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.
How long a rash lasts depends on its cause. However, most rashes usually disappear within a few days. For example, the rash of a roseola viral infection usually lasts 1 to 2 days, whereas the rash of measles disappears within 6 to 7 days. Rashes caused by an antibiotic allergy may last 3 to 14 days, whereas diaper rash almost always clears up within 1 week (if diapers are changed frequently). Rashes resulting from lupus or dermatomyositis may last for an extended period of time.