Human Factors Study of Methotrexate Prefilled Pen (50 mg/mL) in Patients With Juvenile Idiopathic Arthritis

Main Inclusion Criteria: * patient of either gender aged ≥2 to \<21 years of age * is a suitable candidate for treatment with injectable methotrexate for JIA per the patient's primary rheumatologist, with the previous or current diagnosis of active polyarticular course JIA Main Exclusion Criteria: * Is a female patient who is pregnant, trying to become pregnant, or breastfeeding, or of childbearing potential, sexually active but not practicing a highly reliable method of birth control during the study and at least 6 months thereafter * Has contraindications for methotrexate * Has a history of or current inflammatory arthritis or rheumatic autoimmune disease other than JIA * Is unable, or does not have a caregiver able to comprehend written labeling and training materials