Assessment of pain types in recently diagnosed patients with Inflammatory Arthritis

Objective Up to 40% of patients with inflammatory arthritis (IA) experience persistent pain, traditionally thought to be associated with a shift from peripheral to centrally mediated pain during the disease course in some patients. We assessed sensory profiles of recently diagnosed individuals with IA, hypothesising that pain reported at this early stage of diagnosis is driven predominantly by peripheral joint inflammation. Methods Recently diagnosed IA patients with pain numerical rating scale (NRS) scores of ≥3 were recruited. We collected data on: Arthritis activity (Disease Activity Score‐28 (DAS‐28), musculoskeletal ultrasound); quality of life (Musculoskeletal Health questionnaire (MSK‐HQ), Euro Quality of Life questionnaire (EQ‐5D)); mental health status (Patient Health Questionnaire Anxiety, Depression Scale (PHQ‐ADS)), and pain characteristics (fibromyalgia criteria, painDETECT, Static and Dynamic Quantitative Sensory Testing, QST). Results 61 participants (57% Female, 62% Rheumatoid Arthritis) were enrolled: mean age 49.8 ±15 years; time since diagnosis 1.2±2.3 months. 97% had peripheral joint inflammation, with a mean DAS‐28 score of 3.8±1. However, 21% met the fibromyalgia criteria, 25% had a painDETECT score of ≥19 and 20% had a tender minus swollen joint count of ≥7, which significantly correlated with DAS28, MSK‐HQ and PHQ‐ADS scores. QST revealed lowered pressure pain thresholds at non‐articular sites in a subset of participants and facilitated temporal pain summation and deficient pain modulation in 18% and 61% of patients respectively. Conclusion This study provides evidence of centrally mediated pain at the time of diagnosis, challenging the notion that, even at the early stage of disease, pain is driven only by peripheral mechanisms.