SAT0574 Sensitisation and pain severity in patients with hand osteoarthritis
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> Sensitisation, a hyperexcitability of nociceptive pathways, contributes to pain severity in patients with knee osteoarthritis, but this association has not yet been examined in patients with hand osteoarthritis (HOA). <h3>Objectives</h3> This study explored the occurrence of central and peripheral sensitisation in patients with HOA and the relationship between sensitisation and hand pain severity. <h3>Methods</h3> Three hundred subjects (89% women) with clinical and/or ultrasound-verified HOA were included in this cross-sectional study. Hand pain severity was assessed with the numeric rating scale (0–10 NRS) of hand pain during the last 24 hours, the pain subscale (0–20) of the Australian/Canadian (AUSCAN) hand index and a modified version (0–42 scale) of the Intermittent and Constant OsteoArthritis Pain (ICOAP) questionnaire. Pressure pain thresholds (PPT) were measured with an algometer at two sites: dorsum of the OA finger joint reported to be most painful to test peripheral sensitisation, and at a remote site (mid-portion of tibialis anterior) to test widespread hyperalgesia. Temporal summation (TS), the increase in perceived pain to repetitive noxious stimuli reflecting central sensitisation, was assessed with a mechanical probe at the right wrist. First, probes with increasing weight (32, 64, 128, 256 or 512 mN) were applied at the wrist until the patients reported pain of at least 4/10. The selected probe was applied to the wrist ten times at 1 Hz. Subjects reported NRS pain on the first, fifth and tenth touch. The magnitude of enhanced TS was defined as TS-Δ: highest pain value of fifth or tenth touch minus the first pain value. Subjects were categorised into sex-specific PPT tertiles. We then used linear regression to analyse whether PPT tertiles and TS-Δ were associated with pain severity with and without adjustments for age, sex, BMI, use of analgesics (NSAIDS, acetaminophen and opioid-like drugs) and several psychosocial factors (highest degree of completed education (1–7 scale), sleep disturbance (0–4 scale), the Pain Catastrophizing Scale (PCS) and the Hospital Anxiety and Depression Scale (HADS)). <h3>Results</h3> Median age was 61 (IQR 57, 67) years, symptom duration 6 (IQR 3, 13) years, and mean body mass index (BMI) was 26.5 (SD 4.9) kg/m<sup>2</sup>). Median TS-Δ among the participants was 1 (IQR 0, 2) and TS-Δ of 2 or more was found in 41%. Subjects in the lowest PPT tertile of their painful OA joint and tibialis anterior reported more hand pain than subjects in the highest PPT tertile. Unadjusted, the relation of PPT to NRS and ICOAP were statistically significant, and for the tibialis anterior only, it was also significantly associated with AUSCAN. After adjusting for potential confounders, the relationships were only statistically significant for NRS (Table). We found positive adjusted associations between increasing TS-Δ and NRS (beta 0.18, 95% CI 0.04, 0.32) and ICOAP (beta 0.63, 95% CI −0.16, 0.3), but not for AUSCAN pain (beta 0.12, 95% CI 0.11, 1.16). <h3>Conclusions</h3> In patients with HOA, sensitisation, as reflected by lower PPTs and enhanced TS, was significantly associated with greater pain severity. Future studies are needed to explore whether sensitisation is a result of OA pathology or traits of certain patients, and whether treatments aiming to reduce sensitisation might reduce pain in patients with HOA. <h3>Disclosure of Interest</h3> None declared