Recovery from Copperhead Snake Envenomation: Role of Age, Sex, Bite Location, Severity, and Treatment
Few data exist to understand the recovery phase of pit viper envenomation. A recently published placebo-controlled clinical trial affords this opportunity. The purpose of this study is to examine the time course of recovery from copperhead snake (Agkistrodon contortrix) envenomation patients managed with and without the use of antivenom, stratified by age, sex, anatomic site of envenomation, initial severity of envenomation, and geographic region.
This is a post-hoc subgroup analysis of data from a multi-center double-blinded clinical trial of Fab antivenom (FabAV) vs. placebo. Outcomes were the Patient-Specific Functional Scale (PSFS) score at 3, 7, 10, and 14 days after envenomation. Least-squares mean PSFS score curves were calculated for each subgroup, and repeated measures ANOVA was used to estimate between-group comparisons.
Seventy-two subjects were included, of whom 44 received FabAV. Males demonstrated better overall recovery than females (model predicted PSFS score 6.18 vs 4.99; difference 1.19; 95% CI 0.12 to 2.25; p = 0.029). No sex difference was found in response to FabAV. Overall recovery and effect of FabAV were similar in adult vs adolescent patients, patients with upper vs lower extremity envenomation, and patients with initially mild vs moderate envenomation signs. Analysis by geographic location was not successful due to ANOVA mode instability.
Male victims of copperhead snake envenomation demonstrate slightly better recovery than females, but response to Fab antivenom overall is similar across all subgroups studied.
KeywordsEnvenomation Snake Agkistrodon Antivenins Snake Fab Copperhead
Compliance with Ethical Standards
Conflict of Interest
This clinical trial and the subsequent subgroup analysis were funded by BTG International, Inc. In addition, the Denver Health and Hospital Authority (EJL, RJB, JS, and VJA) has research, consulting, and call center agreements with BTG International, Inc., and has completed research arrangements with the manufacturer of a competing antivenom. Duke University (CJG) has received research funding from BTG for projects beyond the current trial. Dr. Green has received income from BTG for professional consulting. No other author has received personal funds or has other conflicts to disclose.
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