Statins are a class of drugs used to reduce low-density lipoprotein, LDL cholesterol, within the body. They are prescribed to people with high LDL cholesterol, when levels are above two to three milliliters
of cholesterol per liter of blood. These individuals are at risk of cardiovascular diseases such as heart disease, stroke and heart attack. The drug works by inhibiting the
enzyme involved in the body's ability to produce this form of cholesterol.
But statins have a reputation that precedes them, with people often worried about taking them, or going as far as declining them, without always knowing the evidence behind their decision. There have been reports of the drug causing side effects that include an increased risk of hemorrhagic stroke, muscle pain and weakness and diabetes, causing acceptance of the drug to be split.
The new study
conducted analyzed all available evidence on the safety and efficacy of statin therapy, to provide the evidence needed to help people make their decision. It was decidedly in their favor.
"Statins have had a huge impact on reducing cardiovascular events," said Rory Collins
, BHF professor of medicine and epidemiology at the Nuffield Department of Population Health, part of the University of Oxford.
"There are many misleading claims about statins ... [but] people tend to underestimate the benefits," he said.
How beneficial are they?
After reviewing all the available evidence on the harms and benefits of statins, the study had a few key findings, including one based on the daily use of 40 mg of the drug atorvastatin for five years and by 10,000 patients. Among these 10,000 patients, the study predicted the drug would prevent 1,000 people having major cardiovascular events (heart attacks, strokes and coronary artery bypasses) who had pre-existing heart conditions. The same regimen would also prevent 500 cardiovascular events in people who are at increased risk, due to diabetes or hypertension for example, but haven't had a heart condition.
"You avoid 1,000 or 500 people having a heart attack, stroke or similar," said Collins.
When put into perspective in the United Kingdom, Collins added that among the 4 million people with previous heart events, and 2 million people at increased risk in the country, 80,000 heart attacks would be prevented each year, while 600 might develop myopathy (a rare condition involving muscle pain, tenderness or weakness that can be severely disabling and sometimes fatal).
A further analysis found that for each 1 mmol/L reduction in LDL cholesterol made using statin therapy, the risk of coronary deaths and heart attacks, strokes and coronary bypass procedures is reduced by approximately 25% for each year the drugs are taken after the first year.
But one concern among some experts, and opponents, is the eventual use of statins to treat people who have high cholesterol, but have not had previous cardiovascular issues and do not have diabetes of hypertension, meaning more people take them than needed. Fewer studies have shown that statins reduce the risk of cardiovascular diseases in healthy people
with high cholesterol.
What about the harms?
The study also reviewed the occurrence of side effects, such as muscle pain, hemorrhagic stroke and myopathy, to identify whether the controversies around the use of statins are warranted.
Among the 10,000 patients, the researchers found the drug would cause five cases of myopathy, as well as five to 10 hemorrhagic strokes -- caused by weak blood vessels bursting -- 50 to 100 new cases of diabetes, and up to 100 cases of symptomatic adverse events, such as muscle pain.
"The reality is that the harms associated with statins are tiny," said Collins, who emphasized that the harms should still be acknowledged and informed to patients, but along with their likelihood. "There have been problems of people believing the harms are common," he said.
Other studies have also stated that statins may increase the likelihood of a range of other conditions, including memory loss, cataracts, kidney injury, liver disease, sleep disturbance, aggression, suicidal behavioral, erectile disjunction and neuropathy, which the researchers stress would be extremely rare and that evidence for them is not sufficient.
"The best available scientific evidence tells us that statins are effective, safe drugs," said Liam Smeeth
, head of the Department of Non-Communicable Disease Epidemiology. "[They] have a crucial role in helping prevent cardiovascular disease, the leading cause of morbidity and mortality worldwide."
Other experts not involved in the study agree. "A series of high-quality clinical trials conducted over more than a quarter of a century and originating in multiple populations have consistently demonstrated reductions in cardiovascular death, and major complications in patients taking statins," said Robin Choudhury, professor of Cardiovascular Medicine, University of Oxford.
Statins are, however, typically prescribed to those at greater risk of developing heart disease and recommendations often made before this stage are lifestyle based: a healthier diet, regular exercise and reducing the amount of alcohol you drink and cigarettes you may smoke. Other drug options are also available, including the drug Repatha, approved last year
, which is prescribed on a more limited basis.
Understanding what's out there
"There are a lot of high-risk patients who are not taking statins," said Collins, who wants people to better understand the information available to them regarding these drugs.
The researchers highlight in the paper that studies based on observations within a population do not produce reliable evidence about the effects of drug treatments for common health conditions, such as heart disease, and cannot attribute the cause of any benefits or side-effects specifically to a drug.
They instead highlight the credibility of randomized controlled trials, which can directly link any benefits, or harms, to the drug being trialed. For such trials, the evidence on statins was seen to be overwhelmingly in favor of the treatment.
"[This study] is an unusually comprehensive document that explains not only the evidence derived from these studies but the rationale and relative merits for evaluating drugs," added Choudhury, who was not involved in the study. "Wrong decisions based on incomplete, misleading, or misguided interpretation of the data and the consequent confusion leads to the squandering of actual benefits to real patients."
"This is really serious stuff ... and anything you can do to prevent them really matters," said Smeeth. "The problem we have with statins is that misleading claims that are not supported by scientific evidence have really come to the fore ... and they're demonstrably wrong."
Collins added that the team wanted to make people know which evidence they should trust. "People should make informed choices," he said. "I hope this helps recreate some of the balance."