Crystal Watson,1 Christine Prosser,2 Sebastian Braun,2 Pamela B Landsman-Blumberg,3 Erika Gleissner,4 Sarah Naoshy1 1Health Economics and Outcomes Research, Global Market Access, Biogen, Cambridge, MA, USA; 2Real World Evidence, Xcenda GmbH, Hanover, Germany; 3Applied Data Analytics, Xcenda LLC, Palm Harbor, FL, USA; 4Market Access, Biogen, Ismaning, Germany Background: Multiple sclerosis (MS), a progressive neurodegenerative disease, greatly impacts the quality of life and economic status of people affected by this disease. In Germany, the total annual cost of MS is estimated at €40,000 per person with MS. Natalizumab has shown to slow MS disease progression, reduce relapses, and improve the quality of life of people with MS.Objective: To evaluate MS-related and all-cause health care resource utilization and costs among German MS patients during the 12 months before and after initiation of natalizumab in a real-world setting.Methods: The current analysis was conducted using the Health Risk Institute research database. Identified patients were aged ≥18 years with ≥1 diagnosis of MS and had initiated natalizumab therapy (index), with 12-month pre– and post–index-period data. Patients were stratified by prior disease-modifying therapy (DMT) usage or no DMT usage in the pre-index period. Outcome measures included corticosteroid use and number of sick/disability days, inpatient stays, and outpatient visits. Health care costs were calculated separately for pre- and post-index periods on a per-patient basis and adjusted for inflation.Results: In a final sample of 193 natalizumab-treated patients, per-patient MS-related corticosteroid use was reduced by 62.3%, MS-related sick days by 27.6%, and inpatient costs by 78.3% from the pre- to post-index period. Furthermore, the proportion of patients with MS-related hospitalizations decreased from 49.7% to 14.0% (P<0.001); this reduction was seen for patients with and without prior DMT use.Conclusions: In a real-world setting in Germany, initiation of natalizumab treatment in people with MS significantly reduced MS-related hospitalizations, corticosteroid use, sick days, and associated costs. Keywords: multiple sclerosis, relapsing–remitting, health care resource utilization, costs, outcomes, natalizumab