Assessing the sensitivity to change of the OMERACT ultrasound structural gout lesions during urate-lowering therapy

Abstract

ObjectivesTo evaluate the sensitivity to change of ultrasound structural gout lesions, as defined by the Outcome Measures in Rheumatology (OMERACT) ultrasound group, in patients with gout during urate-lowering therapy (ULT).MethodsUltrasound (28 joints, 26 tendons) was performed in patients with microscopically verified gout initiating or increasing ULT and repeated after 3 and 6 months. Joints and tendons were evaluated by ultrasound for presence of the OMERACT structural gout lesions—double contour sign (DC), tophus, aggregates and erosion—scored binarily. A sum score was calculated at patient and lesion level. Changes at 3 and 6 months in patient sum scores and lesion scores at different locations were evaluated.Results50 patients (48 men), mean age 68.9 (range, 30–88) years, were included. Ultrasound showed a statistically significant decrease in DC and tophus sum scores from 0 months (3.16 and 2.68, respectively) to 3 months (2.33 and 2.43) and 6 months (1.34 and 1.83) (all p<0.002). The aggregate sum score only decreased significantly from 3 to 6 months (6.02 to 5.02, p=0.002), whereas erosion sum score remained almost unchanged. All four structural lesions were most commonly found in metatarsophalangeal (MTP) 1 joints (>1 lesions bilaterally), and furthermore MTP2–4 and knee joints were common sites especially for DC. Likewise, these regions were the locations with most pronounced changes in scores.ConclusionUltrasound assessment of the OMERACT structural gout lesions scored binarily seems to be a useful tool for monitoring urate depositions during ULT. Particularly DC and tophus showed sensitivity to change after only 3 months of treatment.

Correspondence on ‘Ultrasound shows rapid reduction of crystal depositions during a treat-to-target approach in gout patients: 12-month results from the NOR-Gout study’

“…Previous researchers have taken benzbromarone in consideration during ULT research. 2 Also, the proportions and a subgroup analysis of patients using different medicines (allopurinol and febuxostat) are recommended for verifying effectiveness. Last but not the least, according to European League Against Rheumatism (EULAR), a lower target (under 5 mg/dL or 300 μmol/L) might be given if patients have severe gout with tophi, chronic arthropathy or very frequent attacks.…”

Sonographic estimation of monosodium urate burden predicts the fulfillment of the 2016 remission criteria for gout: a 12-month study

“…In fact, it is one of the most common US finding indicating MSU deposits in patients with both early and established gout [11,33]. Moreover, it was the most sensitive to change US feature in patients undergoing ULT [12][13][14][15]34]. Therefore, the presence of DC sign is a strong imaging biomarker that should induce the clinicians to maintain or even to increase the ULT.…”

“…In fact, although the US MSU burden was significantly lower in patients who fulfilled the remission criteria, MSU deposits were still detectable by US in a relevant number of these patients ranging from 19.0% with DC sign to 47.6% with aggregates. The US identification of aggregates in patients in clinical remission (47.6%) may be explained by the new formation of aggregates from the dissolution of larger tophi [12,13] or by the misinterpretation of non-crystalline hyperechoic spots [26], as the specificity of OMERACT-defined aggregates has been recently questioned [35]. The persistence of tophi even in patients in clinical remission (38.1%) may be related to a "dense" collection of MSU crystals requiring a more aggressive or a more prolonged ULT or to the histological composition of the tophus itself.…”

“…Such evidence led to the inclusion of US in the 2015 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) classification criteria and in 2018 updated EULAR evidence-based recommendations for the diagnosis of gout [2,9]. In addition, several recent studies highlighted the role of US in the management of ULT in gouty patients to monitor the MSU crystals' dissolution and to decide when stopping gout flare prophylaxis [12][13][14][15].…”

Quantitative assessment of crystal dissolution in gout during urate-lowering therapy with computer-aided MicroPure imaging: a cohort study

“…Several studies have shown that ultrasound-detected crystal depositions gradually decrease and reduce tophi size during efficient ULT (12)(13)(14). However, to our knowledge, there are only two recent studies that have reported a scoring system to quantify changes in aggregates, erosion, and the DCS (15,16). These studies demonstrated that USdetected urate crystal depositions were reduced during effective ULT, thus encouraging clinicians and gout patients to persist in the treat-to-target approach of ULT (15,16).…”