Abdominal aortic calcification and renal resistive index in patients with chronic kidney disease: is there a connection?

Background: We aimed to evaluate the relationship between abdominal aortic calcification (AAC) and renal resistive index (RRI), parameters associated with cardiovascular outcome, in non-dialysis chronic kidney disease (CKD) patients.

Methods: Seventy-seven stable patients mainly in CKD stages 3B and 4 (44 and 28%), median age 69 years, with a positive history of systemic atherosclerosis were prospectively enrolled. RRI, carotid intima-media thickness (IMT), Kauppila score for AAC (AACs), cardio-ankle vascular index (CAVI) and ankle-brachial index (ABI) were assessed. Traditional and non-traditional atherosclerosis risk factors were also evaluated.

Results: Vascular (50%), diabetic (26%) and primary glomerular nephropathies (8 %) were the main causes of CKD. AAC was highly prevalent (77%). In the whole cohort, RRI was directly related to AACs (rs = 0.35, p < 0.001). AACs correctly identified patients with RRI >0.7 in 69% (56-81%) of cases, a cut-off of 5 resulting the best combination of sensitivity (65%) and specificity (68%). Compared to those with AACs <5, patients with AACs >5 were older, had higher serum cholesterol, C-reactive protein and IMT, lower ABI, but similar CAVI, estimated glomerular filtration rate, serum calcium and phosphate. In the whole cohort, AACs was negatively correlated with ABI (rs = -0.51, p < 0.001) and positively with IMT (rs = 0.27, p = 0.01), supporting a role for Kauppila score in integrating information on both intra- and extrarenal atherosclerosis.

Conclusions: As Kauppila score correlates with RRI in non-dialysis CKD patients, it could be a fast, convenient and relatively inexpensive tool for estimating RRI, and consequently the intrarenal vascular status, but further research is warranted.