Aortic knob width as an indicator of cardiovascular risk in chronic kidney disease patients

Introduction: The most common cause of mortality in Chronic Kidney Disease (CKD) patients is due to cardiovascular events. The Aortic Knob Width (AKW) has been found to positively correlate with the severity of coronary artery disease. This study describes the use of chest x-ray in evaluating CKD population who are at risk for cardiovascular events. Aim: To measure the Aortic Knob Width (AKW) by chest x-ray in CKD patients and compare Aortic knob width with Framinghams’ risk score and other parameters like urea, creatinine, magnesium, calcium, phosphate, albumin, haemoglobin and C-reactive protein Materials and Methods: A cross sectional study was done between September 2015 and September 2017 in 60 patients belonging to stage 3 to stage 5 CKD. The aortic knob width as measured using chest x-ray was compared with the Framingham’s risk score and other lab parameters like urea, creatinine, magnesium, calcium, phosphate, albumin, haemoglobin and C-reactive protein routinely measured in CKD patients. Statistical package SPSS version 17.0 was used. p<0.05 was considered as significant and Receiver Operating Characteristic(ROC) curves were used to arrive at a cut-off for AKW which correlated with increased cardiovascular risk. Results: The mean AKW was 3.2±0.43 cm. The AKW had a significant positive correlation with Framingham’s 10-year cardiovascular risk scoring (p<0.0001). Using the Receiver Operating Characteristic (ROC) curve, we found that AKW more than 3.1 centimetres corresponds with moderate to high risk as calculated using Framingham’s scoring system with a sensitivity of 82% and specificity of 86%. Karl Pearson’s correlation test showed no significant correlation between AKW and Duration of disease as well as various parameters like urea, creatinine, magnesium, calcium, phosphate, albumin, haemoglobin and C-reactive protein. Conclusion: The findings of the study allow us to use chest x-ray as a screening tool in CKD patients who are at increased risk of adverse cardiovascular events.