Early administration of Fab antivenom resulted in faster limb recovery in copperhead snake envenomation patients

Background: No previous research has studied whether early snake antivenom administration leads to better clinical outcomes than late antivenom administration in North American pit viper envenomation. Methods: A secondary analysis of data from a clinical trial of Fab antivenom (FabAV) versus placebo for copperhead snake envenomation was conducted. Patients treated before the median time to FabAV administration were classified as receiving early treatment and those treated after the median time were defined as the late treatment group. A Cox proportional hazards model was used to compare time to full recovery on the Patient-Specific Functional Scale (PSFS) instrument between groups. Secondary analyses compared estimated mean PSFS scores using a generalized linear model and the estimated proportion of patients with full recovery at each time point using logistic regression. To evaluate for confounding, the main analysis was repeated using data from placebo-treated subjects. Results: Forty-five subjects were treated with FabAV at a median of 5.47 h after envenomation. Patients in the early treatment group had a significantly shorter time to full recovery than those treated late (median time: 17 versus 28 days, p = .025). Model-estimated PSFS scores were numerically higher at each time point in the early group. No difference was found between patients treated early versus late with placebo. Conclusions: In this secondary analysis of trial data, recovery of limb function was faster when Fab antivenom was administered soon after envenomation, as opposed to late administration.

背景：目前尚无研究探讨北美蝮蛇咬伤中毒时，早期给予蛇毒抗血清是否较晚期给药能获得更优的临床结局。方法：本研究针对一项针对铜头蛇咬伤中毒的Fab片段抗蛇毒血清（Fab antivenom, FabAV）与安慰剂对照的临床试验数据进行二次分析。以FabAV给药的中位时间为界，给药时间早于该中位值的患者被纳入早期治疗组，晚于该中位值者则为晚期治疗组。采用Cox比例风险模型比较两组患者采用患者特异性功能量表（Patient-Specific Functional Scale, PSFS）评估的完全恢复时间。二次分析分别采用广义线性模型比较两组的PSFS评分估计均值，采用logistic回归比较各时间点的完全恢复患者比例估计值。为评估混杂因素的影响，本研究还使用仅接受安慰剂治疗的受试者数据重复了主要分析步骤。结果：共45名受试者接受FabAV治疗，给药中位时间为咬伤中毒后5.47小时。早期治疗组患者的完全恢复时间显著短于晚期治疗组（中位恢复时间：17天 vs 28天，p=0.025）。模型估计显示，早期组在各时间点的PSFS评分均略高于晚期组。仅接受安慰剂治疗的受试者中，早期与晚期给药患者的恢复情况无显著差异。结论：基于本次临床试验数据的二次分析结果显示，相较于延迟给药，北美铜头蛇咬伤中毒后尽早给予Fab片段抗蛇毒血清，可更快实现肢体功能恢复。