To evaluate the ability of 2015 American College of Rheumatology/European League Against Rheumatism (ACR/EULAR) classification criteria to diagnose gout compared with the widely used 1977 American Rheumatism Association (ARA) criteria and other criteria in clinical practice in Chinese patients, and to compare the sensitivity and specificity of different classification criteria for gout in early and established diseases.
The patients who had ankle arthritis and visited the Department of Rheumatology and Clinical Immunology, Peking University First Hospital between February 2012 and February 2016 were screened. The patients who had been already diagnosed with gout or pyrophosphate deposition disease through arthrocentesis or tissue aspiration and those who had been diagnosed with rheumatoid arthritis, spondyloarthritis, and osteoarthritis were excluded. The patients were diagnosed by two experienced rheumatologists and all of them were followed up for at least one year. Early disease was defined as symptom onset of no more than 2 years; established disease was defined as symptom duration of more than 2 years. The 2015 ACR classification criteria were divided into clinical form with clinical parameters included and complete form with not only clinical parameters but also synovial fluids tests, imaging findings and monosodium urate (MSU) included. The two forms above were short for "clinical form (incorporating clinical parameters)" and "complete form (incorporating imaging and MSU data)" respectively.
In this study, 284 patients suffering from ankle arthritis were inclu-ded in the study, 219 of them were classified as gout and 65 of them had alternative diagnoses. The sensitivity and specificity of 2015 ACR complete form (incorporating imaging and MSU data) for diagnosing gout were 88.13% and 95.38%, respectively. The area under the curves (AUC) of 2015 ACR "complete form (incorporating imaging and MSU data)", 2015 ACR "clinical form (incorporating clinical parameters)", 2010 Netherlands criteria and 1977 ARA criteria were 0.982, 0.983, 0.963, and 0.928, respectively. For the 94 early gout patients, the AUC of the above criteria were 0.973, 0.968, 0.916, and 0.910, respectively. For the established gout patients, the AUC were 0.987, 0.991, 0.982, and 0.936, respectively. For the patients with disease duration within two years, the odd ratio (OR) for sensitivity of 2015 ACR "complete form (incorporating imaging and MSU data)", 2015 ACR "clinical form (incorporating clinical parameters)", 2010 Netherlands criteria and 1977 ARA criteria were 1.562 (1.003-2.435), 1.500 (1.001-2.346), and 1.812 (1.177-2.791), nevertheless, for the patients with established gout, the OR were 1.702 (1.300-2.229), 1.607 (1.224-2.110), and 1.821 (1.396-2.377), respectively.
The 2015 ACR/EULAR criteria are more accurate in gout diagnosis compared with the 1977 ARA criteria by elevating the sensitivity and specificity, in respective of the disease duration. The 2015 ACR/EULAR criteria may serve as new diagnostic tools in daily clinical practice in Chinese patients.