Cumulative Effects of High Cholesterol Levels, High Blood Pressure, and Cigarette Smoking on Carotid Stenosis

Abstract

Single measurements of cardiovascular risk factors may not accurately reflect a person's past exposure to those risk factors. We therefore studied the long-term associations of cardiovascular risk factors such as high serum cholesterol levels, high blood pressure, and cigarette smoking with the prevalence of carotid stenosis. We studied cross-sectional and longitudinal information from a sample of 429 men and 661 women in the Framingham Heart Study who underwent B-mode ultrasound measurements of the carotid artery. Their mean age was 75 years, and each had attended most of the biennial clinic examinations over the 34 years before the carotid ultrasound study. We used time-integrated measurements to assess the associations between various cardiovascular risk factors and the degree of carotid stenosis. Moderate carotid stenosis (>25 percent) was present in 189 men and 226 women. We assessed the odds ratios for this degree of stenosis as compared with minimal stenosis (<25 percent) according to increases in risk factors. In the men, the odds ratio for moderate carotid stenosis associated with an increase of 20 mm Hg in systolic blood pressure was 2.11 (95 percent confidence interval, 1.51 to 2.97). The odds ratio for an increase of 10 mg per deciliter (0.26 mmol per liter) in the cholesterol level was 1.10 (95 percent confidence interval, 1.03 to 1.16), and for an increase of five pack-years of smoking it was 1.08 (95 percent confidence interval, 1.03 to 1.13). The results were similar in the women. Time-integrated measurements of diastolic blood pressure showed significant associations with carotid stenosis in men and insignificant associations in women. Over the long term, high systolic blood pressure, high cholesterol levels, and smoking were associated with an increased risk of carotid stenosis in this elderly population.