Clinical Utility of Carotid Ultrasonography in the Prediction of Cardiovascular Events in Patients with Diabetes: A Combined Analysis of Data Obtained in Five Longitudinal Studies

Aim: It remains unclear whether measures used in carotid ultrasonography such as the intima–media thickness (IMT) and ultrasonic tissue characterization of the carotid using the gray-scale median (GSM) can add prognostic information beyond the conventional cardiovascular risk markers in pati ents with diabetes. Methods: This study employed a combined analysis of data obtained in five longitudinal studies including a total of 3263 patients with diabetes but without apparent cardiovascular disease (CVD) at baseline. The associations between carotid ultrasonography measures and the first occurrence of CVD (488 cases), which were defined as cardiovascular death, coronary artery diseases, stroke, or peripheral artery disease, were analyzed. Results: Common carotid artery (CCA)-mean-IMT, CCA-max-IMT, Max-IMT, plaque-GSM, and the presence of low-GSM echolucent plaques at baseline were prognostic factors for CVD even after adjustment for conventional risk factors. Time-dependent receiver-operating-characteristic (ROC) curve analysis indicated that the use of CCA-mean-IMT, CCA-max-IMT, and Max-IMT in addition to the conventional risk factors improved significantly the prediction of occurrence of CVD. Increments in the CCA-mean-IMT (hazard ratio [HR] 2.37 for every 0.1-mm/year increment [95% confidence interval [CI]: 1.63–3.47], p < 0.001), Max-IMT (HR 1.51 for every 0.1-mm/year increment [95% CI: 1.07–2.14], p = 0.020), and Mean-GSM (HR 0.22 for every 10-U/year increment [95% CI: 0.06–0.76], p = 0.016) during the observation period were also prognostic factors for CVD even after adjusting for the baseline value of the respective measure. Conclusions: Addition of carotid ultrasonography measures to conventional risk factors significantly improved the stratification of patients by cardiovascular risk. Changes over time in carotid ultrasonography measures may be used as therapeutic outcome measures. Abbreviations: CAC, coronary artery calcium; CCA, common carotid artery; CVD, cardiovascular disease; DM, diabetes mellitus; FRS,Framingham Risk Score; GSM, gray-scale median; HR, hazard ratio; IMT, intima–media thickness; PAD, peripheral artery disease