Tophus resolution with pegloticase: a prospective dual-energy CT study

Objective To investigate the effect of intensive lowering of serum uric acid (SUA) levels by pegloticase on the resolution of tophi in patients with refractory gout. Methods Descriptive study in patients with refractory gout receiving pegloticase treatment. SUA levels were measured before and after each infusion. Dual-energy CT (DECT) scans were taken from all patients before the first infusion and after the last infusion. Computerised tophus volumes were calculated for the baseline and follow-up assessments and compared with each other. Results 10 patients with refractory gout and baseline mean SUA level of 8.1 mg/dL were enrolled. Patients were treated for a mean of 13.3 weeks. Pegloticase effectively reduced tophi in all patients showing a decrease in volume by 71.4%. Responders, showing reduction of SUA level below 6 mg/dL during at least 80% of the treatment time, were virtually cleared from tophi (−94.8%). Dependent on their anatomical localisation, resolution of tophi showed different dynamics, with articular tophi showing fast, and tendon tophi slow, resolution. Conclusions Tophi are highly sensitive to pegloticase treatment, particularly when located at articular sites. Debulking of disease and a tophus-free state can be reached within a few months of pegloticase treatment. DECT allows for comprehensively assessing tophus burden and monitoring treatment responses.