Structural gout lesions, as defined by the Outcome Measures in Rheumatology (OMERACT) ultrasound group, displayed sensitivity to urate deposition improvements in patients undergoing urate-lowering therapy (ULT), according to study data published in RMD Open. Ultrasounds of patients showed significant decreases in OMERACT structural gout lesions over 6 months of ULT exposure, supporting the efficacy of OMERACT criteria for monitoring therapy outcomes.

This 6-month prospective observational cohort enrolled adult patients (aged ≥18 years) receiving treatment at a specialized rheumatology hospital in Denmark. Eligible patients had recently initiated ULT or increased their ULT dosing schedule. Investigators conducted clinical, laboratory, and ultrasound evaluations at baseline, 3 months, and 6 months. Clinical assessments captured medical history, tobacco and alcohol consumption, disease duration, and areas of involvement; laboratory tests captured p-urate and C-reactive protein levels.

Researchers performed bilateral examinations of 30 joints at baseline and follow-up and assessed pain and physical function by patient report. They performed ultrasound on 28 joints and 26 tendons at each study visit and evaluated joints and tendons for the presence of the 4 OMERACT-defined structural gout lesions: double contour sign (DC), tophus, aggregates, and erosion. Investigators calculated changes at 3 and 6 months in patient sum scores and lesion scores.


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The study cohort comprised 50 patients (48 men) with a mean age of 63.9±14.5 years (range, 30-88 years). The majority completed their 3-month (92%) and 6-month (82%) follow-up visits. P-urate and C-reactive protein values decreased significantly between baseline and 6-month follow-up (both P ≤.001).

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Researchers observed statistically significant decreases in mean DC (3.16 to 2.33; P <.001) and tophi (2.68 to 2.43; P =.002) sum scores between 0 and 3 months. Mean DC and tophi scores further declined to 1.34 and 1.83, respectively, between months 3 and 6 (both P <.001). Between 3 and 6 months, aggregate sum score decreased from 6.02 to 5.02 (P =.002), although no significant change was observed between 0 and 3 months. Erosion sum score did not change significantly over the trial period. OMERACT structural lesions were most observed in metatarsophalangeal (MTP) 1 joints, MTP2-4 joints, and knee joints, among which DCs were the most common lesion form. Patients had an average of 1.1 DCs and 1.4 tophi bilaterally in MTP1 joints. During follow-up, the MTP1-4 and knee joints displayed the most pronounced improvements in structural lesions. DC and tophi lesions declined significantly between 0 and 3 months in MTP1.

These results suggest that OMERACT-defined structural lesions are an appropriate parameter for monitoring urate depositions in gout, even during ULT. OMERACT was particularly sensitive to change in DCs and tophi. As study limitations, investigators cited the absence of a control group and the use of a binary OMERACT scoring system for the presence of structural lesions. Further research is necessary to explore the use of a semiquantitative scoring system for evaluating gout lesions.

Disclosure: Several study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures

Reference

Christiansen SN, Østergaard M, Slot O, et al. Assessing the sensitivity to change of the OMERACT ultrasound structural gout lesions during urate-lowering therapy. RMD Open. 2020;6:e001144.