Background/Purpose: The primary objective of this prospective, longitudinal, observational study was to evaluate the predictive value of ultrasound (US)-detected elementary lesions of dactylitis together with US-assessed inflammation in other peripheral sites in relation to PsA diagnosis in psoriatic (PsO) patients with finger arthralgia. In addition, we investigated the relation between serum levels of different proinflammatory cytokines and PsA diagnosis in this population

Methods: We included adult patients diagnosed with PsO with or without other musculoskeletal complaints. Exclusion criteria were the presence of PsA or any other inflammatory arthropathy at inclusion and treatment with DMARD in the previous 6 months. Patients were recruited by local dermatologists, general practitioners, or rheumatologists. Patients were clinically assessed at baseline, 6 and 12 months by an expert rheumatologist blinded to the US findings. At baseline, patients underwent a B-mode (BM) and power Doppler mode (DM) US assessment by the same rheumatologist, highly expert in this technique and blinded to clinical data. The US evaluation included bilateral detection and scoring of synovitis (3 joints, 0-3), tenosynovitis (flexor tendons, 0-3), enthesitis (9 sites, 0-1), peri-extensor tendoninflammation (PETI)(0-3), and subcutaneous tissue inflammation(SCTI) (0-3) in 2nd-5th fingers. In addition, synovitis, tenosynovitis and enthesitis were detected and scored (0-3) bilaterally at 4 extradigital sites each. Global indices of digital and extra-digital lesions were obtained from the sum of the scores of the corresponding sites. Serum levels of proinflammatory cytokines were measured at baseline employing a cytokine antibody array. The primary outcome was to diagnose PsA judged by an expert rheumatologist during the 12-month follow-up

Results: 70 patients [44 women; mean (SD) age 51 (12.4) years]were included, of whom 64 completed the study.Of these, 15 (23.4%) were diagnosed with PsA during the 12-month follow-up period. At finger level, the presence of baseline BM synovitis (χ²=8.04; p=0.006), DM synovitis (χ²=13.55; p=0.001), BM tenosynovitis (χ²=21.13; p=0.001), BM enthesitis (χ²=30.36; p< 0.001), DM enthesitis (χ²=29.87; p< 0.001), BM PETI(χ²=17.72; p< 0.001), and DM PETI(χ²=10.28; p=0.011) were associated with PsA diagnosis.Table 1 and Table 2 show the comparison of baseline global indices of digital and extra-digital lesions, respectively, between patients who were and were not diagnosed with PsA. At finger level, global BM synovitis, DM synovitis, BM tenosynovitis, DM tenosynovitis, BM enthesitis, DM enthesitis, BM PETI, and DM PETI were significantly higher in patients diagnosed with PsA(p< 0.05).In multivariate analysis of digital and extra-digital US variables, a final model including 4 US variables was predictive of PsA diagnosis (χ2=44.75; p< 0.001) with a sensitivity of 80.0% and a specificity of 89.8% (Table 3).Regarding serum concentration of cytokines, only IL-22 and IL-17F were significantly different between groups

Conclusion: US-detected lesions of dactylitis together with extra-digital inflammation predict the diagnosis of PsA in PsO patients with finger arthralgia

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/ultrasound-assessed-dactylitis-as-a-biomarker-in-the-early-diagnosis-of-psoriatic-arthritis/