THU0080 DEVELOPMENT OF ULTRASOUND DETECTABLE ARTHRITIS AMONG ACPA POSITIVE SUBJECTS WITH MUSCULOSKELETAL SYMPTOMS: THE RISK RA PROSPECTIVE STUDY
Authors: Aase Hensvold, Yogan Kisten, Alexandra Circiumaru, Monika Hansson, Meng Sun, Guozhong Fei, Nancy Vivar, Erik Af Klint, Hamed Rezaei, Lars Klareskog, Aleksandra Antovic, Anca Catrina
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background:</h3> Retrospective studies have shown that anti-citrullinated protein antibodies (ACPA) are a risk factor for the development of clinical arthritis. <h3>Objectives:</h3> We aimed to investigate in a prospective setting if ACPA and other biomarkers could predict development of ultrasound detected arthritis. <h3>Methods:</h3> Subjects with positive ACPA-test referred from primary care to the Rheumatology clinic that lacked arthritis in hands, feet and any other symptomatic joints by clinical and ultrasound examination (according to EULAR-OMERACT definition), were recruited into the Risk-RA research program during 2015-2016 and were followed up to the end of 2017. At inclusion a detailed clinical examination was performed and blood samples were analyzed for 13 specific ACPA reactivities (using a custom made peptide microarray) as well as 92 inflammation-associated protein biomarkers (using a multiplex immunoassay with Olink proximity extension technology). Presence of HLA-SE was analyzed using DR low-resolution kit. Univariate and multivariate analysis were used to investigate the association between clinical and laboratory parameters and development of ultrasound detected arthritis adjusting for the follow-up time. <h3>Results:</h3> 42% (27 out of 65) of the Risk RA subjects developed ultrasound detectable arthritis during a median follow up of 8 months. The remaining 58% (38 out of 65) were followed for a median of 25 months (range 12-44) without any signs of ultrasound detectable arthritis. Subjects developing arthritis had higher prevalence of HLA-SE (89% vs 56%) and increased occurrence of ultrasound detected tenosynovitis (44% vs 5%), as compared to those not developing arthritis. ACPA reactivities to citrullinated vimentin peptides (cit vim 2-17: 22% vs 6%; and cit vim 60-75: 70% vs 43%) and citrullinated histone peptides (cit H4 31-50: 89% vs 49%; and cit H3 21-44: 48% vs 23%) were a more common occurrence in subjects developing ultrasound detectable arthritis. Backward selection in a Cox regression model showed that ultrasound detectable arthritis could be predicted in a model including HLA-SE, tenosynovitis and ACPA reactivity to cit H4 31-50. Hazard ratio (HR) for arthritis development were 3.4 (95% CI 1.0-12, p 0.06) for HLA-SE carriers, 2.9 (95% CI 1.3-6.7, p 0.01) for tenosynovitis and 4.1 (95% CI 1.2-14, p 0.02) for Anti-citrullinated H4 31-50 positivity. Only modest differences were observed for few of the tested inflammatory markers in those developing as compared to those not developing ultrasound detectable arthritis: Interleukin- 6 (3.9 vs 3.3 AU/ML), Programmed death-ligand 1 (4.9 vs 5.2 AU/ML) and Chemokine (C-X-C motif) ligand 6 (9.2 vs 9.5 AU/ML). <h3>Conclusion:</h3> Certain ACPA fine specificities, HLA-SE and tenosynovitis predict the development of ultrasound detectable arthritis in seropositive individuals with musculoskeletal symptom who are at risk for RA.&nbsp; <h3>Disclosure of Interests:</h3> Aase Hensvold: None declared, Yogan Kisten: None declared, Alexandra Circiumaru: None declared, Monika Hansson: None declared, Meng Sun Grant/research support from: Yes, but not for presented project., Guozhong Fei: None declared, Nancy Vivar: None declared, Erik Af Klint: None declared, Hamed Rezaei: None declared, Lars Klareskog Grant/research support from: Yes, but not for the presented study., Aleksandra Antovic: None declared, Anca Catrina Grant/research support from: Yes, but not for the presented study.&nbsp;&nbsp;