Inclusion Criteria:  All the patients diagnosed with Rheumatoid Arthritis by the American College of Rheumatology (ACR) 2010 criteria, with Giant Cell Arteritis by International League of Associations for Rheumatology (ILAR) criteria, with Still disease by classification criteria (Yamaguchi et al.) and with Idiopathic Juvenile Arthritis by ACR 1990 criteria. All of them treated with anti-IL-6R monoclonal antibodies in the last 5 years and with active follow-up in Hospital de la Santa Creu i Sant Pau.  Exclusion Criteria:  <18 years at recruitment Another rheumatic disease different of the ones in the inclusion criteria