Serum leptin, adiposity, and their link to symptomatic hand osteoarthritis in individuals with radiological signs – A cross-sectional HALLOA cohort study

Objective: To investigate the relationship between serum leptin levels and symptomatic hand osteoarthritis (OA) in individuals with radiographically confirmed hand OA. Method: This cross-sectional study included 90 individuals with radiographically confirmed hand OA. Symptomatic hand OA was diagnosed according to the American College of Rheumatology (ACR) criteria. Serum leptin levels, body mass index (BMI), and bioimpedance were measured. Participants reported pain intensity in the Numeric Rating Scale (NRS), self-reported upper-extremity disability (QuickDASH), number of bodily pain sites, and underwent pain pressure threshold (PPT) and grip strength measurements. Characteristics were compared between individuals with and without symptomatic hand OA. Binary logistic regressions were used to investigate the relationship between serum leptin levels and symptomatic hand OA. Adjustments were made stepwise for 1. age and sex, 2. adiposity, 3. radiographic severity of hand OA, and 4. PPT. Results: Symptomatic hand OA was diagnosed in 51 participants, whereas 39 did not have symptomatic hand OA. Participants with symptomatic hand OA had more hand pain, worse function, weaker grip, but also lower PPTs and more bodily pain. Metabolic factors did not differ between groups. Serum leptin levels were not associated with symptomatic hand OA. In a secondary finding, female sex was associated with symptomatic hand OA, an effect that was attenuated after adjustment for PPTs. Conclusion: Compared to those without symptoms, participants with symptomatic hand OA had lower PPTs and more widespread pain, consistent with features of central sensitization. While serum leptin was not independently associated with symptomatic hand OA, differences in pain sensitivity may contribute to the higher prevalence of symptomatic hand OA among women.