Predictors of functional impairment and pain in erosive osteoarthritis of the interphalangeal joints: Comparison with controlled inflammatory arthritis

Objective To compare levels of pain and functional limitation in patients with erosive osteoarthritis (OA) of the interphalangeal finger joints with those in patients with nonerosive OA and patients with controlled inflammatory arthritis affecting the hands, and to explore predictors of functional impairment in erosive OA. Methods A cross-sectional study including 270 patients with OA of the hands who were referred to rheumatology clinics was performed. A group of patients with inflammatory arthritis (rheumatoid arthritis or psoriatic arthritis) with a low Disease Activity Score in 28 joints (<3.2; n = 79) was examined. Levels of functional impairment (measured by the Functional Index for Hand OA [FIHOA] and Australian/Canadian OA Hand Index [AUSCAN]) and pain were compared between the groups. Predictors of functional impairment in erosive OA were evaluated by generalized linear models. Results Of 270 patients with hand OA, 167 (61.9%) were classified as having erosive OA. Despite a higher percentage of patients taking analgesics (almost 60%), patients with erosive OA had worse functional outcome and pain scores than patients with controlled inflammatory arthritis or nonerosive OA. Pain scores remained significantly higher in patients with erosive OA after correction for potential confounders. FIHOA and AUSCAN function scores showed a trend toward more disability in patients with erosive OA. Female sex and the number of radiographic affected joints (consisting of joints in the erosive and remodeled radiographic phases) were the strongest predictors of functional impairment in erosive OA. Whether the carpometacarpal joints were affected did not influence functional status in patients with erosive OA. Conclusion Our findings indicate that patients with erosive OA have more functional impairment and significantly more pain compared to patients with controlled inflammatory arthritis affecting the hands. This highlights the significant clinical burden of erosive OA and warrants the search for new treatment strategies.