Radiographic structural damage is worse in the dominant than the non-dominant hand in individuals with early rheumatoid arthritis

Objective: The relationship between mechanical stress and radiographic progression in rheumatoid arthritis (RA) is unclear. The assumption is that mechanical stress is greater in the dominant hand. Therefore, the aim of the present study was to compare the presence and progression of erosions and joint space narrowing (JSN) in the dominant and non-dominant hand. Methods: Data from 194 patients recently diagnosed with seropositive RA, and with hand radiographs taken at the time of diagnosis and at 2-year follow-up, were analyzed retrospectively. Radiographs were scored using the van der Heijde-modified Sharp Score (HSS) method. Each joint group within each hand was rated separately by two independent examiners in a doubleblinded manner. Results: One hundred and ninety-four patients were enrolled (80% female, 88% positive rheumatoid factor, 92% positive anti-citrullinated protein antibody, and 95.4% right-handed). The baseline, follow-up erosion and JSN HSS were significantly higher in the dominant hand than in the non-dominant hand. The annual rate of radiographic progression was also higher in the dominant hand. The erosive progression in the wrist joints varied significantly according to handedness, but the erosion in the proximal interphalangeal joints and metacarpophalangeal joints was similar in both hands. The radiographic progression was associated with the dominant hand, an abnormal baseline C-reactive protein level, and joint damage at baseline. There was no significant difference in bone mineral density between the right and left hands. Conclusion: Radiological damage was worse and progressed faster in the dominant hand, suggesting that mechanical stress is associated with radiographic joint damage in early and active RA.