Background Ultrasound (US) is playing an increasingly important role in the early evaluation of psoriatic arthritis (PsA) being capable of detecting inflammatory changes at the enthesis, synovium and extra capsular tissues. Peri-articular radiographic erosions in PsA and rheumatoid arthritis are associated with a worse outcome. Further, US is shown to be a more sensitive imaging technique than conventional radiography (CR) to identify erosions in early RA. By contrast, there is a paucity of data in the literature on the prevalence of erosions and/or the capability of US to detect erosions in early PsA.
Objectives To assess the prevalence of erosions in early PsA using CR and high resolution US.
Methods We studied 860 joints of 43 patients (Table 1) with early PsA, all fulfilling CASPAR criteria from the Leeds Spondyloarthropathy Register for Research and Observation study (SpARRO) which is a prospective longitudinal observational cohort of patients with early spondyloarthritis. Radiographic and sonographic erosions of the wrists, MCPs (2, 3), PIPs (2, 3), and MTPs (1–5) bilaterally were independently evaluated. We looked at the frequency of erosions using both imaging methodologies. CR and US scoring systems used for defining erosions were the van der Heijde version of the Sharp and OMERACT respectively.
Results Erosions were identified in a total of 8 patients, all negative for RF and CCP antibodies; 40% (3/8) of whom were ex-smokers. Four patients had six erosions at MTP4, MTP5, and PIP3 by CR whilst six patients had six erosions on US. The exact agreement between the 2 methods was 99%. Agreement on absence of erosions in both CR and US was 99% while agreement on their presence was 17%. The proportions of joints where the CR and US disagreed in either direction (US>XR, US
Conclusions In keeping with the emerging data in PsA, these results show a low frequency of erosions at clinical presentation on CR. Unlike studies in early RA, in this preliminary study of early PsA the burden of erosive disease detected using US was not measurably different.
Weiner, S M,Jurenz, S,Uhl, M,Lange-Nolde, A,Warnatz, K,Peter, H H,Walker, U A.Ultrasonography in the assessment of peripheral joint involvement in psoriatic arthritis: a comparison with radiography, MRI and scintigraphy. Clinical rheumatology, vol. 27, no. 8, p. 983–989, 0770–3198 (August 2008)
Acknowledgement Dr Richard Fawcett who works as a radiology fellow at Chapel Allerton Hospital
Disclosure of Interest None declared