Presence of monosodium urate crystal deposition by dual-energy CT in patients with gout treated with allopurinol. Issue 3 (16th November 2017)

• Record Type: Journal Article
• Authors: Dalbeth, Nicola; Nicolaou, Savvas; Baumgartner, Scott; Hu, Jia; Fung, Maple; Choi, Hyon K
• Is Part Of: Annals of the rheumatic diseases. Volume 77:Issue 3(2018)
• Page Start: 364
• Page End: 370
• Publication Date: 2017-11-16
• Subjects: gout -- treatment -- patient perspective; Rheumatism -- Periodicals; 616.723005
• DOI: 10.1136/annrheumdis-2017-212046
• Languages: English
• ISSNs: 0003-4967

Abstract

Abstract : Objective: Dual-energy CT (DECT) detects and quantifies monosodium urate (MSU) crystal deposition with high precision. This DECT study assessed crystal deposition in patients with gout treated with stable-dose allopurinol, and investigated potential clinical determinants for crystal deposition. Methods: Patients with gout treated with allopurinol ≥300 mg daily for at least 3 months were prospectively recruited from the USA and New Zealand, using monitored enrolment to include approximately 25% patients with palpable tophi and approximately 50% with serum urate (sUA) levels <6.0 mg/dL (<357µmol/L). MSU crystal deposition was measured in the hands/wrists, feet/ankles/Achilles and knees bilaterally. The presence and total volume of crystals were assessed by DECT and analysed according to sUA levels and gout characteristics. Results: Among 152 patients receiving allopurinol ≥300 mg/day for 5.1 years on average, 69.1% had crystal deposition on DECT, with a median total crystal volume of 0.16 cm 3 (range: 0.01–19.53 cm 3 ). The prevalence of crystal deposition ranged from 46.9% among patients with sUA <6.0 mg/dL and no palpable tophi to 90.0% among those with sUA ≥6.0 mg/dL and tophi. Total volume of crystal deposition was positively associated with sUA ≥6.0 mg/dL, gout flares within the past 3 months and tophi. Total volume of crystal deposition correlated positively with Patient Global Impression of Disease Activity scores. Conclusion: A substantial proportion of patients without palpable tophi have MSU crystal deposition, despite receiving allopurinol doses ≥300 mg/day for a considerable duration. Patients with higher sUA and clinical features of severe disease have a higher frequency and greater volume of MSU crystal deposition.