Calcium Pyrophosphate Deposition Disease

The aim of this clinical trial is to determine the efficacy of tocilizumab (an IL-6 inhibitor) in treatment-refractory chronic inflammatory forms of CPPD. The main questions this trial aims to answer are: * Can tocilizumab improve joint pain in patients with chronic inflammatory CPPD disease? * Does tocilizumab improve quality of life in patients with chronic inflammatory CPPD disease? Participants will receive a monthly infusion of tocilizumab or placebo for three months.

The goal of this clinical trial is to describe the transcriptomic and metabolomic profile of patients with chronic Calcium Pyrophosphate Deposition (CPPD) compared to those with acute CPPD. The hypotheses are as follows : * It is hypothesised that there is a transcriptomic and metabolomic signature of CPPD which explains why therapeutic responses to different anti-inflammatory treatments differ from one phenotype to another one * It is hypothesised that the acute and chronic clinical phenotypes of CPPD have different clinical, biological and imaging characteristics, as well as a differing predisposition toward crystalline deposition and inflammatory pathway activation. The management of participants with chronic forms of the disease included in this research was modelled on the usual recommended management, including a biological workup, joint puncture, ultrasound and radiographic workup. Double-energy CT scans and transcriptomic and metabolomic analyses on plasma are not routine tests.

The aim of this clinical trial is to determine if baricitinib is effective in treating calcium pyrophosphate deposition disease (CPPD) in adults. The primary objective is to assess its impact on joint inflammation. The key questions the study seeks to answer are: * Can baricitinib reduce inflammation in affected joints? * Will baricitinib lead to changes in ultrasound findings, such as calcium crystal deposition and synovitis? Researchers will compare baricitinib to other treatments, including methylprednisolone, colchicine, hydroxychloroquine, and methotrexate with folic acid, for managing CPPD.