Background/Purpose: Ultrasound is sensitive for detecting depositions of uric monosodium urate (MSU) crystals and is included in the ACR/EULAR classification criteria for gout. The OMERACT ultrasound group has developed definitions for elementary lesions in gout including the double contour (DC) sign (depositions of crystals on the surface of cartilage), tophus (larger hypo-echoic aggregation of crystals, usually well delineated) and aggregates (small hyper-echoic deposits). The present objective was to explore by ultrasound the longitudinal change of MSU depositions during a treat-to-target (T2T) approach with urate lowering therapy (ULT) in patients with gout.

Methods: In a prospective observational study, patients with crystal-proven gout were included if they presented after a recent gout flare and had increased serum urate levels ( >360 μmol/L). The T2T approach focused on ULT and increasing drug doses with monthly follow-up until the treatment target was met (< 360 μmol/L, or < 300 μmol/L if clinical tophi), and no scheduled visits between 12 and 24 months. An extensive ultrasound assessment was performed (GE E9 machine, grey scale 15MHz) at baseline and after 3, 6, 12 and 24 months to assess MSU depositons (DC, tophi and aggregates) with bilateral assessment of radiocarpal joint, MCP 2, insertion of triceps and quadriceps, proximal and distal patellar and the Achilles tendon, cartilage of distal femur (maximal flexed knee), the talar cartilage of tibiotalar joint and MTP 1 joint. The degree of elementary lesions was semi-quantitatively scored 0-3 (0=none, 1=possible, 2=certain, 3=major deposits). Total sum scores of DC, tophi and aggregates separately as well as all lesions combined were calculated at each visit. Changes from baseline were explored by paired samples T-test.

Results: 207 patients were included at baseline (94.3% men, mean (SD) age 56.3 (13.7) years, disease duration 7.9 (7.7) years). The mean (SD) serum urate level decreased from 496 (81) μmol/L at baseline to 332 (75) μmol/L at 24 months. The treatment target was met in 87% at 12 months and in 76% at 24 months. Sum scores of MSU depositions decreased over 24 months (table) and the numeric decrease was most pronounced for DC (figure). At baseline/24 months the percentages of patients with no presence of DC sign was 7%/70%, no tophi; 7%/27% and no aggregates 1%/7%. Of patients having DC at baseline, 62% had no detected DC at 24 months, for tophi the corresponding percentages was 20, and for aggregates 6.

Conclusion: This study shows that most of the patients reached the target during T2T lowering therapy, and that this was followed by a major reduction of the ultrasound detected MSU depositions, especially DC.

Table 1

Figure DC

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/ultrasound-demonstrates-rapid-reduction-of-crystal-depositions-during-a-treat-to-target-approach-in-gout-patients-two-year-results-from-a-longitudinal-observational-study-nor-gout/