Prevalence, treatments and medical cost of multiple sclerosis in Japan based on analysis of a health insurance claims database.

Objective: To understand, through an analysis of health insurance claims data, the current treatment status and medical cost of multiple sclerosis (MS) in Japan. Methods: We analyzed claims data (January 2005-January 2016) from the Japan Medical Data Center Co., Ltd., identifying MS patients, except those with neuromyelitis optica, using an algorithm based on diagnosis codes. Prescription drug usage and medical costs for MS patients were analyzed. Results: A total of 713 MS patients were identified in the database. Between 2011 and 2015, the age-adjusted prevalence of MS in the database increased from 0.015% to 0.019%, and the female-to-male ratio increased from 1.70 to 2.03. The prescription rate for disease-modifying therapy drugs was higher in larger care settings. Prescriptions for fingolimod increased from 2011, with a concomitant decrease in prescriptions for interferon. The per patient per month cost for MS was ¥124 337 (US$1190 or €1084, as of October 2016). This was higher than the costs for Parkinson's disease (¥84 410), myasthenia gravis (¥82 944) and rheumatoid arthritis (¥53 843). However, the total per member per month cost for MS, which represents the population-based economic impact, was ¥25.2, which was lower than the parallel costs for Parkinson's disease (¥123.0) and rheumatoid arthritis (¥311.6) because of the low prevalence of MS in Japan. Conclusions: Using real-world data, we obtained up-to-date prevalence, treatment status and medical cost information for MS in Japan. The present results showed the efficacy of a real-world database to obtain the latest national trends for rare diseases, such as MS; this could have important implications for clinicians and policymakers.