Associations between Smoking and Newer Risk Factors for Cardiovascular Disease

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The summary below is from the full report titled "Relationship Between Cigarette Smoking and Novel Risk Factors for Cardiovascular Disease in the United States." It is in the 3 June 2003 issue of Annals of Internal Medicine (volume 138, pages 891-897). The authors are L.A. Bazzano, J. He, P. Muntner, S. Vupputuri, and P.K. Whelton.

What is the problem and what is known about it so far?

Heart disease and strokes (cardiovascular disease) are leading causes of death and disability in most western countries. Smoking, high-fat diets, high cholesterol, high blood pressure, diabetes, and kidney disease increase a person's risk for cardiovascular disease. Recently, researchers identified several additional risk factors for cardiovascular disease. These newer risk factors include proteins that are involved in blood clotting and are released in response to inflammation (fibrinogen and C-reactive protein). They also include an amino acid (homocysteine) that may be elevated when intake of vitamins, such as folic acid, is low. How the newer risk factors relate to older, more established risk factors, such as smoking, is not well studied.

Why did the researchers do this particular study?

To study the relationships between smoking and newer risk factors for cardiovascular disease.

Who was studied?

17,353 adults who had participated in a national survey.

How was the study done?

Researchers looked at data from a sample of the U.S. population that was collected from 1988 to 1994. Participants in the survey answered questions about cigarette smoking and medical history and had their blood pressure and weight measured. They also gave blood samples that were used to measure newer risk factors. The researchers then looked at whether people who smoked were more likely to have elevated levels of the newer risk factors, even after controlling for other traditional risk factors, such as diabetes and high blood pressure.

What did the researchers find?

Cigarette smoking was associated with elevated levels of fibrinogen, C-reactive protein, and homocysteine. Current smokers had higher levels of these risk factors than former smokers. Also, smoking more cigarettes daily was associated with higher levels of the risk factors.

What were the limitations of the study?

The study did not examine relationships over time. Whether smoking actually caused the elevated levels of the new risk factors could not be determined.

What are the implications of the study?

Smoking cigarettes is associated with elevated levels of several recently identified risk factors. These newer risk factors may be important mechanisms by which smoking promotes cardiovascular disease.