The American College of Cardiology (ACC) and American Heart Association (AHA), along with several other specialty organizations, have released a new "Guideline on the Management of Blood Cholesterol." Of note, this multi-specialty collaboration did not include primary care organizations like the American Academy of Family Physicians (AAFP) or the American College of Physicians (ACP); family physicians will find many similarities between this guideline and the 2013 ACC/AHA cholesterol guidelines, but a few changes may further complicate risk assessment and treatment discussions.
There is no change regarding the ACC/AHA's emphasis on lifestyle change as the basis for ASCVD prevention. There are also no changes to the treatment of two patient populations: individuals with clinical atherosclerotic cardiovascular disease (ASCVD) and individuals with serum low density lipoprotein cholesterol (LDL-C) levels greater than 190 mg/dL. For both groups, risk calculation with the ASCVD risk score is unnecessary; prescribe high-intensity (or maximally tolerated) statin therapy.
Recommendations regarding the use of statin medication for the primary prevention of ASCVD in persons with diabetes mellitus (DM) have been slightly revised. Moderate-intensity statin therapy is still recommended, as a starting point, for all patients with DM between the ages of 40-75 years. Previously, an ASCVD risk score greater than or equal to 7.5% was an indication for high-intensity statin therapy in this population; the 2018 guideline expands this recommendation to also include patients with one or more "diabetes-specific risk enhancers" (long duration of DM, albuminuria, eGFR < 60 mL/min, retinopathy, neuropathy, ankle-brachial index < 0.9) regardless of ASCVD risk score.
Perhaps the most complex changes center around those individuals aged 40-75 years who do not have DM and do not have clinical ASCVD. The 2013 guideline stratified these individuals into 2 risk categories, but the 2018 guideline now has 4:
- Low risk: ASCVD risk score < 5%
- Borderline risk: ASCVD score 5-7.4%
- Intermediate risk: ASCVD score 7.5-19.9%
- High risk: ASCVD score > 20%
Per this new guideline, low risk persons should focus on a healthy lifestyle. Borderline risk persons with one or more "risk enhancers" (see list below*) may consider moderate-intensity statin therapy after risks/benefits discussion with their physician. Intermediate risk persons should initiate moderate-intensity statin therapy if one or more risk enhancers* are present. High risk persons should initiate high-intensity statin therapy.
The 2018 ACC/AHA guideline also emphasizes following patients' LDL-C levels to both confirm adherence to therapy and to maximize benefit. They recommend that moderate-intensity statin therapy should lower LDL-C by 30-49%, and high-intensity statin therapy should lower LDL-C by at least 50%. The sources cited by the guideline to support these recommendations are expert opinion, however, and not randomized controlled trials (RCTs). It remains to be seen if primary care organizations such as the AAFP and ACP will endorse all or some of this guideline, especially this change regarding lipid monitoring.
The 2016 United States Preventive Services Task Force (USPSTF) recommendations regarding statins are similar regarding the benefit of primary prevention of those persons at highest risk (ASCVD risk score > 20%). The task force was less convinced regarding statins' primary prevention benefits among those at lower risk, giving a "B" grade for adults aged 40-75 years with an ASCVD risk score > or equal to 10% and at least one risk factor and a "C" grade for similarly aged adults with an ASCVD risk score between 7.5-9.9% and at least one risk factor. Statin therapy for primary prevention in persons > 75 years of age received an "I" grade, which is reasonably consistent with the 2018 ACC/AHA guideline's statement that "[f]or patients > 75 years of age, RCT evidence for statin therapy is not strong." The USPSTF also pointed out that most of the trials evaluating statins' efficacy in primary prevention enrolled participants based on the presence of risk factors, not based on the results of risk assessment tools.
The 2018 ACC/AHA cholesterol guideline contains much more content including a discussion regarding the use of statins in patients younger than 40 and also recommendations about appropriate candidates for coronary artery calcium scoring. The entire guideline has been published online ahead of print here. This "top 10 points" summary of the guideline may also be of interest. There's an AFP By Topic on Hyperlipidemia if you'd like to read more, which includes this Medicine by the Numbers article on "Statins in Persons at Low Risk of Cardiovascular Disease."
* ACC/AHA's ASCVD "risk enhancers" include: family history of premature ASCVD, persistently elevated LDL-C > 160 mg/dL, chronic kidney disease, metabolic syndrome, women with history of pre-eclampsia or premature menopause, history of inflammatory diseases (for example, rheumatoid arthritis, psoriasis, HIV), ethnicity, persistently elevated triglycerides > 175 mg/dL.