A systematic review found a lack of direct evidence for assessing the benefits and harms of screening for treatment of dyslipidemia in younger adults.

Thus, researchers must estimate the benefits of lipid-lowering therapies or lifestyle modifications based on trials of older people. The researchers defined younger adults as those between 21 and 39 years old.

Lead researcher Robert Chou, MD, of the Oregon Health & Science University in Portland, and colleagues published their results online in the Annals of Internal Medicine on Aug. 8.

In the U.S., 105.3 million adults have dyslipidemia, accounting for approximately 53 percent of the adult population, according to the researchers. They added that approximately 36 percent of adults between 20 and 29 years old and 43 percent of adults between 30 and 39 years old met levels recommended by the National Cholesterol Education Program for all lipids.

In 2008, the U.S. Preventive Services Task Force (USPSTF) recommended lipid screening for men from 20 to 35 years old and women from 20 to 45 years old who had risk factors for coronary heart disease. The USPSTF made its recommendation based on data showing some younger adults with coronary heart disease risk factors were at high risk and could benefit from lipid-lowering therapies.

However, the USPSTF made no recommendation for or against lipid screening in adults in those age groups who did not have coronary heart disease risk factors.

The USPSTF plans on using this analysis to update its previous recommendation from 2008. The Agency for Healthcare Research and Quality (AHRQ) funded the study under a contract to support the work of the USPSTF. The AHRQ did not have a role in the study selection, quality assessment, synthesis or development of conclusions, although it did perform a final review of the manuscript to ensure the analysis met its methodological standards.

After searching numerous databases, the researchers did not find any studies that assessed the benefits or harms of screening versus no screening for dyslipidemia on cardiovascular outcomes in adults between 21 and 39 years old who had no symptoms. They also did not find any studies on the diagnostic yield of alternative strategies for dyslipidemia screening in the same population.

“Our findings are in accordance with prior USPSTF reviews, which also found no direct evidence regarding benefits or harms of screening or subsequent treatment in this population,” the researchers wrote. “Although individuals with familial hypercholesterolemia are at increased risk for early cardiovascular events, a factor limiting potential benefits of screening for this condition is that this is a low-prevalence condition (estimated at 1 in 500 persons) and that even among this population, most (85 percent to 90 percent) do not experience a [coronary heart disease] event before the age of 40.”

The researchers mentioned that large, long-term trials may not be feasible, but they noted that initial screening trials should target individuals with a family history of hypercholesterolemia or early coronary heart disease. They also recommended that initial treatment trials could include people with very elevated lipid levels.

“Trials of delayed versus immediate lipid-lowering therapy for younger adults with dyslipidemia also would be helpful for understanding the effectiveness of earlier treatment, and studies are needed to understand harms associated with very long-term statin therapy,” the researchers wrote.