Supplementary Material for: Intra-Arterial versus Intravenous Contrast and Renal Injury in Chronic Kidney Disease: A Propensity-Matched Analysis

<b><i>Background/Aims:</i></b> contrast-induced nephropathy (CIN) is well described following an administration of intraarterial contrast, but its occurrence after intravenous (IV) contrast is being questioned. We evaluated the incidence of acute kidney injury (AKI), post-contrast AKI (PC-AKI), CIN, dialysis and mortality in patients with chronic kidney disease (CKD) undergoing non-contrast computed tomography (NCCT) or contrast CT (CCT) or coronary angiography (CoA). <b><i>Methods:</i></b> We identified individuals who had CoA or CCT or NCCT between 2010 and 2015 in the Cleveland Clinic CKD registry. We used propensity scores to match patients in the 3 groups. We evaluated the proportion of patients that developed AKI and CIN across the groups with chi-square tests. We generated Kaplan-Meier plots comparing mortality and ESRD among patients who developed AKI (in the NCCT group), PC (multifactorial AKI, CIN) AKI and no AKI. <b><i>Results:</i></b> Out of 251 eligible patients, 200 who had CoA were matched to each of the other CT scan groups. The incidence of AKI was 27% in CoA, 24% in CCT and 24% in NCCT (<i>p</i> = 0.72). The incidence of CIN AKI was 16.5% in CoA and 12.5% in CCT (<i>p</i> = 0.26). The Kaplan-Meier survival at 2 years was 74.8 (95% CI 63.8–87.7) for those with CIN and 53.2 (95% CI 39.7–71.4) for those with multifactorial AKI and 56.5 (95% CI 43.4–73.6) for those with AKI-NCCT and 71.4 (95% CI 67.2–76.0) for those without AKI. The Kaplan-Meier ESRD-free estimates at 2 years were 89.9 (95% CI 80.8–100) for those with CIN and 89.4 (95% CI 78.7–100) for those with multifactorial AKI and 77.4 (95% CI 63.6–94.3) for those with AKI-NCCT and 94.4 (95% CI 91.9–97.1) for those without AKI. <b><i>Conclusion:</i></b> The administration of both IV and intra-arterial contrast is associated with a risk of AKI. Multifactorial AKI was associated with worse outcomes, while CIN was associated with better outcomes.