Nonradiographic axial spondyloarthritis. What brings the new concept?

It has recently been proposed to introduce a new terminology to identify patients with axial spondyloarthritis earlier: nonradiographic axial spondyloarthritis [1]. This new concept, which does not define a new nosological entity, is the last act, for now, of a long and interesting journey that began in the 1960s and still continues nowadays, fascinating many rheumatologists. Until the second half of last century, rheumatologists regarded the ankylosing spondylitis or “Morbus Bechterew” as a spinal variant of the rheumatoid arthritis [2]. However, the attentive and careful clinical observation allowed by some rheumatologists among which highlight JM Moll and V Wright intuits that a heterogeneous group of patients with apparently very different diseases shared a lot of clinical aspects and familial aggregation. So, in this way, the concept of the spondyloarthropathies (SpA) was introduced by Moll et al. in 1974 as a family of interrelated disorders sharing clinical and genetic characteristics distinct from rheumatoid arthritis (RA) [3]. At the base of the concept stood the clinical observation of the aggregation of some common diseases (psoriasis, spondylitis, peripheral arthritis, enthesitis, acute anterior uveitis, chronic inflammatory bowel disease) in the same patient or in different members of the same family. One finding that has helped to strengthen the concept of SpA has been, without doubt, its association with HLA-B27, observation made independently but at same time by Brewerton et al. [4] and Schlosstein et al. [5], confirming pathophysiologically the clinical suspicion. Twenty years later, the evidence that a rat transgenic for HLA-B27, spontaneously developed some characteristics of these diseases, provided a definite support for the suspicion long intuited by the pioneers of spondyloarthritis [6]. Presently, it is accepted that the spondyloarthropathies or spondyloarthritis are a heterogeneous group of interrelated rheumatic inflammatory diseases that share common etiopathogenesis, clinical, genetic, and radiological features. SpA encompasses ankylosing spondylitis (AS), reactive arthritis, psoriatic arthritis, inflammatory bowel, and diseaserelated arthritis, whose estimated prevalence ranges 0.3–0.5% for AS and 1–2 % of SpA, which is higher than rheumatoid arthritis [7]. These groups of diseases frequently show familial aggregation and are strongly associated with HLA-B27; however, the strength of this association varies markedly between the various types of SpA of which AS remains as the paradigm. Identification of patients with these diseases has also been a long and interesting road, marked by progress in the deepest knowledge of the clinical expression with new technologies. Initially the patient was identified by appearance: “Complains of back being “set” for 3 years; cannot turn her head to the side or bend it backwards; is stiff when walking, but is better by day than by night; has pain at lower end of spine and in the hips” [8]. Radiological findings have been the cornerstone in which the diagnosis has been based, as stated in an early (perhaps the first) serious review by Buckley [9]. Radiographic sacroiliitis has been considered a hallmark of AS and is present in all patients with an established disease, and it is also a requirement for the fulfillment of the modified New York criteria for AS established in 1984, which are widely used as classification and diagnostic criteria in clinical E. Collantes-Estevez (*) Rheumatology Department, “Reina Sofia” Hospital/IMIBIC/ University of Cordoba, Cordoba, Spain e-mail: educollantes@yahoo.es