Risk factors for poor response to initial first-line immunotherapy and subsequent immunotherapy on prognosis in pediatric anti-NMDA receptor encephalitis.

Objective: To identify factors associated with poor response to initial first-line immunotherapy in pediatric patients with anti-NMDAR encephalitis.

Methods: This monocentric prospective cohort study included pediatric anti-NMDAR encephalitis between January 2017 and December 2021. The modified Rankin Scale (mRS) score was used to assess neurological severity.

Results: This study included 152 patients, 74 of them (48.7%) had a poor response to initial first-line immunotherapy. Decreased consciousness (p = 0.001, OR = 6.889), autonomic dysfunction/central hypoventilation (p = 0.003, OR = 4.704), speech dysfunction (p = 0.007, OR = 4.272), mRS score before immunotherapy > = 4 points (p < 0.001, OR = 10.968), and age < = 3 years (p = 0.044, OR = 5.169) significantly affected the response to initial first-line immunotherapy. At 12 months, the good responders demonstrated a significantly better outcome than did the poor responders (100% vs. 74.3%, p < 0.001), although the recurrence rate was comparable between the two group (11.5% vs. 14.9%, p = 0.544). Of the 74 poor responders, 45 patients underwent subsequent immunotherapy, and they exhibited a greater proportion of favorable outcomes compared to the group without subsequent immunotherapy at 12 months.

Conclusions: Pediatric anti-NMDAR encephalitis with decreased consciousness, autonomic dysfunction/central hypoventilation, speech dysfunction, mRS score > = 4 points before immunotherapy, and age < = 3 years had a greater risk of poor response to initial first-line immunotherapy, and poorer prognosis. Subsequent immunotherapy can improve long-term prognosis for poor responders.