LAUSR

Background Contrast to sp-RA, sn-RA was less studied. The report by Nordberg et al mentioned ultrasonic presentations for the first time. They declared early RA patients(with the duration <2 years) without the treatment of DMARDs had more severe synovitis than sp-RA. However, according to the criteria, for the diagnosis of sn-RA, more than 10 swollen joints is necessary. The huge gap of swollen joints counts(SJC)between two groups may influence the sum ultrasound scores and thus cause a prominent selective bias, which was questioned to affect the fact that sn-RA had more synovitis due to more joints involved relative to grouping rules. Objectives To investigate and compare the disease progress of seronegative Rheumatoid arthritis (sn-RA) and seropositive Rheumatoid arthritis (sp-RA) on typical sites including wrists and hands by means of ultrasound and x-ray in Chinese patients. Methods All cases were DMARDs-naïve (DMARDs) and conformed to 2010 classification criteria with the characteristics of abnormal swollen or pain in wrists, Proximal Interphalangeal (PIP), Metatarsophalangeal (MCP) joints. 5-joints ultrasound scoring system was improved from Backhaus’s US7 scoring system. Erythrocyte sedimentation rate (ESR, mm/h), C reactive protein (CRP, mg/L), Visual analogue scale (VAS) scores (VASs), patient global assessment of disease activity on VASs (PGA), the physician’s assessment of disease activity on VASs(PhGA), DAS28(Disease Activity Score-28, DAS28), van der Heijide-modified Sharp scores(vdHSS) were also used to evaluate the disease activity among1 Group A: sp-RA (positive rheumatoid factor(RF) and/or anticitrullinated peptide antibody(ACPA)) combined with swollen joint counts(SJC)>10;2 Group B: sp-RA combined with SJC ≤10 and3 Group C: sn-RA (negative RF and negative ACPA), according to the 2010 criteria with SJC >10. Results 29 (11.6%) of 249 patients were seronegative. The score of DAS28, CRP, ESR, the sum ultrasound scores, vdHSS, phisican global VAS, Patient global VAS and pain VAS were significantly lower(p<0.05) in Group C than Group A, but no difference between Group B and Group A. The sum ultrasound scores were prominently lower in Group C with the duration over 2 years (p<0.05), and vdHSS were remarkably higher in all groups with the duration over 5 years, but more specifically, for the duration over 2 years(p<0.05), the vdHSS was shown to go up much more earlier in Sp-RA than Sn-RA patients. Conclusions Seronegative RA group had milder synovitis and delayed progress of bone erosion than seropositive RA on hands and wrists at the same level with SJC >10. References [1] Nordberg LB, Lillegraven S, Lie E, Aga AB, Olsen IC, Hammer HB, et al. Patients with seronegative RA have more inflammatory activity compared with patients with seropositive RA in an inception cohort of DMARD-naïve patients classified according to the 2010 ACR/EULAR criteria. Ann Rheum Dis. 2017;76:341–345. [2] Backhaus M, Ohrndorf S, Kellner H, Strunk J, Backhaus TM, Hartung W, et al. Evaluation of a novel 7-joint ultrasound score in daily rheumatologic practice: a pilot project. Arthritis Rheum. 2009;61:1194–201. [3] van der Heijde D. How to read radiographs according to the Sharp/van der Heijde method. J Rheumatol2000;27:261–3. Disclosure of Interest None declared