Justification And Evaluation of Baricitinib Plus Corticosteroids Versus corticosteroiDs Alone in pOlymyalgia RhEumatica

Polymyalgia rheumatic (PMR) is an inflammatory rheumatic disease affecting the elderly. The diagnosis is based on established ACR/EULAR classification criteria. The activity of the disease is evaluated using the PMR-AS, a disease activity score based on morning stiffness, ability to elevate the upper limbs, physician's global disease assessment and pain assessment measured by the patient using VAS, and the C-reactive protein (CRP) level. The PMR-AS-CRP (PMR-AS) is considered as relevant to define disease activity (low activity \17), flare (\>10), remission (\one year by steroids. Our goal is now to demonstrate in a large cohort the ability of a 6-month treatment with baricitinib in comparison to placebo to decrease glucocorticoids and then to maintain low disease activity without corticosteroids in PMR and a good safety profile. Due to the possible lower risk of 2 mg than 4 mg of baricitinib, but probably a lower efficacy, the investigators plan to compare both baricitinib (4 mg and 2 mg) to placebo. The study will be conducted in France.

Inclusion Criteria: * At least 50 years of age. * Fulfilling ACR/EULAR classification criteria for PMR newly diagnosed or treatment resistant. * No GCs or GCs \17. * Absence of other inflammatory arthropathy, connective tissue diseases or vasculitis. * Able to give informed consent. * French health insurance holder Exclusion Criteria: * Clinical evidence of giant cell arteritis. * Uncontrolled high blood pressure or cardiovascular disease. * High risk of VTE because of a history of VTE (DVT and/or PE) within 12 weeks prior to randomization or a history of recurrent (\>1) VTE (counting co-occurring DVT+PE as 1 single event). * Clinical evidence of significant unstable or uncontrolled acute or chronic diseases not due to PMR * Planned major surgical procedure during the study or medical history, blood abnormalities or any clinical condition that compromises inclusion. * Current smoker if age \>65 years. * Current active uncontrolled infection. * Treatment by probenecid. * Alkaline phosphatase (ALP) ≥2 x ULN. * Total bilirubin level (TBL) ≥1.5 x ULN. * Neutropenia (absolute neutrophil count \