~ Dr. Irv Loh
Since the somewhat controversial 2013 ACC/AHA guidelines on lipid management recommendations, there has been some uncertainty on whom to initiate with what statin therapy. Some of the controversy revolved around millions of individuals becoming newly eligible for statin therapy, with the commensurate cost and potential for adverse effects of drug therapy. Last week, the U.S. Preventive Services Task Force provided a couple of draft recommendations on lipid screening and statin therapy (1) for public comment. If you have strong feelings on this topic, I encourage you to follow the link provided and throw in your two bits…I did.
Overall, these seem to be focused clarifications of the extant 2013 ACC/AHA guidelines. They again moved away from using target LDL-C level triggers for initiation of therapy that have been hallmarks of the prior iterations of the NCEP/ATP Guidelines. In the setting of secondary prevention, there has not been much debate on whether statins are warranted. However the subject of initiating statins for primary prevention in adults has been a subject of vigorous discussion. Here, the USPS Task Force again recommended assessment of the 10-year cardiovascular event risk using the ACC/AHA risk calculator (2), itself a subject of controversy due to concerns about potential overestimation of risk, to identify adults aged 40-75 who have a ≥10% 10-year risk of a major cardiovascular event. If the risk is calculated slightly lower at 7.5-10%, the task force felt that the benefits of primary prevention are less, but that clinicians “may choose” to initiate low-to-moderate dose statin therapy. There is the implication that the lower risk patient should have a greater voice in the decision making process as well. The recommendation is firmer for the higher calculated risk group if they have one or more traditional risk factors, e.g., lipid abnormalities, hypertension, diabetes, or cigarette smoking.
For older patients, as well as in patients less than 20 years, they felt the evidence base for benefit is insufficient to make a recommendation.
Given the current information base, it is laudable that the USPSTF is de-emphasizing lipid numbers in favor of risk estimation. However, my feeling is that they are also not taking into account the issue of lipid-year exposure that I discussed in a prior post (3.9.15). Given an elevated level of apo-B containing atherogenic particle, e.g., LDL-cholesterol, initiating aggressive therapy early has a greater cumulative benefit than starting it late. This is similar to the pack-year smoking risk assessment, and perhaps more like altering the trajectory of a moon shot more significantly if done early rather than late when it is clear that you have missed the target. This is even more critical in patients with familial hypercholesterolemia, when therapy should be initiated with the establishment of the diagnosis, whether by clinical assessment (e.g., Simon Broome, World Health Organization, or Dutch Lipid Clinic criteria) or genetic testing.
In my estimation, the quantitative considerations for therapy will be resurrected when the outcomes data from the ongoing PCSK9 inhibitor trials become available in 2017 (assuming they are positive results) though it may be sooner. Targeted numeric lipid goals, likely lower than in the past, may again become the standard of care when dealing with patients at higher risk of atherothrombotic events.