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 peripherally to centrally mediated pain during the disease course in some patients. We assessed sensory profiles of recently diagnosed individuals with IA, hypothesizing that pain reported at this early stage of diagnosis is driven predominantly by peripheral joint inflammation.

Methods: Recently diagnosed patients with IA with pain numerical rating scale scores of ≥3 were recruited. We collected data on the following: arthritis activity (Disease Activity Score in 28 joints [DAS28], musculoskeletal ultrasonography), quality of life (Musculoskeletal Health Questionnaire [MSK-HQ], EuroQol 5-domain), 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: Sixty-one participants (57% female, 62% with rheumatoid arthritis) were enrolled (mean ± SD age 49.8 ± 15 years; mean ± SD time since diagnosis 1.2 ± 2.3 months). Ninety-seven percent had peripheral joint inflammation, with a mean ± SD DAS28 score of 3.8 ± 1. However, 21% met the fibromyalgia criteria, 25% had a painDETECT score of ≥19, and 20% had a tender joint count minus swollen joint count of ≥7, which significantly correlated with DAS28, MSK-HQ, and PHQ-ADS scores. QST revealed lowered pressure pain thresholds at nonarticular 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.