Q&A: Making sense of the statins controversy
Heart attacks and strokes, combined, kill one in three Americans. In November, the American College of Cardiology (ACC) and the American Heart Association (AHA) issued new guidelines and a calculator to help cardiologists determine patients’ risk for these conditions.
The new calculator has caused uproar: Two Harvard Medical School professors, including a past ACC president, said the risk calculator is significantly flawed. They say it is based on studies from the 1990s that associate blood pressure and cholesterol levels with heart attacks and strokes – and that the populations with these conditions have changed significantly in the past two decades.
Given its flawed basis, the critics say, the calculator greatly overestimates some individuals’ risk and could lead to tens of millions of people being prescribed cholesterol-controlling statins unnecessarily. They call for the new guidelines to be halted.
Dr. David Dichek, associate director of research in UW’s Division of Cardiology, addresses the issue and gives guidance to patients.
Q: As a class of drugs, what do statins do to the body, generally?
Dichek: Statins decrease the ability of cells in the body to produce cholesterol. Numerous well-executed human studies show that statins lower blood cholesterol and reduce a person’s risk of developing cardiovascular disease or dying from it. These studies also show that statins reduce a person’s risk of developing cardiovascular disease in proportion to the risk that person has without statin therapy. In other words, the higher your risk for developing cardiovascular disease without taking statins, the higher your potential benefit from taking statins.
Q: Briefly, what is new in these guidelines?
Dichek: There are 3 major changes from past guidelines. First is the use of a new 10-year risk calculator rather than using pre-treatment blood-cholesterol levels to identify some people who should be treated with statins. The new risk calculator also estimates lifetime risk, which many felt was inappropriately ignored in the past. Second, these guidelines are based on hard evidence from clinical patient trials and do not extrapolate from the precise clinical trial evidence. Third, there is a focus on intensity of statin therapy (high or moderate) rather than levels of blood cholesterol as a guide for physicians’ recommendation of statin drugs.
Q: Apart from unnecessary costs, are there downsides of taking a statin if you are not truly at risk?
Dichek: Almost everybody has at least a low risk of developing cardiovascular disease, if not in the next 10 years then at some point later in life. So I will answer your question in relation to those with less than 5% risk of developing cardiovascular disease in the next 10 years.
For every 1,000 people who take statins, one to three of them will develop diabetes as a result. Also, about one in 10,000 people who take statins will have muscle damage as a result. These small risks must be balanced against statins’ benefits, which unequivocally include decreasing cardiovascular disease and prolonging life for many people.
In considering statin therapy, low-risk individuals are balancing a relatively low benefit from statins against the low risk of side effects. People at high risk for developing cardiovascular disease are likely to have a greater benefit from statins, balanced against the same low risk of side effects. The purpose of the new calculator is to help some people – primarily those who do not yet have evidence of cardiovascular disease – determine their risk. This determination will help lower-risk patients and their physicians decide whether statin therapy makes sense for them.
Q: Can you talk about the assertion that people's risk for stroke and heart attack has changed so much in the past 20 years that it renders the calculator invalid? Are people, by and large, healthier than they were in the 1990s?
Dichek: Yes, there is a legitimate concern that the risk calculator overestimates cardiovascular risk in 2013 because it relies on data from the past, when rates of developing cardiovascular disease were higher. This is a common problem in developing clinical guidelines: We always use yesterday’s results to guide today’s therapies. However, this potential flaw does not invalidate the new guidelines. Concerns of overestimated risk do not apply to the large number of people who have any of these three conditions:
- strong evidence of existing atherosclerosis
- an LDL of 190 or higher
My suggestion: People at or just above the risk level at which statin therapy is suggested (a 5% to 10% 10-year risk of cardiovascular disease) should consider the possibility that their risk is overestimated by the calculator. People who wish to lower their risk also can modify their lifestyles to include smoking cessation, regular exercise and a proper diet.
Q: How comfortable are you with applying this new calculator to determine a person’s cardiovascular risk? What factors external to the calculator, if any, would you consider?
Dichek: I am comfortable applying this risk calculator, which seems superior to the Framingham instrument it is intended to replace to determine 10-year risk. For individual patients I would also consider:
- the potential for risk overestimation
- family history, especially early-onset cardiovascular disease in close relatives
- results of past tests including C-reactive protein, coronary artery calcium score, an abnormal “ankle-brachial index” (measurement of atherosclerosis in arteries that supply the legs)
Most importantly I would engage patients in a discussion of risks and benefits of statin therapy and take their preferences into account.
Q. Given these circumstances, what can patients ask their physician about a statin prescription? What info would help a patient feel more confident?
Dichek: A patient can ask their physician for help in interpreting her/his risk for developing cardiovascular disease, using the new calculator and guidelines. People should also ask about individual risks for statin-related side effects (higher in some people than others), and about the potential interactions between a statin and other drugs they are taking.