The aim of this study was to assess if any of the different types of radiographic damage [true joint space narrowing (JSN), (sub)luxation and erosions] are preferentially related to disability in patients with RA.
Longitudinal data from 167 RA patients from the European Research on Incapacitating Diseases and Social Support study over 10 years were analysed to investigate the relationship between the three types of radiographic damage and disability [grip strength, HAQ and the dexterity scale in the Arthritis Impact Measurement Scales (AIMS)]. A longitudinal analysis including separate models per type of damage and joint group and combined models including all information was conducted.
All types of damage were inversely related to grip strength in the analysis of separate models, but only true JSN independently remained statistically significant in the combined analysis [β = -0.087 (95% CI -0.151, -0.022)]. Neither JSN, (sub)luxation nor erosions were associated with HAQ score, while erosions were associated with AIMS dexterity only in the analysis of separate models. After stratifying for hand joint group, erosions at MCP joints [β = -0.288 (95% CI -0.556, -0.019)] and true JSN at the wrist [β = -0.132 (95% CI -0.234, -0.030)] were significantly related to grip strength. Erosions at the PIP [β = 0.017 (95% CI 0.005, 0.028)] and MCP joints [β = 0.114 (95% CI 0.010, 0.217)] was the only type of damage associated with HAQ and AIMS dexterity, respectively.
All types of radiographically visible joint damage interfere with important aspects of physical functions. True JSN is most closely related to hand function.