Anti-N-methyl-d-aspartate receptor encephalitis in Maori and Pacific Island children in New Zealand.

AIM: To investigate the incidence and severity of anti-N-methyl-d-aspartate (anti-NMDA) receptor encephalitis in children from New Zealand. METHOD: A retrospective case series was undertaken of all children (≤18y) diagnosed with anti-NMDA receptor encephalitis from January 2008 to October 2015. RESULTS: Sixteen patients were identified with anti-NMDA receptor antibodies in the cerebrospinal fluid, three of whom had an associated teratoma. Fifteen children had Maori and/or Pacific Island ancestry. The incidence of anti-NMDA receptor encephalitis in Maori children was 3.4 per million children per year (95% confidence interval [CI] 1.4-7.0) and the incidence in Pacific children was 10.0 per million children per year (95% CI 4.3-19.8) compared with 0.2 per million children per year (95% CI 0.0-1.0) in children without Maori or Pacific Island ancestry. Sixty-seven per cent of children had a good outcome (modified Rankin Score ≤2) at 2 years' follow-up. This compares unfavourably with other cohorts despite a shorter median time to first-line immunotherapy (13d; range 4-89) and a higher proportion of children being treated with second-line therapy (50%). INTERPRETATION: Maori and Pacific Island children have a higher incidence of anti-NMDA receptor encephalitis and possibly a more severe phenotype. These data suggest a genetic predisposition to anti-NMDA receptor encephalitis in these populations.

Racial and Ethnic Disparities in the Incidence of Anti-NMDA Receptor Encephalitis.

OBJECTIVES: To estimate the incidence of anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis. METHODS: We conducted a retrospective cohort study of >10 million person-years of observation from members of Kaiser Permanente Southern California, 2011-2022. The electronic health record of individuals with text-string mention of NMDA and encephalitis were reviewed to identify persons who met diagnostic criteria for anti-NMDAR encephalitis. Age-standardized and sex-standardized incidences stratified by race and ethnicity were estimated according to the 2020 US Census population. RESULTS: We identified 70 patients who met diagnostic criteria for anti-NMDAR encephalitis. The median age at onset was 23.7 years (IQR = 14.2-31.0 years), and 45 (64%) were female patients. The age-standardized and sex-standardized incidence of anti-NMDAR encephalitis per 1 million person-years was significantly higher in Black (2.94, 95% CI 1.27-4.61), Hispanic (2.17, 95% CI 1.51-2.83), and Asian/Pacific Island persons (2.02, 95% CI 0.77-3.28) compared with White persons (0.40, 95% CI 0.08-0.72). Ovarian teratomas were found in 58.3% of Black female individuals and 10%-28.6% in other groups. DISCUSSION: Anti-NMDA receptor encephalitis disproportionately affected Black, Hispanic, or Asian/Pacific Island persons. Ovarian teratomas were a particularly common trigger in Black female individuals. Future research should seek to identify environmental and biological risk factors that disproportionately affect minoritized individuals residing in the United States.