Objectives 1. to assess the correlation between US findings and clinical parameters, 2. to evaluate the prognostic value of US findings as predictors for clinical outcome and 3. To assess US imaging as an outcome measure in the management of psoriatic arthritis.
Methods A cross-sectional study that included 113 patients (58 women/55 men) referred early psoriatic arthritis (ePsA), defined as inflammatory joint symptoms and signs, disease duration <1 year, in association with psoriasis (99/113)/or past psoriasis (14/113). The patients were diagnosed according to the CASPAR criteria. The patients were assessed both clinically and with US at baseline, 3, 6 and 12 month of therapy. Clinical assessment included 68 joints, VAS for disease activity parameters and DAS-44. Total PASI and Maastricht Enthesitis Index scores were assessed. X-ray of the hands, feet, spine and pelvis was also taken for every patient. US examination included: 1. Joints (56 joints) were assessed using Grey-Scale (GS) and Power Doppler (PD). US findings were scored separately on a 0-3 semi-quantitative scale. Erosions were also scored quantitatively (maximum diameter of the erosion: >0- <2 mm: grade 1; ≥2 - <3 mm: grade 2; ≥3 mm: grade 3). Entheses: were scored according to the 0–36 Glasgow Ultrasound Enthesitis Scoring System (GUESS) and with PD signal (calculated with semiquantitative system, score 0–3). Nail: scored quantitatively: grade 1: minimal loss of the hyperechoic definition involving only the ventral nail plate, grade 2: thickening of the nail bed >2.5mm, grade 3: thickening of the nail bed and inhomogeneous thickening of the nail plate. Skin: grade 0: normal, grade 1: thickening of both epidermis and dermis with respect to the surrounding normal skin, and the presence of a hypoechoic band under the psoriatic area
Results There was significant correlation between clinically and US detected synovitis (p<0.01). At baseline US joint score showed a significant correlation with TJC68, SJC66, DAS-44, patient global assessment and functional disability. Subclinical US synovitis was found in 51% of all the joints examined whereas subclinical enthesitis was found in 31% of the patients. US joint examination had a sensitivity of 86% (GS)/94% (PD) with a positive predictive value of 88% (GS) and 96% (PD), in comparison to 55% for clinical examination. Arthritis and enthesitis scores were significantly higher (p<0.01) in patients with nail disease. No correlation was found between the PASI and enthesitis scores. Longitudinal data analysis showed a significant correlation (p<0.01) between relative changes in the US scores and changes in clinical parameters at 6 and 12 months of follow-up. Intra-observer agreement was high (interclass correlation coefficient 0.94).
Conclusions The results of these studies support the use of US in the early detection of PsA. US findings correlated significantly with clinical disease activity at baseline as well as longitudinally over the treatment course. Entheses are affected early in PsA, and the incidence of involvement is independent of the diagnostic subtype or presentation pattern. Nail involvement in psoriasis is linked to a more extensive subclinical enthesopathy and arthritis. US is a valid and reliable outcome measure for both the diagnosis and management of PsA.
Disclosure of Interest None Declared