KDIGO Clinical Practice Guideline for Acute Kidney Injury
Recommendations and Rationale

Chapter 4.2: Assessment of the population at risk for CI-AKI

At present, millions of doses of intravascular contrast media are being administered worldwide.^406,407 Most of these radiological examinations are performed in ambulatory populations who do not need special preventive measures. However, contrast media are also increasingly used in an elderly population, many of whom have CKD and diabetes—the principal risk factors for CI-AKI. It is, thus, of utmost importance to screen the population at risk for CI-AKI.

• 4.2.1: Assess the risk for CI-AKI and, in particular, screen for pre-existing impairment of kidney function in all patients who are considered for a procedure that requires intravascular (i.v. or i.a.) administration of iodinated contrast medium. (Not Graded)

Rationale

Screening for pre-existing impairment of kidney function

Pre-existing renal functional impairment is the most important risk factor above all other risk factors for developing CI-AKI⁴⁰⁸ and screening for both acute and chronic kidney disease is highly recommended. There is no sharp GFR threshold below which the risk for CI-AKI is clearly increasing. Both the KDOQI guideline and KDIGO recommend that, in stable patients, an eGFR should be used.⁴⁰⁹

A CI-AKI Consensus Working Panel⁴¹⁰ agreed that the risk of CI-AKI becomes clinically important when the baseline SCr concentration is ≥ 1.3 mg/dl ( ≥ 115 µmol/l) in men and ≥ 1.0 mg/dl ( ≥ 88.4 µmol/l) in women, equivalent to an eGFR < 60 ml/min per 1.73 m². However, Bruce et al.³⁹⁰ showed that the incidence of ‘‘true’’ AKI became significant only between controls and contrast-media administered patients from a baseline SCr concentration of > 1.8 mg/dl ( > 159 µmol/l) onward. The CI-AKI Consensus Working Panel⁴¹⁰ recommended that precautions to reduce the risk should be implemented in patients with a baseline eGFR < 60 ml/min per 1.73 m². In light of more recent information, this threshold could probably be lowered to 45 ml/min per 1.73 m².

In many institutions, point-of-care SCr testing is present, and the results can be available quite fast. In places without point-of-care laboratories, the appropriate blood tests should be requested, but an emergent imaging/intervention, where the benefit of very early imaging outweighs the risk of waiting, should not be delayed.

For its relative simplicity, only SCr is used at many hospitals to determine whether a patient is a candidate for intravascular contrast-media administration, but the thresholds used and the acceptable time between the determined SCr value and administration of contrast media to perform the radiology examination differs among radiology departments.