OBJECTIVES: Anti-aquaporin-4 autoantibody positive neuromyelitis optica spectrum disorder (AQP4+ NMOSD) is a rare disease of the central nervous system characterised by unpredictable attacks that can cause blindness, paralysis, cognitive impairment, and death. This study examined mortality in patients with AQP4+ NMOSD.

METHODS: A cohort of patients from the UK National NMOSD Data Set maintained by Oxford University Hospital (Oxford, UK) was followed over a 6-year period (2014–2020) and used to compare mortality among patients with AQP4+ NMOSD versus the general population. Age- and sex-matched adults from the general UK population (2019 data) were used for comparison. The standardized mortality ratio (SMR) is the ratio of the observed number of deaths in patients with AQP4+ NMOSD versus the number of deaths expected in the age- and sex-matched cohort of the general population. Excess mortality was calculated by subtracting the expected mortality from the observed mortality in patients with AQP4+ NMOSD. An SMR of > 1.0 was used to indicate excess death; excess mortality was represented by > 0%.

RESULTS: Seventy-four patients with AQP4+ NMOSD were included in the analysis. The mean age was 54 years (standard deviation: 17 years; range: 18-85 years); 65/74 (87.8%) patients were female. Mean and median disease durations were 7.7 and 8.0 years, respectively. The mean annual death rate among patients with AQP4+ NMOSD was 2.64%, with mean and median ages at death of 63 and 66 years, respectively. The average weighted mortality rate of the age- and sex-matched general population was 0.71%, resulting in an SMR of 3.72 (95% confidence interval: 3.71–3.72) and an excess mortality rate of 1.93% annually among patients with AQP4+ NMOSD.

CONCLUSIONS: The excess mortality of patients with AQP4+ NMOSD is 1.93% annually, suggesting that despite available treatment options, NMOSD negatively affects the mortality of patients who are AQP4+.