Background:The UPSTREAM (NCT03330769) is a 24-month multi-center prospective cohort study that primarily aims to evaluate the additional value of musculoskeletal ultrasound (msk-US) over clinical examination in predicting 6-month minimal disease activity in Psoriatic Arthritis (PsA). (1)Objectives:To develop and preliminarily validate an activity msk-US score and a damage msk-US score for PsA using the UPSTREAM database.Methods:Patients classified with PsA according to CASPAR criteria and starting a new course of therapy for clinically active peripheral joint disease were eligible. The information regarding objectives, study design, clinical and US assessment has already been published (1). The msk-US examination was performed in 42 joints, 36 tendons, 12 entheses and 2 bursae defined through a web-based exercise (2). The sonographic elementary lesions were allocated to disease activity [i.e. synovitis (sy), tenosynovitis (ts), peritendinitis (pt), bursitis (bs) all evaluated both in Grey Scale (GS) and Power Doppler (PD) and active enthesitis (en)] and to damage (i.e. joint erosion, bone proliferation, tendon tear, enthesophyte, calcification and irregular enthesis bone profile). Hands and feet X-ray were assessed using the modified Sharp-Van der Heijde (mSVH) score. A principal component (PC) analysis (PCA) was performed for each score and the number of PCs was defined by means of parallel analysis using baseline data. Each PC was normalized (n) taking into account the proportion between the observed value (e.g. sy-GS count) and the maximum expected value (e.g. 42 for sy-GS). Spearman’ correlation was used to investigate the construct and discrimination validity of the new scores.Results:Between February 2017 and May 2020, 312 PsA patients (155 men), with a mean (SD) age of 52.8 13.4, were enrolled from 19 centers; 22 expert sonographers were involved with substantial agreement for US lesions evaluated (k ≥0.7). The median [IQR] disease duration was 1.3 [0.1-6.1] years and the median [IQR] tender joint and swollen joint counts were 6 [3-13] and 2 [1-5], respectively. The weight derived from PCA for each sonographic lesions and the final equation for calculating the scores are reported in Figure 1 (1A activity and 1B damage). The final msk-US activity score [n(ts-GS + ts-PD)*2.87] + [n(bs-GS + bs-PD)*1.76] + [n(pt-GS + pt-PD)*1.43] + [n(active en)*1.00] + [n(sy-GS)*0.83] + [n(sy-PD)*0.45] has the best construct and discrimination validities according to a significant correlation with all clinical variables usually related to clinical activity (Table 1). The msk-US damage score correlated with mSVH score, HAQ and other clinical variables (Table 1).Table 1.VariablesMsk-US activity scoreMsk-US damage scoreSpearman correlationP-valueSpearman correlationP-valueESR0.1960.0020.0750.235CRP0.209<0.0010.0680.254TJC0.338<0.0010.286<0.001SJC0.338<0.0010.0720.221Dactylitis count0.284<0.001-0.0610.306LEI0.1940.0010.214<0.001Physician GA0.150.0120.0160.793Patient GA activity0.1380.018-0.0730.221Patient GA pain0.1990.001-0.0270.648HAQ0.238<0.0010.1460.014BASDAI0.237<0.0010.1750.003PSAID-90.70.0040.1480.013DAPSA0.392<0.0010.228<0.001Sharp van Der Heijde score0.1150.20.2660.003Figure 1.Conclusion:These newly developed and preliminary validated msk-US activity and damage scores could be used in patients with PsA in the context of observational and controlled trials.References:[1]Canzoni M et al. BMJ Open. 2018;8:e021942.[2]Zabotti A et al. Ann Rheum Dis 2018;77:1537–1538.Acknowledgements:Alberto Batticciotto; Oscar Massimiliano Epis; Luisa Arcarese; Luca Navarini; Marta Caprioli; Mirco Magnani; Roberta Ramonda; Marco Amedeo CimminoDisclosure of Interests:Alen Zabotti: None declared, Matteo Piga: None declared, Anna Zanetti: None declared, Marco Canzoni: None declared, nicola boffini: None declared, valentina picerno: None declared, Giovanni Zanframundo: None declared, Ettore Silvagni: None declared, Ivan Giovannini: None declared, BERND RAFFEINER: None declared, Palma Scolieri: None declared, Paola Mancini: None declared, Simone Parisi: None declared, Alessandra Bortoluzzi Grant/research support from: GSK, Garifallia Sakellariou Consultant of: Consultant for Abbvie and Novartis, Orazio De Lucia: None declared, Ilaria Tinazzi: None declared, Fabiana Figus: None declared, Luca Idolazzi Speakers bureau: Received grants as speaker for Eli Lilly, UCB, Celgene, MSD, Abbvie, Novartis, Paid instructor for: Paid instructor for UCB during Product specialist Meeting, Mariagrazia Lorenzin: None declared, Sara Zandonella Callegher: None declared, Alberto Cauli: None declared, Greta Carrara: None declared, Carlo Alberto Scirè: None declared, Annamaria Iagnocco: None declared

OP0223 DEVELOPMENT AND PRELIMINARY VALIDATION OF ULTRASONOGRAPHIC DISEASE ACTIVITY AND DAMAGE SCORES IN PSORIATIC ARTHRITIS PATIENTS: RESULTS FROM THE UPSTREAM (ULTRASOUND IN PSORIATIC ARTHRITIS TREATMENT) STUDY