Subclinical Enthesitis in Psoriasis Patients as Predictors of Arthritis: The EPESCA Study

Background: Enthesitis, a key feature of psoriatic arthritis (PsA), can be detected subclinically by ultrasound (US) in patients with psoriasis (PsO), where it may signal an increased risk of future articular involvement. Purpose: This observational study aimed to investigate the prevalence of subclinical enthesitis in PsO patients without musculoskeletal symptoms, analyze the differences between patients with enthesis alterations (i.e. active enthesitis - AE, inactive enthesitis - En, enthesopathy - Ep or none - wE, per OMERACT criteria) and evaluate the 1 year PsA incidence. Research design: All consecutive PsO patients ≥18 years attending a dermatology outpatient clinic were screened. A rheumatologist and a radiologist experienced in US performed greyscale and Power Doppler (PD) examination on six bilateral enthesal sites (Achilles, quadriceps, distal/proximal patellar, plantar fascia, and triceps enthesis). The chi-square test or Kruskall-Wallis test detected the differences between the groups. After 1 year, rheumatologists reassessed En and AE patients for PsA onset. A P-value ≤0.05 was considered statistically significant. Results: Among 211 enrolled subjects, AE, En, and Ep prevalences were 6.6%, 35.6%, and 31.8%, respectively. There were no alterations in 23.2% while 2.8% showed only PD signal. BMI was higher in En than in wE and Ep (28, 24 and 25 kg/m^2 respectively) (P < 0.05). Female were less prevalent in En than in Ep (52% vs 25%, P < 0.01). None developed PsA during the 1-year follow-up. Conclusion: Subclinical enthesitis is common in PsO patients (about 40%), with inactive enthesitis more frequent in higher-BMI individuals. Active enthesitis was rare (<7%), and no cases progressed to PsA.