Contrast-induced acute kidney injury and clinical outcomes after intra-arterial and intravenous contrast administration: risk comparison adjusted for patient characteristics by design.

BACKGROUND:Direct comparisons between risk of contrast induced acute kidney injury (CI-AKI) after intra-arterial versus intravenous contrast administration are scarce. We estimated and compared the risk of CI-AKI and its clinical course after both modes of contrast administration in patients who underwent both. METHODS:One hundred seventy patients who received both intra-arterial and intravenous contrast injections within one year between 2001 and 2010 were included. Primary outcome was occurrence of CI-AKI. Secondary outcomes were duration of hospital stay, the need for dialysis, recovery of renal function, and mortality. RESULTS:The risk of CI-AKI was 24/170 (14.0%, 95% CI 9.6-20.2) after intra-arterial contrast injection versus 20/170 (11.7%, 95% CI 7.7-17.5) after intravenous contrast administration, which led to a relative risk of 1.2 (95% CI 0.7-2.1). None of the patients had a need for dialysis. Median duration of hospital stay in CI-AKI patients was 15.0 days (2.5-97.5, percentile 1-92) after intra-arterial and 15.5 days (2.5-97.5, percentile 0-38) after intravenous contrast procedures. Renal function recovered after CI-AKI in 13/24 after intra-arterial and in 10/20 patients after intravenous contrast administration. Mortality risks in CI-AKI patients were slightly higher than in non-CI-AKI patients, hazard ratios 1.6 (95% CI 0.7-3.7) for intra-arterial and 1.7 (95% CI 0.7-4.4) for intravenous contrast administration, adjusted for confounders. CONCLUSION:The risk of CI-AKI, and its clinical course was similar after intra-arterial and intravenous contrast media administration, after adjustment by design for patient-related risk factors.