THU0417 THE SEVERITY OF STRUCTURAL AND INFLAMMATORY FEATURES OF HAND OSTEOARTHRITIS ASSOCIATE WITH PERIPHERAL PAIN SENSITIZATION
Authors: Pernille Steen Pettersen, Tuhina Neogi, Karin Magnusson, Hilde Berner Hammer, Tore K. Kvien, Till Uhlig, Ida Kristin Haugen
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background</h3> Increased sensitivity to pain in the area around joints with osteoarthritis (OA), i.e., peripheral sensitization, is associated with higher pain severity. The mechanisms underlying peripheral sensitization in hand OA have not been substantially explored in previous studies. <h3>Objectives</h3> We aimed to explore whether the severity of structural or inflammatory OA features in the distal and proximal interphalangeal (DIP/PIP) joints were associated with lower pressure pain thresholds (PPT) at the same joint in a large study sample of persons with hand OA. <h3>Methods</h3> In these cross-sectional analyses we included 277 persons with hand OA from the Nor-Hand cohort. All participants underwent radiography and ultrasound examination (GE S8, ML 6-15MHz probe) of both hands. Pressure pain threshold (PPT) was tested with a hand-held algometer (FPIX25, 1cm<sup>2</sup> flat rubber probe) in perpendicular position at the dorsal side of the DIP/PIP joint reported to be the most painful. Information about demographics and psychosocial factors was collected with questionnaires. We examined whether increasing radiographic severity (Kellgren-Lawrence 0-4 score) and ultrasound-detected inflammation (grey-scale synovitis 0-3 score and presence of power-Doppler activity) were associated with PPT at the same joint. We conducted separate analyses of linear regression with adjustments for age, sex, BMI, education level, use of analgesics, sleep disturbance, the Pain Catastrophizing Scale and the Hospital Anxiety and Depression Scale. <h3>Results</h3> The majority of the study population were women (89%), median age was 61 (IQR 57-66) years, mean BMI was 26.3 (SD 4.6) kg/m<sup>2</sup> and median duration of hand OA symptoms was 6 (IQR 3-13) years. The DIP/PIP joints demonstrated a wide range of PPT (mean (SD) 3.9 (1.9), range 0.6-11.4 kg/cm<sup>2</sup>) and OA severity (Table). We found that both increasing radiographic severity and inflammation were associated with lower PPTs (Table). When including grey-scale synovitis and power Doppler as confounders in analysis of radiographic severity, the results became weaker but remained significant (Table). Adjusted for age, sex, BMI, analgesics, education, sleep disturbance, the Pain Catastrophizing Scale and the Hospital Anxiety and Depression Scale. *Additional adjustments for grey-scale synovitis and power Doppler. <h3>Conclusion</h3> Both structural and inflammatory hand OA features in DIP/PIP joints were associated with lower pressure pain thresholds, i.e. pain sensitization, at the same joint. Our results suggest that peripheral sensitization might be driven by structural and inflammatory features, and that targeting the disease early might prevent peripheral sensitization and reduce pain.&nbsp; <h3>Disclosure of Interests:&nbsp;</h3> Pernille Steen Pettersen: None declared, Tuhina Neogi: None declared, Karin Magnusson: None declared, Hilde Berner Hammer Grant/research support from: AbbVie, Pfizer and Roche, Paid instructor for: AbbVie, Pfizer, UCB, Novartis, Roche, Speakers bureau: AbbVie, Pfizer, UCB, Novartis, Roche, Tore K. Kvien Grant/research support from: AbbVie, BMS, MSD, Pfizer, Roche and UCB., Consultant for: AbbVie, Biogen, BMS, Boehringer Ingelheim, Celgene, Celltrion, Eli Lilly, Hospira, Merck-Serono, MSD, Novartis, Oktal, Orion Pharma, Pfizer, Roche, Sandoz, Sanofi, Mylan and UCB, Speakers bureau: AbbVie, Biogen, BMS, Boehringer Ingelheim, Celgene, Celltrion, Eli Lilly, Hospira, Merck-Serono, MSD, Novartis, Oktal, Orion Pharma, Pfizer, Roche, Sandoz, Sanofi and UCB, Till Uhlig Consultant for: Grünenthal, Novartis, Speakers bureau: Grünenthal, Novartis, Ida Kristin Haugen Grant/research support from: ADVANCE research grant from Pfizer, Consultant for: Advisory board Abbvie&nbsp;