Conference Coverage

Fibrinogen concentrate effective, safe for postop bleeding



– Fibrinogen concentrate was noninferior to cryoprecipitate for controlling bleeding following cardiac surgery in the randomized FIBRES trial, Canadian investigators reported.

Dr. Jeannie Callum of Sunnybrook Health Sciences Centre in Toronto Neil Osterweil/MDedge News

Dr. Jeannie Callum

Among 827 patients undergoing cardiopulmonary bypass, there were no significant differences in the use of allogenenic transfusion products within 24 hours of surgery for patients assigned to receive fibrinogen concentrate for control of bleeding, compared with patients who received cryoprecipitate, reported Jeannie Callum, MD, from Sunnybrook Health Sciences Centre in Toronto, on behalf of coinvestigators in the FIBRES trial.

Fibrinogen concentrate, commonly used to control postoperative bleeding in Europe, was associated with numerically, but not statistically, lower incidence of both adverse events and serious adverse events than cryoprecipitate, the current standard of care in North America.

“Given its safety and logistical advantages, fibrinogen concentrate may be considered in bleeding patients with acquired hypofibrinogenemia,” Dr. Callum said at the annual meeting of the AABB, the group formerly known as the American Association of Blood Banks.

Results of the FIBRES trial were published simultaneously in JAMA (2019 Oct 21. doi: 10.1001/jama.2019.17312).

Acquired hypofibrinogenemia, defined as a fibrinogen level below the range of 1.5-2.0 g/L, is a major cause of excess bleeding after cardiac surgery. European guidelines on the management of bleeding following trauma or cardiac surgery recommend the use of either cryoprecipitate or fibrinogen concentrate to control excessive bleeding in patients with acquired hypofibrinogenemia, Dr. Callum noted.

Cryoprecipitate is a pooled plasma–derived product that contains fibrinogen, but also fibronectin, platelet microparticles, coagulation factors VIII and XIII, and von Willebrand factor.

Additionally, fibrinogen levels in cryoprecipitate can range from as low as 3 g/L to as high as 30 g/L, and the product is normally kept and shipped frozen, and is then thawed for use and pooled prior to administration, with a shelf life of just 4-6 hours.

In contrast, fibrinogen concentrates “are pathogen-reduced and purified; have standardized fibrinogen content (20 g/L); are lyophilized, allowing for easy storage, reconstitution, and administration; and have longer shelf life after reconstitution (up to 24 hours),” Dr. Callum and her colleagues reported.

Despite the North American preference for cryoprecipitate and the European preference for fibrinogen concentrate, there have been few studies directly comparing the two products, which prompted the FIBRES investigators to design a head-to-head trial.

The randomized trial was conducted in 11 Canadian hospitals with adults undergoing cardiac surgery with cardiopulmonary bypass for whom fibrinogen supplementation was ordered in accordance with accepted clinical standards.

Patients were randomly assigned to received either 4 g of fibrinogen concentrate or 10 units of cryoprecipitate for 24 hours, with all patients receiving additional cryoprecipitate as needed after the first day.

Of 15,412 cardiac patients treated at the participating sites, 827 patients met the trial criteria and were randomized. Because the trial met the prespecified stopping criterion for noninferiority of fibrinogen at the interim analysis, the trial was halted, leaving the 827 patients as the final analysis population.

The mean number of allogeneic blood component units administered – the primary outcome – was 16.3 units in the fibrinogen concentrate group and 17.0 units in the cryoprecipitate group (mean ratio, 0.96; P for noninferiority less than .001; P for superiority = .50).

Fibrinogen was also noninferior for the secondary outcomes of individual 24-hour and cumulative 7-day blood component transfusions, and in a post-hoc analysis of cumulative transfusions measured from product administration to 24 hours after termination of cardiopulmonary bypass. These endpoints should be interpreted with caution, however, because they were not corrected for type 1 error, the investigators noted.

Fibrinogen concentrate also appeared to be noninferior for all defined subgroups, except for patients who underwent nonelective procedures, which included all patients in critical state before surgery.

Adverse events (AEs) of any kind occurred in 66.7% of patients with fibrinogen concentrate vs. 72.7% of those on cryoprecipitate. Serious AEs occurred in 31.5% vs. 34.7%, respectively.

Thromboembolic events – stroke or transient ischemic attack, amaurosis fugax (temporary vision loss), myocardial infarction, deep-vein thrombosis, pulmonary embolism, other-vessel thrombosis, disseminated intravascular coagulation, or thrombophlebitis – occurred in 7% vs. 9.6%, respectively.

The investigators acknowledged that the study was limited by the inability to blind the clinical team to the product used, by the adult-only population, and by the likelihood of variable dosing in the cryoprecipitate group.

Advantages of fibrinogen concentrate over cryoprecipitate are that the former is pathogen reduced and is easier to deliver, the investigators said.

“One important consideration is the cost differential that currently favors cryoprecipitate, but this varies across regions, and the most recent economic analysis failed to include the costs of future emerging pathogens and did not include comprehensive activity-based costing,” the investigators wrote in JAMA.

The trial was sponsored by Octapharma AG, which also provided fibrinogen concentrate. Cryoprecipitate was provided by the Canadian Blood Services and Héma-Québec. Dr. Callum reported receiving grants from Canadian Blood Services, Octapharma, and CSL Behring during the conduct of the study. Multiple coauthors had similar disclosures.

SOURCE: Callum J et al. JAMA. 2019 Oct 21. doi:10.1001/jama.2019.17312.

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