(405) A Comparison of Safety and Clinical Outcomes Between CroFab and Anavip for Copperhead Envenomations

Introduction: Current published literature comparing CroFab and Anavip for the treatment of pit viper envenomations in the United States has largely been focused on outcomes in rattlesnake envenomation. The purpose of this study is to assess efficacy and safety outcomes between these agents for treatment of Copperhead envenomations, as the majority of patients seen in our institution are affected by this species.

Methods: Patients who presented to the emergency department for treatment of snake envenomation between January 1, 2018 and September 30, 2023 were screened for inclusion. The primary outcome of efficacy was measured via average total grams of antivenom given per envenomation, coagulation parameters, and hospital length of stay. The primary safety outcome was measured by incidence of hypersensitivity reactions. Secondary outcomes in the study included incidence of complication (infection, compartment syndrome, tissue necrosis, rhabdomyolysis, delayed venom effects), dose re-administration rate, cost of treatment, and time from order placement to antivenom administration.

Results: A total of 85 patients met inclusion criteria, 29 and 54 in the Anavip and CroFab groups, respectively. Hospital length of stay, improvements in coagulation parameters, hypersensitivity reactions, and complication rates during treatment did not differ significantly between the two agents. Anavip patients required an average total of 1.56 grams of antivenom for treatment compared to 7.96 grams of CroFab (p < 0.001). Dose re-administration rates of CroFab exceeded that of Anavip, and Anavip patients received doses about 33 minutes faster than CroFab patients. Average Anavip therapy cost per patient was approximately $3,600 cheaper than CroFab.

Conclusions: This study demonstrated no statistically significant difference in coagulation panel changes, length of stay, hypersensitivity reaction rate, and treatment complication rate between Anavip and CroFab for treatment of copperhead envenomation. The data does suggest an advantage to the use of Anavip given faster time to administration and lower cost of treatment. Further studies are needed to address follow-up guidance and monitoring after discharge for patients treated with Anavip for Copperhead envenomation.