Distal interphalangeal joint involvement in patients with rheumatoid arthritis: Where are we?

Background/aim: Rheumatoid arthritis (RA) usually affects the wrist, metacarpophalangeal joint, and proximal interphalangeal joint of the hands. However, the distal interphalangeal (DIP) joints may also be involved in RA patients. In this study, we aimed to evaluate the frequency and associated factors of DIP joint erosion in patients with RA. Materials and methods: Medical records of patients with RA were reviewed retrospectively. Patients with major trauma affecting DIP joints, osteoarthritis, erosive osteoarthritis, psoriatic arthritis, systemic sclerosis, calcium pyrophosphate dihydrate disease, and gout were excluded. Anteroposterior hand X-rays were evaluated and patients were divided into groups according to autoantibody profile. Results: We reviewed 1213 patients with a mean age of 54.3 ± 12.5 years; 82.8% of them were female, and 95.4% had RA-type erosive changes. The DIP erosion rate was 12%. DIP involvement was generally unilateral and asymmetric, with the 3rd finger being the most commonly affected joint. Patients with DIP erosions had a significantly longer disease duration (p = 0.036). Older age was an independent predictive factor for DIP erosion (p = 0.001). Conclusion: In this large-sample study, we reported DIP joint involvement in patients with RA. Advanced age could have affected the results because hand erosions increase above 50 years in a healthy population. Our results may provide a different perspective on joint involvement in RA.