SAT0423\u2005WHERE SHOULD WE EXAMINE FOR URIC ACID DEPOSITS? RESULTS FROM THE NOR-GOUT ULTRASOUND STUDY

Abstract

Background Ultrasound (US) has received an increasing attention in detecting uric monosodium urate (MSU) deposits, and US is included in the ACR/EULAR classification criteria for gout. OMERACT has developed definitions for US elementary lesions in gout including double contour (DC) sign (deposits of crystals on the surface of cartilage), tophus (larger hypo-echoic aggregation of crystals, usually well delineated) and aggregates (small hyper-echoic deposits). Objectives The present objective was to explore by US the most frequent locations of MSU deposits. Methods Baseline data from a prospective observational study were used where patients with crystal-proven gout who presented after a recent gout flare were included (202 patients (mean (SD) age 56.6 (14.2) years, disease duration 8.0 (7.7) years, 94.1% men), all with insufficiently treated serum uric acid level (>360 μmol/L/>6 mg/dl). We performed an extensive assessment with US (GE E9 machine, grey scale 15MHz) for semi-quantitative scoring of MSU deposits (0=none, 1=possible/small, 2=moderate, 3=major) using OMERACT definitions for DC, tophi and aggregates. The following locations were examined bilaterally; radiocarpal, MCP 2 and MTP 1 joints, triceps and quadriceps insertions, patellar (proximal and distal) and Achilles tendons as well as distal femur (maximal flexed knee) and talar cartilage. Sum scores for each crystal deposit were calculated and correlations were performed by use of Spearman rho, comparisons by paired samples test, and frequencies of deposits were calculated as percentages. Results The baseline mean (SD) serum uric acid level was 494 (87) μmol/L. Table 1 shows uric acid deposits to be correlated with kidney function and disease duration. Table 2 includes frequencies with at least moderate US scores (≥2) in the different joint and tendon localisations and shows DC primarily to be found in MTP1, followed by talar and femoral cartilage. Tophi and aggregates were primarily found in MTP1, followed by distal patellar and triceps tendons. There were no major differences between right and left side. In 25 patients (12.5%) DC was seen on femoral or talar cartilage but with no depositions in the MTP1 joint. Conclusion Uric acid deposits were associated with reduced kidney function as well as disease duration. When gout is suspected the present study suggests US examinations of MTP1, distal patellar and triceps tendons as well as talar and femoral cartilage to be the most important sites to examine for presence of MSU deposits.Table Disease duration Uric acid μmol/L Creatinine μmol/L Creatinine μmol/L Sum score DC 0.35** 0.30** 0.26** -0.27** Sum score tophi 0.27** 0.13 0.27** -0.37** Sum score aggregates 0.16* 0.05 0.22* -0.36** Sum score DC, tophi and aggregates 0.29** 0.16* 0.29** -0.40**Table 2 Percentages of patients with different forms of ultrasound detected uric acid deposits Double contour Tophus Aggregates Right Left Right Left Right Left Wrist 1.5 0.5 7.0 8.5 6.0 7.0 MCP 2 2.0 1.0 5.0 2.5 4.0 3.0 Distal femur cartilage 16.9 16.9 NA NA NA NA Talar cartilage 15.4 16.9 NA NA NA NA MTP 1 36.0 35.8 44.0 45.5 51.5 50.3 Triceps NA NA 15.0 12.5 32.8 31.8 Quadriceps NA NA 5.5 8.0 10.1 15.9 Proximal patellar tendon NA NA 5.0 7.0 9.5 13.4 Distal patellar tendon NA NA 19.5 15.0 42.5 37.3 Achilles NA NA 9.5 8.0 12.1 6.0 Disclosure of Interests Hilde Berner Hammer Grant/research support from: AbbVie, Pfizer and Roche, Paid instructor for: AbbVie, Pfizer, UCB, Novartis, Roche, Speakers bureau: AbbVie, Pfizer, UCB, Novartis, Roche, Lars Fridtjof Karoliussen: None declared, Lene Terslev Speakers bureau: Speakers fee from : Roche, Novartis, Pfizer, MSD, BMS, Celgene, Tore K. Kvien Grant/research support from: AbbVie, BMS, MSD, Pfizer, Roche and UCB., Consultant for: AbbVie, Biogen, BMS, Boehringer Ingelheim, Celgene, Celltrion, Eli Lilly, Hospira, Merck-Serono, MSD, Novartis, Oktal, Orion Pharma, Pfizer, Roche, Sandoz, Sanofi, Mylan and UCB, Speakers bureau: AbbVie, Biogen, BMS, Boehringer Ingelheim, Celgene, Celltrion, Eli Lilly, Hospira, Merck-Serono, MSD, Novartis, Oktal, Orion Pharma, Pfizer, Roche, Sandoz, Sanofi and UCB, Till Uhlig Consultant for: Grünenthal, Novartis, Speakers bureau: Grünenthal, Novartis