FRI0091 Somatosensory dysfunction in rheumatoid arthritis – a quantitative sensory testing assessment
Authors: T.M. Rocha, M. Barbosa, S. Pimenta, M. Bernardes, A. Bernardo, R. Lucas, L. Costa, J. Vollert, C. Maier
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Background</h3> Significant pain persists in a substantial proportion of Rheumatoid Arthritis (RA) patients and features suggestive of neuropathic pain (NP) were described. Few studies applied quantitative sensory testing (QST) to evaluate the somatosensory phenotype of RA pain. <h3>Objectives</h3> To explore the sensory abnormalities in RA and study its association with clinical and disease activity parameters. <h3>Methods</h3> Cross-sectional study was performed with RA patients followed at our rheumatology department. QST was performed in patients classified with NP (according to LANSS and/or pain DETECT scores) in both the most painful and non-painful contralateral joint areas. The evaluation followed the protocol of the German Research Network on Neuropathic Pain. Patients with diagnosed neuropathy or non-RA risk factors for NP were excluded. Proportions of abnormal detection/pain thresholds were calculated after z-transformation of QST data based on gender, age and site reference values. Correlations were studied (Spearman correlation coefficient) and comparison between groups was performed (Mann-Whitney and χ<sup>2</sup> tests). <h3>Results</h3> From 112 evaluated RA patients, 47% were classified with NP and 39 performed QST. Thirty four (87%) were women, with a mean age of 53.5±11.8 years and median disease duration of 11 years;<sup>2–31</sup> 74% were seropositive for Rheumatoid Factor and/or ACPA; 90% were treated with conventional synthetic Disease-Modifying Antirheumatic Drugs (DMARDs) and 39% with biological DMARDs (bDMARDs). Mean DAS28 CRP was 3.44±0.7. For non-nociceptive parameters, 23 (59%) patients exhibited sensory loss (Lo), 6 to thermal stimuli (L1), 10 to mechanical stimuli (L2) and the reminder for both (L3). Concerning nociceptive parameters, hyperalgesia (Ga) was noted in almost all the patients (97%), 1 to thermal (G1), 20 to mechanical (G2) and 17 for both stimuli (G3). Twenty two (60%) patients presented both Lo and Ga findings. Higher proportion of Lo was noted in bDMARDs group (86% vs 46%, p=0.02). Lo patients had significant lower median CRP and ESR levels, but no differences were observed concerning disease activity scores. Thermal Lo (L1 and L3) was also more frequent in the bDMARDs group (57% vs 21%, p=0.04) and cold Lo in hydroxychloroquine (HCQ) treated patients (90% vs 21% p=0.02). Cold Ga was more frequent in patients under methotrexate (MTX) (48% vs 6%, p=0.04) and less frequent in the bDMARDs group (7% vs 46%, p&lt;0.05). A weak correlation of Z cold detection and Z warm detection values with CRP and ESR levels was noted (r=0.34 and r=0.35, p=0.04). Time exposure to HCQ, MTX and bDMARDs was negatively correlated with Z cold detection (r=−0.34, p=0.03), Z pressure pain (r=−0.33, p=0.04) and Z vibration detection (r=−0.32, p=0.04), respectively. <h3>Conclusions</h3> Almost all patients presented hyperalgesia, but a sizable proportion also had sensory loss, frequently involving Aβ fibres. CRP and ESR levels possibly influence small fibre function, but no association with disease activity scores was found. Possible association of bDMARDs and HCQ treatment with sensory detection loss and of MTX with lower pain thresholds was pointed. <h3>References</h3> [1] Koop SM, et al. Arthritis Res Ther2015;17:237. [2] Lee YC, et al. Arthritis Care Res (Hoboken). 2018;70(2):197–204. <h3>Disclosure of Interest</h3> T. Rocha Grant/research support from: Portuguese Society of Rheumatology/Alfa Wassermann on May 2015, M. Barbosa: None declared, S. Pimenta: None declared, M. Bernardes: None declared, A. Bernardo: None declared, R. Lucas: None declared, L. Costa: None declared, J. Vollert: None declared, C. Maier: None declared