Performance of the 2015 American College of Rheumatology/European League against Rheumatism Classification Criteria for Gout in Korean Patients with Acute Arthritis

Background: We aimed to assess the performance of the 2015 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) classification criteria for gout in Korean patients with acute arthritis and to compare the performance of the ACRJ EULAR criteria to that of other sets of criteria for gout classification. Methods: Patients with acute arthritis who underwent diagnostic arthrocentesis at one of the four participating rheumatology clinics were consecutively enrolled between February and December 2017. Crystal-proven gout was diagnosed upon confirming the presence of monosodium orate (MSU) crystals in patients with a clinical impression of gout as judged by the rheumatologist. The performance of the ACR/EULAR and other gout classification criteria, including the Rome, New York, American Rheumatism Association (ARA), Mexico, and Netherlands criteria, was analyzed regardless of the presence/absence of MSU crystals. Results: The study enrolled 118 gout patients (all crystal-proven) and 95 non-gout patients. According to the area under the curve, the diagnostic performance was the highest for the ACRJEULAR classification criteria (sensitivity, 80.5%; specificity, 95.8%; area under the curve, 0.966), followed by the Netherlands, Rome, ARA, New York, and Mexico criteria. All six sets of criteria demonstrated lower sensitivity in patients exhibiting the first episode of acute arthritis. Conclusion: In Korean patients with acute arthritis, the ACR/EULAR classification criteria outperformed other sets of gout classification criteria even in the absence of information regarding the presence of MSU crystals. However, to enhance diagnostic sensitivity, synovial fluid analysis should be considered in patients with the first episode of acute arthritis.