Editorial [Hot topic: Utilization of Biology Therapy in Spondyloarthropathy (SpA) in Asia Countries (Guest Editor: Chung-Tei Chou)]

Ankylosing spondylitis (AS) is a common rheumatic disorder in Chinese and other Asia populations. The prevalence of AS in Chinese is 0.2 to 0.3%, and the positive rate of B27 in AS is ranged from 90% to 97%. Undifferentiated spondloarthropathy (USpA) is classified as a form of SPA that does not meet the criteria for other SPA including AS, Reiter's syndrome, psoriatic arthritis (PsA) or inflammatory bowel disease related arthritis. For psoriasis, the lower incidence rate in Pacific Asian countries is due to the lower prevalence of HLA-CW6 within the population. Early diagnosis of AS is not possible by the previous classification criteria because radiologic changes of at least bilaterial class II sacroiliitis require 5 or more years to develop. The early diagnosis may need a new criteria which consists of clinical, laboratory (B27) and imaging findings (MRI). AS may develop acute and chronic inflammation at the different time. ESR and CRP are commonly used in rheumatoid arthritis (RA) but seems not working well to be used as a good disease activity biomarker in AS. In this issue, candidate biomarkers for the AS or for evaluation of response to the treatment will be discussed. Before the era of biologic agents, NSAIDs were only drugs proved to be useful in treating patients with SPA. However, approximately 20% are non-responder. From the serologic, synovial fluid and synovial pathology findings, TNF-α is highly associated with AS or other SPA. Early studies of anti-TNF-α therapy in SPA showed a very good efficacy for pain and inflammation as in RA. However, it is not certain for the biologic therapy to reduce the new bone formation in AS. This is still a treatment barrier but need to break through.