This is a Phase 2/3, long term, open-label, follow-up study. Subjects will have previously participated in qualifying/index JIA studies of tofacitinib. Those who have already completed such participation and enroll outside the 14 day window following completion of the End of Study (EOS) Visit of the qualifying/index study will participate in a screening Visit to determine eligibility. A Baseline Visit will then occur within 28 days after the Screening Visit. For subjects who are completing participation in a qualifying study of tofacitinib and enrolling on the same day of the EOS Visit of the qualifying/index study, the EOS Visit of the qualifying/index study can be combined with the Screening and Baseline Visits for this study. The subjects who enroll within the 14 day window following completion of the EOS Visit of the qualifying/index study will participate in a combined Screening and Baseline Visit for this study. After the Baseline Visit, visits will occur at 1 month (1 month=30 days) and 3 months, then every 3 months thereafter as long as the subject remains in the study.~Approximately 340 participants are projected to enroll into this open label extension study after completing a qualifying/index study in the JIA program.~For subjects who entered this study from the A3921103 and A3921104 qualifying/index studies, their participation in this study ends after the first marketing approval of tofacitinib for the treatment of polyarticular course Juvenile Idiopathic Arthritis (pJIA) in any country. This study will end once the last subject, and all other subjects, who entered from index study A3921165 have completed approximately 1 year in this study, or after the first marketing approval of tofacitinib for the treatment of systemic JIA, whichever comes first.~The total duration of an individual subject's participation may vary depending upon when they enter the trial.
Evaluate long-term safety and tolerability of tofacitinib in patients with JIA, who have previously participated in tofacitinib JIA studies.