Diagnostic Value and Treatment Responsiveness of Ultrasound Features in correlation with clinical findings in Early Peripheral Spondyloarthritis

Objective

To investigate the diagnostic performance of ultrasound features in the evaluation of enthesitis and arthritis in very early peripheral spondyloarthritis (pSpA).

Methods

The CRESPA trial was a double‐blinded, placebo‐controlled trial investigating induction of clinical remission in very early pSpA (symptom duration <12 weeks) using TNF‐inhibition. Standardized clinical and ultrasound evaluation of 4 pairs of entheses and 8 pairs of lower limb joints were performed repeatedly in 54 patients. Analyses focused on the prevalence of ultrasound features of joints and entheses, their correlation with clinical findings, and their response to treatment.

Results

At baseline, synovial hypertrophy was uncommon in this early pSpA cohort and showed no independent predictive value for clinical evaluation. In contrast, Power Doppler (PD) ≥1 (Odds Ratio (OR) 9.5) and ultrasound joint effusion (OR 8.3) were strong predictors of a swollen joint. Golimumab treatment significantly predicted resolution of PD signal, synovial hypertrophy, and joint effusion on ultrasound evaluation compared to placebo.

Among entheses, 45% (21/46) of clinical tender sites displayed no ultrasound abnormality, whereas 19% (72/386) non‐tender entheses did. Across all 432 entheses at baseline, only entheseal thickening (OR 10.89) and PD ≥1 (OR 5.94) predicted tenderness. Treatment with golimumab was also associated with disappearance of entheseal thickening, hypoechogenicity, and Power Doppler signal.

Conclusion

Ultrasound in enthesitis and arthritis demonstrates high responsiveness to TNF‐inhibition in early pSpA but is limited by nonspecific findings and clinical overestimation of enthesitis. Development of standardized scoring systems and validated thresholds is essential to improve diagnostic accuracy and treatment monitoring.