Incidence of contrast-induced nephropathy in intensive care patients undergoing computerised tomography and prevalence of risk factors

Abstract

Computerised tomography (CT) with contrast is frequently used in intensive care. Contrast-induced nephropathy (CIN) is an important complication largely studied in stable cardiology patients and can lead to acute renal failure. The aim of this study was to determine the incidence of CIN in an intensive care unit (ICU) setting and describe the prevalence of associated risk factors. We performed a retrospective analysis by review of electronic laboratory database and manual chart review of all patients in two tertiary intensive care units in Newcastle, New South Wales who underwent CT with intravenous contrast during their ICU stay in 2006. CIN was defined as an absolute increment in serum creatinine of 44.2 micromol/l or a relative increment of 25% from baseline at 48 to 72 hours following intravenous contrast. Patients' demographic, biochemical and contrast media data, physiological parameters, fluid and drug administrations and previously described as well as ICU specific risk factors were analysed. We compared CIN positive and CIN negative patients to identify risk factors associated with CIN. In total, 2043 patients were admitted to ICU during 2006 and 509 CT studies were performed. One hundred and forty-one of these included administration of intravenous contrast and 139 charts were reviewed. Sixteen out of 139 patients developed CIN (11.5%). More than 70% of patients had two or more risk factors. Age was the only risk factor found to be significantly associated with the development of CIN in a multivariate analysis (P value 0.04, OR 1.041, 95% confidence interval 1.002 to 1.081). Mortality was higher in CIN positive patients (31 vs 13%, P value 0.068). ICU and hospital length of stay was not significantly different in CIN positive and negative patients and persisting renal impairment was not found in CIN positive survivors. Based on this study, we cannot predict who will develop CIN in ICU using the described risk factors. Further prospective studies are needed to evaluate the incidence and outcomes of CIN in an ICU setting.