A High Abdominal Aortic Calcification Score by Dual X-Ray Absorptiometry (DXA) is Associated with Cardiovascular Events after Kidney Transplantation

Abstract

Introduction It is unknown whether aortic calcification is associated with increased risk for cardiovascular events in renal transplant recipients. Therefore, this study focused on the association of abdominal aortic calcification (AAC) and cardiovascular events, using a dual X-ray absorptiometry (DXA) scoring methodology for AAC. Methods Renal transplant recipients, referred for a DXA procedure within 6 months after transplantation, were included in a single-centre study, between 2008 to 2014, with an end of follow-up at December 2017. Primary endpoint was the occurrence of cardiovascular events, defined as myocardial infarction, cerebrovascular accident or transient ischemic attack, within 36 months after transplantation. AAC was quantified using an 8-score scale system and patients were divided into 3 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. Univariate Cox proportional hazard analysis of the high-AAC score showed a hazard ratio (HR) of 3.3 (95% CI 1.7 – 6.3, p < 0.01) for cardiovascular events, while results were not significant for the low-AAC score, HR 1.0 (95% CI 0.5 – 2.1, p = 0.91). Multivariate analysis showed an independent significant association between a high-AAC score and cardiovascular events, HR 2.4 (95% CI 1.2 – 5.0), p = 0.02). Conclusions An independent association between a high-AAC score and cardiovascular events was identified and provides an opportunity for physicians for early cardiovascular risk stratification in renal transplant recipients.