Optimal Cut-off Value of Ultrasound Double Contour Sign Combined with Serum Uric Acid in Gout

Abstract Objectives. We searched for the optimal cut-off value of the ultrasound double contour (DC) sign and the value of the DC sign combined with serum uric acid (SUA) for diagnosing gout. Methods. Gout patients, rheumatoid arthritis or osteoarthritis patients (RA/OA group), and healthy individuals were included in this study based on the inclusion criteria. SUA and the length of the DC sign in the knee and were detected and compared. The optimal cut-off values for diagnosing gout by DC sign and SUA were analyzed using the receiver operating characteristic (ROC) curve. We also plotted the ROC curve to compare the value of the ultrasound DC sign, SUA, and DC sign combined with SUA (in parallel and in series). Results.In this study, we included 330 subjects (n = 110 in the gout group, 110 in the RA/OA group, and 110 in the healthy control group). The optimal cut-off value of the DC sign for the diagnosis of gout was 1.67 cm. The results of the ROC curve analysis showed that the DC sign in parallel SUA had the highest diagnostic value (1.67 cm), which was higher than the value recorded in combined detection based on the presence or absence of the DC sign. Conclusions. The optimal cut-off value of the ultrasound DC sign for diagnosing gout was 1.67 cm; below this cut-off value, the DC sign in parallel SUA had the highest diagnostic value for gout and provided a reliable basis for the efficient diagnosis of gout.