Ultrasound useful for monitoring crystal dissolution in gout under urate-lowering therapy
Ultrasound accurately shows the disappearance of urate disposition in gout patients undergoing urate-lowering therapy (ULT), according to the results of the USEFUL study.
Researchers followed for 6 months 79 gout patients (mean age 61.8 years; 91 percent male; mean disease duration 6.3 years) showing ultrasound features of tophus and/or double contour sign at the knee and/or first metatarsophalangeal joints. All patients started ULT.
Evaluations were performed at baseline and at months 3 and 6 following treatment. Outcomes investigated included the change in features of gout at month 6 and the final serum urate (SU) level (high, >360 μmol/L; low, 300–360 μmol/L; very low, <300 μmol/L).
At baseline, mean serum urate (SU) level was 530 µmol/L. A total of 74 patients (94 percent) had ≥1 ultrasound tophus, while 68 (86 percent) had double contour sign.
At month 6, among the 67 patients who completed the study, 18 and 39 patients achieved very low and low SU levels, respectively. Ultrasound features of gout decreased significantly in the lowest SU level group (p<0.001).
Final SU level at month 6 positively correlated with decreased tophus size (p<0.0001) and inversely correlated with proportion of double contour sign disappearance (p<0.0001).
USEFUL confirms that ultrasound allows for visualization of monosodium urate crystal deposits clearance under efficient ULT, as well as suggest that a reduction in SU level correlates with a decrease in ultrasound features of gout, researchers said.
In the era of targeted treatment, ultrasound assessment should be used as a tool for follow-up. However, based on the present data alone, it cannot be stated that ultrasound should be considered as the best imaging modality to monitor clearance of urate deposition, researchers pointed out.