The ratio of low-density to high-density lipoprotein cholesterol appears to be a better predictor of heart disease risk than the absolute level of low-density cholesterol, according to an article in the July issue of the American Journal of Preventive Medicine.

According to Sundar Natarajan, MD, MSc, and his American colleagues, people who have similar ratios have similar risk for heart disease regardless of differences in the levels of low-density lipoprotein cholesterol or total cholesterol. People with higher ratios have significantly greater risk for heart disease than people with lower ratios.

U.S. clinical guidelines recommend use of low-density lipoprotein cholesterol levels and other risk factors to identify high-risk patients who may benefit from cholesterol-lowering therapy. However, the authors of the current study suggest that the ratios may be better at identification and at tracking progress on cholesterol-lowering drugs.

"Despite newer recommendations incorporating high-density lipoprotein cholesterol into risk assessment, low-density lipoprotein cholesterol continues to be the major target of cholesterol-lowering therapy," wrote the authors. "However, almost half of all patients with coronary heart disease have normal low-density lipoprotein cholesterol levels but may have low levels of high-density lipoprotein cholesterol, resulting in a high [low-to-high-density] ratio," they added.

The study also has implications for the kinds of treatments recommended for patients with moderate to high cholesterol levels. For instance, certain low-fat diets that reduce both low-and high-density lipoprotein cholesterol levels may be less beneficial than diets that increase high-density lipoprotein cholesterol levels. Similarly, products that are high in trans-fatty acids that reduce low-density lipoprotein cholesterol may also cause an unwelcome decrease in heart-protective high-density lipoprotein cholesterol.

Measures including weight loss, smoking cessation, and increased exercise can increase high-density lipoprotein cholesterol, and the authors recommend that such steps “continue to be emphasized” for treatment of high-risk cholesterol levels.