Abstract Objectives Ultrasound (US) is a valuable tool to detect inflammation in peripheral psoriatic arthritis (pPsA). This multicentre study assessed the intra- and inter-reader reliability of US-detected elementary lesions in peripheral psoriatic arthritis (pPsA) and evaluated the impact of standardized training on reliability, as a first step to guide multicentre assessment in the APACHE cohort. Methods A cross-sectional study was conducted to analyze the reliability of pPsA US lesions, as a first step in an ongoing predictive cohort (APACHE, NCT03768271) study. Three web-based reliability exercises were carried out, between 2020 and 2024. Inter-rater and intra-rater reliability were assessed using Light’s kappa (κ). During the third reliability exercise, a reference atlas of elementary US lesions in dactylitis was developed. Results Experienced and trainee sonographers from thirty recruiting centres participated into the study. In step 1, intra-reader kappas were moderate to good for synovitis (0.50–0.80), tenosynovitis (0.51–0.63), enthesitis (0.62–0.73), and poor for dactylitis (0.31– 0.47); inter-reader kappas were lower for synovitis (0.32– 0.70), tenosynovitis (0.40–0.49), enthesitis (0.47– 0.60), dactylitis (0.13–0.24). In Step 2, reliability improved notably in expert and trainees except for dactylitis (intra-reader: synovitis (0.81–0.90), tenosynovitis (0.66–0.83), enthesitis (0.61–0.81), dactylitis (0.37–0.47); inter-reader: synovitis (0.72–0.84), tenosynovitis (0.55–0.76), enthesitis (0.37–0.59), dactylitis (0.12–0.30). Step 3, achieved moderate-to-good reliability for dactylitis (intra 0.69–0.80, inter 0.46–0.68). An atlas was produced based on expert consensus and lesion’s identification rates among sonographers. Conclusion Standardized training was associated with a marked improvement in intra- and inter-reader reliability for the assessment of elementary pPsA lesions. The consensus-based US atlas provides practical guidance for identifying challenging dactylitis-related lesions in clinical and research settings.
Jousse-Joulin et al. (Tue,) studied this question.