Ultrasound verified enthesophytes are associated with radiographic progression at entheses in psoriatic arthritis

Objectives: The aim of this prospective study was to examine whether ultrasound or clinical abnormalities at enthesal sites predict radiographic progression at entheses in psoriatic arthritis (PsA).

Methods: Consecutive PsA patients were included and subjected to clinical and ultrasound assessments at 14 entheses at baseline, 6 and 12 months. Radiographs were performed at 0 and 12 months. By US, we investigated structural (erosions, osteophytes) and inflammatory changes [grey scale (0-32) and power Doppler (0-14, range global ultrasound score 0-140)], and radiographs were evaluated for enthesophytes and erosions (score range 0-56). Multivariate regression models were conducted to identify the possible association of clinical and ultrasound findings with radiographic progression.

Results: We examined 83 patients at baseline, of whom 43 (51.8%) had complete clinical, ultrasound and X-ray data. Twenty-four of 43 patients (55.8%) developed radiographic progression of entheses. These patients were younger (49.6 vs 59.3, P =0.005), had shorter disease duration (9.7 vs 17.9 years, P=0.015) and lower clinical disease activity at 6-months [disease activity in psoriatic arthritis (DAPSA) 6.7 vs 17.0, P=0.018] as compared with patients without progression. Non-progressors had higher ultrasound enthesophyte scores at baseline than progressors (20 vs 15, P<0.05). The multivariate regression analysis revealed that 48.6% of the variance of the X-ray score at 12-months follow-up (RegcoeffB = 0.827, P=0.000) could be explained by the baseline US enthesophyte score.

Conclusion: Our data indicate that radiographic progression at entheses is linked with age, disease duration and ultrasound verified enthesophytes at baseline. No other ultrasound parameter predicted radiographic progression at entheses.