Antibody prevalence and immunotherapy response in Chinese patients with epilepsy and encephalopathy scores for patients with different neuronal surface antibodies

BACKGROUND: The scale assessment was helpful in predicting the presence of antibodies to autoimmune encephalitis. This study aimed to evaluate the application of antibody prevalence in Chinese patients with epilepsy and encephalopathy (APE2-CHN) and response to immunotherapy in Chinese patients with epilepsy and encephalopathy (RITE2-CHN) for patients with different neuronal surface antibodies. METHODS: A total of 1365 patients with epileptic seizures as the prominent feature in Xuanwu Hospital, Capital Medical University, from June 2016 to June 2020 were enrolled in our study. Of these, 915 patients with epilepsy of unknown etiology whose serum and/or cerebrospinal fluid samples were examined for autoimmune antibodies were selected. All patients were scored with antibody prevalence in patients with epilepsy and encephalopathy (APE2), response to immunotherapy with epilepsy and encephalopathy (RITE2), APE2-CHN, and RITE2-CHN scores. RESULTS: Of the 915 patients, 191 patients were positive for neural-surface specific antibodies (115 N-methyl-D-aspartate receptor (NMDAR) Ab, 47 leucine-rich glioma-inactivated protein 1 (LGI1) Ab, 8 contactin-associated protein 2 (CASPR2) Ab, 4 AMPA2R-Ab, and 11 GABAR-B-Ab; 3 CASPR2-Ab and LGI1-Ab, 2 NMDAR-Ab and CASPR2-Ab, and 1 NMDAR-Ab and myelin-oligodendrocyte glycoprotein [MOG] Ab). The sensitivity and specificity of APE2 ≥4 in predicting the presence of neural-surface specific antibodies in our study were 74.35% and 81.77%, respectively, and the sensitivity and specificity of APE2-CHN ≥4 were 75.92% and 84.53%, respectively. Eight cases had an APE2 score <4 and APE2-CHN score ≥5; all these patients had memory decline as the prominent manifestation. We divided the patients into six groups according to the different antibodies. APE2-CHN scores showed higher sensitivity for the prediction of NMDAR-Ab, but lower sensitivity for LGI1-Ab. A total of 187/191 (97.91%) patients received immunotherapy and 142/191 (74.35%) patients benefited from the treatments. The patients who were positive for LGI1-Ab with RITE2-CHN ≥8 responded well to immunotherapy. CONCLUSIONS: APE2-CHN had the highest value for predicting the positivity of NMDAR-Ab and RITE2-CHN evaluated the response of immunotherapy for anti-LGI1 encephalitis appropriately. However, RITE2 and RITE2-CHN do not appear to be good predictors of immunotherapy outcomes for patients with specific neuronal-surface antibodies and high APE2-CHN scores are often indicative of a poor response to immunotherapy.