How important are LDL cholesterol levels when assessing cardiovascular disease risk?

My husband has researched LDL cholesterol (Nutrition, August 19) and says we’re not getting the whole story. Apparently, there is bad and “not so bad” LDL, but blood tests give only one result unless the other is requested. So, people may be medicated without the full story of LDL types and take statins for no reason. Could you explain?

Answer:

Cardiovascular disease causes more than 30% of deaths worldwide. It also has a significant impact on quality of life and adds substantially to our nation’s healthcare costs. So it makes sense to focus on prevention of this disease. But how important are LDL cholesterol levels when assessing cardiovascular disease risk, and are there different kinds of LDL cholesterol?

Your husband is correct – not all LDL cholesterol particles are equal. Instead, smaller, more tightly packed LDL particles can more easily enter our arteries. A 2021 study published in the Journal of the American Heart Association concluded that small, dense LDL cholesterol particles are more atherogenic, which means they contribute more to the fatty deposits in arteries known as atherosclerosis. But while larger, fluffier LDL particles are not quite as troublesome, they also contribute to atherosclerosis. So, neither form is good for our cardiovascular health.

But while testing for small, dense LDL particle levels may seem like a good idea to assess CVD risk more accurately, that is not necessarily true.

“The newer LDL tests do not as yet have a body of evidence around interpretation, treatment or outcomes and so are not employed in routine practice,” says Dr Luke Bradford, medical director of the Royal New Zealand College of General Practitioners.

A 2020 study in the journal PLoS One found there is still work to be done to determine whether blood tests assessing the levels of small, dense LDL particles (rather than the current standard blood cholesterol tests) can more accurately guide treatment to reduce cardiovascular disease risk. To date, researchers have found that assessing LDL particle size does not produce any more accurate assessment of a person’s risk than the current tests and tools.

Bradford says that in New Zealand, the cholesterol component of our cardiovascular disease risk assessment is a standard lipid panel test measuring total cholesterol, HDL, LDL, triglycerides and the ratio of total to HDL. “There are no separate LDL panels used commonly in New Zealand by general practice.”

However, cholesterol levels alone are rarely used as a trigger for a conversation about statins by GPs. “It is more the total [cardiovascular disease] risk. However, when the total cholesterol is over 8, or the ratio of total cholesterol to HDL cholesterol is over 8, the recommendations are for a chat about statin therapy.