Diagnostic Value and Treatment Responsiveness of Ultrasonography Features in Correlation With Clinical Findings in Early Peripheral Spondyloarthritis

OBJECTIVE: To investigate the diagnostic performance of ultrasonography features in the evaluation of enthesitis and arthritis in very early peripheral spondyloarthritis (pSpA). METHODS: The Clinical Remission in Peripheral Spondyloarthritis (CRESPA) trial was a double-blinded, placebo-controlled trial investigating induction of clinical remission in very early pSpA (symptom duration < 12 weeks) using tumor necrosis factor α (TNFα)-inhibition. Standardized clinical and ultrasonography evaluation of four pairs of entheses and eight pairs of lower limb joints were performed repeatedly in 54 patients. Analyses focused on the prevalence of ultrasonography 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 ultrasonography 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 ultrasonography evaluation compared to placebo. Among entheses, 45% (21 of 46) of clinical tender sites displayed no ultrasonography abnormality, whereas 19% (72 of 386) of nontender 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 PD signal. CONCLUSION: Ultrasonography in enthesitis and arthritis demonstrates high responsiveness to TNFα 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.