The new lipid guidelines and an age-old principle
By Michael Hochman, MD, MPH
With the issuing of its updated report on the management of lipids, the American Heart Association (AHA) hoped to provide a clear message to health care providers and consumers about how to use lipid-lowering medications. Instead, the new recommendations have been mired in controversy due to concerns about the validity of the data used in the report. Although the controversy will detract from the credibility of the new report — and rightfully so — it also sheds light on an important and often overlooked point: the risks and benefits of medical services varies considerably based on a patient’s underlying risk. In the long run, this may do more to improve medical decision-making than a smooth roll-out of the new recommendations would have.
The controversy surrounding the AHA report concerns the calculator that the AHA recommends for predicting cardiovascular risk. According to two renowned Harvard professors, Dr. Paul Ridker and Dr. Nancy Cook, the calculator substantially overestimates risk — by as much as two-fold or more. The reason may be that the calculator chosen by the AHA was developed using decades-old data from a time when cardiovascular event rates were higher due to higher rates of smoking and other factors. Ridker and Cook informed the AHA about their concerns prior to the release of the recommendations, but it appears their concerns were overlooked.
Why is a faulty risk calculator such a concern? The reason is that the risks and benefits of lipid-lowering medications varies considerably based on a patient’s underlying risk. For example, in one famous study (the 4S study), statin medications (the most widely used and effective lipid-lowering medications) were found to reduce cardiovascular events from 28% to 19% — for a net benefit of 9% over five years. In another study (Jupiter), statins reduce cardiovascular events from just 2.7% to 1.5% — for a net benefit of 1.2% over two years. Why the discrepancy? Quite simply, in the first study patients were at much higher risk for cardiovascular disease (all patients in the study had a history of cardiovascular disease) and thus had much more room to benefit.
From the data above, it is clear that high risk patients like those included in the first study should take statin medications. But for healthier patients similar to those included in the second study, the decision is less clear. Although statins are likely to reduce cardiovascular risk among such patients, the benefits are more modest. Since statins also have side effects — muscle aches, liver damage, and possibly increased rates of diabetes and dementia — the harms may outweigh the benefits.
In the report, the AHA recommends statin medications for all patients with a 10-year risk of cardiovascular disease greater than 7.5%. According to the AHA, the benefits of statins outweigh the risks in this population. But for patients with a 10-year risk less than 7.5%, the risk-to-benefit profile is less clear. This is why the concerns raised by Ridker and Cook are so important: if the AHA calculator overestimates cardiovascular risk, it could cause many patients to take statins who might not benefit — or might even be harmed. Clearly it will be important to resolve the risk calculator controversy before further disseminating the new recommendations.
The principle that the risks and benefits of medical services varies based on a patient’s underlying risk is not confined to cardiovascular disease. In fact, it applies to virtually every other condition. As an example, some healthy patients request whole body CT scans from their doctor in the hopes of identifying early-stage cancers that might be treated before they become harmful. While intuitively this seems appealing, the risk of cancer in such patients is low, and any abnormalities identified are likely red herrings that could lead to unnecessary worry and harmful follow-up testing such as invasive biopsies.
In addition, the risks and benefits of medical services can be complex, and often there aren’t good data to provide guidance. For example, no one would recommend a knee replacement for a patient with minor knee pain. But on the other hand, it wouldn’t make sense to give a knee replacement to a patient with severe knee pain if that patient had advanced heart failure and not much time left to live. The challenge for patients and doctors is to find the sweet spot where the benefits of health care services outweigh the risk. This requires using a combination of data and common sense.
Because of the controversy, the new AHA recommendations will not provide the clear guidance on how to use lipid-lowering medications that many had anticipated. But hopefully the controversy will serve as a reminder for all of us to consider underlying risk when making medical decisions.
Dr. Hochman is the Medical Director for Innovation at AltaMed Health Services, the largest independent federally qualified health center in the United States, He recently authored 50 Studies Every Doctor Should Know, published by Oxford University Press.
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