Comparison of Antivenom Dosing Strategies for Rattlesnake Envenomation.

Objectives: This study compares maintenance with clinical- and laboratory-triggered (as-needed [PRN]) antivenom dosing strategies with regard to patient-centered outcomes after rattlesnake envenomation.

Design: This is a retrospective cohort study of adult rattlesnake envenomations treated at a regional toxicology center. Data on demographics, envenomation details, antivenom administration, length of stay, and laboratory and clinical outcomes were compared between the PRN and maintenance groups. Primary outcomes were hospital length of stay and total antivenom used, with a hypothesis of no difference between the two dosing strategies.

Setting: A single regional toxicology center PATIENTS:: Three-hundred ten adult patients envenomated by rattlesnakes between 2007 and 2014 were included. Patients were excluded if no antivenom was administered or for receiving an antivenom other than Crofab (BTG International, West Conshohocken, PA).

Interventions: This is a retrospective study of rattlesnake envenomations treated with and without maintenance antivenom dosing.

Main Results: One-hundred forty-eight in the maintenance group and 162 in the PRN group were included. There was no difference in demographics or baseline envenomation severity or hemotoxicity (32.7% vs 40.5%; respectively; p = 0.158) between the two groups. Comparing the PRN with the maintenance group, less antivenom was used (8 [interquartile range, 6-12] vs 16 [interquartile range, 12-18] vials, respectively; p < 0.001), and hospital length of stay was shorter (27 hr [interquartile range, 20-44 hr] vs 34 hr [interquartile range, 24-43 hr], respectively; p = 0.014). There were no differences in follow-up outcomes of readmission, retreatment, or bleeding and surgical complications.

Conclusions: Hospital length of stay was shorter, and less antivenom was used in patients receiving a PRN antivenom dosing strategy after rattlesnake envenomation.