FRI0425 EVALUATION OF THE DOYLE INDEX AS A MEASURE OF PAIN SENSITIZATION IN PERSONS WITH HAND OSTEOARTHRITIS: EXPLORATORY ANALYSES FROM THE NOR-HAND STUDY
Authors: P. Steen Pettersen, T. Neogi, K. Magnusson, B. Slatkowsky-Christensen, H. B. Hammer, T. Uhlig, T. K. Kvien, I. K. Haugen
Journal: Annals of the Rheumatic Diseases (2020)

Background: Pressure pain threshold (PPT) is a measure of pain sensitization; altered pain mechanisms in the peripheral and/or central nervous system causing increased pain sensitivity. PPT testing may be a useful tool to classify pain phenotypes but requires special equipment not available in the clinic. The Doyle index (DI) is a clinical measure of joint tenderness upon palpation. It is considered as an outcome measure of pain and disease activity in hand OA and is a potential alternative to PPT. It is unclear if joint tenderness is related to pain sensitization, as joint tenderness could reflect pure nociceptive pain without sensitization. Objectives: Using data from the Nor-Hand study we will explore how DI performs as a measure of pain sensitization in hand OA by examining associations and agreements between DI and PPT at joint level, and correlations between PPT values and DI sum score at person level. Methods: PPT was tested with a hand-held algometer (FPIX25, 1cm 2 flat rubber tip) at the dorsal side of the most painful DIP/PIP and a non-painful DIP/PIP joint (local PPTs) and left radioulnar joint and mid-portions of the trapezius and tibialis anterior muscle (remote PPTs). Low local PPTs indicate peripheral and/or central sensitization, while low remote PPTs indicate central sensitization. According to DI, tenderness in the bilateral thumb base and finger joints were graded by a rheumatologist by pressing on the lateral joint margins: 0=no pain, 1=patient complains of pain, 2=patient complains of pain and winces, 3=patient complains of pain, winces and withdraws joint. We examined whether increasing DI was associated with local PPT using mixed models. To assess agreement between DI and PPT, we categorized PPT of the painful finger joints into a semi-quantitative scale with the same number of categories (n=4) as DI. We identified the cut-offs for the PPT categories that maximized the agreement (weighted kappa) with DI. Finally, we examined Spearman’s correlations between DI sum score [range 0-90] and PPTs of local and remote sites. Results: The majority of the 285 eligible participants were women (88%) and mean (SD) age was 61 (6) years. Joints with high DI had lower PPT values (Figure 1). We found a linear association of lower PPT with increasing DI for all joints combined (beta -0.7, 95% CI -0.8, -0.6). Similar results were found for the painful joints (beta -0.8, 95% CI -1.0, -0.6), but weaker for non-painful joints (beta -0.5, 95% CI -1.0, 0.0) where few joints had DI grade 2-3 (Figure 1). The analyses on maximized agreement between DI and the PPT categories gave a weighted kappa equal to 0.32 (Table). Median (IQR) DI sum score was 9 (5, 15). We found weak inverse correlations between DI sum score and PPT at local (painful finger: ρ -0.24 (95% CI -0.32, -0.16), non-painful finger: ρ -0.22 (95% CI -0.29, -0.11) and remote sites (radioulnar joint: ρ -0.17 (95% CI -0.29, -0.06), trapezius: ρ -0.25 (95% CI -0.36, -0.14), tibialis anterior: ρ -0.20 (95% CI-0.31, -0.09)). Conclusion: The DI was associated with lower PPT at painful finger joints. Large variance of PPT within each DI grade resulted in fair agreement. DI of non-painful finger joints was weakly associated with PPT, demonstrating that the DI does not differentiate pain sensitization in joints without ongoing nociceptive pain. Correlations between DI sum score and PPT of remote sites were also weak. The two measures seem to assess different constructs and are therefore not interchangeable. Table. Cross tabulation of DI with the best PPT categorization of painful finger joints. Cells = joint count PPT categories (range, kg/cm 2 ) 0 (4.7-12) 1 (3.4-4.6) 2 (2.1-3.3) 3 (0-2.0) DI 0 32 21 11 3 1 21 29 31 7 2 15 22 31 16 3 2 7 15 22 PPT categories 0-3 (i.e. decreasing PPT) represent the categorization that gave maximized agreement with DI (weighted kappa = 0.32) Disclosure of Interests: Pernille Steen Pettersen: None declared, Tuhina Neogi Grant/research support from: Pfizer/Lilly, Consultant of: Pfizer/Lilly, EMD-Merck Serono, Novartis, Karin Magnusson: None declared, Barbara Slatkowsky-Christensen: None declared, Hilde Berner Hammer Consultant of: Has received fees as consultant from Roche, AbbVie and Novartis., Speakers bureau: Has received fees for speaking from AbbVie, BMS, Pfizer, UCB, Roche, MSD and Novartis, Till Uhlig Consultant of: Lilly, Pfizer, Speakers bureau: Grünenthal, Novartis, Tore K. Kvien Grant/research support from: Received grants from Abbvie, Hospira/Pfizer, MSD and Roche (not relevant for this abstract)., Consultant of: Have received personal fees from Abbvie, Biogen, BMS, Celltrion, Eli Lily, Hospira/Pfizer, MSD, Novartis, Orion Pharma, Roche, Sandoz, UCB, Sanofi and Mylan (not relevant for this abstract)., Paid instructor for: Have received personal fees from Abbvie, Biogen, BMS, Celltrion, Eli Lily, Hospira/Pfizer, MSD, Novartis, Orion Pharma, Roche, Sandoz, UCB, Sanofi and Mylan (not relevant for this abstract)., Speakers bureau: Have received personal fees from Abbvie, Biogen, BMS, Celltrion, Eli Lily, Hospira/Pfizer, MSD, Novartis, Orion Pharma, Roche, Sandoz, UCB, Sanofi and Mylan (not relevant for this abstract)., Ida K. Haugen: None declared