Background The accepted outcome measures for gout are seric urate, recurrent outbreaks, tophi regression and joint damage image. The Power Doppler ultrasound (PDUS) has demonstrated validity in the monitoring of treatment in other arthropathies, and it has been correlated with the presence of inflammatory activity.
Objectives To evaluate the role of PDUS as a treatment monitoring tool in a cohort of gout patients.
Methods In this 2 years longitudinal study, we prospectively evaluated patients with a clinical history suggestive of gout and at least one symptomatic flare in the last three months. Crystal identificaction by microscopy was made in all patients. Clinical and laboratory parameters were evaluated and treatment was adjusted to achieve an adequate disease control. In all visits (baseline, 6, 12 and 24 month) a second rheumatologist blinded to clinical data performed the ultrasound examination with a Logiq 9 equipment (General Electric Medical Systems, Milwaukee, WI, USA) with probe 9-14-MHz to scale grey and 5-7.5-MHz Doppler. Standardized examinations were carried out over four joints: first metatarsophalangeals (MTP) and knees (medial and lateral recesses); and the patellar tendons; and PD signal were scored. Mean and standard deviation was calculated for each parameter in the consecutive visits. The comparison between quantitative values was performed by Student t test for paired samples. Sensitivity to change of the US was assessed by estimating the smallest detectable difference (SSD) in the Doppler total score.
Results 24 consecutive patients (95.8% men) were included, with mean age of 60.8 (± 11 years), and mean disease duration of 10.3 years (IQR: 2-15). At baseline, 42, 71 and 50% were being treated with allopurinol, colchicine and NSAIDs, respectively. A significant decrease was observed in clinical and laboratory parameters, and also in the ultrasound Doppler signal (Table 1).
The minimum detectable change at 2 years in Doppler score was 1.92, and it was lower than the difference between the baseline score and the score of the two years, which means that the detected change was independent of chance or measurement error. Despite an adequate disease control (62% of patients with serum urate <6) the Doppler signal persists in a high percentage of patients (67%).
Conclusions PDUS is sensitive to change in monitoring the treatment of gout. The 1stMTP joint is the more useful site for US treatment monitoring. The Doppler signal persists despite adequate control of the disease.
Disclosure of Interest None Declared
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