- Kenny Lin, MD, MPH
Previous AFP Community Blog posts discussed the 2013 American College of Cardiology/American Heart Association cholesterol treatment guideline, provided additional perspectives on its 7.5% 10-year CVD event risk threshold for starting a statin, and noted that existing cardiovascular risk calculators tend to overestimate risk by significant margins. The ACC/AHA guideline has remained controversial in primary care. The American Academy of Family Physicians gave it a partial endorsement with qualifications (disclosure: I am a member of the AAFP Commission that made this recommendation), and a 2014 guideline from the U.S. Departments of Veterans Affairs and Defense recommended higher thresholds for considering (6%) or starting (12%) statins.
Two weeks ago, the U.S. Preventive Services Task Force weighed in with a new recommendation statement on the use of statins for primary prevention of cardiovascular events. The recommendations are similar to those from the ACC/AHA; the USPSTF recommends initiating low- to moderate-dose statins in adults aged 40 to 75 years with at least one CVD risk factor (dyslipidemia, diabetes, hypertension, or smoking) and a calculated 10-year CVD event risk of 10% or greater ("B" recommendation). They recommend shared decision making and selective statin prescribing for similar adults with a 7.5% to 10% CVD risk ("C" recommendation).
The USPSTF's higher risk thresholds for statin therapy compensate for uncertainty regarding the accuracy of CVD risk calculators, and the "C" recommendation recognizes that in persons at lower risk, the benefits of statins are less likely to outweigh the harms, which include liver enzyme abnormalities and muscle toxicity and a small increased risk of new-onset type 2 diabetes.
Although a prior USPSTF statement had recommended screening for lipid disorders in adults as early as 20 years of age, a new systematic review found no direct evidence on the benefits and harms of screening for or treatment of dyslipidemia in adults aged 21 to 39 years. So when should family physicians start checking cholesterol levels in asymptomatic adults, if statins don't become a treatment option until age 40? This is an area to exercise one's clinical judgment on a case-by-case basis, keeping in mind that healthy lifestyle counseling is more likely to be beneficial in adults with CVD risk factors than in adults without known risks.