Outcomes Associated With the Timing of Antivenom Administration in Bothrops and Crotalus Snakebite Envenomations

Snakebite envenomation is a significant public health problem. We aimed to analyze the clinical outcomes associated with the timing of antivenom administration in Bothrops and Crotalus snakebite envenomations.

This descriptive, retrospective, census-based cohort study included patients who attended the Toxicological Information and Assistance Center-Londrina from 2017 to 2024. Sociodemographic, clinical, exposure-related, and antivenom therapy data were obtained from the national DATATOX system and clinical records. Descriptive statistics and Poisson regression (for relative risks [RRs] and 95% confidence intervals [CIs]) were used; significance was set at p<0.05.

Data from 1,162 cases were analyzed, with 72.8% caused by Bothrops and 27.2% by Crotalus. Most patients were male (78.6%), rural workers (59.0%), and residents of rural areas (88.4%). Antivenom therapy was administered with 98.2% adequacy, according to institutional protocols. The median time from bite to completion of antivenom infusion was 450 minutes, with 75% of patients treated within 12 hours; 2.7% of patients developed renal complications and 1.1% died. Both outcomes were more frequent among patients with longer intervals between the bite and antivenom administration (>75th percentile). In the crude analysis, delays were associated with renal complications (RR: 3.21; 95% CI: 1.61-6.41; p=0.001) and death (RR: 4.81; 95% CI: 1.59-14.59; p=0.006). After adjustment, the association remained significant for renal complications (RR: 2.88; 95% CI: 1.37-6.06; p=0.005), but not for death.

Delayed antivenom administration is associated with an increased risk of renal complications, reinforcing the timing of therapy as a critical and modifiable factor influencing snakebite outcomes.