Investigation of health care use and a possible prodrome before the first attack in NMOSD and MOGAD.

ABSTRACT

BACKGROUND: Prodromal phases are well recognized in many inflammatory and neurodegenerative diseases, including multiple sclerosis. We evaluated the possibility of a prodrome in aquaporin-4 antibody positive (AQP4+) neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein antibody disease (MOGAD) using health administrative data. METHODS: We investigated individuals with AQP4 + NMOSD and MOGAD, confirmed by medical chart review, in Ontario, Canada. Each NMOSD and MOGAD participant was matched 15 to general population controls by sex, birth year, immigrant status, and region. Total outpatient visits and hospitalizations were compared in the 5 years preceding the incident attack in multivariable negative binomial models. RESULTS: We identified 96 people with AQP4 + NMOSD, matched to 479 controls, and 61 people with MOGAD, matched to 303 controls. In the 5 years preceding the incident attack, health care use was elevated for outpatient visits and hospitalizations for the NMOSD cohort (adjusted rate ratio (aRR) 1.47; 95% confidence interval (CI) 1.25-1.73; aRR 1.67; 95% CI 1.19-2.36, respectively) but not for MOGAD. Rate ratios steadily increased in NMOSD for outpatient visits in the 2 years preceding the incident attack. CONCLUSION: Our findings support a prodromal phase preceding clinical onset of AQP4 + NMOSD. Earlier recognition and management of NMOSD patients may be possible.