The Relationship Between Ultrasound and Physical Examination in the Assessment of Enthesitis in SpA Patients: Results from the DEUS Multicentre Study

OBJECTIVES:i) To explore the agreement between the OMERACT ultrasound lesions of enthesitis and physical examination in assessing enthesitis in spondyloarthritis (SpA) patients; ii) To investigate the prevalence and clinical relevance of subclinical enthesitis in this population. METHODS:Twenty rheumatology centres participated in this cross-sectional study. SpA patients, including axial SpA (axSpA) and psoriatic arthritis (PsA) patients, underwent both ultrasound scan and physical examination of large lower limb entheses. The OMERACT ultrasound lesions of enthesitis were considered, along with a recently proposed definition for 'active enthesitis' by our group. Subclinical enthesitis was defined as the presence of 'active enthesitis' in ≥1 enthesis in SpA patients without clinical enthesitis (i.e., number of positive entheses on physical examination and Leeds Enthesitis Index score =0). RESULTS:4130 entheses in 413 SpA patients (224 axSpA/189 PsA) were evaluated through ultrasound and physical examination. Agreement between ultrasound and physical examination ranged from moderate (i.e., enthesophytes) to almost perfect (i.e., power Doppler and 'active enthesitis'). Patellar tendon entheses demonstrated the highest agreement, whereas Achilles tendon insertion showed the lowest. Among 158/413 (38.3%) SpA patients with clinical enthesitis, 108 (68.4%) exhibited no 'active enthesitis' on ultrasound. Conversely, of those 255 without clinical enthesitis, 39 (15.3%) showed subclinical enthesitis. Subclinical enthesitis was strongly associated with local structural damage. However, no differences were observed regarding the demographic and clinical profiles of SpA patients with and without subclinical enthesitis. CONCLUSIONS:Our study underscores the need for a comprehensive tool integrating ultrasound and physical examination for assessing enthesitis in SpA patients.