Abstract TP164: Impact Of Baseline Carotid Intima-media Thickness On All Causes And Cardiovascular Disease Mortalities In A General Urban Population: The Suita Study

Abstract

Purpose: This study aimed to explore the association between carotid intima-media thickness (IMT) and the Suita Risk Score for cardiovascular events and all-cause and cause-specific death. Methods: We studied 4,870 Japanese individuals (mean age 55.0±12.2 years, without CVD at the baseline; women 53.9%) who completed a baseline survey and carotid atherosclerosis in the Suita and were then followed for 14.8 years of the median. Carotid IMT was evaluated by high-resolution ultrasonography with atherosclerotic indexes of IMT in the common carotid artery (CCA) and carotid artery bulb (Bulb). We defined Mean CIMT as the mean of the IMT of the proximal and distal walls for both sides of the CCA on a longitudinal scan at a point 10 mm proximal from the beginning of the dilation of each carotid artery bifurcation. The maximum IMT in the CCA (max-CIMT) and the entire area (max-IMT) were defined as the maximum measurable IMT in the scanned CCA and the entire scanned carotid artery areas for both sides. The risks of all-cause mortality across carotid IMT were compared using Cox proportional-hazards models adjusting for the Suita risk score. The 95% CIs of the C-statistic was estimated using 200 bootstrap samples. Similarly, the standard error for the difference in C-statistic between each model was estimated from the bootstrap samples and used to calculate a P value for the difference. Results: We observed 923 deaths during 14.8 years as a median. The fourth quartiles of mean CIMT observed increased risks of all causes of mortalities and CVD mortality (hazard ratio (HR)=2.65, 95%CIs,1.93-3.63; HR=4.89, 95%CIs,1.88-12.72), max-CIMT (HR=1.99, 95%CIs,1.47-2.70; HR=2.92, 95%CIs, 1.21-7.06), and max-IMT (HR=2.13, 95%CIs,1.63-2.78; HR=2.69, 95%CIs, 1.30-5.58), respectively, compared to the first quartiles of then. C-statistic significantly improved by adding the fourth quartiles of mean CIMT and max-IMT to the Suita risk score for all-cause death (+0.003, 95%CIs, 0.0002-0.005, P=0.03 and +0.006, 95%CIs, 0.002-0.010, P<0.01; respectively), although not significantly improved for CVD mortalities. Conclusion: Additional assessment of carotid IMT to the Suita risk score may be helpful to improve the predictive ability for all causes of mortalities, not for CVD mortalities.