The EDSS measures disability status on a scale ranging from 0 to 10, with higher scores indicating more disability. Scoring is based on measures of impairment in eight functional systems on examination by a neurologist. Participants with confirmed progression of disability in EDSS physical functional system scores will be defined as those who meet one of the following criteria: an increase of ≥ 1 point from baseline system score of ≥ 1 or an increase of ≥ 2 points from baseline system score of 0 in at least 2 physical functional systems, or an increase of ≥ 2 points from baseline system score of ≥ 1 or an increase of ≥ 3 points from baseline system score of 0 in any 1 physical functional system. Worsening must be confirmed on a subsequent examination using the same criterion in the same functional system(s) at least 6 months later.

The 29-item Multiple Sclerosis Impact Scale (MSIS-29) is a patient-reported outcome measure to assess the impact of MS on day-to-day life during the past 2 weeks from a patient's perspective; it measures 20 physical items and 9 psychological items. The physical score is generated by summing individual items and then transforming to a scale with a range of 0 to 100, where high scores indicate worse health.

The 29-item Multiple Sclerosis Impact Scale (MSIS-29) is a patient-reported outcome measure to assess the impact of MS on day-to-day life during the past 2 weeks from a patient's perspective; it measures 20 physical items and 9 psychological items. The physical score is generated by summing individual items and then transforming to a scale with a range of 0 to 100, where high scores indicate worse health.

Descriptive system of health-related quality of life states consisting of five dimensions (mobility, self-care, usual activities, pain/discomfort, anxiety/depression) each of which can take one of five responses. The responses record five levels of severity (no problems/slight problems/moderate problems/severe problems/extreme problems) within a particular EQ-5D dimension.

Standard vertical 20 cm visual analogue scale (similar to a thermometer) for recording an individual's rating for their current health-related quality of life state (often referred to as page 3 of the EQ-5D questionnaire)

MFIS-5 is a modified form of the Fatigue Impact Scale that consists of five questions that assess the impact of fatigue on physical, cognitive, and psychosocial functioning, with five response levels ranging from 0 ("Never") to 4 ("Almost always"). Total scores range from 0 to 20, with higher scores representing a greater impact of fatigue.

The Work Productivity and Activity Impairment (WPAI) questionnaire is a validated instrument to measure impairments in work and activities. The WPAI yields four types of scores: 1. Absenteeism (work time missed) 2. Presenteesism (impairment at work / reduced on-the-job effectiveness) 3. Work productivity loss (overall work impairment / absenteeism plus presenteeism) 4. Activity Impairment. WPAI outcomes are expressed as impairment percentages, with higher numbers indicating greater impairment and less productivity.

The Health Care Resource Consumption questionnaire is a survey that asks patients how MS affects their use of healthcare services and the impact it has on particular areas of their life (including number of hospitalizations [MS-related, non-MS related, relapse-related, resulting in steroid use], MS-related emergency room visits, MS-related neurologist visits, visits to other health care professionals for MS-related and other reasons).