THE IMPACT OF DIFFERENT (RHEUMATOID) ARTHRITIS PHENOTYPES ON PATIENTS' LIVES.

OBJECTIVES To compare patient-relevant outcome (PRO) domains between three arthritis phenotypes: namely undifferentiated arthritis (UA), autoantibody-negative (RA-) and positive rheumatoid arthritis (RA+), at diagnosis, after 2 years and over time. METHODS All UA(n = 130), RA-(n = 176) and RA + (n=331) patients from the tREACH trial, a stratified single-blinded trial with a treat-to-target approach, were used. PRO comparisons between phenotypes at baseline and after 2 years were performed with ANOVA, while a linear mixed model compared them over time. Effect sizes were weighted up against the MCIDs for each PRO. RESULTS RA- had a higher disease burden compared to RA+ and UA. At baseline and after 2 years, RA- patients had more functional impairment and a poorer Physical Component Score (PCS) compared to the other phenotypes, while they only scored worse for general health and morning stiffness duration at baseline. The MCIDs were exceeded at baseline, except for functional ability between RA+ and UA, while after 2 years only the MCID of PCS was exceeded between RA- compared to UA and RA. After 2 years the PROs of all phenotypes improved, but PROs measuring functioning were still worse compared to the general population even when patients had low disease activity. CONCLUSION RA- had the highest disease burden of all phenotypes. Although most patients have low disease activity after treatment, all clinical phenotypes still have a similar significant impact on patients' lives, which is mainly physical. Therefore, it is important to assess and address PROs in daily practice, because of persistent disease burden despite low disease activity. TRIAL REGISTRATION ISRCTN26791028.