Long-Term Clinical Outcomes of Rattlesnake Envenomation in Arizona Following Treatment With Crofab vs Anavip: A Retrospective Observational Study

Objectives: The purpose of this study was to compare patient-reported outcomes regarding tissue injury caused by rattlesnake envenomation for patients treated with Crofab or Anavip. Methods: We performed a chart review of the Arizona Poison and Drug Information Center's records from January 2017 through December 2021 for patients who received antivenom for rattlesnake envenomation. We present responses to standardized questions asked on days 7, 14, 90, and 180 regarding the presence of pain, edema, and functional impairment, with full recovery defined as the resolution of all 3. Results: Patients treated with Crofab (n = 272) and Anavip (n = 241) were similar with regard to age, sex, bite location, and time to treatment. At each time point, the percentage of patients reporting resolution of pain, edema, or function was higher in patients treated with Crofab, when compared with those treated with Anavip. Clinically important differences in the percentage of patients reporting full recovery favoring Crofab were identified at 7 days (15.1% vs 6.6%, difference 8.5%, 95% CI: 3.1%-13.7%), 14 days (34.6% vs 24.9%, difference 9.7%, 95% CI: 1.8%-17.5%), and 90 days (60.3% vs 52.7%, difference 7.6%, 95% CI: −1.0% to 16.2%). Conclusion: Following rattlesnake envenomation in Arizona, patients treated with Crofab had higher rates of full recovery from tissue injury than patients treated with Anavip at 7, 14, 90, and 180 days.