Risk of intravenous contrast material-mediated acute kidney injury: a propensity score-matched study stratified by baseline-estimated glomerular filtration rate.
OBJECTIVE
To determine the effect of baseline estimated glomerular filtration rate (eGFR) on the causal association between intravenous iodinated contrast material exposure and subsequent development of acute kidney injury (AKI) in propensity score-matched groups of patients who underwent contrast material-enhanced or unenhanced computed tomography (CT).


METHODS
This retrospective study was HIPAA compliant and institutional review board approved. All patients who underwent contrast-enhanced (contrast material group) or unenhanced (non-contrast material group) CT between 2000 and 2010 were identified and stratified according to baseline eGFR by using Kidney Disease Outcomes Quality Initiative cutoffs for chronic kidney disease into subgroups with eGFR of 90 or greater, 60-89, 30-59, and less than 30 mL/min/1.73 m(2). Propensity score generation and 1:1 matching of patients were performed in each eGFR subgroup. Incidence of AKI (serum creatinine [SCr] increase of ≥0.5 mg/dL [≥44.2 μmol/L] above baseline) was compared in the matched subgroups by using the Fisher exact test.


RESULTS
A total of 12 508 propensity score-matched patients with contrast-enhanced and unenhanced scans met all inclusion criteria. In this predominantly inpatient cohort, the incidence of AKI significantly increased with decreasing baseline eGFR (P < .0001). However, this incidence was not significantly different between contrast material and non-contrast material groups in any eGFR subgroup; for the subgroup with eGFR of 90 or greater (n = 1642), odds ratio (OR) was 0.91 (95% confidence interval [CI]: 0.38, 2.15), P = .82; for the subgroup with eGFR of 60-89 (n = 3870), OR was 1.03 (95% CI: 0.66, 1.60), P = .99; for the subgroup with eGFR of 30-59 (n = 5510), OR was 0.94 (95% CI: 0.76, 1.18), P = .65; and for the subgroup with eGFR of less than 30 mL/min/1.73 m(2) (n = 1486), OR was 0.97 (95% CI: 0.72, 1.30), P = .89.


CONCLUSIONS
Diminished eGFR is associated with an increased risk of SCr-defined AKI following CT examinations. However, the risk of AKI is independent of contrast material exposure, even in patients with eGFR of less than 30 mL/min/1.73 m(2).
From the Departments of Radiology (J.S.M., R.J.M., D.F.K., E.E.W.), Health Sciences Research (R.E.C.), and Neurosurgery (D.F.K.), College of Medicine, Mayo Clinic, 200 1st St SW, Rochester, MN 55905; and Department of Radiology, Medical University of South Carolina, Charleston, SC (R.W.K.).
Jennifer S
JS
McDonald
Robert J
RJ
McDonald
Rickey E
RE
Carter
Richard W
RW
Katzberg
David F
DF
Kallmes
Eric E
EE
Williamson
D058186:Acute Kidney Injury / Q000139:chemically induced*; D000328:Adult; D003287:Contrast Media / Q000009:adverse effects*; D003404:Creatinine / Q000097:blood; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D057216:Propensity Score; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
D003287:Contrast Media; D003404:Creatinine