Background/Purpose: The ultrasound (US) finding of proliferative synovitis (PS) in Rheumatoid Arthritis (RA), is associated with ACPA, erosions and changes in therapy [1]. However, no previous studies have analyzed whether clinical and US findings differ between RA and Psoriatic Arthritis (PsA) presenting with hand inflammation. The aim of this study was to characterize the clinical and US pattern of patients with active RA and PsA presenting with hand arthritis. Secondly, we wanted to validate the previously found association of US PS with both erosive disease and use of therapy in patients with chronic arthritis.

Methods: Cross-sectional, multicenter study. Clinical and US variables were collected from RA and PsA patients with active hand inflammation in the physical assessment. Synovial hypertrophy (SH) and Power Doppler (PD) signal were evaluated in carpal, metacarpophalangeal, carpal extensor tendons, and hand flexor tendons. US PS was defined as SH>2+PD. 

Results: Two hundred and thirty-one patients were included (Table 1). Eighty-four patients (36.3%) had seropositive (sero+) RA, 43 patients (18.6%) seronegative (sero-) RA and 104 PsA (45%).  

Overall, 115 patients (50%) had erosive disease, and 91 (39.4%) were on targeted therapies. Ninety-three patients (40.3%) were receiving oral glucocorticosteroids (GC).  

Disease duration was significantly higher and erosive disease more frequent in sero+ RA, whereas disease activity and CRP levels were higher in sero- RA. Joint counts and CRP levels were lower in PsA patients. The use of conventional DMARDs (p 0.039) and targeted therapies (p 0.333) was higher in sero+ RA. GC was taken in half of both sero+ and sero- RA patients, but only in 25% of PsA patients.  

One hundred and twenty-two patients (53%) met criteria for US PS (sero+ RA, 75.9%; sero- RA, 51.2%; PsA patients, 35.6%). Twenty-eight patients (12.2%) had tendon inflammation without joint involvement. Extensor paratendonitis (44 patients, 19.6%) was significantly more frequent in PsA (p 0.002) although not exclusive, being also found in 16.7 and 8.8% of sero- and sero+ RA, respectively. Thirteen patients (6.1%) had radiographic finger ankylosis, all of them in PsA patients with US paratendonitis. 

Among 121 patients with US PS, 72.7% exhibited erosive disease, whereas only 24.1% without US PS showed radiographic erosions (p 0.0001). Moreover, the US score was significantly higher in erosive patients (16.3 versus 12.3, p 0.02). 

In the multivariable analysis, after adjusting for age, sex, diagnosis, smoking, time of evolution, disease activity, and treatment, the presence of erosive disease [OR 7.6 (3.8-14.9), p 0.0001] and use of GC [OR 2.5 (1.2-5.1), p 0.008] were independently associated with the presence of US PS.  

Conclusion: In patients with active hand arthritis, RA patients had higher disease burden than PsA patients, although the use of targeted therapies was similar. PS was more frequent in RA, although the previously reported association with erosive disease and therapy needs (GC) was maintained in both RA and PsA groups. Paratendonitis was associated with, but not exclusive of PsA. This US finding was related to the presence of finger ankylosis. 

References 

1. Ramírez J, et al. Clin Exp Rheumatol. 2022 May;40(5):960-966.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/active-hand-inflammation-differing-clinical-and-ultrasound-patterns-in-patients-with-rheumatoid-arthritis-and-psoriatic-arthritis-a-cross-sectional-and-multicenter-study/