Monday, November 6, 2017

Do statins benefit patients at low risk of cardiovascular disease?

- Kenny Lin, MD, MPH

There has been no shortage of recent guidance on statin use for the primary prevention of cardiovascular disease (CVD). The American College of Cardiology / American Heart Association and the U.S. Preventive Services Task Force (USPSTF) disagree about the appropriate 10-year CVD event risk threshold at which clinicians should recommend statins - 7.5% and 10%, respectively - but both agree that the benefits significantly outweigh the harms. So what should clinicians make of the Medicine By the Numbers in the Nov. 1 issue of AFP, which gave a Red (no benefits) rating to statins in persons at low (less than 20% 10-year) risk of cardiovascular disease?

Dr. John Abramson calculated the numbers needed to treat (NNT) to benefit and harm based on data from the 2012 Cholesterol Treatment Trialists (CTT) meta-analysis and the USPSTF's 2016 systematic review. Excluding patients with existing cardiovascular disease or a greater than 20% 10-year CVD event risk, the results showed no statistically significant mortality benefit, but 1 in 217 persons avoided a nonfatal myocardial infarction and 1 in 313 avoided a nonfatal stroke. On the harms side of the scale, 1 in 21 persons experienced pain from muscle damage, and 1 in 204 developed diabetes mellitus as a result of taking statins. Dr. Abramson acknowledged that his conclusion of "no benefit" relied on value judgments about the importance of these harms compared with cardiovascular events prevented:

In summary, studies have found no significant overall mortality benefit with statin therapy in low-risk patients, as well as no reduction in the risk of serious illness overall and very small benefits for nonfatal heart attack and stroke. Statins also appear to cause diabetes. Although this is uncommon, diabetes may occur more often than the prevention of a heart attack or stroke in patients taking statins. ... With no mortality benefit, no reduction in serious illness, an approximately 1% chance of avoiding a nonfatal heart attack or stroke, a similar or greater chance of developing diabetes, and a one in 21 chance of muscle damage, it seems wiser to focus on lifestyle changes (such as adopting a Mediterranean diet, exercising, and not smoking) instead of cholesterol drugs in low-risk patients.

These findings are broadly consistent with a 2011 Cochrane for Clinicians that noted that because "most trials included large numbers of persons with known CVD, ... clear evidence of the effectiveness of statins to prevent a first cardiovascular event is lacking." Other Cochrane reviews have found that statins reduce all-cause mortality in patients with non-dialysis chronic kidney disease, but do not prevent dementia or cognitive decline. A previous AFP article summarized considerations for safe use of statins, which should be part of shared decision making discussions with patients when the benefits and harms are so closely balanced.

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