Studies have shown ultrasonographic findings to be associated with radiographic progression and relapse from clinical remission in rheumatoid arthritis (RA).1,–,5 Our group has reported a predictive value of an overall ultrasonography score6 and a cross-sectional association between ultrasonographic erosions and erosions assessed by MRI and conventional radiographs.7 However, most previous studies did not include multivariate analyses, and we wanted to further examine the predictive value of inflammatory ultrasonographic findings of the wrist, including tenosynovitis, in early RA patients.

Patients were recruited from a cohort of early RA patients (disease duration ≤ 1 year) examined by joint counts, serology, conventional hand radiographs, MRI and ultrasonography at 0, 12 and 36 months.8 The regional ethics committee approved the study and all patients gave their informed consent. Sixty patients had complete 1-year data and were included in the main analyses. Ultrasonographic examinations were performed by an experienced ultrasonographer (HBH) with an 8–16 MHz linear array transducer (Diasus; Dynamic Imaging, Livingston, UK). B-mode synovitis and tenosynovitis was scored semiquantitatively as 0=none, 1=minor, 2=moderate and 3=high6 and later dichotomised into absent or present. The power Doppler technique was not available at this time. Magnetic resonance images of the dominant wrist with contrast enhancement (GE Signa 1.5 Tesla; General Electric, Milwaukee, WI, USA) were scored according to the OMERACT RA MRI Score (RAMRIS).8 Conventional radiographs were scored using the van der Heijde modified Sharp score (vdHSS, secondary analysis). Progression of radiographic joint damage was defined as a change of ≥1 unit on the RAMRIS erosion score/vdHSS per year.6 8

Thirty-nine of sixty patients were classified as progressors according to the RAMRIS erosion score after 1 year. Possible predictors of 1-year progression of RAMRIS erosions were tested with univariate logistic regression models (table 1). Variables with a p value <0.20 were included in multivariate model building with stepwise backwards elimination, resulting in a final regression model (table 1). The independent odds ratio for progression for patients with presence of extensor carpi ulnaris (ECU) tenosynovitis was 7.2 (CI=1.6–32.9, p value=0.01). Twenty-one of twenty-four patients with ECU tenosynovitis had progression of 1-year RAMRIS erosion score. The sensitivity of US assessed ECU tenosynovitis for detection of progressors was 0.54, the specificity 0.86, the positive predictive value 0.88 and the negative predictive value 0.50. ECU tenosynovitis was associated with more progression in 1-year RAMRIS erosion score of the distal ulna (6/24 vs 1/36 cases, p value=0.009, χ² statistics) and triquetrium erosion score (2/36 vs 6/24 cases, p value=0.03).

In secondary analyses, focusing on vdHSS and 3-year follow-up data, baseline ECU tenosynovitis was a statistically significant univariate predictor of 3-year progression of RAMRIS erosion score (OR=3.4, p value=0.05), and was a borderline significant predictor of 1-year progression in vdHS erosion score (OR=2.85, p value=0.06) and total vdHSS (OR=2.50, p value=0.09) in univariate analysis.

ECU tenosynovitis is common in RA patients8,–,10 and our findings suggest that tenosynovitis represents an imaging biomarker in this cohort. This may be due to its co-existence with other inflammatory processes, or tenosynovitis may be directly involved in the pathophysiology leading to erosive disease. The latter hypothesis may be supported by the finding of a more erosive change in the nearby ulna and triquetrum in patients with ECU tenosynovitis, especially since no differences were found for other wrist bones. The odds ratios from the final multivariate model are not comparable, as the ECU tenosynovitis score is dichotomised, whereas RAMRIS bone marrow oedema has a range of 0–45. Limitations include the lack of power Doppler and the number of patients.

This study demonstrates that ultrasonography-assessed tenosynovitis predicts the development of erosive joint damage in a cohort of early RA patients, and highlights the need for further research in this field, including studies with improved ultrasonography technology.