Incidence of Delayed and Recurrent Coagulopathies in North American Rattlesnake Bite Patients Initially Treated with Crotalidae Polyvalent Immune Fab (ovine) (CroFab)

Abstract

Objectives: To determine the incidence of late coagulopathy and characterize those requiring antivenom retreatment among rattlesnake envenomation patients managed by the Arizona Poison and Drug Information Center (APDIC). Methods: This descriptive, retrospective chart review used data extracted from APDIC charts. Data included coagulopathy lab values recorded during treatment, vials of antivenom required to achieve initial control, total vials during therapy, incidence of initial coagulopathy, use of extended infusion, time until treatment, and permanent sequelae due to snakebite. Demographic information was also recorded. Late coagulopathy is defined as coagulopathy occurring after completion of maintenance dosing, and can be considered recurrent or delayed. Delayed coagulopathy occurs in the absence of an initial coagulopathy, while recurrent coagulopathy requires an initial event previously controlled by antivenom therapy. Results: Of 321 identified reports, 120 patients were treated with antivenom, had outpatient follow-up, and were included in analysis. Sixty-one (50.8%) patients did not have an initial coagulopathy, while 59 (49.2%) had an initial coagulopathy. Late coagulopathy occurred in 63 (52.5%) of patients. Delayed coagulopathies occurred in 19 (31.1%) of patients with no initial coagulopathy; Of those with an initial coagulopathy, recurrent coagulopathies occurred in 44 (74.5%) of patients. Patients with initial coagulopathy were statistically more likely to develop a late coagulopathy than those with no initial coagulopathy (p<0.001). Seventeen patients required retreatment post-discharge. Conclusions: Patients envenomated by rattlesnakes are at high risk for developing late coagulopathies. Close outpatient follow-up is imperative for monitoring of coagulopathies. Need for retreatment with FabAV post-discharge is not uncommon.