# The OROCHI (Observational Research of Clinical Course After mamusHI) Study: A Prospective, Observational, Multicenter Study on the Efficacy of Mamushi (Gloydius blomhoffii) Antivenom Serum

## TL;DR

This study examined the effectiveness of antivenom serum for mamushi snake bites and found no significant reduction in hospital stays but observed some benefits in pain and swelling.

## Contribution

This is the first multicenter observational study evaluating the efficacy of mamushi antivenom serum in Japan.

## Key findings

- Mamushi antivenom serum did not significantly reduce hospital stay duration compared to no treatment.
- Pain and swelling were worse in the antivenom group immediately after treatment but not after 48 hours.
- Cepharanthine treatment was associated with longer hospital stays compared to antivenom.

## Abstract

Background: Evidence on the efficacy of mamushi antivenom serum is limited.

Objective: To investigate the effectiveness of mamushi (Gloydius blomhoffii) antivenom serum.

Methods: The Observational Research Of the Clinical course after mamusHI bite (OROCHI) study was a prospective multicenter study conducted at 24 hospitals in Japan. Patients hospitalized due to mamushi bite were registered. The primary endpoint was the length of hospital stay. Secondary endpoints were adverse effects, pain (numerical rating scale), and grade of swelling. We performed a cohort analysis to compare outcomes between patients treated with mamushi antivenom serum (antivenom group) and those who were not treated with the serum (no-antivenom group).

Results: Overall, 106 patients were registered across 18 hospitals between April 22, 2020, and October 31, 2022. Of these, 92 were eligible for the analyses, with 53 and 39 in the antivenom and no-antivenom groups. The median (interquartile) length of hospital stay was not significantly different between the antivenom and no-antivenom groups (5 (3-6) days vs. 3 (1-8) days, P = 0.369). In multivariable analysis, the adjusted odds ratio for a hospital stay of >4 days was 1.331 in patients treated with mamushi antivenom serum (95% confidence interval (CI) = 0.744‒2.015, P = 0.574) and 6.154 in patients treated with cepharanthine (95% CI = 1.442-26.258, P = 0.014). Pain and the grade of swelling were worse in the antivenom group than in the no-antivenom group up to 24 h after arrival, but there were no differences in these outcomes after 48 h.

Conclusion: Although the effectiveness of mamushi antivenom serum in reducing the length of hospitalization was not demonstrated, beneficial effects on pain and swelling were observed.