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; time since diagnosis 1.2±2.3 months. 97% had peripheral joint inflammation, with a mean DAS-28 score of 3.8±1. However, 20% had a tender minus swollen joint count of ≥7, 21% met the fibromyalgia criteria and 25% had a painDETECT score of ≥19, 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.

SIGNIFICANCE AND INNOVATIONS

• This study is the first to record comprehensive sensory profiles incorporating clinical examination, ultrasound, questionnaire, and quantitative sensory testing data in the early stage of inflammatory arthritis diagnosis.

• Of those tested, 97% had peripheral joint inflammation confirmed by clinical assessment and ultrasound. In addition, clinical, patient-reported and QST outcome measures revealed the likely presence of centrally mediated pain in a subset of participants.

• These findings challenge the current belief that only peripheral mechanisms driven by joint inflammation underpin pain in the early stage of disease progression, highlighting a role for centrally mediated pain even in the early stage of disease.