Off-Label Utilization Trend for Recombinant Factor VIIa in Children's Hospitals in the United States
Authors: Gupta Shveta , Stanek Joseph R. , O'Brien Sarah H. 
Published: November 2019

Background: Recombinant FVIIa (rFVIIa) was approved by the Food and Drug Administration (FDA) as a hemostatic agent in 1999 for the treatment of patients with hemophilia and inhibitory antibodies against either factor VIII or IX and subsequently approved for use in patients with congenital factor VII deficiency and Glanzmann Thrombasthenia refractory to platelet transfusions in 2005 and 2014 respectively. These are rare disorders and the use of rFVIIa in these conditions has been found to be effective and safe. Despite this very narrow indication for usage, rFVIIa is being used for a diverse range of off-label indications. Along with uncertainty regarding clinical efficacy, available data suggests that the risk of thromboembolic events is increased when rFVIIa is used in off-label settings. Studies on the off-label use of rFVIIa in children are limited to a few large case series. In a retrospective multicenter cohort study utilizing the Pediatric Health Information System (PHIS) administrative database, Witmer et al demonstrated a 10-fold increase in the annual rate of off-label admissions from 2000 to 2007. The mortality rate in the off-label group was 34% and thrombotic events occurred in 11% of the off-label admissions. We conducted a follow up study to characterize the evolution of the off-label use of rFVIIa in children.
Objective: To describe current trends of off-label utilization and adverse effects of rFVIIa in children.
Study design: A retrospective multicenter cohort study utilizing the PHIS administrative database was conducted. The PHIS dataset includes 51 children's hospitals in the United States and is representative of tertiary care centers in the nation. In patients, 18 years of age or younger who received rFVIIa between 2012-2018 were included. A label admission was defined as an admission with an International Classification of Diseases (ICD-9 and ICD-10) diagnostic code for hemophilia, Factor VII deficiency or Glanzmann thrombaesthenia; admissions without these codes were classified as off-label. Data were analyzed descriptively.
Results: There were 7,738 number of admissions, representing 6,493 unique individual subjects. A total of 78.3 % of the admissions were off-label. The rate of off-label use was stable at approximately 80% of the admissions from 2012-18. The most frequent admitting services for the off-label admissions included cardiology (29.8%), cardiovascular/thoracic surgery (15.7%), critical care (15.0%), neonatal-perinatal medicine (8.7%), and hematology/oncology (6.1%). Over half (54.6%) of off-label administration occurred in children younger than 1 year old. Among the off-label admissions 57 % were male and the median days of use of rFVIIa was 1 day. The mortality rate in the off-label group was 22.3 %. Thrombotic events occurred in 11.4% of the off-label admissions. Among the off-label admissions with thrombotic events, the most common admitting services were cardiology (35.0%) and critical care (21.2%).
Conclusion: We have demonstrated that on a per admission basis the predominant use of rFVIIa is off-label. Thrombotic events are common. Although the mortality rate in the pediatric patients who received off-label rFVIIa is high; its lower when compared with the previous review. This may likely reflect, in part, the severity of illness in this patient group. In the absence of clearly supportive data demonstrating safety and efficacy, restraint should be exercised with careful consideration of risk versus benefit for use of rFVIIa in off-label settings.

Disclosures
Gupta: Novo Nordisk: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Novartis: Honoraria, Speakers Bureau; Octapharma: Honoraria, Membership on an entity's Board of Directors or advisory committees; CSL Behring: Research Funding; Takeda-Shire: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. O'Brien:Pfizer: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Research Funding.

OffLabel Disclosure:
Recombinant FVIIa (rFVIIa) was approved by the Food and Drug Administration (FDA) as a hemostatic agent in 1999 for the treatment of patients with hemophilia and inhibitory antibodies against either factor VIII or IX and subsequently approved for use in patients with congenital factor VII deficiency and Glanzmann Thrombasthenia refractory to platelet transfusions in 2005 and 2014 respectively. These are rare disorders and the use of rFVIIa in these conditions has been found to be effective and safe. Despite this very narrow indication for usage, rFVIIa is being used for a diverse range of off-label indications.