Pediatric Arthritis Study of Certolizumab Pegol

Prior treatment

• Study participant has previously been exposed to more than 2 biologic agents
• Study participant previously failed to respond to treatment with more than one tumor necrosis factor alpha (TNFα) antagonist drug
• Study participant is currently receiving or has received any experimental (biological or nonbiological) therapy (within or outside a clinical study) in the 3 months or 5 half-lives prior to Baseline (Visit 2), whichever is longer
• Study participant had previous treatment with a biological therapy for juvenile idiopathic arthritis (JIA) that resulted in a severe hypersensitivity reaction or an anaphylactic reaction
• Study participant previously participated in this study or has previously been treated with CZP (whether in a study or not)
• Study participant has a current sign or symptom which may indicate infection (eg, fever, cough), a history of chronic or recurrent infections within the same organ system (more than 3 episodes requiring antibiotics/antivirals during the 12 months prior to Screening \[Visit 1\]), had a recent (within the 6 months prior to Screening \[Visit 1\]) serious or life-threatening infection (including herpes zoster), or is at a high risk of infection in the Investigator's opinion (eg, study participants with leg ulcers, indwelling urinary catheter, and persistent or recurrent chest infections or permanently bed-ridden or wheelchair bound)

Other illness

• Study participant has a history of systemic JIA, with or without systemic features
• Study participant has a secondary, noninflammatory type of rheumatic disease or of joint pains (eg, fibromyalgia) that in the Investigator's opinion is symptomatic enough to interfere with evaluation of the effect of study medication
• Study participant has other inflammatory arthritis (eg, systemic lupus erythematosus, inflammatory bowel disease-related)
• Study participant has active uveitis or a history of active uveitis within the preceding 6 months
• Study participant has current, chronic or recurrent clinically significant infections

• Study participant is 2 to 17 years of age (inclusive) at Baseline (Visit 2)
• Study participants must weigh ≥10 kg (22lb) at Baseline (Visit 2)
• Study participants must have had onset of signs and symptoms consistent with a diagnosis of Juvenile Idiopathic Arthritis (JIA) (according to the International League of Associations for Rheumatology Classification of Juvenile Idiopathic Arthritis, 2001) and initiation of JIA treatment for at least 6 months prior to Baseline (Visit 2). Eligible JIA categories include: polyarthritis rheumatoid factor-positive, polyarthritis rheumatoid factor-negative, extended oligoarthritis, juvenile psoriatic arthritis, and enthesitis-related arthritis (ERA)
• Study participants must have active polyarticular-course disease, defined as ≥5 joints with active arthritis at Screening and at Baseline
• Study participants must have had an inadequate response to, or intolerance to, at least 1 disease-modifying antirheumatic drug (DMARD) (nonbiologic or biologic). For example, study participant had prior inadequate response to methotrexate (MTX) (based on the Investigator's clinical judgment)
• If the study participant is using MTX, then the study participant must have been on MTX for a minimum of 3 months at Screening. In addition, the dose must have been stable for at least 1 month before Screening at ≥10 to ≤15 mg/m\^2 per week. If the study participant is not using MTX, then the treatment must have been previously withdrawn for documented reasons of intolerability or inadequate response
• If the study participant is using oral corticosteroid therapy, the dose must have been stable for at least 7 days prior to the Baseline arthritis assessment at a maximum dose of 10 mg or 0.2 mg/kg prednisone (or equivalent) per day, whichever is the smaller dose