Performance of the ASAS classification criteria for axial and peripheral spondyloarthritis: A systematic literature review and meta-analysis

Objective: To summarise the evidence on the performance of the Assessment of SpondyloArthritis international Society (ASAS) classification criteria for axial spondyloarthritis (axSpA) (also imaging and clinical arm separately), peripheral ( p)SpA and the entire set, when tested against the rheumatologist's diagnosis ('reference standard'). Methods: A systematic literature review was performed to identify eligible studies. Raw data on SpA diagnosis and classification were extracted or, if necessary, obtained from the authors of the selected publications. A meta-analysis was performed to obtain pooled estimates for sensitivity, specificity, positive and negative likelihood ratios, by fitting random effects models. Results: Nine papers fulfilled the inclusion criteria (N=5739 patients). The entire set of the ASAS SpA criteria yielded a high pooled sensitivity (73%) and specificity (88%). Similarly, good results were found for the axSpA criteria (sensitivity: 82%; specificity: 88%). Splitting the axSpA criteria in 'imaging arm only' and 'clinical arm only' resulted in much lower sensitivity (30% and 23% respectively), but very high specificity was retained (97% and 94% respectively). The pSpA criteria were less often tested than the axSpA criteria and showed a similarly high pooled specificity (87%) but lower sensitivity (63%). Conclusions: Accumulated evidence from studies with more than 5500 patients confirms the good performance of the various ASAS SpA criteria as tested against the rheumatologist's diagnosis. © 2017, BMJ Publishing Group. All rights reserved.