Using medical files, death certificates and an interview at home for the survivors, a long term retrospective follow-up study was done for 82 subjects operated for carotid stenosis. Causes of death, survival rates and medical history of survivors were studied. Subjects were classified in two preoperative risk categories according to their medical history prior to angiography: low risk (36 subjects) and medium risk (46 subjects). None of the subjects were lost during the follow-up period which varies from 81 to 105 months.
At seven years, observed survival rate is significantly lower for the medium risk patients than for the low risk patients (43.0 ±8.6 versus 80.6 ± 6.6; X2 M-H, p = 0.006). The difference between the survival rates is markedly noticeable after the fifth year of follow-up. Besides, the percentage of survivors who have developed cerebrovascular problems after the operation is significantly higher in the medium risk group than the low risk group (54.5% versus 25.0%, X2 p ≃ 0,04).
Does this mean that the preoperative risk classification separates two different stages or two different forms of atherosclerosis? Can. J. Neurol. Sci. 1983; 10:27–31