Ultrasound dactylitis predicts bone erosion in early psoriatic arthritis: A longitudinal cohort study

OBJECTIVE: Bone erosion is a hallmark of progressive joint damage and poor prognosis in psoriatic arthritis (PsA). Early identification of high-risk patients is critical for implementing aggressive interventions that can mitigate inflammation and prevent irreversible structural joint damage. This study aimed to identify clinical and ultrasonographic features associated with bone erosion in patients with early PsA. METHODS: A total of 82 patients with early PsA with articular and/or the entheseal involvement of less than 6-month duration were prospectively enrolled from the Rheumatology Department of the First Affiliated Hospital with Nanjing Medical University between March 2022 and January 2025 and followed for 24 months. Data about demographic and clinical characteristics, clinical enthesitis and dactylitis, and medication were collected. Musculoskeletal ultrasound was performed at baseline and the 2-year visit.Inflammatory and structural changes were scored with the modified MAdrid Sonographic Enthesitis Index (MASEI) and Novel and reliable DACTylitis glObal Sonographic (DACTOS) score. Erosions were defined by two radiology experts based on at least two imaging techniques. Logistic regression analysis was performed to identify variables associated with bone erosion occurring within 2 years of initial diagnosis. This trial has been registered on ClinicalTrials.gov under identifier NCT06730334. RESULTS: Early PsA patients with bone erosion had later onset of the disease (40.70 ± 13.35 vs 32.33 ± 13.98, p = 0.008), higher proportion with metabolic syndrome (p = 0.043), a greater number of swollen joints at baseline (p = 0.029), and higher DACTOS scores (p = 0.026). Over the 24-month follow-up, a higher proportion of patients without bone erosion received IL-17 inhibitor therapy (p = 0.034). Multivariate analysis identified older age at symptom onset (OR 1.049, p = 0.012) and higher DACTOS score (OR 1.082, p = 0.036) as independent predictors of bone erosion. CONCLUSION: Our findings establish that an older age at symptom onset and a higher ultrasonographic dactylitis burden, quantified by the DACTOS score, are independent risk factors for bone erosion in early PsA. This supports the integration of ultrasound into early risk stratification to identify patients at greater risk for structural damage.