SAT0413 SIZE MATTERS – EXTENT OF MONOSODIUM URATE DEPOSITS BUT NOT SERUM URATE LEVEL PREDICTS COMPLETE RESOLUTION OF MONOSODIUM URATE CRYSTAL DEPOSITS IN PATIENTS WITH GOUT

Background: Gout is based on the deposition of monosodium urate (MSU) crystals. While it is well established that life-style intervention and/or conventional urate lowering therapy can lead to a decrease in serum urate levels, the impact of such interventions to resolve already existing MSU deposits is very limited. Objectives: In this study we wanted to determine if and to what extent MSU deposits resolve if patients follow structured life-style intervention or continuously conventional urate lowering therapy. Methods: Subjects with diagnosis of gout and the presence of MSU deposits in the feet in baseline dual energy CT (DECT) scan, received either life-style intervention only (N=24) or additional conventional urate lowering therapy (allopurinol: N=29, febuxostat: N=22, benzbromarone N=2) for a mean period of 18 months before receiving a follow-up DECT examination. MSU deposits were quantified by volumetric measurement and semi quantitative scoring at baseline and follow up. Results: Serum uric acid (SUA) level decreased from 7.2±1.7 to 6.7±1.7mg/dl with life-style intervention; from 7.0±1.5 to 5.5±1.8mg/dl with allopurinol and from7.8±3.0 to 5.1 ± 2.5mg/dl with febuxostat. MSU volume significantly decreased in patients undergoing life-style intervention (baseline: 0,07cm3 ± 0,09; follow up: 0,05 ± 0,15cm3; p=0.007), treatment with allopurinol (0,11 ± 0.15 cm3 to follow up: 0.02 ± 0,04 cm3, p Conclusion: We show that both life-style intervention and conventional urate lowering drug therapy reduce the volume of monosodium urate deposits. The size of MSU deposits, but not serum urate level, was the main factor that influenced complete resolution of deposits. This finding reemphasizes that the burden of deposits essentially defines the likelihood and time for complete resolution of gout. References [1] Manger B, Lell M, Wacker J, Schett G, Rech J. Detection of periarticular urate deposits with dual energy CT in patients with acute gouty arthritis. Ann Rheum Dis. 2012;71(3):470-2. [2] Bongartz T, Glazebrook KN, Kavros SJ, Murthy NS, Merry SP, Franz WB, 3rd, et al. Dual-energy CT for the diagnosis of gout: an accuracy and diagnostic yield study. Ann Rheum Dis. 2015;74(6):1072-7. [3] Bayat S, Aati O, Rech J, Sapsford M, Cavallaro A, Lell M, et al. Development of a Dual-Energy Computed Tomography Scoring System for Measurement of Urate Deposition in Gout. Arthritis Care Res (Hoboken). 2016;68(6):769-75. Disclosure of Interests: Sara Bayat: None declared, Hanna Ellmann: None declared, Elizabeth Araujo: None declared, Bernhard Manger: None declared, Melanie Hagen: None declared, Arnd Kleyer Grant/research support from: Lilly, Consultant for: Lilly, Speakers bureau: Abbvie, Alexandeer Cavallaro: None declared, Michael Lell: None declared, Hannah Schenker : None declared, David Simon Grant/research support from: Novartis, Consultant for: Lilly, Speakers bureau: Janssen, Koray Tascilar: None declared, Herbert S.B. Baraf: None declared, Georg Schett: None declared, Jurgen Rech Grant/research support from: Bristol-Myers Squibb and Celgene (greater than $10,000), Consultant for: Bristol-Myers Squibb, Celgene, Chugai, GlaxoSmithKline, Janssen, Eli Lilly, Novartis, Roche, Sanofi Aventis, and UCB (in total more than $10,000), Speakers bureau: Bristol-Myers Squibb, Celgene, Chugai, GlaxoSmithKline, Janssen, Eli Lilly, Novartis, Roche, Sanofi Aventis, and UCB (in total more than $10,000)