Defining enthesitis in spondyloarthritis by ultrasound: Results of a Delphi process and of a reliability reading exercise

Objective: To standardize ultrasound (US) in enthesitis. Methods: An Initial Delphi exercise was undertaken to define US detected enthesitis and its core components. These definitions were subsequently tested on static images taken from Spondyloarthritis (SpA) patients in order to evaluate their reliability. Results: High-good agreement (>80%) was obtained for including hypoechogenicity, increased thickness of the tendon insertion, calcifications, enthesophytes, erosions and Doppler activity as core elementary lesions of US detected enthesitis. US definitions were subsequently obtained for each elementary component. On static images the intra-observer reliability showed a high degree of variability for the detection of elementary lesions with kappa coefficients ranging from 0.14 - 1. The inter-observer kappa value was variable with the lowest kappa for enthesophytes (0.24) and the best for Doppler activity at the enthesis (0.63). Conclusion: This is the first consensus based definition of US enthesitis and its elementary components and the first step performed to ensure a higher degree of homogeneity and comparability of results between studies and in daily clinical work. Defining Enthesitis By Ultrasound.