Abbott received FDA approval to market Humira as a treatment to reduce signs and symptoms of moderately to severely active polyarticular juvenile idiopathic arthritis (JIA) in patients four years of age and older. The approval is based on safety and efficacy results from a study of JIA patients four to 17 years old. Humira is the first biologic treatment to receive FDA approval for this condition since 1999.     JIA is the most common chronic rheumatic disease in children with onset before ag...