Value of ultrasound-assessed dactylitis in the early diagnosis of psoriatic arthritis.

PURPOSE: The primary objective of this prospective, longitudinal, observational, single-centre study was to evaluate the association between ultrasound-assessed lesions of dactylitis and the diagnosis of psoriatic arthritis (PsA) in patients with psoriasis (PsO) and hand arthralgia.

METHODS

We included adult patients diagnosed with PsO with hand arthralgia, with or without other musculoskeletal complaints. They were clinically assessed at baseline, 6 and 12 months by a rheumatologist blinded to the ultrasound findings. At baseline, patients underwent a B-mode (BM) and power Doppler (PD) ultrasound assessment by other rheumatologist blinded to clinical data. The ultrasound evaluation included bilateral detection and scoring of synovitis (3 joints, 0-3), tenosynovitis (flexor tendons, 0-3), enthesitis (9 sites, 0-1), peri‑extensor tendon inflammation (PETI) (0-3), and subcutaneous tissue inflammation (SCTI) (0-3) in the 2nd-5th fingers.

RESULTS

Seventy 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 and amount of baseline BM and PD synovitis, BM tenosynovitis, BM and PD enthesitis, and BM and PD PETI were associated with PsA diagnosis (p < .05). A predictive model including two variables, presence of PD synovitis and BM enthesitis, was found to predict PsA diagnosis (χ2 = 35.38; p < .001) with an accuracy of 89.1 %, a sensitivity of 86.7 % and a specificity of 89.8 %.

CONCLUSIONS

Ultrasound-assessed lesions of dactylitis were associated with a diagnosis of PsA and the short-term development of PsA in patients with PsO and hand arthralgia.