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

Abstract

Purpose: To assess the performance of the Antibody Prevalence in Chinese Patients with Epilepsy and Encephalopathy (APE²-CHN) and Response to Immunotherapy in Chinese Patients with Epilepsy and Encephalopathy (RITE²-CHN) scores in Chinese patients with epilepsy of unknown etiology.

Methods: We conducted a retrospective study of selected 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 diagnostic code of seizure or epilepsy were selected in our study. An APE²-CHN score was assigned to each patient and a RITE²-CHN score was calculated for each patient who received immunotherapy. Receiver-operating characteristic (ROC) curve was used to assess each score.

Results: 191 patients were enrolled in our study. 36 were identified with specific etiologies. The remaining 155 patients had unknown etiology. Central nervous system-specific antibodies were detected in 76 (49.0 %) patients, after excluding patients with only anti-thyroid peroxidase or glutamic acid decarboxylase antibodies. N-methyl-d-aspartate receptor (NMDAR) antibody (48.7 %, 37/76) was the most common subtype of our sample, followed by γ-aminobutyric acid type B receptor (GABAR) (14.5 %, 11/76). Clinical features including new-onset epilepsy, neuropsychiatric changes, speech disorder, movement disorder and inflammatory CSF profile correlated with positive antibody results. The sensitivity and specificity of APE²-CHN ≥ 5 in predicting the presence of neural-specific autoantibodies 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 RITE² -CHN ≥ 8 in predicting favorable seizure outcome were 98.6 % and 63.2 % respectively. The area under the curve (AUC) of RITE²-CHN was greater than that of RITE² (Z = 3.196, p < 0.05) while there was no significant difference in AUC between APE² and APE²-CHN (Z = 1.058, p = 0.290).

Conclusion: The APE²-CHN and RITE²-CHN scores may be useful screening tools in predicting positive antibody findings and prognosis of suspected autoimmune seizures or associated epilepsy in the Chinese population.

Keywords: Autoimmune seizures; Diagnosis; Immunotherapy.