Temporal Clinical Ultrasound Asynchrony in Psoriatic Arthritis Enthesitis: Implications for Personalized Monitoring

Area of Science:

• Rheumatology
• Immunology
• Musculoskeletal Diseases

Background:

• Psoriatic arthritis (PsA) involves entheseal disease, assessed by clinical tenderness and ultrasound (US).
• The longitudinal relationship between clinical and US findings after biologic disease-modifying antirheumatic drug (bDMARD) initiation is unclear.
• Early discordance between clinical and US assessments during follow-up requires further investigation.

Purpose of the Study:

• To evaluate the longitudinal agreement between clinical and US assessments of enthesitis in PsA patients starting bDMARDs.
• To identify predictors of discordant findings, specifically persistent US activity despite clinical remission.
• To understand the clinical significance of asynchronous resolution of enthesitis activity.

Main Methods:

• Retrospective observational cohort study of PsA patients with active enthesitis at baseline.
• Paired, same-day, blinded clinical and US assessments at 6 and 12 months post-bDMARD initiation.
• Analysis of agreement using Cohen's kappa and logistic regression for predictors of discordance (Clin-/US+).

Main Results:

• At 6 months, fair agreement (κ = 0.286) was observed, with 23.2% of entheses showing US activity despite no clinical tenderness (Clin-/US+).
• Agreement significantly improved to substantial/almost-perfect levels (κ = 0.779) by 12 months, with only 1.2% remaining Clin-/US+.
• NSAID exposure was a significant predictor of Clin-/US+ status at 6 months (OR = 6.16).

Conclusions:

• Clinical and US assessments of enthesitis in PsA patients on bDMARDs exhibit partial discordance at 6 months, converging by 12 months.
• Enthesitis activity may resolve asynchronously, necessitating integrated, time-aware interpretation of clinical and imaging data.
• Residual US abnormalities with clinical improvement warrant cautious interpretation within the overall clinical context.