The main aim of the present study was to determine the prevalence of subclinical entheseal involvement at lower limbs by ultrasound (US) in patients with psoriasis. The secondary aim was to determine the interobserver reliability of the Glasgow Ultrasound Enthesitis Scoring System (GUESS) and power Doppler (PD) technique in the assessment of enthesopathy.
The study was conducted on 45 patients with psoriasis and 45 healthy sex- and age-matched controls. All patients with no clinical evidence of arthritis or enthesitis underwent an US examination. All US findings were identified according to GUESS. The interobserver reliability was calculated in 15 patients with psoriasis.
A total of 450 entheses in 45 patients with psoriasis were evaluated by US. In 148 of 450 (32.9%) entheses, grayscale US found signs indicative of enthesopathy. In 4/450 (0.9%) entheses PD signal was detected. In the healthy population, US found signs of enthesopathy in 38 of 450 (8.4%) entheses and no PD signal was detected. The GUESS score was significantly higher in patients with psoriasis than in healthy controls (P < 0.0001). Both concordance correlation coefficient and unweighted κ values for US findings showed an excellent agreement (0.906 and 0.890, respectively).
Our results indicate that both grayscale US and PD findings indicative of enthesopathy were more frequent in patients with psoriasis. The US ability to detect signs of subclinical enthesopathy should be the object of longitudinal investigations to define its value in predicting the clinical onset of psoriatic arthritis.