Half of adults with severe encephalitis requiring intensive care unit care may have poor prognosis at 3 months

1. Poor prognosis (disability or death) at 3 months was observed in half of adult patients with severe encephalitis requiring intensive care unit care.

2. 1-year recovery trajectories varied by cause of encephalitis, with autoimmune encephalitis showing more favorable outcomes than others.

Evidence Rating Level: 2 (Good)

Encephalitis is commonly caused by infectious pathogens, but can also result from autoimmune disorders, toxins, or other diseases. The functional outcomes and long-term recovery following severe encephalitis are not well understood. This study thus aimed to characterize functional outcomes and recovery trajectories through 1 year among adults with encephalitis admitted to the intensive care unit (ICU). This prospective cohort study was conducted across 31 French centers from October 2017 to April 2021 and included adults (>18 years) with probable or confirmed encephalitis requiring ICU care. Causes of encephalitis were split into 4 different categories: infectious, autoimmune, other causes, and unknown origin. The primary endpoint was an unfavorable outcome (severe disability or death) at 3 months, assessed using the modified Rankin scale. Out of the 310 patients were included in the study (median [IQR] age, 60 [43-70] years; 177 male [57.1%]), 123 (39.7%) were diagnosed with infectious encephalitis, 42 (13.5%) with autoimmune encephalitis, 37 (11.9%) with other encephalitis causes, and 108 (34.8%) with encephalitis of unknown origin. At 3 months, 161 patients (51.9%) had an unfavorable outcome, which included 84 deaths (27.1%). Independent factors associated with an unfavorable outcome included age (odds ratio [OR] per 5-year increment, 1.28, 95% CI, 1.16 to 1.41) and immunocompromised status (OR, 3.12; 95% CI, 1.57 to 6.40), while early intravenous acyclovir on the day of ICU admission was associated with a favorable outcome (OR, 0.38; 95% CI, 0.20 to 0.72). From 3 months to 1 year, the proportion of patients achieving functional independence remained unchanged (difference in proportions 1.1%; 95% CI, −6.9% to 9.2%). Patients with autoimmune encephalitis showed improvement through 1 year (difference in proportions, 8.9%; 95% CI, 1.2% to 16.6%), whereas no changes were seen in patients with infectious causes, other causes, or unknown origin. Overall, this study found that about half of adult patients with severe encephalitis requiring ICU care had a poor prognosis at 3 months. Additionally, 1-year recovery trajectories varied by cause of encephalitis, with autoimmune encephalitis showing more favorable outcomes than others. These findings highlight the need for tailored long-term support for patients with encephalitis.

Click to read this study in JAMA Network Open

Image: PD

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