[The significance of a carotid bruit. The preliminary experience of the OPI program. The Obiettivo prevenzione ictus (Stroke Prevention Objective)].

BACKGROUND

Carotid bruit has been correlated to occlusive atherosclerotic carotid disease and cerebrovascular ischemic disease, based on selected series or small population cohorts. The OPI programme has been accomplished to investigate the prevalence of carotid lesions in a population aged 45 to 75 and resident in the USSL (Sanitary District) n. 69, Lombardia.

OBJECTIVE

To establish the frequency of carotid bruit in an unselected population and the correlation of this sign to the internal carotid lesion.

METHODS

In this paper 16,379 people of both sexes are considered: all underwent physical examination, oriented to vascular problems, and C.W. Doppler ultrasound examination, from 1990 to March, 31st 1992. A further examination completed with color flow imaging was carried out for subjects showing either carotid bruit, or C.W. Doppler alterations, history of cerebrovascular disorders, previous vascular operations, concomitant extracarotid vascular occlusive diseases. Carotid kinking has been considered as "carotid lesion", for its attitude to cause flow alterations fitting to carotid bruit.

RESULTS

The prevalence of carotid bruit in the considered population was 3.7%, a total of 806 carotid bruits in 612 subjects. Male to female ratio was 0.69. A strong correlation of bruit to age was recorded (p < 10(-6)): subjects over 70 years old have a five-fold probability to harbor carotid bruit than younger people (45 to 50 years old). Likewise hypertensive people have a two-fold probability of carotid bruit than normotensive (p < 10(-6)). Only 302 carotid lesions (36%) of the 864 found showed bruit, while 539 (64%) did not. Among the 31,917 unaffected carotids 504 (1.6%) had bruit and 31,413 had not (98.4%); sensitivity of bruit to carotid lesion was 35.9%, and specificity 98.4%. The probability for carotids with bruit to be affected with lesion (stenosis, occlusion or kinking) is approximately 35 times as high as for carotids without bruit (odds ratio = 34.9).

CONCLUSIONS

Notwithstanding its low sensitivity, that prevents its use as a simple screening test for carotid lesion, the high specificity of carotid bruit makes it possible to separate a group at elevated risk of harboring carotid lesion. The absence of bruit does not rule out the presence of carotid lesion. A strong correlation to age and hypertension has been proved. Carotid bruit must be considered as a risk factor for carotid lesion, not a means to make diagnosis.