Little-used cholesterol test could prevent more heart attacks and strokes

A routine blood test taken by millions in the U.S. each year to measure “bad” cholesterol is not the best measure to guide treatment and prevent heart attacks and strokes, suggests a new Northwestern Medicine study published in JAMA. The study found that another blood test called apolipoprotein B (apoB) outperformed LDL and non-HDL cholesterol in guiding cholesterol-lowering therapy, such as taking statins and other medications.

“We found that apoB testing to intensify cholesterol-lowering medication would prevent more heart attacks and strokes than current practice, and that these health benefits were achieved at a cost that represents good value for U.S. health care payers,” said study lead author Ciaran Kohli-Lynch, assistant professor of preventive medicine in the division of epidemiology at Northwestern University Feinberg School of Medicine.

According to Kohli-Lynch, this is the first comprehensive study to show that using apoB testing to guide cholesterol-lowering treatment is cost-effective.

Heart disease remains the leading cause of death in the U.S. and a major driver of health care costs. When small, cholesterol-carrying particles get struck in arteries, they form plaques, which over time can cause blockages that can lead to heart attacks and strokes.

Rethinking how risk is measured

For years, clinicians have focused on LDL, often called “bad cholesterol,” and non-HDL goals to decide when to start and intensify cholesterol-lowering treatment. Those cholesterol tests, while helpful, don’t give patients a full picture of their risk.

“Research strongly shows that apolipoprotein B (apoB) is better at identifying who is at risk, because it counts the total number of harmful particles in the blood,” explained Kohli-Lynch.

Despite this evidence, apoB is not widely used in routine care. Kohli-Lynch says that’s partly because of cost and convenience, since measuring apoB typically requires an additional blood test besides the standard cholesterol panel.

“Our study asked: Is it worth spending extra money to use apoB instead of LDL to guide treatment intensification?” Kohli-Lynch said.

What the study found

To answer that question, the Northwestern scientists used a large computer simulation model representing 250,000 U.S. adults eligible for statins but without existing cardiovascular disease.

They compared three strategies for guiding treatment:

• LDL cholesterol (goal <100 mg/dL)
• Non-HDL cholesterol (goal <118 mg/dL)
• ApoB (goal <78.7 mg/dL)

If patients did not meet their assigned goal, treatment was intensified first with stronger statins, then by adding another medication, ezetimibe. The model tracked outcomes for each strategy over a lifetime, including heart attacks, strokes, life expectancy, quality of life, and health care costs.

ApoB-guided care outperformed the other two strategies, improving population health and saving more lives in a cost-effective manner.

New cholesterol guidelines make this study timely

Over the past decade, the number of medications available to doctors to lower cholesterol has vastly expanded. What is more, the American Heart Association and 10 other medical associations issued new guidelines earlier this year that recommended starting cholesterol-lowering therapy at younger ages for many patients.

“This means it is increasingly important to accurately identify who would benefit most from intensive treatment,” Kohli-Lynch said.