The Value Of Framingham Risk Score And Maximum Wall Thickness Measured By Ultrasound For Screening Carotid Vulnerable Atherosclerotic Plaques In The Asymptomatic Elderly:Comparison To MR Vessel Wall Imaging

ObjectivePart 1: To investigate whether Framingham Risk Score(FRS)can be used to screen carotid vulnerable atherosclerotic plaques in the asymptomatic elderly(?60years old).Part 2: To investigate whether maximum wall thickness measured by ultrasound(US-Max WT)can be used to screen carotid vulnerable atherosclerotic plaques in the asymptomatic elderly(?60 years old)whose FRS is higher than 10%.MethodsPart 1: FRS of every subject was calculated and the MR imaging characteristics of carotid atherosclerotic plaques on three-dimensional MR vessel wall imaging were evaluated.FRS was compared between subjects with and without carotid vulnerable plaques.Univariate logistic regression was used to calculate the odds ratio(OR)and95% confidence interval(CI)of FRS in determining the presence of carotid vulnerable plaques.Receiver Operating Characteristic(ROC)curve was used to evaluate the ability of FRS in determining the presence of carotid vulnerable plaques and the appropriate cut-off value was set.Part 2: Logistic regression was used to calculate the OR and 95%CI of US-Max WT in determining the presence of carotid vulnerable plaques.ROC curve was used to evaluate the ability of US-Max WT in determining the presence of carotid vulnerable plaques and the appropriate cut-off value was set.ResultsPart1: A total of 134 subjects were recruited in this study,which consisted of 62 males and 72 females with mean age being 72.3±5.5 years old.Seventeen out of 134(12.7%)had carotid vulnerable plaques.Subjects with carotid vulnerable plaques had significantly higher FRS [37.8%(27.4%-60.0%)vs 16.6%(8.9%-27.4%),P=0.002]compared to those without.In determining carotid vulnerable plaques,the OR of FRS with an increasement of 10% was 1.556(95%CI 1.204-2.011,P=0.001).ROC curve analysis showed that the AUC of FRS in determining the carotid vulnerable plaques was 0.732.If cut-off value of FRS was 10%,the sensitivity and specificity in determining carotid vulnerable plaques were 94.1% and 30.8%.If cut-off value of FRS was 20%,the sensitivity and specificity in determining carotid vulnerable plaques were 76.5% and 59.8%.Part2: A total of 84 subjects were recruited in this study,which consisted of 54 males and 30 females with mean age being 73.9±5.3 years old.Fifteen out of 84(17.9%)had carotid vulnerable plaques.Subjects with carotid vulnerable plaques had significantly higher FRS [37.9%(21.0%-62.7%)vs 23.1%(15.9%-36.7%),P=0.016]and US-Max WT [3.6mm(3.2mm-3.8mm)vs 2.2mm(1.6mm-2.8mm)] compared to those without.In determining carotid vulnerable plaques,the OR of US-Max WT with an increasement of 0.1mm was 1.173(95%CI 1.080-1.273,P <0.001).ROC curve analysis showed that the AUC of US-Max WT in determining the carotid vulnerable plaques was 0.886.When US-Max WT was more than 2.8mm,the sensitivity and specificity of determining carotid vulnerable plaques were 93.3% and 79.7%respectively.ConclusionOur study suggested that FRS can be preliminarily used to screen carotid vulnerable plaques in the asymptomatic elderly(?60 years old).US-Max WT can beused to screen carotid vulnerable plaques in the asymptomatic elderly whose FRS was higher than 10%.An advanced imaging examination(MR)is needed to evaluate carotid vulnerable plaques for the asymptomatic elderly whose FRS is higher than10% and US-Max WT is more than 2.8mm.