Background Remission is nowadays the primary goal of RA treatment, As the traditional remission criterion of DAS28 <2.6 seemed to be not stringent enough, the EULAR and ACR have proposed a new definition. Since 2008, the Swiss Sonography in Arthritis and Rheumatism (SONAR) group has developed a standardized semi-quantitative US score for RA using OMERACT criteria for synovitis. The score has been learned by 70 rheumatologists and since 2009 included as a routine evaluation tool in the Swiss SCQM RA cohort.
Objectives The aims of the present study were: to evaluate whether this SONAR score applied to patients of the Swiss RA registry could differentiate the two clinical scores of remission and to compare them with ultrasound remission definition.
Methods The first available visit with SONAR data in DAS28 (ESR) and or the new ACR/EULAR remission was selected. The SONAR score includes a semi-quantitative B mode and Doppler evaluation (22 joints, grade: 0 to 3, maximum of 66 points each).
In order to establish ultrasound remission definition, the score was also applied to 40 matched controls (age and sex) recruited like the patients in different centers.
Results 362 RA patients had, at the time of US examination, complete data for calculation of DAS28ESR and 177 for ACR/EULAR remission criteria. 121 patients fulfilled the DAS remission (33%) and only 29 the new ACR/EULAR definition (17%). Both groups were similar as for the age, sex, RF and duration of RA.
RA patients in remission according to the DAS28 only or the ACR/EULAR criterion did not significantly differ in terms of B mode or Doppler score.
In B mode, the mean total score (±SD) was higher but insignificantly in RA patients by either definition (mean ± SD: 8.2±6.5, p: 0.06 for DAS criteria) and (7.7±5.6, p: 0.16, for ACR/EULAR) as compared to the controls (5.5±2.4).
The cut-off in B mode for significant ultrasound synovitis was defined by a total score >8, as 90% of the controls were below these values. When considering this cut-off, remaining synovitis were present among more than a third of RA patients in remission according to DAS28 (38.6%, 95% Wilson CI 30% – 48%) or the ACR/EULAR criteria (37.9%, IC 23% – 56%).
Furthermore, the mean number of joints with b-mode synovitis of at least grade 2 was significantly higher in RA patients in clinical remission (6.7 for DAS, and 6.3 for ACR/EULAR p=0.0001 for both) compared to the controls (0.3).
Finally, the mean Doppler score was very similar between the two remission kinds (p=0.45) but significantly higher in RA patients in clinical remission by either definition (0.8, for DAS, p=0.001) and (0.6, for ACR/EULAR, p=0.02) as compared to controls (0.1).
Conclusions This study shows that the SONAR score applied by different examinators to RA patients is not different in those fulfilling the DAS remission and the new ACR/EULAR criteria. More than a third of all RA patients in clinical remission (either DAS or ACR/EULAR) still present signs of ultrasound synovitis suggesting that they have reached a low activity instead of a true remission state.
Disclosure of Interest None Declared
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