The primary aim of this project is to determine whether there are differences in access to, efficacy and tolerability of Ocrelizumab in men and women of different racial and ethnic origins and socio-economic backgrounds with RRMS and PPMS in two large academic MS Centers with a high volume of patients on Ocrelizumab. The study is a retrospective analysis of multiple sclerosis patients cared for at Brigham and Women's Hospital and Boston Medical Center who were treated with Ocrelizumab during the 4 year study period.

This study will be a two-center retrospective/observational analysis with data collected from the Research Patient Data Registry (RPDR), Brigham Multiple Sclerosis Center Patient Database (Oracle), and Boston Medical Center MS Clinic Database (BMC-MS).

Using the Oracle database, BMC-MS database and electronic medical records (EPIC), the investigators will capture all MS patients who satisfy inclusion criteria. This study will collect age, sex, race, socio-economic status by residence zip code, disease duration, previous treatment, current treatment status, the reason for discontinuing or switching to another treatment, expanded disability status scale (EDSS), and functional systems scores (FSS) where available.

Additionally, the investigators will collect the date, dose, and interval between each ocrelizumab infusion, as well as any pertinent laboratory values and MRI scan results.

Inclusion Criteria:

• All MS patients at the Brigham MS Center and Boston Medical Center MS Clinic who have been diagnosed with RRMS or PPMS, ages 18 or older, on Ocrelizumab for at least one year and have received at least 3 treatments (two loading treatments of 300mg each, and one full dose treatment of 600 mg), who have been followed at these institutions for clinical care and brain and/or spinal cord MRI, and who have received Ocrelizumab infusions at these institutions for the duration of the study period.

Exclusion Criteria:

• Simultaneous use of high dose monthly IV steroids,
• Secondary progressive MS (SPMS) disease category,
• Additional serious medical or neurologic co-morbid diseases,
• Additional concomitant immunosuppressive therapy of any kind,
• Additional concomitant MS-specific therapy (DMT) of any kind,
• Change of infusion or care site and absence of neurologic or imaging follow-up.

Adult patients with relapsing remitting or primary progressive MS evaluated at Brigham and Women's Multiple Sclerosis Clinic or Boston Medical College Multiple Sclerosis Clinic between 03/2017 and 07/2021 who were started on ocrelizumab in that time period.