Tenderness and radiographic progression in rheumatoid arthritis and psoriatic arthritis

Objective The aim of this study was to assess the predictive value of tenderness in the absence of swelling with consideration of other potential risk factors for subsequent radiographic progression in rheumatoid arthritis (RA) and psoriatic arthritis (PsA). Methods Clinical and sonographic (grey scale and power Doppler (PD)) examination of 22 joints of the hand were performed in patients with RA and PsA. The impact of tenderness on progression after 2 years was analysed in non-swollen joints for RA and PsA separately with multilevel mixed logistic regression analysis. Results We included 1207 joints in 55 patients with RA and 352 joints in 18 patients with PsA. In RA, tenderness was associated with radiographic progression after 2 years (model 2: OR 1.85 (95% CI 1.01 to 3.27), p=0.047), although the association of PD (OR 2.92 (95% CI 1.71 to 5.00), p<0.001) and erosions (OR 4.74 (95% CI 2.44 to 9.23), p<0.001) with subsequent structural damage was stronger. In PsA, we found a positive but not significant association between tenderness and radiographic progression (OR 1.72 (95% CI 0.71 to 4.17), p=0.23). In contrast, similarly to RA, erosions (OR 4.62 (95% CI 1.29 to 16.54), p=0.019) and PD (OR 3.30 (95% CI 1.13 to 9.53), p=0.029) had a marked effect on subsequent structural damage. Conclusion Our findings imply that tenderness in non-swollen joints in RA is associated with subsequent damage. In both diseases, additional risk factors, such as sonographic signs for synovitis and baseline radiographic damage are associated with radiographic progression.