Registry Study Supports Curbing Cholesterol Screening for Young Adults Because of Low Overall Risk

New observational data seem, despite conflicting guideline recommendations, to suggest the futility of lipid-panel screening in young adults without risk factors for cardiovascular disease.

Currently, the American College of Cardiology and American Heart Association recommend testing all adults over 20 years for atherosclerotic cardiovascular disease risk, according to guidelines released in 2013. However, in a 2008 document the US Preventive Services Task Force (USPSTF) recommended a more conservative approach: initial screening at 35 years for men and 45 years for women unless at least one traditional risk factor is met.

“Just because the test is easily available and cheap to perform does not mean it should be done regularly in patients who are not likely to be treated based on the result of the test,” lead study author Krishna Patel, MD (Saint Luke’s Hospital of Kansas City, MO), told TCTMD in an email. “We believe repeat cholesterol testing in low-risk young adults is wasteful, as it does not provide much actionable information. Some patients might also end up being overtreated and might be at risk of side effects and potential harm.”

The researchers looked at atherosclerotic disease risk in 9,608 adults from the National Health and Nutrition Examination Survey representing 67.9 million adults between 1999 and 2012. Slightly less than half were considered “low prevalence”—defined as people in whom a greater than 1% prevalence of elevated CV risk over 10 years could be ruled out.

Broadly, in nonsmoking, nonhypertensive men younger than 40 and women younger than 50, only 0.09% and 0.04% of the population, respectively, had elevated risk (> 5%) for developing atherosclerotic CV disease within 10 years. This percentage varied substantially depending on age, sex, smoking status, and hypertension status (0% to 75.9%). Overall, only 2.9% of the population had LDL cholesterol levels of at least 4.92 mmol/L (190 mg/dL), the recommended level for identifying patients with familial hypercholesterolemia (FH) and those who might benefit from statins.

Their results were published online today ahead of print in the Annals of Internal Medicine.

Which Tack to Take?

Patel said she was surprised by both how high the risk for smokers was and how low the risk was for those without risk factors, even those past 40. Also, she did not expect to see so many individuals with LDL levels below the FH threshold and that family history did not necessarily dictate LDL levels.

According to Patel, her findings will change her own screening practices. “We do screen all adults once for familial hyperlipidemia to make sure they don't have severely elevated LDL-cholesterol levels which would warrant treatment. However, screening most young, healthy adults without any risk factors repeatedly every few years rarely provides any actionable information. We have a discussion with our young healthy patients where we encourage a healthy lifestyle for everyone and include their preferences regarding repeat cholesterol screening before ordering it by default.”

However, in an editorial accompanying the study, Paul Ridker, MD, MPH, and Nancy Cook, ScD (Brigham and Women’s Hospital, Boston, MA), take a different stance.

“We do not believe that measuring cholesterol levels is imperative in all environments,” they write. “In settings where laboratory testing is unavailable or only near-term risk identification is of interest, a nonlaboratory approach might simplify risk evaluation. In the developed world, however, basic lipid evaluation is inexpensive and almost universally accessible.”

The main study flaws according to Ridker and Cook are its cross-sectional design, the lack of recording of clinical events, and the exclusion of patients younger than 50 already on statins and those who had previous vascular events. The latter group “very likely had a strong family history or elevated cholesterol levels—exactly the group the authors sought to identify. This systematic bias might substantially alter the effective screening rates,” they write.

If we aren’t going to treat, there is really no point in screening. Krishna Patel

Also, “failing to detect high lifetime risk at an early stage undermines the core lifestyle messages of targeted risk factor reduction (primordial prevention),” the editorialists add.

In reply, Patel said her group’s aim “was to estimate the yield of identifying high-risk individuals in a real-world young adult population through cholesterol screening and not look at the causal association of early or late cholesterol screening with cardiovascular outcomes. So, we believe the cross-sectional design of our study is appropriate to answer our question.”

Young adults can benefit from one-time early screening to rule out FH, though, she said.

“I would add that although atherosclerosis does begin early as the editorialists point out, interventions to reduce risk, including statins, are extremely effective, even when started later in life,” Patel continued. “There is no evidence that starting statins at early ages will improve outcomes more than starting them later, and there is no evidence that it is safe to do so. We do not have good data on what happens if people take statins for 30-plus years. If we aren’t going to treat, there is really no point in screening. If anything, we might offer people false reassurance and potentially discourage them from making the lifestyle choices that they should make which has been shown before.”

Still, Ridker and Cook conclude that they “disagree with the USPSTF recommendation to delay lipid screening until mid-adulthood simply because clinical trial evidence is not available in younger persons. . . . If anything, we support the principled biologic approach promoted by the American Academy of Pediatrics, which recommends that all children be screened for high cholesterol levels at least once between the ages of 9 and 11 years, and again between ages 17 and 21 years.”