Do Not Start Cholesterol Screening for Low-Risk Patients Until Age 40, Analysis Says

Marcia Frellick

May 17, 2017

KANSAS CITY, MO — Repeated cholesterol screening for people under the age of 40 who are at low risk for cardiovascular disease is wasteful and may result in overtreatment, say authors of a study published May 15, 2017 in the Annals of Internal Medicine[1].

Controversy about who should be screened and when comes from two conflicting sets of guidelines, observed the authors, led by Dr Krishna K Patel (Mid America Heart Institute, Saint Luke's Hospital of Kansas City, University of Missouri–Kansas City), in their report. The 2016 US Preventive Services Task Force (USPSTF) recommendations, they note, say that in the absence of cardiovascular risk factors, cholesterol screening should start at age 35 in men and age 45 in women.

But the 2013 American College of Cardiology (ACC)/American Heart Association (AHA) guidelines recommend that screening start at age 20 and be repeated every 4 to 6 years, regardless of risk factors.

Patel and colleagues side with the USPSTF approach, with the tweak that screening be delayed until age 40 for men and age 50 for women.

For their analysis, the group explored how much information would come from screening nondiabetic adults under age 50 without increased risk for atherosclerotic cardiovascular disease (ASCVD) and how it might influence screening recommendations. They used National Health and Nutrition Examination Survey (NHANES) data (1999–2000 to 2011–2012) and estimated 10-year risk by using the ACC/AHA ASCVD risk calculator.

They found that among nonsmokers with normal blood pressure, only 0.09% of the men younger than age 40 and 0.04% of the women younger than age 50 had an increased ASCVD risk.

However, they did find overall that 2.9% had an LDL-C level of 4.9 mmol/L (190 mg/dL) or more, which is the recommended threshold for identifying patients with familial hypercholesterolemia (FH), and that "can't be ignored," Patel told heartwire from Medscape.

"Based on that finding, we do think that all these patients should at least be screened once to identify the 3% of patients who have really high cholesterol levels and warrant treatment early in life," she said. "But that's essentially all that’s needed—you don't need to repeat the tests if they don't have any other risk factors."

She points to a lack of evidence that statins should be started before middle age or that it would be safe to do so.

Patel says the recommendation for most younger people with high cholesterol but without other risk factors would be to encourage a more healthy lifestyle, rather than treatment.

"If you're not going to treat them if you're low risk—what's the point in screening them every 5 years?" she asks. Also, she said, screening may also harm in that it might offer false assurance and potentially discourage people from making healthy lifestyle choices.

Cholesterol tests in people who smoke are the exception, Patel said. In both sexes, smokers had at least a 5.5% chance of elevated CVD risk at every age. "Smokers should definitely be screened at all ages we tested and potentially screened every 5 years to update their risk profile."

But otherwise, the authors say, about half the 30- to 49-year-old US population could delay screening into middle age.

In an accompanying editorial[2], Dr Paul M Ridker and Dr Nancy R Cook (Brigham and Women's Hospital, Boston, MA) take exception to that view and the USPSTF recommendation to delay screening.

They point out that the authors excluded all people under 50 years old who were already on statins or had had a major vascular event. This group likely had a family history of high cholesterol, "exactly the group the authors sought to identify," they write.

"FH is considerably underdiagnosed in the United States, because initial cholesterol screening is often delayed well into middle age."

Although such patients were not included in the primary analysis, observed Patel, the group conducted a sensitivity analysis for patients already on statins and, after looking at their cholesterol levels and other risk factors, the findings were not very different. "The cutoff for a man without risk factors was 35 and for women 45," she said.

The editorialists also take issue with the argument for delaying testing in younger adults because of a lack of trial evidence. "Absence of evidence is not evidence of absence," they write.

In places where lab testing is not available, checking cholesterol levels may not be possible, they write; but in developed countries, such testing is almost universally available and inexpensive.

"[We] believe that at least one-time LDL-C screening should be universally recommended for all patients in their late teen or early adult years," they write.

The study received support from the National Heart, Lung, and Blood Institute of the National Institutes of Health and National Center for Advancing Translational Sciences. The study authors and Dr Cook disclosed no relevant financial relationships. Dr Ridker reports grants from AstraZeneca, Novartis, Kowa, and Pfizer, and personal fees from Pfizer and AstraZeneca outside the submitted work.

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