FRI0524 Central sensitisation in hand osteoarthritis and associations with radiographic severity, synovitis on ultrasound and symptom duration
Authors: P. Steen Pettersen, T. Neogi, K. Magnusson, H.B. Hammer, T. Uhlig, T.K. Kvien, I.K. Haugen
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Patients with painful hand osteoarthritis (HOA) have enhanced central pain sensitisation (CS). Structural and inflammatory joint tissue damage over time might lead to CS. However, increased pain sensitisation can also represent an 'a priori trait' of a subgroup of patients. <h3>Objectives</h3> This study explored whether structural pathology, inflammation and symptom duration of HOA are associated with enhanced CS. <h3>Methods</h3> Through a cross-sectional study we included 300 subjects (89% women, median age 61 years (IQR 57, 67), mean body mass index (BMI) 26.5 (SD 4.9) kg/m<sup>2</sup>) with clinical and/or ultrasound verified HOA. All were examined with ultrasound (grey scale (GS) synovitis and power Doppler activity (PD)) and conventional radiographs of both hands. GS-synovitis was scored on a semi-quantitative 0–3 scale and PD to be present or not. The bilateral interphalangeal, metacarpophalangeal, first carpometacarpal and scaphotrapeziotrapezoidal joints were scored for global HOA (using Kellgren and Lawrence scale (KL, 0–4). Erosive HOA in the interphalangeal joints was defined with the Verbruggen-Veys anatomical phase score (VV). In addition, participants answered a question about the year of onset of their hand symptoms. CS was measured with temporal summation (TS), the increase in perceived pain to repetitive noxious stimuli, using a mechanical probe. First, probes with increasing weight (32, 64, 128, 256 or 512mN) were applied at the wrist until the patients reported pain of at least 4/10. The selected probe was applied to the wrist times at 1 Hz. Subjects reported pain on first, fifth and tenth touch. Enhanced TS is a marker of central sensitisation and we defined the magnitude of TS as TS-Δ: highest pain value of fifth or tenth touch minus the first pain value. We analysed whether sum scores of KL (0–128), GS (0–90), PD (0–30), number of erosive interphalangeal joints (0–20) and symptom duration were associated with TS-Δ using separate models of linear regression with adjustments for age, sex and BMI. <h3>Results</h3> Median radiographic KL sum score was 28 (IQR 15, 44) and ultrasound sum scores (GS, PD) were 3 (IQR 1, 7) and 0 (IQR 0, 1), respectively. Median number of erosive joints was 0 (IQR 0, 1) and symptom duration was 6 (IQR 3, 13) years. Median TS-Δ among the participants was 1 (IQR 0, 2). Neither KL sum score (p=0.18), GS-synovitis sum score (p=0.18), PD sum score (p=0.86), number of joints with erosive HOA (p=0.078) nor symptom duration (p=0.21) were associated with TS-Δ (table 1). Table 1 Associations between OA features and temporal summation * <h3>Conclusions</h3> We found no relationship between the severity of HOA pathology and CS. This is in line with the hypothesis that factors other than OA disease severity itself contribute to CS associated pain, and that CS may be a trait in some individuals. However, it does not exclude other aspects of HOA as an initiator of CS in a subgroup of patients. <h3>Disclosure of Interest</h3> None declared