Anti-aquaporin-4 antibody in Chinese patients with central nervous system inflammatory demyelinating disorders

To determine seroprevalence of aquaporin-4 (AQP4) antibody in Chinese patients with central nervous system (CNS) inflammatory demyelinating disorders.

AQP4 antibody was detected by anti-AQP4 antibody assay. We measured seroprevalence in 200 patients with neuromyelitis optica (NMO, n=44), multiple sclerosis (MS, n=46), transverse myelitis (TM, n=44), optic neuritis (ON, n=13), acute disseminated encephalomyelitis (ADEM, n=2), and other neurological diseases (OND, n=51).

AQP4 antibody seropositivity was 88.6% in patients with NMO, 4.3% in patients with MS, 30.8% in patients with ON and 51.7% in patients with LETM (longitudinally extensive TM). No patients with acute partial TM, ADEM, OND were positive for AQP4 antibody. Sensitivity of the test was 88.6% (95% CI 80-95) in patients with NMO. Specificity is 97.9% (95% CI 95.1-100) in 46 MS patients, with 51 OND patients as the control group. If the patients with recurrent ON, LETM were considered high risk for NMO (n=37) and the remaining patients (n=119) were considered controls, the sensitivity of this assay would be 48.6% (95% CI 33.4-64.1) and the specificity 97.5% (95% CI 94.7-100).

This study confirms that AQP4 antibody is a sensitive and specific biomarker for discrimination between NMO and other CNS autoimmune diseases.