A Study of Baricitinib (LY3009104) in Participants With Rheumatoid Arthritis

This post-marketing study is designed to compare the safety of baricitinib versus tumor necrosis factor (TNF) inhibitors with respect to venous thromboembolic events (VTEs) when given to participants with rheumatoid arthritis.

Inclusion Criteria: * Participants must have at least one of the following characteristics: * Documented evidence of a VTE prior to this study * At least 60 years of age * A body mass index (BMI) greater than or equal to 30 kilograms per meter squared (kg/m²), or * Age 50 to less than 60 years and BMI 25 to less than 30 kg/m². * Participants must have an inadequate response or intolerance to at least 1 disease-modifying antirheumatic drug (DMARD) (synthetic or biologic). Exclusion Criteria: * Participant should have no reason to not take a TNF inhibitor. * Participants must not be pregnant or breastfeeding. * Participants must not have had more than one VTE. * Participants must not have cancer. * Participants must not have active herpes zoster, serious infection, active tuberculosis, or any other serious illness. * Participants must not have had a live vaccine within four weeks of study start. * Participants must not have participated in any other clinical trial within four weeks of study start. * Participants must not have a history of IV drug use, other illicit drug abuse, or chronic alcohol abuse in the past year.