Background Power Doppler (PD) ultrasonography (US) is playing an increasing role in the evaluation of patients with inflammatory arthropathies, due to its ability in detecting inflammatory and structural abnormalities and the higher sensitivity compared with clinical evaluation. Several studies evaluated the role of US in diagnosis and follow-up of Rheumatoid Arthritis (RA) patients. A growing number of papers investigated the potential of US in the assessment of psoriatic arthritis (PsA). Indirect data suggested similar US findings in RA and PsA patients. However, to our knowledge, no study specifically designed to compare PDUS findings in RA and PsA patients has been performed.
Objectives We assessed the ultrasonographic changes in terms of prevalence and severity of synovitis in clinically active RA and PsA patients.
Methods In this cross-sectional study, we enrolled patients affected by RA and PsA with active peripheral joint involvement. The patients underwent clinical, laboratory and US evaluation. Disease activity was evaluated by the 28-joint DAS. We excluded all the patients in remission (i.e. DAS28<2.6). Bilateral high-resolution US at level of II metacarpophalangeal (MCP), wrist and knee was performed. Those joints were selected on the basis of an already published reduced-joint-count method (1). US-detected lesions [joint effusion (JE), synovial hypertrophy (SH) and PD] were evaluated with a dichotomous score (absence or presence) and then graded according to a semi-quantitative scale ranging from 0 to 3. US inflammatory scores, calculated by adding the values given to each elementary lesion, were elaborated for each joint. Finally, a total score was obtained by adding the scores from each joint.
Results We enrolled 43 PsA (M/F 20/23; mean age 54.8±15.2 years; mean disease duration 112.6±70.8 months) and 70 RA patients (M/F 11/59; mean age 56.4±14.8 years; mean disease duration 158.7±40.4 months). DAS28 values resulted significantly higher in RA compared with PsA (5.3±1.1 versus 4.3±1.1, P=0.0001). US evaluation demonstrated a significantly higher prevalence of all US-detected lesion in RA patients compared with PsA (JE 60.9% versus 41.1%, P<0.0001; SH 54.8% versus 31.3%, P<0.0001; PD 28.8% versus 11.6%, P<0.0001). The US score in all joints as well as the total US score were significantly higher in RA than in PsA patients (Table 1). When analysing results according with disease activity defined by DAS28, RA patients showed a significantly higher global score compared with PsA in subjects with low (13.3±14.7 versus 1.5±2.1, P=0.03) and moderate disease activity (12.6±9.2 versus 7.4±6.7, P=0.01).
Conclusions The present study demonstrate that PDUS synovitis is more severe in RA than in PsA patients, regardless of the disease activity. Concerning the prevalence of each US-detected abnormality, JE, SH and PD signal resulted significantly more frequent in RA patients than PsA.
Perricone C et al. The 6-joint ultrasonographic assessment: a valid, sensitive-to-change and feasible method for evaluating joint inflammation in RA. Rheumatology (Oxford) 2012;51:866-73.
Disclosure of Interest None declared