Resource utilization, costs and treatment patterns of switching and discontinuing treatment of MS patients with high relapse activity

BACKGROUND: Multiple sclerosis (MS) is a chronic disease that affects mainly adults in the prime of their lives. However, few studies report the impact of high annual relapse rates on outcomes. The purpose of this study was to identify high relapse activity (HRA) in patients with MS, comparing differences in outcomes between patients with and without HRA. METHODS: A retrospective longitudinal study was conducted using the MarketScan® Commercial Claims and Encounters and Medicare Supplemental Database. Patients had to have at least one ICD-9 for MS (340.XX) in 2009 and one in 2008, be older than 18 years, and have continuous enrolment in the years 2009–2010. HRA was defined as having ≥2 relapses in 2009. Multivariate analyses compared all-cause and MS-specific emergency room (ER) visits, hospitalizations, and all-cause costs, excluding disease modifying therapy (DMT) costs, in 2010 between patients with and without HRA, controlling for baseline characteristics. A subgroup analysis using treatment exposure was also performed. RESULTS: 19,219 patients were included: 5.3% (n=1,017) had ≥2 relapses in 2009. Patients with HRA were more likely to have all-cause and MS-specific resource utilization than patients without HRA. Mean total all-cause non DMT costs were $12,057 higher for the HRA group. In the subgroup analysis, HRA treatment-naïve patients were more likely to start treatment, and HRA treatment-experienced patients were more likely to discontinue or switch index DMT (P<0.01). CONCLUSIONS: Patients with ≥2 relapses annually have higher resource utilization and costs. The difference in cost was over twice as large in treatment-naïve patients versus treatment-experienced patients. HRA was also associated with an increased likelihood of starting DMT treatment (treatment-naïve patients), and switching or discontinuing DMT therapy (treatment-experienced patients).