Prognostic factors and tumor predictors in anti-AMPAR encephalitis: A combined cohort analysis

The prognostic factors in patients with antibodies against the α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor (AMPAR) and predictors of associated tumors remain poorly understood.

This study used longitudinal data from 92 patients: 6 diagnosed at our hospital and 86 identified through systematic review. Clinical manifestations, treatment responses, and outcomes were analyzed.

Among the 92 patients, 75 (81.5%) had concurrent tumors. Tumors were diagnosed in 17 cases before encephalitis onset, 35 within one month after onset, 14 within 1-6 months. The absence of tumor association in anti-AMPAR encephalitis was defined as no tumor detected during a follow-up period exceeding one year. Multivariate binary logistic regression identified prognostic factors for poor outcomes: age ≥ 61 years (OR = 11.368, 95% CI: 1.723-75.013, p = 0.012), tumor status (p = 0.043), and the modified Rankin Scale score at diagnosis (OR = 1.911, 95% CI: 1.036-3.523, p = 0.038). The model showed an area under the curve (AUC) of 0.827 (95% CI: 0.738-0.916, p < 0.001). Two predictors of associated tumor were identified: mental disorders (OR = 11.338, 95% CI: 1.518-84.672, p = 0.018) and multiple anti-neuronal antibodies (OR = 13.751, 95% CI: 1.150-164.450, p = 0.038). This model demonstrated an AUC of 0.850 (95% CI: 0.735-0.965, p < 0.001).

Our study indicates the critical importance of close follow-up in the first six months after anti-AMPAR encephalitis onset. Older age, concurrent tumors, and severe symptoms predict poor prognosis, while mental disorders and multiple anti-neuronal antibodies increase the likelihood of tumor occurrence.