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.
To be considered an MS relapse: 1  Old symptoms of MS must have become worse or new symptoms appeared. 2  Symptoms must last at least 24 hours. 3  Symptoms must occur at least 30 days after the last relapse.  There must be no other explanation for the symptoms.