Burden and cost of comorbidities in patients with neuromyelitis optica spectrum disorder

Background: Neuromyelitis optica spectrum disorder (NMOSD) is associated with various comorbidities, including non-autoimmune and autoimmune conditions. The burden and cost of illness for NMOSD are unclear, particularly in the context of comorbidities. Methods: Claims data from IBM MarketScan Commercial and Medicare Supplemental Databases between 2014 and 2018 were analyzed. Patients with NMOSD were specified as having inpatient or outpatient claims for NMOSD diagnosis or specific NMOSD symptoms claims and no subsequent claims for multiple sclerosis (MS) or use of MS disease-modifying therapy (DMT). Continuous enrollment > 6 months before and > 1 year after the first claim (index date) was required for study inclusion. Total costs stratified by comorbidities within 12 months post-index date were calculated per patient and compared 1:5 with matched non-NMOSD controls. Results: A total of 162 patients with NMOSD and 810 non-NMOSD controls were evaluated. A significantly higher proportion of NMOSD patients had comorbidities than non-NMOSD controls (66.7% vs 41.5%; P < 0.001). Concomitant autoimmune disease occurred in 19.1% vs 4.9% (P < 0.001) of patients with NMOSD vs nonNMOSD controls. NMOSD patients incurred significantly higher total median (interquartile range) healthcare costs per patient ($68,386.48 [$23,373.54-$160,862.70]) than matched non-NMOSD controls with autoimmune disease ($17,215.13 [$6715.48-$31,441.93]; P < 0.001) or patients with NMOSD without autoimmune comorbidity ($23,905.42 [$8632.82-$67,251.54]; P = 0.022). Similarly, patients with NMOSD and nonautoimmune comorbidities incurred higher median healthcare costs than matched controls. Conclusions: Patients with NMOSD experience significant disease burden and cost that are amplified by comorbidities. Effective therapies are needed, particularly for patients with concomitant autoimmune disease.