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.
According to the National Multiple Sclerosis Society, an MS attack is defined as the worsening of MS symptoms, and/or the appearance of new symptoms, which lasts at least 24 hours and is separated from a prior exacerbation by at least one month.