Prevalence of extracranial carotid artery disease: a survey of an asymptomatic population with noninvasive techniques.

To investigate the prevalence of internal carotid arterial stenosis in an unselected asymptomatic population over 50 years of age, 102 volunteers from one church congregation were studied with ultrasonic arteriography, spectral analysis, and ocular pneumoplethysmography. Fifty subjects were 50 to 59 years old; 33 were 60 to 69 years of age; and 19 were older than 70 years. Forty-five were men and 57 were women. Risk factors included diabetes mellitus (4%), heart disease (9%), hypertension (24%), peripheral vascular disease (20%), and smoking (46%). Disease was found in 11 subjects (10.8%). Of the 204 internal carotid arteries, 13 (6.4%) were abnormal. Two vessels had 20% diameter stenosis; four had stenoses of 20% to 39%; five had stenoses of 40% to 59%; one had a stenosis of 60% to 79%; and one was occluded. Stenoses greater than 40% occurred in 4% of the 50 to 59 years of age group, 6% of the 60 to 69 years of age group, and 11% of the greater than 70 years of age group. Although the prevalence of carotid stenosis was increased in all subjects who had risk factors, only the association with heart disease reached statistical significance. These results indicate that carotid stenosis is present in an appreciable number of asymptomatic subjects over the age of 50 years and suggest that its prevalence is associated with age and other risk factors.