Application of the APE2-CHN and RITE2-CHN scores for autoimmune epilepsy in Chinese patients: a retrospective study

Abstract Background : Autoimmune epilepsy is recognized as a distinct entity of epilepsy with underestimated incidence. Our previous study reported that prompt diagnosis and early-initiated immunotherapy led to better outcome. We proposed to assess the feasibility and reasonability of the Antibody Prevalence in Chinese Patients with Epilepsy and Encephalopathy (APE 2 -CHN) and Response to Immunotherapy in Chinese Patients with Epilepsy and Encephalopathy (RITE 2 -CHN) scores in predicting Chinese patients with autoimmune epilepsy. Methods : We conducted a retrospective study of consecutive patients from Xiangya Hospital, Central South University (01/01/2017-02/28/2019) whose serum and/or cerebrospinal fluid (CSF) samples were examined for autoimmune encephalitis antibodies. Of these, patients with new-onset epilepsy or established epilepsy of unknown etiology were selected in our study. An APE 2 -CHN score was assigned to each patient and a RITE 2 -CHN score was calculated for each patient who received immunotherapy. Results : 191 patients meeting the diagnostic criteria for epilepsy were enrolled in our study. 36 were subsequently identified with specific etiologies. The rest of the 155 patients had an unknown etiology. Central nervous system-specific antibodies were detected in 76 (49.0%) of them, after excluding solely thyroid peroxidase antibody or glutamic acid decarboxylase antibody. N-methyl-D-aspartate receptor antibody (48.7%, 37/76) was the most common antibody specificity, followed by γ-aminobutyric acid type B receptor antibody (14.5%, 11/76). Certain clinical features such as new-onset epilepsy, autonomic dysfunction, viral prodrome, facio-brachial dystonic seizures/oral dyskinesia, inflammatory CSF profile, and mesial temporal magnetic resonance imaging abnormalities correlated with positive antibody results. Sensitivity and specificity of an APE 2 -CHN score ≥ 5 to predict the presence of specific neural auto-antibodies in our study were 85.5% and 58.9%, respectively. In the subset of patients who received immunotherapy (n = 112), sensitivity and specificity of a RITE 2 -CHN score ≥ 8 to predict favorable seizure outcome were 98.6% and 63.2% respectively. Conclusion : The APE 2 -CHN and RITE 2 -CHN scores were preferable tools in predicting positive serologic findings and prognosis of autoimmune epilepsy in Chinese patients with epilepsy.