Association between musculoskeletal sonographic features and response to treatment in patients with psoriatic arthritis.

Objective: To investigate the association between musculoskeletal sonographic features and clinical features, as well as treatment outcomes, in patients with active psoriatic arthritis (PsA).

Methods: A prospective cohort study was conducted involving patients with active PsA. Disease activity was assessed clinically at baseline and 3-6 months after initiating therapy, with a Disease Activity Index for PsA (DAPSA) score calculated. A baseline ultrasound examination of 64 joints, 28 tendons and 16 entheses evaluated the following lesions: synovitis, peritenonitis, enthesitis, tenosynovitis, new bone formation and erosions. Total scores for each lesion and total inflammatory and structural scores were calculated. The association between baseline sonographic scores and treatment outcomes was assessed using Cox proportional hazards models (for drug persistence) and generalised estimating equation models for DAPSA change.

Results: A total of 135 treatment periods (107 patients) were analysed. Multivariable analysis showed that a greater reduction in DAPSA score at follow-up was associated with higher baseline synovitis (β -3.89), peritenonitis (β -3.93) and enthesitis structural scores (β -2.91). Additionally, the total inflammatory score independently predicted DAPSA change (β -5.23) regardless of the total structural damage score. Drug persistence was analysed in 105 treatment periods, revealing that a higher sonographic erosion score was associated with earlier drug discontinuation (adjusted HR 1.28, 95% CI 1.03 to 1.61).

Conclusion: The study results provide preliminary evidence supporting the utility of musculoskeletal ultrasound in predicting treatment response and drug persistence in PsA.