Background Psoriasis patients with enthesitis can classify as psoriatic arthritis since the introduction of the CASPAR classification criteria in 2006. However, clinical assessment of the entheses could be challenging. In addition, the presence of a tender enthesis is not necessarily indicative for underlying inflammatory disease as it could be related to overuse, metabolic disease or ageing. Therefore, we need a better way to identify the inflammatory component of entheseal involvement in psoriasis. To detect these inflammatory components in the entheses, ultrasound (US) examination can be used to identify inflammatory disease at the entheses.
Objectives Our aims were to determine the prevalence of US abnormalities among psoriasis patients in primary care and to determine the concordance of clinical and US information at individual entheseal sites.
Methods Adult patients with psoriasis were invited to participate in the SENSOR study. Patients who reported pain in joints, entheses or the lower back were eligible for clinical evaluation. If physical examination indicated a painful enthesis on the LEI/MASES or if arthritis was present, US examination of the entheses was performed. The six entheses of the Madrid Sonographic Enthesis Index (MASEI) and the lateral epicondyle tendon insertion (elbow) were evaluated according to the MASEI scoring system. Enthesitis was defined as US inflammation (positive power Doppler (PD) signal or a thickened enthesis of the plantar fascia) in combination with one clinical feature at the same enthesis. Structural changes detected by ultrasound were calcifications, increased thickness, irregular fibre structure and erosions.
Results Of 524 patients who participated in the SENSOR study, 111 patients were assessed both by physical examination and by US. In 106 (95%) patients we detected US abnormalities. In 56 (50%) patients we found structural changes without indication for inflammatory disease. In 50 (45%) patients we found US abnormalities indicating inflammatory disease at the enthesis (positive PD: n=35; thickened plantar fascia: n=15). When we combined the US data with the clinical information, 36% of US inflammatory disease were confirmed [Figure 1].
Conclusions We found US abnormalities in 95% of the primary care psoriasis patients with musculoskeletal complaints, which is a combination of both structural and inflammatory US components. In 45% of primary care psoriasis patients we observed US inflammatory disease, which was confirmed in 36% of the patients by clinical information.
Acknowledgements This study was financially funded by an investigator-initiated grant from Pfizer bv.
Disclosure of Interest None declared