range of high-risk patients for whom there had previously been uncertainty about using cholesterol-lowering therapy:
- women as well as men;
- people aged over 70 as well as younger people;
- people with blood levels of total cholesterol below 200mg/dl (approx. 5mmol/l) or of �bad� LDL cholesterol below 120mg/dl (approx. 3mmol/l), as well as those considered to have �high� levels.
- About 5 years of statin treatment typically prevents heart attacks, strokes or other major vascular events in:
- 100 of every 1000 people who�ve previously had a heart attack
- 80 of every 1000 people with angina or some other evidence of coronary heart disease
- 70 of every 1000 patients who�ve previously had a stroke
- 70 of every 1000 people with occlusive disease in leg or other arteries
- 70 of every 1000 people with diabetes
- In addition, cholesterol-lowering reduces the risk of being hospitalised because of worsening angina � typically, about 30 fewer admissions per 1000 treated for 5 years.
- The benefits increase throughout the study treatment period (so more prolonged therapy might be expected to produce even bigger benefits), and are additional to those of other treatments used to prevent heart attacks and strokes.
- This trial provides uniquely reliable evidence about the safety of this simvastatin regimen, with no support for previous concerns about possible adverse effects of lowering cholesterol on particular non-vascular causes of death, on cancers or on strokes due to bleeding.
Professor Collins, HPS lead investigator, said: �We knew from other studies that statins lowered �bad� LDL cholesterol, and reduced heart disease risk in some circumstances. But, HPS now provides the first direct evidence that cholesterol-lowering therapy cuts the risk of heart attacks and strokes by at least one third not just in people who already have coronary disease but also in those who have diabetes, narrowing of arteries in their legs or a previous history of stroke. It shows that, for high-risk patients, cholesterol-lowering therapy produces substantial benefits even among those considered to have �low� cholesterol levels. It also provides the first clear evidence of benefit in women and the over 70s. The study�s size, and the wide range of high-risk patients included, means that doctors now have evidence that is uniquely clear and reliable.
"In this trial, 10 thousand people were on a statin. If now, an extra 10 million high-risk people worldwide go onto statin treatment, this would save about 50,000 lives each year � that�s a thousand a week. These results are at least as important as previous findings for aspirin�s effects on heart attack and strokes. Those findings changed medical practice, and we expect these to have the same effect. In fact, statins are the new aspirin."
HPS clinical coordinator Dr Jane Armitage said that the trial provided much reassuring safety evidence.
"We�ve shown that the benefits of cholesterol-lowering are additional to those of other treatments, such as aspirin and blood pressure-lowering drugs, commonly used in patients at risk of vascular disease. Furthermore, none of the previous concerns about safety with cholesterol-lowering therapy was substantiated."
HPS statistician Professor Richard Peto said: "This study shows that people who�ve had a heart attack or stroke, or who are at risk of one, benefit substantially from statin treatment even if their cholesterol levels do not appear to be elevated. So, irrespective of the blood cholesterol level, a statin should now be considered for anybody with a history of heart disease, stroke, other occlusive vascular disease or diabetes."
The Heart Protection Study also assessed the effects of antioxidant vitamins by separately allocating half of the patients to receive antioxidant vitamins (600mg vitamin E, 250mg vitamin C and 20mg beta-carotene daily) and half to receive dummy vitamin capsules. This comparison in HPS did not provide any evidence that these vitamins could prevent deaths, heart attacks, strokes or other vascular disease outcomes in any of the groups studied.
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It did, however, provide strong safety evidence. �We found no excess risk of strokes due to bleeding or of cancers at any site. This contradicts the apparent adverse trends in some previous smaller studies of vitamin E and of beta-carotene. We shall continue to follow the health of the study volunteers for years to come, so should know if some benefit emerges later,� said Professor Collins.
Source: Clinical Trial Service Unit
