Contrast Media and Acute Kidney Injury in the <scp>ICU</scp>

BACKGROUND: Acute kidney injury (AKI) is frequent and influences the prognosis of intensive care unit (ICU) patients. AKI may be categorised as contrast-associated AKI (CA-AKI). We investigated the development of CA-AKI, including temporal and dose-response relationships. METHODS: Adult patients admitted between 2010 and 2015 with a minimum ICU stay of 54 h were eligible for inclusion. AKI was scored on an hourly basis to enable temporal analyses. CA-AKI was defined as an increase in Kidney Disease: Improving Global Outcomes (KDIGO) AKI stage occurring within 48 h of contrast media administration. For the matched analysis, contrast-exposed patients were matched to unexposed patients on duration of stay and renal function. RESULTS: Of 1057 patients, 277 patients were exposed to contrast media. Sixteen percent (n = 43) developed CA-AKI (KDIGO AKI stage 1/2/3: 63%/23%/14%). AKI preceded contrast in 76.2% of cases (95% confidence interval [CI]: 66%-85%, p < 0.001). After contrast exposure, AKI reversal occurred in 65 cases. The proportion of CA-AKI was similar between dose quartiles (p = 0.746). The length of ICU stay (length of stay [LOS]) was longer in the exposed group (10.9 vs. 5.5 days, p < 0.001) regardless of CA-AKI status. In the matched analysis, exposed patients had longer remaining LOS (mean difference 1.47 days, 95% CI: 1.35-1.60) and higher ICU mortality (OR: 1.67, 95% CI: 1.1-2.6), but use of renal replacement therapy (RRT) was similar. CONCLUSIONS: CA-AKI was observed in one of six ICU patients exposed to contrast media and associated with higher mortality and ICU LOS. However, AKI most often precedes contrast. AKI reversal was more common than AKI following exposure. No clear evidence of a dose-response relationship was found. The findings question whether AKI in an ICU population is related to contrast media exposure, but the observational design precludes ruling out contrast media as a cause of AKI. EDITORIAL COMMENT: This ICU cohort analysis presents kidney injury findings where there is intravenous contrast exposure. Where some kidney injury was sometimes present before contrast exposure, this makes exploring the relation of contrast to injury and recovery more complex.