Up to 40% of Americans Are Unaware They Have High Cholesterol

People with elevated LDL, or 'bad cholesterol,' are at higher risk for heart attack and stroke, making awareness and treatment critical for heart disease prevention.

Although most people know that having high cholesterol raises the risk of heart attack and stroke, sorting through the different types of cholesterol can be confusing.

In a nutshell, HDL (high-density lipoprotein), AKA 'good cholesterol,' helps the body eliminate cholesterol by transporting it to the liver, where it is removed. In contrast, LDL (low-density lipoprotein), or 'bad cholesterol,' promotes cholesterol build-up in the arteries.

Having elevated LDL cholesterol can increase a person’s risk of coronary artery disease.

Knowing total cholesterol numbers can help people make the changes needed to lower their LDL levels. These changes can include dietary adjustments and lifestyle choices and taking cholesterol-lowering medications like statins.

A previous 2023 American Heart Association survey found that 70% of people who survived a heart attack or stroke didn't know that LDL is considered 'bad cholesterol,' and 47% were unaware of their LDL numbers.

Now, a new study using data from the National Health and Nutrition Examination Survey found that among people with LDL cholesterol levels high enough to receive treatment, up to 40% are unaware of their numbers or aren't being treated with cholesterol-lowering drugs.

To conduct the study, published as a research letter on November 1 in JAMA Cardiology, researchers collected cholesterol data on 23,667 participants from 1999 to 2020.

They identified participants with LDL numbers of 160 to 189 mg/dL and 190 mg/dL or greater across ten survey cycles.

Health experts consider LDL numbers 160 to 189 mg/dL as 'high' and 190 mg/dL or more as 'very high.'

Moreover, doctors typically prescribe cholesterol-lowering drugs to treat individuals with very high LDL numbers and may consider it for those with high levels.

Therefore, the scientists also classified participants as 'unaware' if they never had an LDL measurement or were never informed of having elevated LDL numbers and as 'untreated' if they did not take a statin, ezetimibe, bile acid sequestrant, or proprotein convertase subtilisin/kexin type 9 inhibitor.

The researchers found that the number of participants with high LDL cholesterol declined from 12.4% in 1999 to 2000 to 6.1% between 2017 to 2020. The number of people with very high HDL numbers also decreased during the study period, from 3.8% in 1999 to 2000 to 2.1% between 2017 to 2020.

Among people with high HDL cholesterol, 52.1% were unaware or untreated from 1999 to 2000. While that rate dropped to 42.7% when scientists looked at 2017 to 2020 data, that still means 6.1 million people in the United States don’t know or aren’t being treated for high cholesterol.

Moreover, from 1999 to 2000, 40.8% of participants with very high LDL levels either didn't know they had high LDL cholesterol or were untreated for the condition. During 2017 to 2020, that rate declined to 26.8%, representing 1.4 million people.

The scientists also discovered that being unaware or untreated for high or very high LDL cholesterol was more common among males, younger adults, Hispanic and non-Hispanic Black individuals, socioeconomically disadvantaged participants, and those without health insurance.

"Although the prevalence of severely elevated LDL-C has declined, 1 in 17 US adults still have LDL-C levels of 160 to 189 mg/dL, and 1 in 48 adults have LDL-C levels of 190 mg/dL or greater. Among those with an LDL-C of 190 mg/dL or greater, 1 in 4 are unaware and untreated, with a higher proportion for an LDL-C of 160 to 189 mg/dL," the study authors wrote.

While it's challenging to determine why some individuals don't know they have high cholesterol or aren't aware of treatment options, the study's authors suggest that barriers to accessing primary care, low rates of cholesterol screening, or discrepancies in screening recommendations may play a role.

The researchers also say that identifying people with high LDL levels and developing strategies to treat these individuals could help improve outcomes and reduce the disparities observed in the study.