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

Background Predicting 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. Methods This 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. Results Overall, 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 cm 3 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 cm 3 (specificity 61%, sensitivity 77%). Conclusions This is the first study showing that the extent of MSU burden measured with DECT but not US is predictive of the risk of flares.