Young Dae Kim, et al. 236 (15.6%) in three arteries, 183 (12.1%) in four arteries, and the remaining 413 (27.2%) in five or more arteries. Vascular risk factors and their association with atherosclerotic burden A total of 1,794 patients (91.8 %) had at least one or more A B Fig. 2. Temporal changes in the frequency of atherosclerosis in the cerebral arteries in 1,955 patients excluding those with potential cardiac sources of embolism (PCSE) (A), and in 2,657 patients including those with PCSE (B). The frequencies of atherosclerosis in both study groups have been increasing during the eight-year study period. The proportion of involved sites is expressed as the percentage in each subgroup. classic risk factors for atherosclerosis. There has been a significant increase in the presence of risk factors (p = 0.029) during the study period. Among individual risk fac- tors, the frequencies of hypertension (p < 0.001) and diabetes mellitus (p = 0.003) have increased whereas history of previous stroke has decreased (p = 0.003). There was no difference in the mean age of the patients among the years (p = 0.162). The patients with atherosclerosis were older than those without atherosclerosis and were more likely to have vas- cular risk factors (p < 0.001). The number of arteries with atherosclerosis increased as the number of risk factors increased (r = 0.223, p < 0.001). Among the patients with atherosclerosis, those with combined EC and IC atheros- clerosis were older (p < 0.001) and had a higher possibility (p < 0.001) of having risk factors and increased number (p < 0.001) of risk factors identified than those with isolated EC or IC atherosclerosis. On univariate analysis, age (64.48 ± 10.49 years in a group with atherosclerosis versus 60.85 ± 11.60 years in a group without, p < 0.001), hypertension (p < 0.001), diabetes mellitus (p < 0.001), hyperlipidemia (p = 0.025), and previous stroke (p = 0.001) were associated with the presence of atherosclerosis. On multivariate logistic regres- sion analysis, the year was also significant (Table 3). With respect to the number of arteries with atherosclerosis, the year and vascular risk factors including age, hypertension, diabetes mellitus, hypercholesterolemia, and previous cerebrovascular attacks were independently associated (Table 3). DISCUSSION The distribution of atherosclerosis is known to differ among races in that atherosclerosis of the IC arteries is more common in non-Caucasians while that of the EC arteries is Table 3. Multivariate Analysis on the Presence and the Number of Atherosclerotic Stenosis Presence of atherosclerotic stenosis Number of atherosclerotic stenosis 95% 95% Odds ratio Confidence p value Estimate Confidence p value interval interval Year 1.198 1.138 - 1.262 < 0.001 1.101 1.081 - 1.122 < 0.001 Age 1.030 1.020 - 1.041 < 0.001 1.021 1.017 - 1.025 < 0.001 Male sex 1.084 0.836 - 1.405 0.543 1.046 0.955 - 1.146 0.330 Hypertension 1.714 1.343 - 2.187 < 0.001 1.385 1.242 - 1.543 < 0.001 Diabetes mellitus 1.653 1.288 - 2.120 < 0.001 1.242 1.144 - 1.349 < 0.001 Hyperlipidemia 1.469 1.008 - 2.142 0.046 1.214 1.083 - 1.361 < 0.001 Smoking 1.260 0.960 - 1.654 0.096 1.024 0.928 - 1.129 0.639 Previous stroke 1.547 1.137 - 2.105 0.005 1.197 1.087 - 1.318 < 0.001 322 Yonsei Med J http://www.eymj.org Volume 51 Number 3 May 2010