Prevalence and predictors of abdominal aortic calcification in healthy living kidney donors

Abstract

Vascular calcification (VC) is common and is both a marker and a cause of increased cardiovascular morbidity and mortality, especially so in chronic kidney disease (CKD) patients. Renal transplantation is the cornerstone of the successful long-term management of CKD, and in order to satisfy transplantation needs, more use is made now of living kidney donors (LKD). Prior to selection for transplantation, much screening of potential LKD takes place, including for cardiovascular issues. It is not known; however, how much these potentially healthy LKD may be prone to clinically silent VC. We identified 103 living kidney donors from 2011 renal transplant records. Abdominal aortic calcification (AAC) was assessed using existing abdominal CT imaging using multi-channel CT aortograms (used primarily to assess renal vascular anatomy). Using these CT scans, manual calcium scoring was undertaken to calculate total aortic calcium load (AAC severity score). The prevalence, severity and associations of AAC between calcified and non-calcified donors were then compared. A total of 103 donors were identified from records. Ninety three of these had detailed clinical records to complement their CT scans. Fifty of ninety-three donors were male, and the mean age was 45.9 ± 1.8 years. Mean MDRD eGFR was 88.73 ± 2.97 ml/min/1.73 m(2). 7.14 ± 3.07 % of the aorta in these donors was calcified with a mean AAC severity score of 0.98 ± 0.56. In kidney donors >50 years of age, there was significantly more AAC than in those <50: 2.47 ± 1.56 versus 0.31 ± 0.29, p < 0.001. There was no relationship between the presence or severity of aortic VC and donor GFR, systolic blood pressure, pulse pressure, calcium-phosphate product or smoking. AAC prevalence, patterns and severity in this important donor population have not previously been described in the literature. There was relatively little VC in what would be regarded as a "healthy" donor population. VC was more common with age, but the other possible risk factors for the presence or severity of VC did not impact on overall AAC scores. VC did not influence vascular stiffness as represented by pulse pressure. Following the evolution of AAC over time in those who have donated a kidney, and lost some global renal function as a consequence, would be of considerable interest.