To enable emergency physicians to make well-informed triage and treatment decisions, accurate tools to evaluate the severity of diquat poisoning are needed. This study establishes severity indices for diquat poisoning (SIDPs) in assessing the risk of death for patients with acute diquat poisoning for triage purposes and 28-day mortality.

Self-poisoning with pesticides is a global public health concern, and its effective control is of importance in reducing both morbidity and mortality. In China, poisoning consistently ranked as the fifth leading cause of death from 2009 to 2013, and the overall incidence rate was 39.43/100,000 population in 2019, with intentional poisoning, mostly related to self-harm. Paraquat (1,1'-dimethyl-4,4'-bipyridinium) and, after its ban in China, diquat (1,1'-ethylene-2, 2'-bipyridinium) are the agents with the highest rate of mortality due to their inherent toxicity affecting various organs paired with a lack of effective treatments. As reported from different hospitals, the inhospital case fatality rate of diquat poisoning was 18.6%, whereas the proportion of case fatalities increased to 60% after follow-up in China. Although uncommon, diquat poisoning occurs in many countries, including the United States, where 2,128 cases were identified between 1998 and 2011, and 466 cases were documented in 2023, according to the Annual Report of the National Poison Data System. The lethality of diquat underscores the necessity for precise prognosis. Estimating survival probability empowers physicians to tailor treatment decisions for patients and enhance communication, especially given the variability in capability of emergency departments (EDs) around the world.

The following criteria were used for patient inclusion:

1. history of oral exposure to diquat solution reported by patient or proxy;
2. a specimen for the diquat plasma concentration collected immediately upon admission;
3. documentation that patients or, in case of unconsciousness of the patient, legal proxies were aware of and agreed to treatment plans.

Patients were excluded if:

1. they had ingested other toxicants in addition to diquat;
2. diquat was not detected in biological samples;
3. patients with over half of incomplete information;
4. patients with an exposure time (time from exposure to presentation at ED) longer than 48 hours.

Patients with acute diquat poisoning