Background The Assessment of SpondyloArthritis international Society (ASAS) classification criteria (ASAScc) for both axial and periheral spondyloarthritis (SpA) have been designed to classify patients early in the disease course. The criteria have been studied mostly in SpA cohorts but not largely in patients with other conditions that may mimic RA. Thus, it is not known how these criteria for SpA (both axial and peripheral) perform to identify SpA in patients seen in routine clinical care.
Objectives To evaluate the performances (sensitivity, specificity,) of the ASAScc for axial and peripheral SpA in a general rheumatology practice.
Methods 242 consecutive new and established patients from an outpatient clinic of a university rheumatology center were recruited after being screened by their primary rheumatologist and were included if they had an at least 3 month history of backpain started before the age of 45 years or joint symptoms. The ASAScc were applied, as laid out by the task force, by a 2 physicians with questions followed by a targeted musculoskeletal exam. The patients were followed retrospectively and prospectively for additional exam findings, laboratory and radiographic tests, and physician diagnosis not present at time of screening. The gold standard for the diagnosis of SpA was the primary rheumatologist’s diagnosis. Sensitivity and specificity were calculated.
Results 220 patients were eligible for the analysis. The mean age of the patients was 37.8 years, with 38% women, an average duration of disease of 3.1 years. Seventy-one percent of the patients were included to the axial arm and 29% to the peripheral arm of the criteria application. Sensitivity and specificity for axial ASAScc were 0.85 and 0.73, respectively. For patients presenting with peripheral symptoms, sensivitity and specificity were 1 and 0.53, respectively. When ESSG cirteria were tested in the same population, sensitivity was found as 0.93 ans spesificity as 0.37.
Conclusions To our knowledge, this study is among the first few studies examining the new criteria for SpA in consecutive patients seen in routine care. While the sensitivity of both of the criteria sets are acceptable, specificity for both axial and for peripheral sets were far from satisfactory.
Disclosure of Interest None Declared