Objectives To evaluate agreement between clinical (C) and ultrasound (US) assessment of synovitis (B, D and B+D mode) in active rheumatoid arthritis (RA) before and after treatment by antiTNF, and then to study factors associated with a good agreement.
Methods 76 active (necessitating an anti-TNF therapy) RA (1987 ACR criteria) patients have been included in a prospective, 2 year follow-up multicenter cohort. For each patient, 38 joints were evaluated (2 wrists, 2 elbows, 2 shoulders, 2 knees, 10 MCP, 10 PIP, 10 MTP). Synovitis grade was collected at baseline using a semi-quantitative variable for both the physical examination (from 0=definitively no synovitis to 3=yes obvious and important), US Grey Scale (GS) (from 0=absence of synovial thickening to 3=marked synovial thickening) and US Power Doppler (PD) (from 0=absence of signal, no intra-articular flow to 3=marked signal in more than half of the synovial area. The kappa coefficient was determined to evaluate the reliability of categorical variables (synovitis if grade ≥1). Factors associated with a good agreement were evaluated using both uni and multivariate analysis (all items statistically significant in univariate model and not correlated with other items were included).
Results Concordance before anti TNF between C and US assessment (kappa -0.08 to 0.51) as well as agreement between B and D mode (0.30 to 0.67) were variable according to the evaluated joint site. C and US agreement was particularly low on MTP and shoulders (kappa<0.3); they were excluded for the evaluation of factors associated with good C-US agreement. Practically all synovitis detected using D mode were also detected using B mode which was more sensible. Factors associated with good C-US agreement according to the multivariate analysis before anti TNF were: 1] B mode: low DAS 28, high physician VAS and positivity of rheumatoid factors (RF) 2] D mode: no semi recent evolution of RA (2-5 years), moderate activity of RA (DAS 3.2-5.1), age between 40-50 yrs and female sex. After anti TNF they were: 1] B mode: joint site (knees, elbows, MCP 4 and 5, IPP 2 to 5), male sex, low BMI, no semi recent evolution of RA (2-5 years), moderate disability on HAQ and low DAS 28. 2] D mode: joint site (knees, elbows, MCP 4 and 5, IPP 1 to 5), low BMI, recent evolution of RA, moderate disability on HAQ, low DAS 28, low physician VAS and positivity of rheumatoid factors (RF).
Conclusions Agreement between C and US assessment is joint site dependent. C assessment underestimates particularly MTP and shoulder synovitis. Factors associated to a good agreement on the other sites are numerous and variable according to US mode (factors associated to C-US mode B and D good agreement are different) and treatment (joint site, HAQ, low BMI are associated to a good C-US agreement after but not before TNF therapy).
Disclosure of Interest None Declared