All about statins – answers to some common questions
What are statins?
Cardiovascular disease is the leading cause of death worldwide and is also a major cause of long-term disability, for example from heart attacks and strokes. It is therefore a very important condition to prevent or treat. Statins are a type of medication, taken in tablet form once a day, which can reduce our risk of cardiovascular disease by reducing ‘bad’ cholesterol levels.
Statins have been used since the 1990s and are among the most studied drugs in the world. They are affordable and very commonly prescribed, with millions of people taking them worldwide.
What is cholesterol?
Our bodies need a fatty substance called cholesterol to function properly. For example, it helps our bodies make hormones. It can also be found in all the cells that combine to make our bodies.
Cholesterol is carried around the body in our blood by proteins. When cholesterol and proteins are combined, they are called lipoproteins. There are several types of these, but they can generally be divided into two main types – high density lipoprotein (HDL) cholesterol or ‘good’ cholesterol, and low density lipoprotein (LDL) cholesterol or ‘bad’ cholesterol.
If there is too much LDL or ‘bad’ cholesterol in our blood, it can lead to fatty material building up in the walls of our arteries, narrowing and hardening them; this is known as ‘atherosclerosis’. This can restrict, or even block, our flow of blood to important organs such as the heart or brain, leading to heart attacks or strokes. This can result in death or leave people with significant disabilities that affect their quality of life.
How do statins work?
Statins lower the amount of LDL or ‘bad’ cholesterol by blocking the action of the enzyme in our liver that helps to make it. By lowering the LDL cholesterol levels in our bodies, statins help prevent heart attacks and strokes, by stopping too much fatty material building up in our artery walls. Statins can also slightly increase the amount of HDL or ‘good’ cholesterol in our bodies.
There are a number of different types of statin but they all work in similar ways. They come in different doses, and are categorised according to their ‘strength’ or intensity. For example, higher intensity statins are designed to produce greater reductions in LDL cholesterol.
What are the benefits of taking statins?
By reducing levels of LDL or ‘bad’ cholesterol, statins can prevent people at risk of cardiovascular disease from having their first heart attack or stroke. This is called ‘primary prevention’. For people who have already had a heart attack or stroke, they are even more effective at preventing them from having a second one. This is called ‘secondary prevention’.
For example, for every 1000 people taking a moderate strength statin for five years who have already been diagnosed with cardiovascular disease, statins could prevent about 50 serious cardiovascular events, such as heart attacks and strokes. For those who do not already have cardiovascular disease, about 25 heart attacks and strokes would be prevented.
Statins have been found to work in a wide range of people including those with diabetes, those at low risk of vascular disease, in both women and men, and in people of all ages, including those over the age of 75.
When are people prescribed statins?
Your doctor might recommend statins based on their assessment of your risk of developing cardiovascular disease over the next ten years, or if you have had a heart attack or stroke already. Doctors use a number of tools to work out your risk, including a test to measure your levels of good and bad cholesterol, your age, your family history of cardiovascular disease, your blood pressure and whether or not you have diabetes. Which ‘strength’ or intensity of statin you are offered is typically based on your estimated risk of cardiovascular disease.
If someone is prescribed statins, how long do they need to take them?
Once you’ve been prescribed statins, your doctor will usually recommend that you take them for life. This is because statins will only keep your levels of bad cholesterol low whilst you are taking them. If you stop taking them, your bad cholesterol levels will rise again, increasing your risk of a heart attack or stroke.
The longer that you take statins, the more effective they are at preventing cardiovascular disease.
How do doctors know all of this?
Since statins were first discovered in the late 1970s, scientists have carried out large numbers of research studies to work out if they are safe and effective. This includes randomised controlled trials, also known as randomised clinical trials (RCTs).
RCTs generally produce the best quality evidence about treatments because they are designed to carry out an unbiased or ‘fair test’ of those treatments. The statin RCTs divided people randomly into two groups. This meant that the characteristics of the people in the two groups were similar (such as a balanced number of men and women, smokers, or people with diabetes).
In the statin RCTs, one group was given a statin tablet, and the other group an exact copy of the statin, without the active ingredients, called a placebo (or dummy tablet). This meant that the only difference between the groups should have been the treatment under study – the statin. To make the test even fairer, neither the people in the groups, nor their usual medical team nor the researchers working on the trial knew which tablet each person was taking until the end of the trial (after the results had been determined).
After a few years, researchers compared the numbers of people in the group taking a statin who had a heart attack or stroke, with the numbers of people in the group taking a placebo who had a heart attack or stroke. This provided evidence about the effects of statins.
The results of these very large studies confirmed that statins significantly reduce the risk of having a heart attack or stroke in a wide range of people.
What are the risks from taking statins?
For most of us, the benefits of statins far outweigh any risks and the majority of people are able to take statins without any serious problems. However, one rare side effect that has previously been found is myopathy which is typically diagnosed by having muscle symptoms (such as pain or weakness) alongside a blood test result that indicates significant muscle damage. Statin use also appears to cause a slight increase in the chances of developing type two diabetes. Less commonly, statins have been linked to a particular type of ‘bleeding’ stroke, different to the type of stroke that statins help to prevent.
However, there has been uncertainty amongst patients, the public and doctors as to whether statins have more side effects than previously thought, and if so, how common and important they are. This is partly due to media reports based on data that has not come from randomised clinical trials, so is less reliable.
Unfortunately, this has led to some people being unwilling to start taking statins, or stopping their statin, when it might really benefit them.
What is being done to address these concerns?
To address these concerns, an international group of scientists – known as the Cholesterol Treatment Trialists’ Collaboration (CTT) – led by researchers at Oxford Population Health – has been analysing data from all the previous large statin RCTs to get the most reliable evidence about any possible side-effects.
They collected, sorted and organised information from all the large-scale, high-quality randomised clinical trials from around the world – around 38 million pieces of information from over 155,000 people. This has enabled them to look into all statin effects, without knowing which people took statins and which took a placebo. They were then able to compare both groups fairly.
What do the CTT’s results show?
The group has published results that relate to muscle problems such as muscle pains, cramps or weakness. These symptoms are often reported by people taking statins, but it has not been clear if statins are the cause or not, or if they are the cause, how frequently they cause these problems. This is because muscle problems are common in people as they get older and can occur for other reasons.
The CTT’s results showed that muscle symptoms were very common; they occurred in about a quarter of people in the trials. The frequency of muscle symptoms was very slightly greater in those taking a statin, but the excess was tiny (less than 1%).
In those taking statins, statins were not the cause in 14 out of 15 reports of muscle symptoms (that is, more than 90%). In the instances where statins truly were causing muscle symptoms, the symptoms were generally mild and mainly occurred during the first year of treatment.
The group is now examining potential effects relating to diabetes, along with other potential side effects.
How can I find out more?
Visit the British Heart Foundation website for information on statins, including answers to other commonly asked questions.