Radiology: Restrictive guidelines cut NSF cases

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Implementation of restrictive guidelines regarding gadolinium-based contrast agents (GBCA) administration proved effective in preventing nephrogenic systemic fibrosis (NSF), according to a study to be published in the July issue of Radiology.

Within the past five years, use of GBCA has been linked to the development of NSF, a rare disorder mainly affecting patients with severe kidney disease.

Massachusetts General Hospital (MGH) in Boston began implementing restrictive GBCA guidelines in May 2007 to protect patients from possibly developing NSF. The guidelines require a blood test on patients over age 60 or at risk for kidney disease. The blood test is converted via a formula to estimate the glomerular filtration rate (eGFR).

The guidelines stipulate a maximum GBCA dose of 20mL for patients with a low eGFR (below 60 mL/min/m2) and prohibit GBCA administration to patients currently undergoing dialysis treatment or with a very low eGFR (below 30 mL/min/ m2).

To determine the incidence of NSF before and after implementation of the guidelines, Hani H. Abujudeh, MD, MBA, of the department of radiology at MGH, and colleagues reviewed the hospital’s medical records during the pre-guideline and transition period (January 2002 through December 2007) and the post-adoption period (January 2008 to March 2010).

Prior to adoption of the guidelines and during the transition period, 113,120 contrast-enhanced MRI exams were performed, and 34 cases of NSF were subsequently identified. During the post-guideline period, 52,954 contrast-enhanced MRIs were performed with no new cases of NSF identified.

During the pre-guidelines and transition periods, 11 percent of studies performed on patients with a creatine level measurement obtained 30 days prior to the MRI had an eGFR of 30 to 59 mL/min/m2 and 1.1 percent were performed in patients with an eGFR lower than 30 mL/min/m2.

After the restrictive guidelines were implemented, pre-study creatine levels were available for 74 percent of patients, up from 67 percent in the earlier period and a statistically significant increase. Twelve percent of studies were performed in patients with an eGFR lower than 60 mL/min/m2, with 0.07 percent performed in patients with an eGFR lower than 30 mL/min/m2. Both changes reached statistical significance.

“These data suggest our referring physicians’ and radiologists’ overall compliance to the guidelines and increased awareness of the risks associated with GBCA use, especially in the setting of renal impairment,” wrote Abujudeh and colleagues.

The researchers indicated that the MGH program was successful because it incorporated key observations from published literature. Specifically, data have linked patients who receive higher cumulative doses of gadopentetate dimeglumine with a higher risk of developing NSF than those who receive lower doses.

At MGH, physicians offered alternate imaging studies and limited the maximal weight-based dose of GBCA to 20 mL for any patient with renal disease, explained the researchers. In addition, patients with eGFRs lower than 30 mL/min/m2 were referred for a nephrology consult and underwent hemodialysis within 24 hours of the contrast-enhanced MR study, if it was deemed appropriate.

Abujudeh and colleagues pointed out that MGH’s use of gadopentetate dimeglumine deviates from American College of Radiology recommendations, a change made after two cases of severe reaction to an alternate agent—gadobenate dimeglumine. “[T]he absence of new observed cases of NSF during the post-adoption period suggest that gadopentetate dimeglumine can be used safely, as long as the administration is in accordance with our GBCA guidelines,” they wrote.

The researchers concluded, “[T]he adoption of GBCA guidelines probably prevented the occurrence of new cases of NSF at our institution and that it facilitates the safe use of gadopentetate dimeglumine, even in patients who are undergoing chronic dialysis treatment and/or have eGFRs lower than 60 mL/min/m2.”

They planned to continue to revise GBCA guidelines according to the study indication and anatomy imaged so that the minimum amount of contrast is used to produce diagnostic-quality images.