Severe hyperbilirubinemia is associated with higher risk of contrast-related acute kidney injury following contrast-enhanced computed tomography

Introduction Contrast-induced acute kidney injury (CI-AKI) is associated with high risks of morbidity and mortality. Hyperbilirubinemia might have some renal protection but with no clear cutoff value for protection. Related studies are typically on limited numbers of patients and only in conditions of vascular intervention. Methods We performed this study to elucidate CI-AKI in patients after contrast-enhanced computed tomography (CCT). The outcomes were CI-AKI, dialysis and mortality. Patients were divided to three groups based on their serum levels of total bilirubin: <= 1.2 mg/dl, 1.3-2.0 mg/dl, and > 2.0 mg/dl. Results We enrolled a total of 9,496 patients who had received CCT. Patients with serum total bilirubin > 2.0 mg/dl were associated with CI-AKI. Those undergoing dialysis had the highest incidence of PC-AKI (p<0.001). No difference was found between the two groups of total bilirubin <= 1.2 and 1.3-2.0 mg/dl. Patients with total bilirubin > 2mg/dl were associated with CI-AKI (OR = 1.89, 1.53-2.33 of 95% CI), dialysis (OR = 1.40, 1.01-1.95 of 95% CI) and mortality (OR = 1.63, 1.38-1.93 of 95% CI) after adjusting for laboratory data and all comorbidities (i.e., cerebrovascular disease, coronary artery disease, peripheral arterial disease, and acute myocardial infarction, diabetes mellitus, hypertension, gastrointestinal bleeding, cirrhosis, peritonitis, ascites, hepatoma, shock lung and colon cancer). We concluded that total bilirubin level > 2 mg/dl is an independent risk factor for CI-AKI, dialysis and mortality after CCT. These patients also had high risks for cirrhosis or hepatoma. Conclusion This is the first study providing evidence that hyperbilirubinemia (total bilirubin > 2.0 mg/dl) being an independent risk factor for CI-AKI, dialysis and mortality after receiving CCT. Most patients with total bilirubin > 2.0mg/dl had cirrhosis or hepatoma.