Background Ultrasound (US) evaluation is a bedside tool increasingly more used to access disease activity of Rheumatoid Arthritis (RA) patients. The ACR/EULAR proposed criteria to define remission in RA does not include image criteria.

Objectives Identify possible discrepancies between clinical assessment of ACR/EULAR remission criteria and evidence of disease activity using an US evaluation (synovitis or Power Doppler (PD) positivity), in patients on biological DMARDs (bDMARDs). Compare the ultrasound score with clinical evaluation.

Methods Forty one patients diagnosed of RA, on bDMARDs, followed in a day-care hospital unit, were evaluated using a 12 joint US assessment (bilateral elbow, wrist, 2nd metacarpophalangeal (MCP), 3rd MCP, knee and ankle) within 3 hours of the routine clinical examination. The US assessment was performed by the same Rheumatologist, blinded to the clinical and laboratory findings; the Rheumatologists who made the clinical assessment were blinded to US evaluation. Both synovitis and PD were graded semi quantitatively from 0-3; the final US score was the sum of the highest synovitis and PD scores at each joint. Surgically replaced joints were excluded.

Results The mean US score was 3.22±5.12, range 0-30 (mean synovitis score of 2.51±4.24 and mean PD score of 0.71±1.27); 14 patients had an US score of 0. In the group of patients with SDAI ≤3.3 (n=7), 6 had an US score of 0 and the other patient had an US score of 1; 8 patients with SDAI >3.3 had US score of 0. In the group of patients with DAS28 ≤2.6 (n=15), 8 had an US score of 0, and 7 had an US score >0 (range 1-6). Comparing clinical and US assessment by considering the joints included both in the DAS28 and US score, 21 (5.2%) joints were considered to be swollen and had evidence of US synovitis; 27 (6.7%) had US evidence of synovitis but were not considered to be swollen; 10 (2.5%) were considered to be swollen but had no US evidence of synovitis. The US score correlated strongly with SDAI (r=0.87, p<0.01) and physician VAS (r=0.87, p<0.01), moderately strongly with DAS28 (r=0.70, p<0.01) and moderately with C-reactive protein (r=0.56, p<0.01); it did not correlate with the number of years since RA diagnosis, months since on bDMARD, months on current bDMARD, patient VAS, HAQ or Erythrocyte Sedimentation Rate. No significant statistical difference between patients with positive or negative Rheumatoid Factor was observed, neither between different bDMARDs. There was a trend to a greater US score in patients on the 2nd or more bDMARD (mean 5±7.90) as compared to patients on the 1st bDMARD (mean 2.39±2.97), but the difference was not statistically significant.

Conclusions The ACR/EULAR proposed SDAI cutoff for remission criteria leaves out a significant proportion of patients with no US signs of disease activity. DAS28 ≤2.6 is less stringent in defining remission, but includes a great number of patients with US disease activity. A regular and standardized US assessment of RA patients is needed to complement clinical evaluation and better define disease activity.

References

1. Naredo, E., et al., Validity, reproducibility, and responsiveness of a twelve-joint simplified power doppler ultrasonographic assessment of joint inflammation in rheumatoid arthritis. Arthritis Care & Research, 2008. 59(4): p. 515-522.

Disclosure of Interest None declared