What are statins?
Statins are drugs that lower your cholesterol. They block a substance your that body needs to make cholesterol and may also help your body reabsorb cholesterol that's built up in plaques on your artery walls, preventing further blockage in your blood vessels. (see an animation)
Statins include well-known medications: atorvastatin (Lipitor), simvastatin (Zocor), lovastatin (Mevacor), pravastatin (Pravachol), rosuvastatin (Crestor) and others. Lower cost generic versions of many statin medications are also available.
When did statins first become available?
In the nineteen seventies, teams in Japan and Britain began working on drugs to reduce cholesterol levels. By 1978, a Japanese scientist had isolated lovastatin which comes from a common fungus found in soil. This chemical was eventually developed by Merck and released as Mevacor in 1987. Now known as statins, they are amongst the most popular class of drugs sold worldwide.
What is 'high' cholesterol?
In Canada, you are considered to have high cholesterol, if your total cholesterol level is 6.22 millimoles per liter, or mmol/L or higher, or your low-density lipoprotein cholesterol (LDL, or "bad" cholesterol) level is 3.37 mmol/L or higher. (see a chart with recommended levels)
According to IMS Brogan more than 38 million prescriptions for statins were filled in Canadian pharmacies in 2012.
When are statins prescribed?
Statins have typically been prescribed to keep patients' cholesterol levels in check, often with the intention of helping them hit certain cholesterol 'targets'. But over time, many doctors have started thinking about statins more generally as risk-reduction medications rather than just cholesterol fighters, since they seem to lower inflammation and may have other beneficial benefits.
This view is reflected in new guidelines that were released in the US in November 2013 by the American Heart Association which placed less emphasis on patients' cholesterol numbers and more on their overall risk. These guidelines also reflected the reality that no trials have tested the methodology of treating cholesterol to specific target numbers.
In the United States, statins are now currently recommended for:
- anyone who has already had a heart attack or stroke
- anyone with a very high level of harmful LDL of greater than 4.9 mmol/L
- anyone with diabetes between the ages of 40 and 75
- anyone with a greater than 7.5% chance of having a heart attack or stroke in the next 10 years as determined by a risk calculator
Experts say that the new guidelines will increase the number of people taking statins in the United States - something that not all doctors agree with.
Statins generally cost about $1 a day and must be taken for life.
Are the guidelines in Canada different?
In 2012, the Canadian Cardiovascular Society published new guidelines that set helpful cholesterol benchmarks for doctors treating heart disease. Read the CCS response to the newer American guidelines.
Do statins have side effects?
Side effects include:
- muscle pain and damage (most common)
- liver damage
- digestive problems
- increased blood sugar or type 2 diabetes
- neurological effects such as memory loss or confusion
- sexual dysfunction
People taking multiple medications, women, people over 65, drinkers and people with diabetes, kidney or liver disease are considered to be at higher risk of suffering side effects. So far, studies show that about 10% of people prescribing statins can have side effects.
However, critics have argued that researchers do not have the necessary data to calculate the prevalence of side effects; statin trials, most of which are funded by pharmaceutical companies, typically do not release full data sets.
Are statins effective?
Over the last two decades, multiple large-scale randomized trials have shown that statins reduce risk of heart disease and cardiac events. But vigorous debate continues. Who should really take them? Is the protection they provide meaningful for lower-risk patient populations, when diet and exercise can provide similar results?
The new American guidelines were released after a large 27 trial meta-analysis on statins published in The Lancet in May 2013. The study found that the risk of heart disease or stroke was reduced by 10% for every 1.0 mmol/L reduction in LDL cholesterol levels. And more importantly, this reduction was seen in all five study groups, even those people at lowest risk for developing heart disease. In general, trials have reported that statins reduce a patient’s risk of heart attack anywhere from 20 – 50 percent.
Some researchers, however, remain unimpressed. If a patient is at low risk to begin with, the risk-reductions provided by statins is less meaningful. They point to the difference between the two concepts of risk: 'relative' and 'absolute' risk.
Many studies and advertisements state the 'relative' risk of developing heart disease instead of the 'absolute risk' which can make the results seem impressive to a lay person. (see video below for an explanation)
Critics often say it's better to look at the NNT (the ‘number needed to treat’) to prevent one serious cardiac event. How many people have to be on statins for a defined period of time to stop one heart attack, or stroke? Some studies suggest this number to be anywhere from 100 to 250. The Cochrane Collaboration, a widely respected independent organization, reported that 1000 patients without heart disease would need to be treated for 5 years to prevent 18 cardiovascular events. So, on average, 56 people need to be treated over 5 years to stop 1 event such as a heart attack.
In contrast, antibiotics have an NNT of 1.1 (if 11 people get the drug, 10 will be cured).
Critics also argue that cholesterol is just one part of the equation. Some patients with high cholesterol levels do not go on to develop heart disease, while many heart attack victims don't have high cholesterol levels. Does it make sense to “mop up the problem” of cholesterol, rather than preventing the spill through lifestyle and diet?
On the other hand, proponents of wider statin usage argue that a high NNT doesn't mean that a drug shouldn't be used. They say the drugs are safe, and over a population of millions, many thousands of lives are still being saved. Furthermore, since cardiovascular disease takes many years to develop, 5-year studies do not capture the benefits of lowering and controlling cholesterol over the long term.
The Bottom Line?
Everyone agrees that statins make sense in patients who have had major cardiac events, such as a heart attack or stroke, and who have established heart disease. But in patients without cardiovascular disease (‘primary prevention’) who have certain risk factors, such as high cholesterol, debate continues about where to draw the line on prescribing statins - especially in women.
For primary prevention, many doctors will attempt to modify lifestyle (exercise, diet, smoking cessation, etc.) before prescribing the drugs. But it remains a case-by-case analysis, and a discussion between doctor and patient.