Session Title: Metabolic and Crystal Arthropathies II: Clinical Practice
Session Type: ACR Concurrent Abstract Session
Session Time: 9:00AM-10:30AM
Background/Purpose: Dual energy computed tomography (DECT) allows reliably detecting and quantifying tophus burden in patients with chronic gout. Longitudinal studies on the effect of uric acid lowering drug therapy on tophus burden assessed by DECT are currently lacking with the exception of a small study performed in patients treated with Pegloticase (1). Aim: To assess and compare the effects of uric acid lowering drugs on reducing tophus volume in patients with chronic gout by means of dual energy computed tomography scans
Methods: Follow-up DECT scans were performed in 94 patients with initially DECT positive chronic gout receiving stable treatment with either Allopurinol, Febuxostat, Benzbromaron or Pegloticase or had solely life-style intervention with no concomitant uric acid lowering drug therapy. Baseline and follow-up scans of both feet captured automatically the urate volume (Somatom Definition Flash/Force CT; Syngo DE Gout software; Siemens). Artefacts were manually excluded. Changes in tophus volume were calculated in a descriptive (tophus volume at baseline minus tophus volume at follow-up) and inferential way (Wilcoxon signed-rank test). Demographic data, medication and blood values (CRP, creatinine, serum urate) were recorded at the time of each DECT scan.
Results: 94 patients (75 men and 19 women) were analyzed. Mean disease duration until the first DECT examination was 3.3 years and mean interval between both DECT examinations was 17 months. The overall baseline serum uric acid level decreased from 7.3 ± 2.5 mg/dl to 5.9 ± 2.8 mg/dl at follow up (- 19%). Baseline tophus volume decreased by 77% with Allopurinol (p < 0.001, r = – 0.50), 35% with Febuxostat (p = 0.001, r = – 0.51) and 90% with Pegloticase (p = 0.005, r = – 0.58). Only 2 patients were treated with Benzbromaron showing numerical decrease of tophus volume at a similar range as seen with Allopurinol (- 75%). Life-style intervention also led to a moderate (- 31%), though significant (p = 0.007, r = – 0.40), decrease in tophus burden. Complete tophus resolution was found in 46,4% of the patients treated with Allopurinol, 34,8% treated with Febuxostat and 8,3% with Pegloticase.
Conclusion: Sustained uric acid lowering drug therapy leads to significant reduction of DECT tophus burden in patients with chronic gout. The effectiveness of urate lowering therapies on reducing serum urate concentration is not necessarily transferable on the resolution of monosodium urate crystal depositions (see in table 2). While Febuxostat led to the greatest change in serum uric acid levels with a reduction of 36%, its effect on reducing tophus burden was rather low (- 34 %). At present, it is common clinical practice to monitor gout treatment based on the uric acid level. However, in order to assess and monitor the real effect of urate lowering therapies on the resolution of monosodium urate depositions, dual energy CT is more accurate.
To cite this abstract in AMA style:Ellmann H, Bayat S, Oliveira I, Englbrecht M, Araujo E, Cavallaro A, Mendonca S, Lell M, Manger B, Schett G, Rech J. A Longitudinal Dual Energy Computed Tomography Study on the Effect of Urate Lowering Therapies on the Reduction of Tophus Burden in Patients with Chronic Gout [abstract]. Arthritis Rheumatol. 2016; 68 (suppl 10). https://acrabstracts.org/abstract/a-longitudinal-dual-energy-computed-tomography-study-on-the-effect-of-urate-lowering-therapies-on-the-reduction-of-tophus-burden-in-patients-with-chronic-gout/. Accessed March 3, 2021.
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