The development and validation of a new diagnostic sonographic enthesitis score for psoriatic arthritis: Diagnostic Ultrasound Enthesitis Tool (
DUET
)
Lihi Eder, Andre L. Ribeiro, Ricardo Acayaba de Toledo, Catherine Bakewell, Philippe Carron, Basant Elnady, Amir Haddad, Arthur Kavanaugh, Arnon Katz, Minna J. Kohler, Josefina Marin, Fahmeen Afgani, Nikolas Malliotis, Nam Nguyen, Adrien Nzeusseu, Ari Polachek, Ernesto Rodriguez, Marcos Rosemffet, Abha Singh, Maria S. Stoenoiu, Agnes Szentpetery, Ilaria Tinazzi, Janeth Yinh, Mu Yang, Dennis McGonagle, Richard Cook, Gurjit S. Kaeley, Sibel Z. Aydin Objective
The Diagnostic Ultrasound Enthesitis Tool (DUET) study aimed to develop and validate a new sonographic scoring system for enthesitis to aid PsA diagnosis.
Methods
We prospectively enrolled patients with early PsA, psoriasis without arthritis (PsO), and non‐inflammatory musculoskeletal symptoms as controls (CTL) from 17 centers. A standardized ultrasound assessment of 16 entheseal sites was performed and images were centrally scored by three blinded readers for inflammatory and structural entheseal lesions. Using a stepwise approach with logistic regression models stratified by age, we identified optimal lesion combinations, weightings, and entheseal sites for distinguishing PsA from CTL. Age‐specific cut‐off points were selected to maintain specificity above 70%. Performance was assessed in a validation cohort of PsA and CTL.
Results
We included 213 PsA, 100 PsO, and 106 CTL in the discovery cohort. The final DUET score combined weighted inflammatory (hypoechogenicity + thickening + Doppler grade x 2) and structural (enthesophyte grade + erosion x 3) scores at three entheseal sites: Achilles, proximal patellar tendon insertion, and triceps. Age stratification (≤55 vs. >55 years) improved discriminative performance. In the discovery cohort, DUET achieved an AUC of 0.65, with specificity of 73‐74% and sensitivity of 47‐49%. In an external validation cohort (101 PsA, 69 CTL), specificity improved to 74‐100% with similar sensitivity (49‐52%). Sensitivity increased up to 63% in patients with tender entheses.
Conclusion
DUET is a novel, externally validated sonographic enthesitis score that could support the diagnostic assessment of patients with early PsA, particularly in individuals with tender entheses.