TRIM21 and rheumatoid arthritis: Furthermore, the prevalence of difficult-to-treat rheumatoid arthritis (D2T-RA) was significantly higher in the Ro52+/Ro60+ (13%) and Ro52+/Ro60− (11%) groups compared to the Ro52−/Ro60− group (3.5%, p = 0.006), suggesting a more refractory disease course in these antibody-positive subgroups.