Millions of people take statins to lower cholesterol. So there was considerable interest when two articles appeared in The BMJ, a leading British medical journal, last year questioning their safety.
This week the journal admitted both had overstated the extent of side effects in some patients. That part of both papers has now been corrected.
But some researchers are worried that coverage has caused confusion and will put some people off taking these drugs. So what are the facts about statins? Jon White spoke to epidemiologist Rory Collins
What are statins?
They are a group of drugs that lower the risk of cardiovascular events such as heart attacks and ischaemic strokes – strokes due to clots in the arteries to the brain – and the need for interventions such as a heart bypass. The short name is “statin” because all the drug names end in it. Simvastatin and atorvastatin are two commonly available ones.
How do they work?
They inhibit a liver enzyme which is involved in making cholesterol; blocking it reduces the amount of cholesterol made in the liver. In response to that, liver cells put more receptors for a form of cholesterol known as LDL – sometimes called bad cholesterol – on their surface. Those receptors pull more LDL out of the blood, so lowering levels. That LDL cholesterol is metabolised by the liver and excreted.
How much of a difference do statins make?
Typically total cholesterol levels in blood might be between 4 or 5 millimoles per litre, most of which is LDL. Statins can reduce the LDL component by about 2 units, which can lower your risk of a major vascular event by about 40 per cent.
Are they expensive?
Simvastatin and atorvastatin are available in generic form, so their cost per patient in the UK is around £2 a month. They have become very cost-effective for the National Health Service.
How well studied are these drugs?
There have been a lot of randomised, placebo-controlled trials done in a wide range of different types of patients, starting off in high-risk patients, typically people who already had coronary disease. As the evidence emerged of both safety and efficacy, more recent trials looked at patients with lower risk factors, such as diabetes alone, or high blood pressure. Again these show benefit. Finally, trials have also been done showing benefits even among people who didn’t have any of the classical risk factors for cardiovascular problems. We have been carrying out, with the University of Sydney, a meta-analysis of all of the major trials – there are about 170,000 patients in around two dozen such trials.
What do your results show?
In a nutshell, for all these types of patients, clear reductions in the risks of non-fatal and fatal heart attacks, ischaemic stroke and the need for revascularisation procedures – be it bypass surgery or balloon angioplasty – which translates into reductions in vascular mortality. There is no evidence of adverse effects on any particular non-vascular cause of death or on any particular site-specific cancer.
And what about downsides?
The label on statins says you can get muscle symptoms such as pain. The reason it says that is there is a very rare side effect called myopathy that affects muscles and that people have to be alert to. It occurs in about one patient per 10,000 per year of treatment. Because people are told they need to be aware of muscle symptoms, when they get them they, quite understandably, attribute it to the drug. Of course the people who get given these tablets are older and prone to muscle symptoms any way.
Studies found a half a per cent increase, in absolute terms, in diabetes over a five-year treatment period. There is a suggestion that there might be a small excess of haemorrhagic stroke, a much rarer kind of stroke due to bleeding, but the evidence is suggestive rather than compelling. Other than that, the evidence really refutes many of the claims that have been made about side effects. For example claims that statins increase cataracts are not supported, and there have been very careful studies on cognitive decline and dementia which found no evidence of such adverse effects.
What’s your overall message on statin safety?
Statins are very effective at preventing heart attacks and strokes and reducing the risk of vascular death, and have been shown, in very carefully controlled studies, to be safe and very well tolerated.
Rory Collins is the British Heart Foundation professor of medicine and epidemiology at the University of Oxford
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