Polyautoimmunity and multiple autoimmune syndrome in patients with neuromyelitis optica spectrum disorder

The coexistence of neuromyelitis optica spectrum disorders (NMOSD) with other autoimmune diseases (AID) has been increasingly reported. The prevalence and significance of this association are not fully understood.

This study aimed to compare the clinical and laboratory characteristics in NMOSD patients with and without AID.

Retrospective cross-sectional observational study was conducted involving adults meeting NMOSD criteria followed in a neuroimmunology clinic at a tertiary center. Descriptive analysis of clinical/paraclinical/treatment/outcome data collected from the medical records was compared between NMOSD patients with AID (polyautoimmunity) and those without AID.

From a cohort of 46 NMOSD patients, 16 (34.8 %) patients, mostly women around 40 years of age, presented with polyautoimmunity: 10 anti-AQP4 positive, 4 anti-MOG positive, and 2 seronegative. Five different organ -specific AID, and six systemic AID were identified in the polyautoimmunity patients group, in addition to 6 cases of multiple autoimmune syndrome. The AID manifestation preceded NMOSD in 10 (62.5 %) patients, with a median interval of 7 years. The NMOSD with polyautoimmunity and NMOSD without AID groups had similar initial clinical manifestations with optic neuritis and/or myelitis being most frequent. Inflammatory CSF, namely elevated proteins, was more common in the polyautoimmunity group (13.0 % in NMOSD vs. 31.3 % in NMOSD+AID, p = 0.003). After a 10±6 years follow-up period, more patients with polyautoimmunity had a relapsing disease (75.0 % in NMOSD vs. 46.7 % in NMOSD+AID, p = 0.012) but no difference in the functional outcome evaluated by the EDSS score was identified.

Polyautoimmunity was common in AQP4 positive NMOSD patients leading to a significantly higher risk of disease recorrence. The presence of polyautoimmunity and multiple autoimmune syndrome in NMOSD patients suggests the existence of common susceptibility factors or pathophysiological mechanisms, emphasizing the importance of a multidisciplinary approach to those patients.