Psychometric properties of the Fibromyalgia Assessment Status (FAS) index: a national web-based study of fibromyalgia.

Fibromyalgia (FM) is a generalized chronic pain condition that is often accompanied by symptoms such as fatigue, sleep disturbances, psychological and cognitive alterations, headache, migraine, variable bowel habits, diffuse abdominal pain, and urinary frequency. Its key assessment domains include pain, fatigue, disturbed sleep, physical and emotional functioning, and patient global satisfaction and health-related quality of life (HRQL). A...