High-dose thiamine use increased for Wernicke encephalopathy in Japan; functional impairment common at discharge.

Background: Clinical evidence on the contemporary management and functional outcomes of patients with Wernicke encephalopathy remains limited. This study aimed to clarify the nationwide patterns of thiamine administration and functional outcomes at discharge. Methods: Using the Japanese nationwide inpatient Diagnosis Procedure Combination database, we identified patients hospitalized with Wernicke encephalopathy between July 2010 and March 2024. Initial intravenous thiamine doses were categorized as low ([&le;]300 mg/day), medium (301-900 mg/day), or high (>900 mg/day). Outcomes included in-hospital mortality and functional status (Barthel Index) at discharge. Results: We identified 7856 patients with Wernicke encephalopathy. Over the 13-year study period, the proportion of patients receiving initial high-dose thiamine increased markedly from 5.4% to 49.0%, while the frequency of low-dose therapy decreased from 83.0% to 37.9%. Despite prompt intervention [median time to initial administration: 0 days (interquartile range, 0 to 0 days)], 56.1% of patients were discharged with impaired activities of daily living (Barthel Index <90), and the in-hospital mortality rate was 3.8%. Conclusions: High-dose thiamine treatment is increasingly implemented for Wernicke encephalopathy in Japan. Although in-hospital mortality was relatively low, the high prevalence of functional impairment at discharge, despite early treatment initiation, indicates substantial burden of Wernicke encephalopathy. Given the limited clinical evidence, further research investigating the optimal thiamine dose and develop effective primary prevention strategies for Wernicke encephalopathy is needed.