Background It is reported RF-negative Rheumatoid Arthritis (RF-nRA) had distinct genetic background and pathogenesis mechanism leading to different prognosis and therapy response from RF-positive Rheumatoid Arthritis (RF-pRA). Ultrasound (US) of wrist, metacarpophalangeal (MCP) and proximal interphalangeal joints (PIP) which are the classical zone of RA involvement might verify whether the joint destruction would be different in both group.
Objectives To verify whether the joint destruction would be different in RF-negative Rheumatoid Arthritis (RF-nRA) and RF-positive Rheumatoid Arthritis (RF-pRA) patients.
Methods It is a blinded, controlled trial. All cases including RF-nRA group and RF-pRA group satisfied 2009 classification criteria with abnormal swollen or pain in wrists, AMCPs or PIPs. RF-pRA group should have x-ray or MRI evidences The most affected side of joints including the 2nd, 3rd MCPs, Athe 2nd, 3rd PIPs and wrists were examined. US examination and scoring system referred to Backhaus's US7 scoring system related regions. In addition, synovitis in gray-scale US (GSUS) on dorsal side of the 2nd, 3rd MCPs and PIPs (0–3 grade) and bone erosions on dorso-median, ulnar, palmo-median sides (0 or 1 if absent/present) of wrist in GSUS were also counted in to get a total of 0–106 scores. DAS 28 (3 variables) was employed to divide each of the 2 groups into 4 subgroup to assess the sonograms in different disease activity levels.
Results 1) 15 RF-nRA cases and 41 RF-pRA cases were enrolled. Mean age (53.8yrs, 57.2yrs), female-male ratio(29:12,16:9), and disease duration(7.53,7.88) of 2 groups were described as above. DAS-28>5.1 subgroups in both 2 groups had the most cases (RF-nRA/RFpRAremission:low:moderate:high=3:2:4:6/1:5:15:20).
2) DAS-28 had highly positive correlation(r=0.95) to US sum scores while poor positive correlation with synovitis GDUS sum scores or synovial Power Doppler(PD) signals sum scores alone.(r=0.57,0.62)
3) No significant differences between RF-nRA and RF-pRA in aspect of synovitis in GDUS, synovial PD signals, and bone erosions in GDUS in wrists, MCPs, PIPs respectively in different levels.
Conclusions Our study has not found any distinctions in most affected joints between RF-nRA and RF-pRA patients.
Disclosure of Interest None declared