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1534. Safety of Off-Label Use of Ferumoxytol as a Contrast Agent for MRI: A Systematic Review and Meta-Analysis of Adverse Events
Authors * Denotes Presenting Author
  1. Faraz Ahmad *; Ottawa Hospital Research Institute
  2. Lee Treanor ; Ottawa Hospital Research Institute
  3. Trevor McGrath ; Ottawa Hospital Research Institute
  4. Daniel Walker ; Ottawa Hospital Research Institute
  5. Matthew McInnes; Ottawa Hospital Research Institute
  6. Nicola Schieda; Ottawa Hospital Research Institute
Objective:
To estimate by systematic review and meta-analysis the rate of adverse events in patients undergoing MRI with ferumoxytol administered as a contrast agent.

Materials and Methods:
MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) were searched for studies using ferumoxytol as an off-label MRI contrast agent in any patient population as of April 2020. Original research studies were eligible for inclusion if they reported number and severity of adverse events (classified by ACR severity of acute reactions) associated with ferumoxytol administration. Risk of bias was assessed using the ROBINS-I tool. Frequency of ferumoxytol administrations with adverse events was estimated using a random-effects meta-analysis of proportions.

Results:
In total, thirty-nine studies including 5411 ferumoxytol administrations in 4336 patients were included. No deaths related to ferumoxytol administration were reported. Sixteen studies reported immediate adverse events in 3849 patients undergoing 4901 ferumoxytol administrations. Ninety-seven immediate adverse events were reported and the pooled adverse event proportion for immediate adverse events was 0.02 (95% CI 0.02-0.02). Twenty-three studies reported time unspecified adverse events in 487 patients undergoing 510 ferumoxytol administrations. Five time unspecified adverse events were reported, the pooled adverse event proportion for time unspecified adverse events was 0.01 (95% CI 0.00-0.04). 88% of adverse events were mild (90/102), 11% (11/102) were moderate, and 1% (1/102) were severe. Sixteen studies were at low risk of bias, 23 studies were at moderate risk of bias. Subgroup analysis by patient population revealed no significant variability (adult vs paediatric). There were no studies which evaluated use of ferumoxytol as an alternative to patients who had prior hypersensitivity reaction to gadolinium-based contrast agents (GBCAs).

Conclusion:
Off-label use of ferumoxytol as an MRI contrast agent has an overall adverse event rate estimated to occur in approximately 2% of administrations with rare severe reactions and zero deaths. Compared to GBCAs, ferumoxytol offers the potential benefits of having no risk of causing Nephrogenic systemic fibrosis (NSF), even in patients with severe renal impairment, and has not been associated with retention in the body outside of the reticuloendothelial system which is not known to have any adverse outcome on patients. Although ferumoxtyol could be an alternative MRI contrast agent in patients with prior GBCAs immediate hypersensitivity reactions, our study demonstrates that ferumoxytol has not been studied for this application to date.