Cholesterol Level Myths

Setting targets for ‘bad’ (LDL) cholesterol levels to ward off heart disease and death in those at risk might seem intuitive, but decades of research have failed to show any consistent benefit for this approach, reveals an analysis of the available data, published online in BMJ Evidence Based Medicine.

Cholesterol-lowering drugs are now prescribed to millions of people around the world in line with clinical guidelines.

Those with poor cardiovascular health; those with LDL cholesterol levels of 190 mg/dl or higher; adults with diabetes; and those whose estimated risk is 7.5% or more over the next 10 years, based on various contributory factors, such as age and family history, are all considered to be at moderate to high risk of future cardiovascular disease.

Although lowering LDL cholesterol is an established part of preventive treatment, the approach has never been properly validated, say the researchers. They systematically reviewed all published clinical trials comparing treatment with one of three types of cholesterol lowering drugs (statins; ezetimibe; PCSK9) with usual care or dummy drugs (placebos) for a period of at least a year in at-risk patients.

Each of the 35 included trials was categorized according to whether it met the LDL cholesterol reduction target outlined in the 2018 American Heart Association/American College of Cardiology guidelines.

The researchers then calculated the number of people who would need to be treated in order to prevent one ‘event’, such as a heart attack/stroke, or death, and the reduction in absolute risk in each study that reported significantly positive results.

Their analysis showed that over three quarters of all the trials reported no positive impact on risk of death and nearly half reported no positive impact on risk of future cardiovascular disease.

And the amount of LDL cholesterol reduction achieved did not correspond to the size of the resulting benefits, with even very small changes in LDL cholesterol sometimes associated with larger reductions in risk of death or cardiovascular ‘events,’ and vice versa.

Thirteen of the clinical trials met the LDL cholesterol reduction target, but only 1 reported a positive impact on risk of death; 5 reported a reduction in the risk of ‘events’.

Among the 22 trials that did not meet the LDL lowering target, four reported a positive impact on risk of death while 14 reported a reduction in the risk of cardiovascular events. This level of inconsistency was evident for all three types of drugs.