SummaryBackground: Enthesitis is a major feature of psoriatic arthritis. However, clinical assessment of enthesitis is known to lack accuracy and have poor interobserver reliability. Objective: To determine effect of training on clinical assessment of enthesitis and to compare ultrasonography with clinical examination for the detection of entheseal abnormalities. Methods: 20 rheumatologists performed repeated assessment of enthesitis in patients with established psoriatic arthritis before and after a 2-hour training session in standardised enthesitis count according to Leeds 5 . LEI has been developed for measuring enthesitis in patients with PsA 6 . However, all the scoring systems are known to have limitations in terms of reliability, validity, and sensitivity 3 . Another limitation of clinical enthesitis count is the specificity of the finding of tenderness in these areas. Many of the entheseal points are relatively near to joints and accepted tender points for fibromyalgia, raising the possibility of misclassification. Imaging modalities such as ultrasound (US) have been investigated to determine whether they improve entheseal disease assessment. Studies have shown that US indices for enthesitis are more sensitive than clinical examination 7,8 . The OMERACT US Specialist Interest Group has achieved agreement on US definition of enthesitis and its elementary components to ensure a higher degree of homogeneity and comparability of results between studies and in daily clinical work 9 . However, the value of US findings at the enthesis is not investigated fully. Although Doppler sign at the enthesis is found more frequently in patients with PsA, as compared to healthy controls 10 , it can also be seen in patients with rheumatoid arthritis 11 . Bone changes such as enthesophytes and erosions may also be found as degenerative changes in weight-bearing entheses 12 . Furthermore, the application of US in daily practice in patients with PsA is limited by the time required to examine multiple sites of enthesitis. Since clinical enthesitis is a hallmark feature of PsA, there is a need for improvement of clinical assessment of enthesitis and evaluation of the benefits of US as an outcome measure in daily practice. The aim of this study was to examine if training in standardised assessment of enthesitis according to LEI and SPARCC is able to improve interobserver variation in patients with established PsA. Furthermore, we aimed to compare US and clinical assessment of enthesitis to determine the added value of US in enthesitis assessment.
Methods
SubjectsOutpatients with PsA according to Classification Criteria for Psoriatic Arthritis (CASPAR criteria) were enrolled from the Departments of Rheumatology, Aalborg University Hospital, Denmark, during routine presentation to the clinic. The inclusion criteria were established PsA requiring systemic treatment with disease modifying anti-rheumatic drugs. Exclusion criteria were treatment with biological drugs or treatment with oral corticosteroids. All patients taking NSAID...