Performance and agreement between classification criteria and rheumatologist's diagnosis of the most widely used SpA classification criteria in a Colombian group of patients with chronic low back pain

Abstract

Objective: To evaluate the performance of the most widely used SpA classification criteria in a Colombian group of patients with chronic low back pain. Methods:We assessed the ASAS and the European Spondyloarthropathy Study Group (ESSG) classification criteria in a group of 133 patients who attended consecutively over a period of six months at outpatient clinic of low back pain. All the patients were evaluated with the same protocol. The patients were divided into two groups according to the diagnosis.The diagnosis was compared with the diagnosis made by a expert rheumatologist blinded to patient information.Results: 81 patients with SpA and 52 with other diagnoses were included. There were no differences in age and age of onset of symptoms between the two groups. The SpA group included 55 males and more common clinical findings were: enthesitis, arthritis, sacroiliitis, HLA-B27-positive, previous infection, and dactylitis. The sensitivity and specificity of criteria were: ASAS criteria 96% of sensibility and 80% of specificity, and ESSG criteria 95% and 100% respectively.The agreement between the classification criteria and the diagnosis established by the rheumatologist showed a Cohen's kappa index of 0.938 for ESSG criteria (95% CI: 0.877-0.998) and 0.790 for the ASAS criteria (95% CI: 0.682-0.898). Conclusion:In a Colombian group of SpA patients, the new ASAS classification criteria have a good concordance with clinical diagnosis but are not superior to the ESSG criteria.