Background: Aortic calcification is associated with an increased risk for cardiovascular events in renal transplant recipients. This study focused on the association of abdominal aortic calcification (AAC) and cardiovascular events assessed using a dual-energy X-ray absorptiometry (DXA) scoring methodology for AAC.
Methods: From 2008 to 2014, renal transplant recipients referred for a DXA procedure within 6 months after transplantation were included in a retrospective, single-centre study. The primary endpoint was the occurrence of cardiovascular events, defined as myocardial infarction, cerebrovascular accident or transient ischaemic attack, after transplantation. AAC was quantified using an 8-point scoring system and patients were divided into three groups; a control group (AAC = 0), a low AAC group (AAC = 1-3) and a high AAC group (AAC = 4-8).
Results: We evaluated 701 patients, 267 (38.1%) had detectable calcifications (low AAC 190 patients, high AAC 77 patients) and 434 (61.9%) had no calcifications. Cardiovascular events were seen in 37 (8.5%) patients in the control group, in 18 (9.5%) in the low AAC group and in 20 (26.0%) in the high AAC group. Univariate Cox proportional hazards analysis of the high AAC score showed a hazard ratio (HR) of 4.23 [95% confidence interval (CI) 2.44-7.33; P < 0.01] for cardiovascular events, while results were not significant for the low AAC score. Multivariate analysis showed an independent significant association between a high AAC score and cardiovascular events [HR 2.78 (95% CI 1.05-7.64); P = 0.04]. Assessment of the continuous net reclassification index (NRI), comparing the combined clinical variables with a model of both AAC scoring and clinical variables, showed an NRI of 0.76 (95% CI 0.65-0.86; P < 0.01).
Conclusions: An independent association between a high AAC score, assessed by DXA, and cardiovascular events was identified and provides an opportunity for early cardiovascular risk stratification in renal transplant recipients.