The association between gout flares and monosodium urate burden assessed using musculoskeletal ultrasound in patients with gout

Background: Ultrasound (US) has a high sensitivity in detecting monosodium urate (MSU) deposition in gout patients. However, the value of US in predicting gout flares has been reported only in a few monocentric studies. Objective: To investigate the association between gout flares in the previous year and US-detected MSU burden using two different US scores. Design: A retrospective study. Methods: Patients with gout were consecutively recruited to undergo musculoskeletal US examinations of their knees, ankles, and feet. The score derived from Outcome Measure in Rheumatology (hereinafter referred to as MSU score) and musculoskeletal US features-based (hereinafter referred to as MSKF score) were used to quantify the MSU burden of gout. Odds ratios for frequent gout flares were calculated. Results: We enrolled 1894 patients with gout (mean age: 45 years; gout duration: 5 years; males: 96.1%), experiencing a median of three flares over the past year. Of these, 428 (22.6%) patients reported frequent (>= 7) gout flares. The MSU and MSKF median scores were 6 and 9, respectively. For each five-point increase in MSU and MSKF score, the odds ratio of frequent gout flares increased 1.13-fold and 1.24-fold, respectively. The area under the curve (AUC) for the MSU and MSKF score was 0.635 [95% confidence interval (CI): 0.604-0.665] and 0.688 (95% CI: 0.659-0.718), respectively, (AUC difference 0.054, p value for AUC difference < 0.001). Conclusion: The MSU and MSKF scores were significantly associated with the number of gout flares in the previous year. The MSKF score outperformed the MSU score in terms of frequent gout flare discrimination.