Enthesitis in a European registry-based cohort of patients with psoriatic arthritis treated with tumour necrosis factor inhibitors: clinical burden, patient-reported outcomes, and treatment response

OBJECTIVE: To explore the registration of enthesitis among biologic-naïve patients with psoriatic arthritis (PsA) initiating tumour necrosis factor inhibitor (TNFi) treatment across 12 European registries, compare the disease burden and patient-reported outcomes (PROs) between patients with and without enthesitis, and assess the enthesitis treatment response.

METHOD: Demographics, clinical characteristics, and PROs at first TNFi (TNFi-1) initiation (baseline) were assessed in patients with PsA, diagnosed by a rheumatologist, with versus without assessment of entheses and between those with versus without enthesitis. Enthesitis scores and resolution frequency were identified at follow-up.

RESULTS: Of 10 547 patients in the European Spondyloarthritis (EuroSpA) Research Collaboration Network initiating TNFi, 1357 underwent evaluation for enthesitis. Eight registries included a validated scoring system for enthesitis. At baseline, 874 patients underwent entheses assessment [Maastricht Ankylosing Spondylitis Enthesitis Score (MASES) 485 patients, Spondyloarthritis Research Consortium of Canada (SPARCC) 389 patients]. Enthesitis was detected by MASES in 170/485 (35%, mean score ± sd 3.1 ± 2.4) and by SPARCC in 236/389 (61%, 4 ± 3.4). Achilles enthesitis was most frequent, by both MASES (unilateral/bilateral 28%/9%) and SPARCC (48%/18%). MASES/SPARCC baseline and follow-up scores for TNFi-1 were available for 100/105 patients. Of these, 63 patients (63%) (MASES) and 46 (43.8%) (SPARCC) achieved resolution of enthesitis. The site-specific enthesitis resolution was overall lower at SPARCC sites (peripheral; 63-80%) than at MASES sites (mainly axial; 82-100%) following TNFi-1. Disease activity and PROs were worse in patients with versus without enthesitis.

CONCLUSION: Entheseal assessments are only registered in a minority of patients with PsA in routine care. When assessed, enthesitis was common, and a substantial proportion demonstrated resolution following treatment with TNFi-1.