Are gout patients with negative dual-energy computed tomography for monosodium urate crystal deposition easy to treat?

Objectives To determine the clinical associations and predictive value of two thresholds of negative dual-energy CT (DECT) for MSU crystal deposition in gout patients initiating urate-lowering therapy (ULT) and identify which threshold is more clinically relevant. Methods Patients from the CRYSTALILLE cohort with a diagnosis of gout naïve to ULT with baseline DECT scans of the knees and feet were selected. Two thresholds of positivity for DECT detection of MSU crystal deposition were considered (<0.01 cm³ and <0.1 cm³). Baseline characteristics and the prediction of key outcomes after ULT initiation, including reaching serum urate (SU) levels <6.0 and 5.0 mg/dl and occurrence of flares at 6, 12 and 24 months, associated with both thresholds of negative DECTs were compared with those of patients having positive DECT scans. Results A total of 211 patients, median age 66.2 years [interquartile range (IQR) 57–75.8], with a median symptom duration of 3 years (IQR 0–7.8) were included. A total of 38/211 (18%) and 90/211 (43%) had negative DECT scans for the 0.01 and 0.1 cm³ thresholds, respectively. Factors associated with negative DECT scans were younger age, shorter symptom duration and an absence of cardiovascular disease for both volume thresholds. A total of 9/39 (23.1%), 3/26 (11.5%) and 1/18 (5.6%) patients with <0.1 cm³ MSU crystals had flares at 6, 12 and 24 months, respectively, compared with 18/45 (40.0%), 9/36 (25.0%) and 2/18 (11.1%) patients with ≥0.1 cm³ (P  > 0.05). Overall, 95 patients (68.3%) reached SU levels <6.0 mg/dl and 68 (48.9%) reached levels <5.0 mg/dl, without any difference between positive and negative DECTs, with ULT dosages that tended to be lower in patients with negative DECTs. Conclusion The 0.1 cm³ threshold was better correlated with clinical presentation and evolution than the 0.01 cm³ threshold. Gout patients with negative DECTs exhibit milder disease and a lower comorbidity burden. They do not exhibit particularly easy-to-treat hyperuricaemia but they may have a lower risk of flares. [ABSTRACT FROM AUTHOR]