Low uric acid predicts severe outcomes in neuronal surface antibody-mediated autoimmune encephalitis

BACKGROUND: Autoimmune encephalitis (AE) mediated by neuronal surface antibodies is a severe neuroinflammatory disorder with heterogeneous clinical manifestations. Early identification of patients at risk for severe outcomes, such as intensive care unit (ICU) admission, remains a challenge. Uric acid (UA), known for its dual role in inflammation as both a danger-associated molecular pattern (DAMP) and an antioxidant, has been implicated in various autoimmune diseases, but its prognostic significance in AE has not been systematically explored. METHODS: This retrospective study enrolled 90 patients with neuronal surface antibody-positive AE. Serum UA levels were measured at admission, and clinical outcomes, including Clinical Assessment Scale for Autoimmune Encephalitis (CASE), discharge modified Rankin Scale (mRS) and ICU admission were analyzed. Statistical methods included Spearman correlation, logistic regression, and receiver operating characteristic (ROC) curve analysis to evaluate predictive value of UA. RESULTS: Patients requiring ICU admission had significantly lower UA levels (median 193.0 vs. 250.0 µmol/L, p = 0.008). UA negatively correlated with CASE scores (r = -0.237, p = 0.024) and discharge mRS (r = -0.267, p = 0.011). Logistic analysis identified UA as a potential adjunct biomarker of ICU admission (yes/no) (OR = 0.985, 95%CI:0.971-1.000, p = 0.044), with an optimal cutoff of 213.5 µmol/L (AUC = 0.703, sensitivity 63.9%, specificity 77.8%). Patients with UA < 213.5 µmol/L were older and had higher CASE scores and worse functional outcomes (p < 0.05). CONCLUSION: Decreased serum UA at admission is associated with increased risk of ICU admission in neuronal surface antibody-mediated AE, and correlate with a more severe disease severity and poorer functional outcomes, suggesting its potential as a prognostic biomarker, possibly reflecting its neuroprotective role.