AB1346 ULTRASOUND ASSESSMENT OF SUB-CLINICAL HAND JOINT INFLAMMATION: A COMPARATIVE STUDY BETWEEN EARLY RHEUMATOID AND PSORIATIC ARTHRITIS

Abstract

BackgroundUltrasound (US) detected subclinical inflammation can be present in early psoriatic arthritis (PsA) and rheumatoid arthritis (RA), and also in patients fulfilling clinical remission criteria[1-2]. Numerous evidences support that the persistence of subclinical synovitis detected by US is associated with a high risk of disease progression [2-3].ObjectivesTo evaluate sub-clinical inflammation of PsA and RA at the level of small joints of the hand and wrist by B-mode and Power Doppler US.Methods30 patients of early PsA and 35 patients of early RA (no clinical evidence of hand joint involvement, PsA disease duration <2 years, and RA disease duration <1 year) were recruited. US [grey scale (GS) and power Doppler (PD)] was performed to assess synovitis, tenosynovitis, joint effusion, and bone erosion of bilateral wrists, metacarpophalangeal joints, proximal and distal interphalangeal joints, as well as the flexor tendons and extensor compartments.ResultsA total of 35 patients were included in the RA group, including 10 males and 25 females. A total of 30 patients were included in the PsA group, including 12 males and 18 females. There were no significant differences in gender composition, age, and duration of disease between the two groups (P>0.05) (Table 1). 19 (63.33%) PsA patients and 16 (45.71%) RA patients had sub-clinical hand joint synovitis. At the joint level, wrist joints were most commonly involved (23.08%), followed by MCP3 (15.38%) and DIP3 (13.46%) in PsA group. In RA group, wrist joints were most commonly involved (55.17%), followed by MCP3 (12.41%), and MCP2 (11.03%). Eight (26.67%) PsA patients and 16 (45.71%) RA patients were detected tenosynovitis. Tenosynovitis was most frequently presented at the extensor tendons in RA and at the flexor tendons in PsA patients (p<0.05). The two most commonly affected were the 4th and 1st extensor compartments in RA patients, and the flexor pollicis longus and flexor digitorum profundus in PsA patients. 81 (6.80%) joint recesses in the RA and 75 (7.35%) joint recesses in PsA were detected effusion. Joint effusion was most frequently detected at radiocarpal and midcarpal joints in RA (30.86%, 25.92%, respectively). Effusion in PsA was most commonly presented at the 3rd PIP joints (26.67%), followed by radiocarpal joints (24.00%). Bone erosions were uncommon, totally 2 (6.67%) PsA patients and 3 (8.57%) RA patients were detected bone erosions.Table 1.Demographic characteristics of RA and PsA patientsRA (n=35)PsA (n=30)PFemale, n(%)25 (71.43%)18 (60.00%)0.33Age, years, mean±SD53.20±14.5054.23±13.650.77Disease duration, years, mean±SD0.72±0.370.91±0.530.07ConclusionThere are significant differences in the US findings of sub-clinical inflammation at the hand and wrist joints, such as the joint effusion and tenosynovitis, which may assist the identification between early RA and PsA. Simultaneously, it should be pointed out that there are some similarities in the joint involvement of sub-clinical synovitis between RA and PsA, physicians should take this into account in clinical work.Figure 1.Gray scale ultrasound sagittal view shows synovitis at the wrist joint in an RA patient (A) and at MCP3 in a PsA patient.