Abdominal aortic calcification in dialysis patients: results of the CORD study

Background. Patients with chronic kidney disease stage 5 have a high prevalence of vascular calcification, but the specific anatomical distribution and severity of abdominal aortic calcification (AAC), in contrast to coronary calcification, is less well documented. AAC may be recorded using plain radiographs. The present report is an analysis of baseline data on AAC in patients enrolled in the CORD (Calcification Outcome in Renal Disease) study. Methods. A total of 47 centres in six European countries participated in this cross-sectional study. Inclusion criteria were age ≥18 years and duration of dialysis ≥3 months. Lateral lumbar radiography of the abdominal aorta was used to determine the overall AAC score, which is related to the severity of calcific deposits at lumbar vertebral segments L1–L4. The reliability of the method was tested by double reading of 64 radiographs (coefficient of correlation 0.9). Results. A lateral lumbar radiograph was obtained in 933 patients. Calcification (AAC score ≥ 1) was present in 81% of the patients; its severity increased significantly from L1 to L4 (P < 0.0001) and affected all of these segments in 51% of patients. Independent predictors for the presence and severity of calcification were age (odds ratio [OR] 1.103/year; P < 0.0001), duration of dialysis (OR 1.110/year; P = 0.002) and history of cardiovascular disease (OR 3.247; P < 0.0001). Conclusions. AAC detected by lateral lumbar radiograph is associated with several risk factors of uraemic calcification. This semi-quantitative method is more widely available and less expensive than the current procedures for studying calcification and could form part of a pre-transplant workup and cardiovascular risk stratification.