This study includes 2 periods (a 48-week double-blind treatment period and a long-term extension period) and a Japan substudy. In Period 1 participants will be randomized in a 1:1:1 ratio to treatment Groups 2, 3, and 4 below, except for participants from Japan, who will be randomized in a 2:1:1:1 ratio to Groups 1, 2, 3, and 4:~Group 1: Upadacitinib 7.5 mg once daily (QD) monotherapy (participants in Japan only)~Group 2: Upadacitinib 15 mg QD monotherapy~Group 3: Upadacitinib 30 mg QD monotherapy~Group 4: Methotrexate monotherapy~Participants who complete the Week 48 visit (end of Period 1) will enter the long-term extension, Period 2 (212 weeks) and continue study treatment per assignment at the end of Period 1 in a blinded fashion. Starting with Protocol Amendment 6, participants receiving upadacitinib 15 mg and 30 mg QD will receive open-label upadacitinib 15 mg QD, and participants receiving methotrexate will receive open-label methotrexate.~A global analysis will be conducted for the comparisons of the primary and secondary efficacy endpoints between the upadacitinib 15 mg QD and 30 mg QD treatment groups versus the methotrexate treatment group for all participants (excluding the Japan specific upadacitinib 7.5 mg treatment group). Analyses will be conducted separately for United States (US)/Food and Drug Administration (FDA), European Union (EU)/European Medicines Agency (EMA), and Japan/Pharmaceuticals and Medical Devices Agency (PMDA) regulatory purposes, each according to a pre-specified sequence of primary and ranked secondary endpoints.~A separate Japan sub-study analysis will be conducted for the comparisons of the efficacy endpoints between the upadacitinib 7.5 mg QD, 15 mg QD, and 30 mg QD treatment groups versus the methotrexate treatment group for participants enrolled in Japan only.
The objectives of Period 1 were the following:~To compare the safety and efficacy of upadacitinib 7.5 mg once daily (QD) monotherapy (for participants in Japan only), 15 mg QD monotherapy, and 30 mg QD monotherapy versus weekly methotrexate monotherapy for the treatment of signs and symptoms of RA in methotrexate-naïve adults with moderately to severely active RA;~To compare the efficacy of upadacitinib 15 mg QD monotherapy and upadacitinib 30 mg QD monotherapy versus weekly methotrexate monotherapy for prevention of structural progression in methotrexate-naïve adults with moderately to severely active RA.~The objective of Period 2 is to evaluate the long-term safety, tolerability, and efficacy of upadacitinib 7.5 mg QD (for participants in Japan only), 15 mg QD, and 30 mg QD in adults with RA who have completed Period 1.