Fatigue is the most common symptom and the most disabling symptom of Multiple Sclerosis, and its inefficient management can be a source of multiple consultations (increase in health costs) and a reduction in productivity (work stoppages).

Hence the need to define the most effective therapeutic strategy to reduce fatigue in Multiple Sclerosis.

One of the aims of this project is to provide clinical indicators that can serve as evaluation criteria for determining the most effective fatigue management strategy in Multiple Sclerosis.

The primary objective of the study is to determine the Minimal Clinically Important Difference (MCID) and the Patient Acceptable Symptomatic State (PASS) for fatigue in Multiple Sclerosis.

The source population consists of all people with Multiple Sclerosis living in Lorraine and registered in the Lorraine Registry of Multiple Sclerosis (RelSEP).

Two-year patient follow-up is planned with data collection at 0, 12 and 24 months.

In addition to data already collected as part of the establishment and monitoring of the ReLSEP registry, more specific data for this study will be collected at 0, 12 and 24 months by self-questionnaires sent to patients' homes.

Inclusion Criteria:

• Patient > or = 18 years old
• Patient with Multiple Sclerosis according to Mc Donald's diagnostic criteria
• Patient registered in the RelSEP registry
• Being able to fill out a questionnaire
• Person who has received complete information on the organization of the research and who has not objected to the exploitation of his data

Exclusion Criteria:

• Patients no longer residing in Lorraine
• Bedridden patients
• Patients under guardianship, curatorship or safeguard of justice
• Patients with other serious pathologies with heavy treatments (eg cancer under chemotherapy or radiotherapy).

The source population consists of all people with Multiple Sclerosis living in Lorraine and registered in the Lorraine Registry of Multiple Sclerosis (RelSEP).