Neuromyelitis optica spectrum disorder in Germany: A claims data analysis of incidence, prevalence, treatment patterns, and diagnostic overlap with multiple sclerosis

Background Neuromyelitis optica spectrum disorders (NMOSD) are rare autoimmune diseases of the central nervous system. Global prevalence estimates vary widely, and data for Germany are limited. Objectives To estimate NMOSD prevalence, incidence, diagnostic settings, comorbid coding with multiple sclerosis (MS), and treatment patterns in Germany. Methods We analyzed German BARMER health insurance claims data (approximately 9 million persons; 2015–2022). NMOSD cases were identified by ICD-10-GM code G36.0. Frequencies, diagnostic settings, comorbid MS coding (G35.-), and treatment patterns (Anatomical Therapeutic Chemical codes) were assessed. Results We identified 527 incident NMOSD cases (0.82 per 100,000 insured persons per year); 69% were female, and 42% aged 40–59 years. Most diagnoses occurred in outpatient care (63%), primarily by neurologists (48%) or general practitioners (28%). Prevalence increased from 2.9 to 4.7 per 100,000 between 2015 and 2022, while NMOSD-specific medication use rose from 16% to 31%. NMOSD and MS codes co-occurred in 64% of cases; 49% had concurrent diagnoses within 9 months, and 42% were first diagnosed with MS. Conclusion NMOSD prevalence and incidence in Germany are increasing, with frequent diagnostic overlap with MS. Findings highlight the need for improved diagnostic differentiation and early specialist involvement.