Monosodium urate burden assessed with dual-energy computed tomography predicts the risk of flares in gout: a 12-month observational study

Abstract

BackgroundPredicting the risk of flares in patients with gout is a challenge and the link between urate burden and the risk of gout flare is unclear. The objective of this study was to determine if the extent of monosodium urate (MSU) burden measured with dual-energy computed tomography (DECT) and ultrasonography (US) is predictive of the risk of gout flares.MethodsThis prospective observational study recruited patients with gout to undergo MSU burden assessment with DECT (volume of deposits) and US (double contour sign) scans of the knees and feet. Patients attended follow-up visits at 3, 6 and 12 months. Patients having presented with at least one flare at 6 months were compared to those who did not flare. Odds ratios (ORs) (95% confidence interval) for the risk of flare were calculated.ResultsOverall, 64/78 patients included attended at least one follow-up visit. In bivariate analysis, the number of joints with the double contour sign was not associated with the risk of flare (p = 0.67). Multivariate analysis retained a unique variable: DECT MSU volume of the feet. For each 1 cm3 increase in DECT MSU volume in foot deposits, the risk of flare increased 2.03-fold during the first 6 months after initial assessment (OR 2.03 (1.15–4.38)). The threshold volume best discriminating patients with and without flare was 0.81 cm3 (specificity 61%, sensitivity 77%).ConclusionsThis is the first study showing that the extent of MSU burden measured with DECT but not US is predictive of the risk of flares.Electronic supplementary materialThe online version of this article (10.1186/s13075-018-1714-9) contains supplementary material, which is available to authorized users.

Performance of Ultrasound in the Clinical Evaluation of Gout and Hyperuricemia

“…For the patients without classic symptoms, MSU crystal deposition could be identified by image-based examination, such as dual-energy computed tomography (DECT) and US. It has been reported that MSU burden volume, which is predictive of the risk of flares (16) can be measured using DECT (17).…”

Association of Specific Comorbidities with Monosodium Urate Crystal Deposition in Urate-Lowering Therapy-Naive Gout Patients: A Cross-Sectional Dual-Energy Computed Tomography Study

“…The following factors were not retained by automatic selection in the reduced model (and did not demonstrate a significant association with MSU crystal DECT volume in multivariate analysis): eGFR, hypertension, history of myocardial infarction, and diabetes mellitus. This model explained only 21% of the variance of MSU crystal deposition, with a residual SD of 10.41 cm 3 . The only variable significantly associated with MSU DECT volume was gout duration (Spearman correlation coefficient 0.36 (0.02; 0.97)), while subcutaneous tophi and CHF, despite high correlation coefficients, did not reach statistical significance as their 95% confidence intervals included 0.…”

“…In addition, a second bivariate analysis was performed by splitting the dataset depending on an arbitrary threshold of DECT MSU volume (1 cm 3 ), which was considered clinically relevant for predicting the risk of gout flares [3]. Student's t or Wilcoxon-Mann-Whitney tests and Chi-squared or Fisher's exact tests were used, where appropriate.…”

“…Table 5. Factors associated in bivariate analysis with monosodium urate (MSU) crystal volumes ≥1 cm 3 as quantified by dual-energy computed tomography (DECT) of the knees and feet/ankles (n = 91). Variables ultimately included in the reduced model and significantly associated with MSU DECT volumes ≥1 cm 3 were: gout duration (OR for each 10-year increase in disease duration 3.15 (1.60; 7.63)), diabetes mellitus (OR 4.75 (1.58; 15.63)), and CHF (OR 7.82 (2.29; 31.38)) ( Table 6).…”

“…Gout causes recurrent flares and chronic gouty arthritis induced by monosodium urate (MSU) crystal deposition secondary to long-standing hyperuricemia [1,2]. The extent of MSU crystal deposition in gout patients appears to determine disease activity [3], and tophaceous gout is associated with an increased mortality risk [4]. Several factors, in particular cardiovascular comorbidities, have been associated with extensive MSU deposition in the subset of tophaceous gout patients, who represent only 10% to 20% of the gout patient population overall [4,5].…”