Spondyloarthritis (SpA) is a heterogeneous group of rheumatic diseases, characterized by sacroiliac-joint inflammation (sacroiliitis), peripheral and extra-articular complaints. The lack of... Show moreSpondyloarthritis (SpA) is a heterogeneous group of rheumatic diseases, characterized by sacroiliac-joint inflammation (sacroiliitis), peripheral and extra-articular complaints. The lack of diagnostic criteria makes diagnosing SpA challenging, yet, classification criteria are available. We tested the performance (sensitivity, specificity) of various classification criteria; the recently developed Assessment of SpondyloArthritis international Society (ASAS) criteria outperformed all other criteria. We investigated the discrepancies in interpretation MRIs and conventional radiographs on the presence of sacroiliitis; agreement on radiographic sacroiliitis between different readers is only moderate, but agreement regarding sacroiliitis on MRI is substantial. Rheumatologists take into account all clinical and laboratory results in addition to the imaging results in the diagnostic process. The diagnostic Berlin algorithm - in which all relevant results are taken into account __ can assist rheumatologists. We proposed a modification of this algorithm, which is accepted by ASAS and also included in the recently published guidelines for the diagnosis and treatment of SpA by the Dutch Society for Rheumatology. Besides, we performed systematic literature reviews, forming the base for the update of the ASAS management recommendations. With these results, SpA-patients can be recognized earlier, offering better treatment options and better outcomes. However, further improvements of care for SpA-patients are necessary. Show less