Comparing different calcification scores to detect outcomes in chronic kidney disease patients with vascular calcification

Background There is no consensus on the most appropriate technique to diagnose vascular calcification in chronic kidney disease. This is primarily because of the absence of direct comparisons of predictive values of the various calcification scores, especially outside the coronary vascular beds, to detect clinical outcomes. Methods We included 93 haemodialysis patients and performed 6 vascular calcification scores: two scores utilised simple X-rays of abdominal aorta and peripheral vessels. CT scans of the thoracic, upper abdominal and lower abdominal aorta were performed to calculate the aortic calcification index and CT of the pelvis for calcification of iliac vessels. Patients were followed for 63 months (mean 46.8 months) for first major cardiovascular events and mortality. Results Nineteen cardiovascular events and 28 deaths occurred. Calcification was detected more sensitively in central and peripheral beds using CT scans compared to X-rays (p < 0.001). CT scans detected calcification more frequently in distal than proximal vascular beds (p < 0.001). Calcification of the pelvic vessels and lower abdominal aorta were most predictive of events including pre-existing cardiovascular disease O.R. 6.5 (95% C.I. 2–22; p = 0.001) and O.R. 3 (95% C.I. 1.1–9; p = 0.035); new major cardiovascular events H.R. 4.2 (95% C.I. 1.5–11; p = 0.006) and H.R. 2 (95% C.I. 0.8–5.3; p = 0.1) as well as mortality H.R. 2.8 (95% C.I. 1.3–6; p = 0.01) and H.R. 2.2 (95% C.I. 1.04–5; p = 0.04) respectively. Conclusions CT based techniques are more sensitive than plain X-rays at detecting peripheral and aortic vascular calcifications. Distal CT scans of the aorta and pelvic vessels have the highest predictive value for cardiovascular events and mortality.