BackgroundThe transition from psoriasis (PsO) to psoriatic arthritis (PsA) is a focus of considerable scientific interest: is it possible to target pre-PsA and very early PsA, in particular for physiopathology and drug studies? Recently, a EULAR taskforce has been set up in this area (1).ObjectivesTo characterize the prodromal and the very early PsA through a systematic literature review (SLR).MethodsA SLR explored MEDLINE, EMBASE and CENTRAL, up to 22 October 2021. The objective was to identify the symptoms, objective signs, lab tests, imaging features and other characteristics of patients later diagnosed as “new onset” PsA in two key populations: 1) patients with PsO and 2) patients with early undifferentiated arthritis (UA). Studies of adult patients published in English were included, if they reported characteristics of pre-PsA or new onset PsA patients, and data were extracted by 2 readers. Meta-analysis was not done due to data heterogeneity (PsA classification criteria, outcome measures and length of observation). Results are reported semi-quantitatively.ResultsOf 31449 references, 22 studies were included of which 12 were prospective; 7 retrospective and 3 cross-sectional. Eighteen studies reported on patients with PsO (n=95828) later diagnosed as PsA (n=2136) with a mean duration of follow up of 5.2 (±3.9) years. Seven out of 18 (38.8%) studies were informative regarding the clinical features of the new onset PsA. Four studies on early UA patients (n=492) later diagnosed as PsA (n=49) were included. Progression to PsA was associated with the presence of musculoskeletal (MSK) complaints (mainly joint tenderness) and the presence of subclinical MSK inflammation detected by imaging. Peripheral oligo-arthritis was the prevalent clinical presentation of new onset PsA.ConclusionAs expected, joint pain and imaging evidence of MSK inflammation were associated with PsA development in PsO patients. The SLR highlights the lack of robust evidence regarding data associated with the development of PsA. More prospective studies focusing on transition from PsO to PsA are needed.Table 1.FeaturesTransition from PsO to PsA (n = 18 studies)Transition from UA to PsA (n = 4 studies)Clinical characterization of New Onset PsA (n = 5 studies)Patient reported symptomsVAS pain+++NAEntheseal pain+NAMorning stiffness+NAFatigue+NAHAQ more compromised++NAArthralgia+++NAClinical examinationJoint tenderness+++++++Swelling joints++++Entheseal tendernessMajor domain of pattern presentationPeripheral arthritis (more frequent)+++PolyarthritisMono-oligoarthritis++Inflammatory marker(s)CRP++ImagingMSK inflammation detected by imaging++++Radiographic evidence of specific damage++Legend:PsO = psoriasis (affecting skin); PsA = psoriatic arthritis; UA = undifferentiated inflammatory arthritis; VAS = visual-analogue scale; NA = not applicable; HAQ = health assessment questionnaire; CRP = C-reactive protein; MSK = musculoskeletal+ = 1 study for positive association; ++ = 2 studies for positive association; +++ >= 3 studies for positive associationReferences[1]https://www.eular.org/ongoing_initiatives.cfmDisclosure of InterestsAlen Zabotti Speakers bureau: Amgen, Lilly, Janssen, Novartis, UCB, Paid instructor for: Amgen, Janssen, Grant/research support from: Novartis, Gabriele De Marco: None declared, Laure Gossec Speakers bureau: AbbVie, Amgen, BMS, Galapagos, Gilead, GSK, Janssen, Lilly, Novartis, Pfizer, Samsung Bioepis, Sanofi-Aventis, UCB, Grant/research support from: Amgen, Galapagos, Lilly, Pfizer, Sandoz, Xenofon Baraliakos: None declared, Jenny Emmel: None declared, Daniel Aletaha Speakers bureau: Abbvie, Amgen, Lilly, Janssen, Merck, Novartis, Pfizer, Roche, Sandoz, Grant/research support from: Abbvie, Amgen, Lilly, Novartis, Roche, SoBi, Sanofi, Annamaria Iagnocco: None declared, Josef S. Smolen: None declared, Dennis McGonagle Speakers bureau: Janssen, Lilly, UCB, Abbvie, Pfizer, Celgene, Grant/research support from: Janssen