Hammer HB, et al. - In patients with established rheumatoid arthritis (RA) during follow-up on bDMARD treatment, researchers explored the cross-sectional and longitudinal relationships between Tender-Swollen Joint count Difference (TSJD) and a spectrum of outcome measures including US scores. In this observational study, 209 subjects with established RA consecutively included when initiating bDMARD and followed with clinical, laboratory and comprehensive US examinations at 0, 1, 2, 3, 6 and 12 months. Patients with predominantly tender joints had higher Composite Disease Activity Scores (CDAS) but lower inflammation levels defined by the US. The study findings suggested that the inclusion of tender joint count (TJC) in CDAS can contribute to misleading inflammatory activity information.