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.
1 Your symptoms last 24 hours or longer. 2  A relapse means a change in your brain, called a lesion.  3 If a symptom lasts less than 24 hours, itâs something transient thatâs not related to a new lesion, says Edward Fox, MD, director of the MS Clinic of Central Texas.