Association between early initiation of anti-herpesvirus therapy and outcomes in herpesvirus encephalitis: A Nationwide Retrospective Propensity Score Analysis in Japan.

BACKGROUND

Prompt initiation of anti-herpesvirus therapy is critical in managing herpes simplex virus encephalitis (HSE). However, real-world evidence on the impact of treatment timing remains limited.

METHODS

We conducted a nationwide retrospective cohort study using the Diagnosis Procedure Combination (DPC) database in Japan from July 2010 to March 2023. Patients with HSE who received intravenous anti-herpesvirus therapy during hospitalization were included. Patients were classified into early (initiated on admission day) and delayed (day 2 or later) treatment groups. Inverse probability of treatment weighting (IPTW) was used to adjust for baseline differences. The primary outcome was in-hospital mortality; secondary outcomes included the composite outcome of death or impaired consciousness at discharge, impaired functional status (Barthel Index <90), total hospitalization cost, and length of stay.

RESULTS

Of 6788 patients, 4368 (64.3%) received anti-herpesvirus therapy on admission day. After IPTW, early treatment was associated with lower in-hospital mortality (odds ratio, 0.51; 95% confidence interval, 0.41-0.62), reduced composite poor outcome (0.70; 0.63-0.78), reduced Barthel Index <90 (0.62; 0.56-0.69), reduced hospitalization cost (-310,000 yen; -403,000 to -216,000), and reduced length of stay (-8.3 days; -10.7 to -5.9).

CONCLUSION

Early anti-herpesvirus therapy was associated with improved survival, functional outcomes, and lower resource utilization in HSE.