Diagnostic accuracy of ultrasound in patients with gout: A meta-analysis

Objective: This study aimed to evaluate the diagnostic performance of ultrasound (US) for patients with gout. Methods: We searched the Medline, Embase, Pubmed, and Cochrane Library databases, and performed a meta-analysis of the diagnostic accuracy of US according to the double contour sign, tophus, snowstorm, or bony erosion in patients with gout. Results: In total, 11 studies including 938 patients with gout, and 788 controls (patients with nongout inflammatory arthritis) were available for the meta-analysis. The pooled sensitivity and specificity of US were 65.1% ([95% confidence interval (CI): 62.0–68.2] and 89.0% (96.6–91.1), respectively. The positive likelihood ratio, negative likelihood ratio, and diagnostic odds ratio were 5.889 (3.365–10.30), 0.359 (0.266–0.485), and 17.61 (11.11–17.92), respectively. The area under the curve of US was 0.858 and the Q^⁎ index was 0.789, indicating good diagnostic accuracy. Some between-study heterogeneity was found in the meta-analyses. Meta-regression showed that the sample size, study design, and diagnostic criteria were not sources of heterogeneity, and subgroup meta-analyses did not change the overall diagnostic accuracy. US signs of tophus, snowstorm, or bony erosion besides the double contour sign were not sensitive (54.3%, 30.8%, and 51.6%), but specific (93.2%, 90.6%, and 93.3%) enough as a diagnostic tool. Conclusions: Our meta-analysis of published studies demonstrates that US offers good diagnostic accuracy with high specificity and can play an important role in the diagnosis of gout.