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.
The way the disease changes and gets worse is different for each of the four types of MS 1  : Relapsing-remitting MS: People with this type have attacks when their symptoms get worse, called relapses, followed by full, partial, or no recovery. 2  These flares seem to change over several days to weeks.