Health Services Research & Policy ■ Clinical Practice Management ■ Training & Education ■ Leadership
Health Services Research & Policy ■ Clinical Practice Management ■ Training & Education ■ Leadership
Health Services Research & Policy
■ Clinical Practice Management
■ Training & Education ■ Leadership

eGFR-Based Screening for Group II GBCM is Optional

Financial Implications of Revised ACR Guidelines for Estimated Glomerular Filtration Rate Testing Before Contrast-Enhanced MRI

Recent edits to the ACR Manual on Contrast Media [1], a common resource for radiology practices designing policies around the safety and use of contrast media, now in version 10.3, has indicated that renal function screening prior to the administration of so-called "group II" gadolinium-based contrast media (GBCM) is considered "optional". This new language was adopted in 2017 for two major reasons: 1) there are zero or single-digit unconfounded cases of nephrogenic systemic fibrosis (NSF) in high-risk patients receiving a group II agent, and 2) multiple studies published since 2007 have investigated high-risk patients (eGFR <30 mL/min/1.73m2) receiving a single dose of a group II agent and have found no evidence of NSF. Although this does not mean that NSF is not possible in this cohort, it indicates that the risk of NSF from a group II agent is considered to be very small (ie, less than 1 in 5,000). In other words, if a contrast-enhanced MRI with a group II agent is indicated, then the risk of NSF is sufficiently low that screening would not affect post-screening decision-making.

Practices using group II agents (gadoterate meglumine [Dotarem], gadobutrol [Gadavist/Gadovist], gadoteridol [ProHance], gadobenate dimeglumine [MultiHance]) may be excited by this news because renal function screening is a complicated and expensive process with the potential for unintended harm. Importantly, patients identified by screening as having severely impaired renal function may be denied a needed contrast-enhanced MRI, which could lead to suboptimal care. This is especially the case in patients not on chronic dialysis because iodinated contrast material is relatively (but not absolutely) contraindicated in that population [1]. Some have referred to this unintended harm as the "harm of not", ie, the harm of not doing something for fear of a study-related complication. Rather than considering risk solely from the point-of-view of the radiology department, the Manual is considering the holistic risk to the patient; failure to perform a needed MRI also has the potential for harm.

In addition to the potential patient-care benefits of this new language, elimination of renal function screening for group II agents is predicted to bring large cost savings to adopting institutions. In a recent publication by Shankar et al [2], the financial implications of these revised guidelines were modeled, and it was shown that at an institution annually performing 28,970 contrast-enhanced MRI examinations (25% of which [n=7,243] met criteria for pre-MRI renal function assessment), adopting universal group II agents and eliminating renal function screening would reduce annual costs by $78,330 after related reimbursements. Their modeling was most sensitive to changes in MRI technologist time (to perform renal function screening) and the cost of the point-of-care testing device. In their practice, renal function screening has been discontinued for group II agents. The only other agent on formulary at that institution (gadoxetate disodium [Eovist]) is a group III agent (ie, insufficient information about risk of NSF), and renal function screening continues prior to administration of that agent.

It is important to point out that the labeling for GBCM has not changed with respect to renal function assessment—all GBCM (including group II agents) still have a black-box warning about NSF, the potential risk in patients with eGFR <30 mL/min/1.73m2, and the need for targeted renal function screening. Therefore, the ACR language indicating that renal function screening is optional for group II agents is off-label from the perspective of the United States Food and Drug Administration (FDA). Whether that warning will eventually be changed, or what level of evidence is needed to change it, is uncertain. Individual practices will need to weigh these issues as they decide what is best for their patients. For those who may be interested, the decision to screen or not is unrelated to issues surrounding gadolinium retention, which is a recently described phenomenon of uncertain significance that can occur regardless of baseline renal function [3]. As practices weigh the characteristics of each GBCM, the need to screen may emerge as one among several important factors to be considered in agent selection [4].

References:

  • 1.American College of Radiology. Manual on contrast media. Version 10.3. Reston, Va: American College of Radiology, 2017.
  • 2.Shankar PR, Parikh K, Davenport MS. Financial implications of revised ACR guidelines for estimated glomerular filtration rate testing before contrast-enhanced MRI. J Am Coll Radiol 2018; 15:250-257.
  • 3.McDonald RJ, McDonald JS, Kallmes DF, et al. Intracranial deposition after contrast-enhanced MR imaging. Radiology 2015; 275:772-782.
  • 4.Davenport MS. Choosing the safest gadolinium-based contrast medium for MR imaging: not so simple after all. Radiology 2018; 286:483-485.
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