Treat-to-SU-Target Strategy May Slow, Prevent Bone Erosion

Long-term urate-lowering therapy using a treat-to-serum urate (SU)-target strategy may slow and potentially prevent bone erosion, and reduce monosodium urate (MSU) crystal deposition in gout, according to study results published in Arthritis and Rheumatology.

In this study, dual-energy computed tomography (DECT) was used to evaluate 183 patients with gout. Researchers determined whether allopurinol dose escalation to achieve SU-target influenced bone erosion or MSU crystal deposition. All patients had an SU level ≥6.48 mg/dL. The study included DECT scans of both feet and plain radiographs of the hands and feet scored for bone erosion and urate volume; scans were conducted at baseline, 1 year, and 2 years.

Patients were randomly assigned to either an immediate allopurinol dose escalation to SU-target group or to a control group of conventional dosing for 1 year followed by dose escalation to SU-target at second year. The dose-escalation group (n=42) received an immediate dose escalation of allopurinol to achieve and maintain the target-SU level of <6.48 mg/dL. The control group (n=45) had no change in allopurinol dosing during year 1, but received a dose escalation to achieve and maintain target-SU level of <6.48 mg/dL during year 2.

The primary end point of the imaging study was change from baseline in CT bone erosion score to measurements at years 1 and 2. Secondary end points included change from baseline in MSU crystal burden, change from baseline in plain radiography erosion score, and change from baseline in plain radiography joint space narrowing score.

Results revealed that at year 2, progression in CT bone erosion score was higher in the control group compared with the dose-escalation group (+7.8% vs +1.4%, respectively; P =.015). There were no significant differences observed in plain radiography erosion or plain radiography joint space narrowing scores between groups. Reduction rate in DECT urate volume between the control group and the dose-escalation group (−20.5% vs −28.3%, respectively; P =.14) was not significant.

The primary limitation of the study was patient dropout and resulting loss of follow-up imaging. This attrition may have affected detection or significance of differences between groups; however, study researchers suggested that findings could indicate that a treat-to-SU-target strategy may positively influence bone erosion in gout and that dose escalation of urate-lowering therapy may substantially reduce MSU crystal burden.

Reference

Dalbeth N, Billington K, Doyle A, et al. Effects of allopurinol dose escalation on bone erosion and urate volume in gout: a dual-energy computed tomography imaging study within a randomized, controlled trial [published online May 13, 2019]. Arthritis Rheumatol. doi:10.1002/art.40929