Objectives To study long-term (up to 20-year) mortality of two treat-to-target trial cohorts in undifferentiated arthritis (UA) and early rheumatoid arthritis (RA).Methods The BeSt (BehandelStrategieen) study (n=508, early RA) was performed between 2000 and 2012. For 10 years, patients were treated-to-target disease activity score (DAS)10 years since treatment start, with smoking as an important risk factor.Pathophysiology and treatment of rheumatic diseasesPublic Health and primary carePrevention, Population and Disease management (PrePoD