MRI predicts response to anti-TNF in ankylosing spondylitis

Rudwaleit and colleagues have recently reported on the role of MRI in predicting response to anti-TNF [1]. Ankylosing spondy litis (AS) is the archetypal axial spondylo arthropathy (SpA). SpA occurs in 0.2–1% of the general population and in 5% of chronic back pain sufferers [2]. AS typically affects young patients in the second and third decades of life [3,4], and causes signifi cant morbidity and work instability [5–7]. For a diagnosis of AS to be made, the modifi ed New York criteria must be fulfi lled which includes radiographic sacroiliitis [8], and it is well recognized that this often only occurs after many years of symptoms [9,10]. MRI is able to detect sacroiliitis and infl ammatory spinal lesions consistent with AS much earlier than conventional radiography. Therefore, MRI is frequently used in AS diagnosis to assess disease activity by quant ifying infl ammatory lesions in the spine and sacroiliac joints (SIJs), and to assess response to treatment. In addition, owing to the long delay in the development of characteristic and diagnostic radiographic features in AS, MRI is being used to diagnose AS early [11,12]. Until recently, the mainstay of treatment in AS has been NSAIDs and physiotherapy. However, in recent years, new biologic drugs, in particular the anti-TNF drugs, have proven to be extremely effi cacious in the symptomatic treatment of AS, both in the short and longer term [13–18] and have revolutionized AS treatment. AntiTNFs have also been shown to be effi cacious in early disease [19,20]. Clinical markers of disease activity including the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), C-reactive protein (CRP) and MRI lesion scores have all been shown to improve considerably after anti-TNF therapy [13–15,17,18]. However, although overall treatment response to anti-TNF in AS is very good in general, some patients do fail to respond, and of the responders some respond better than others [21]. Therefore, it is critical, as with any new treatment, but particularly in the case of the very expensive antiTNF drugs, to identify predictors of response to enable the treatment to be used in the most judicious way. Therefore, this paper by Rudwaleit and colleagues on MRI predicting major clinical response to anti-TNF is a very welcome and important addition to the literature.