To describe the natural history of a condition or disease. To describe the natural history of a condition or disease. To determine effectiveness or cost effectiveness of treatments/services and/or health care products. To measure or monitor safety and harm. To measure quality of care.
According to the NMSS, attacks or flare-ups of symptoms only qualify as exacerbations if: 1  they occur at least 30 days from an earlier flare-up. 2  symptoms last for 24 hours or longer.
ADEM consists of a single flare-up whereas MS is marked with several flare-ups over a long period of time. ADEM is also distinguished by a loss of consciousness, coma and death, which is very rare in MS, except in severe cases. The incidence rate is about 8 per 1,000,000 people per year. Although it occurs in all ages, most reported cases are in children and adolescents, with the average age around 5 to 8 years old.