A novel score can reliably identify the characteristic sonographic features of dactylitis in patients with psoriatic arthritis (PsA), according to study results published in Annals of the Rheumatic Diseases.

Investigators performed a systematic literature review to identify the characteristic features of dactylitis in patients with PsA and evaluate the reliability of musculoskeletal ultrasonography to assess and score these lesions, with the goal of developing a sonographic score for the measurement of dactylitis of the hand in PsA.

Researchers searched the PubMed and Embase online databases from inception to August 2019 for studies examining the use of musculoskeletal ultrasonography in dactylitis in PsA. References for identified studies were manually screened for additionally relevant literature. Data from these studies were extracted into a summary table, which was evaluated by 12 experts using a Delphi questionnaire. The results of the review were used evaluate 118 deidentified sonographic images to develop a consensus on the Dactylitis Global Sonographic (DACTOS) score, with an additional 140 sonographic static images scored by independent experts. Rheumatology sonographers evaluated the hands of 20 patients with symptomatic dactylitis to assess the reliability of the newly developed DACTOS score.

Among the 9 studies selected for the literature review, soft tissue edema, tenosynovitis, and synovitis were the more frequently assessed lesions. Peritendon extensor inflammation was also evaluated. A final score ranging from 0 to 25 points was established based on sonographic assessment of peritendon extensor inflammation, soft tissue edema, flexor tenosynovitis, and synovitis evaluated at the metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints.


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The intra-rater reliability for sonographic lesions evaluated in B-mode (kappa coefficient [ĸ] range, 0.60-0.77) was improved when lesions were assessed with Power Doppler (ĸ range, 0.71-0.98). Similar results were seen with regard to inter-rater reliability, with moderate reliability observed for soft tissue edema (ĸ=0.57) and good reliability for peritendon extensor inflammation (ĸ=0.89) and flexor tenosynovitis (ĸ=0.72) using Power Doppler. Inter-rate reliability of synovitis was also good (ĸ=0.62).

Inter-rater reliability in the patient-based exercise using Power Doppler was moderate for soft tissue edema (ĸ=0.42) but good for flexor tenosynovitis (ĸ=0.75) and excellent for peritendon extensor inflammation (ĸ=1). Inter-rater reliability for synovitis was also excellent after adjusting for prevalence.

Overall, the researchers observed a moderate to excellent agreement of the DACTOS score with the sonographic lesions in PsA dactylitis.

“[D]ue to the growing interest to measure dactylitis, the novel DACTOS score could be a useful and reliable tool to [summarize] key imaging findings for the diagnosis, management and research in patients with PsA,” the researchers concluded. “The next step will be to validate this global score for dactylitis against relevant measures of disease activity in a clinical setting.”

Reference

Zabotti A, Sakellariou G, Tinazzi I, et al. Novel and reliable Dactylitis Global Sonographic (DACTOS) score in psoriatic arthritis [published online May 19, 2020]. Ann Rheum Dis. doi:10.1136/annrheumdis-2020-217191