Objectives This analysis aimed to describe the pattern of specific joint involvement (tender and/or swollen) pre- and post-TNFi treatment and the impact of specific joint pattern involvement on composite score outcomes and pain.

Methods BioTRAC is an ongoing, prospective registry of patients initiating treatment for RA, AS, or PsA with infliximab (IFX) or golimumab (GLM). In this analysis, RA patients included those treated with IFX between 2002-2014 or with GLM between 2010-2014. Based on joint involvement 7 groups were created: shoulder(s), elbow(s), metacarpophalangeal (MCP(s)), wrist(s), proximal interphalangeal (PIP(s)), knee(s), and thumb(s). The impact of specific joints on disease activity indices and pain was assessed with the independent-samples t-test; linear regression produced adjusted estimates.

Results A total of 1030 RA patients were included with 5177 assessments. At baseline, MCP(s) (84.8%) and wrist(s) (66.1%) were the most commonly swollen joints. Tenderness was most frequent at baseline in these two joint types (81.1% and 70.9% of patients, respectively). Swelling/tenderness rates in all joint groups were significantly lower (p<0.001) among patients enrolled in 2010-2013 vs. those enrolled in 2002-2005; no significant differences, however, were observed in joint involvement pattern.

Swelling and tenderness in all joint groups were associated with significantly (P<0.001) higher pain. Upon adjusting for age, gender and the total number of swollen (SJC28) or tender (TJC28) joints, swollen shoulder(s) and knee(s), and tender shoulder(s) and elbow(s) had the biggest impact on pain. Swollen MCP(s), knee(s) and thumb(s) had the greatest impact on DAS28, while for CDAI and SDAI swollen thumb(s) and swollen thumb(s) and knee(s), respectively, showed the highest association. Tender wrist(s), shoulder(s), and knee(s) showed the highest association with DAS28, while tender MCP(s) had the greatest impact on CDAI and SDAI. However, all indices were significantly higher among cases with swollen thumb(s) (unstandardized coefficient (B): B_DAS28=0.25, P=0.006; B_CDAI=2.09, P=0.001; B_SDAI=2.66, P=0.001).

Conclusions Although joint swelling/tenderness documented at anti-TNF initiation has decreased over time, the profile of affected joints has remained stable. Swelling/tenderness in specific joint groups was differentially associated with pain, with larger joints having the greatest impact. Furthermore, differences were observed in levels of disease activity based on the type of affected joint which could be attributed to their impact on patient global assessment. These results suggest that location of joint involvement, in addition to the number of affected joints, has an independent impact on pain.

Disclosure of Interest R. Arendse Consultant for: Janssen, J. Kelsall Consultant for: Janssen, A. Avina-Zubieta Consultant for: Janssen, P. Baer Consultant for: Janssen, J. Rodrigues Consultant for: Janssen, A. Jovaisas Consultant for: Janssen, I. Fortin Consultant for: Janssen, M. Sheriff Consultant for: Janssen, M. Khraishi Consultant for: Janssen, E. Rampakakis: None declared, J. Sampalis: None declared, F. Nantel Employee of: Janssen, M. Shawi Employee of: Janssen, C. Tkaczyk Employee of: Janssen, S. Otawa Employee of: Janssen, A. Lehman Employee of: Janssen