Background Power Doppler (PD) ultrasound examination is nowadays being routinely used for the assessment of disease activity in patients with rheumatoid arthritis (RA). Several scores have been proposed and validated; however, less information is available regarding the pattern of PD signal at the joint level and its possible association with disease activity.

Objectives To address if a specific synovial flow pattern at the joint level (peripheral vs juxta-cortical) is associated with disease activity in patients with RA.

Methods We examined 820 metacarpophalangeal (MCP's) joints of patients with diagnosis of RA (1987 ACR criteria). The pattern of synovial flow was assessed with PD ultrasound and classified as peripheral (when observed in any point of the joint surface but never near or in contact to the bone cortex) and juxta-cortical (when near or in contact to the bone cortex). For the purpose of these analyses, we included only the MCP's with positive PD signal, irrespective of its intensity. Disease activity was assessed using the DAS28-ESR. The association of the PD signal pattern and the DAS28 and its components [(tender joint count, swollen joint count, patient global assessment of disease activity (PtGADA) and erythrocyte sedimentation rate (ESR)] was analyzed using the Mann-Whitney U test. A p value ≤0.05 was considered statistically significant.

Results Patients were predominantly females (80.5%), with a mean age of 50.5 (SD 13.1) years and a median (IQR) disease duration of 80.0 (82.0) months. Median DAS-ESR was 3.1 (0.9). Among the 820 MCP's, 46 had peripheral PD signal pattern and 41 juxta-cortical PD signal pattern. The table below depicts the median (IQR) DAS28-ESR and its components according to the PD signal pattern.

Conclusions In this study we identified two distinct patterns of PD signal at the joint level in patients with RA, peripheral and yuxta-cortical. We also found that the peripheral pattern has a tendency towards an association with disease activity when measured with the DAS28-ESR and a clear association with the number of swollen joints and the ESR. More studies are needed, however, to confirm these findings.

References

1. Mandl P, Naredo E et al. A Systematic Literature Review Analysis of Ultrasound Joint Count and Scoring Systems to Assess Synovitis in Rheumatoid Arthritis According to the OMERACT Filter. J Rheumatol 2011; 38:2055–62.

Disclosure of Interest None declared