The New ASAS Classification Criteria for Axial and Peripheral Spondyloarthritis

Promises and Pitfalls

Sarah Lipton; Atul Deodhar;

Disclosures

Int J Clin Rheumatol. 2012;7(6):675-682. 

In This Article

Abstract and Introduction

Abstract

Spondyloarthritis (SpA), if not diagnosed and treated early, often leads to significant morbidity. Unfortunately, diagnosis and implementation of therapy are frequently delayed, in many cases by years. The Assessment of SpondyloArthritis International Society has recently developed new criteria for classification of both axial and peripheral SpA. The new criteria were formulated with the aim of enhancing design of clinical trials, and ultimately leading to earlier and more effective diagnosis and treatment in the clinical setting. This paper reviews the process of the development of both sets of criteria, and discusses their potential advantages and disadvantages.

Introduction

Spondyloarthritis (SpA) is an umbrella term applied to a group of rheumatic diseases with features in common with and distinct from other inflammatory arthritides, particularly rheumatoid arthritis. SpA encompasses ankylosing spondylitis (AS), reactive arthritis, psoriatic arthritis, inflammatory bowel disease-related arthritis and undifferentiated SpA. Features that link these entities are an association with HLA-B27, a characteristic pattern of peripheral arthritis that is asymmetric, oligoarticular and predominates in the lower extremities, and possible sacroiliitis, spondylitis, enthesitis, dactylitis and inflammatory eye disease.[1] Estimated prevalence of ankylosing spondylitis in Europe is 0.3–0.5%, and of SpA is 1–2%, which is higher than rheumatoid arthritis.[2] Data from National Health and Nutrition Examination Survey (NHANES) suggest that prevalence of SpA in the USA may be as high as 1.4%.[3]

AS, with typical onset at a young age, without treatment or with delayed treatment, is associated with tremendous symptomatic burden and loss of function during years that are normally productive.[4] Opportunities for early treatment are hampered by delayed diagnosis; an average delay of 8–11 years between onset of symptoms and time of diagnosis has been reported.[5] Reasons for the delay in diagnosis are myriad and include lack of a pathognomonic clinical feature or laboratory test. Low back pain afflicts most patients with AS, but is extremely common in the general population, and often the inflammatory origins of back pain are not carefully sought in practice.[4] Furthermore, radiographic sacroiliitis, which has historically been a cornerstone of diagnosing AS, may take several years to develop.[6]

The need for early diagnosis and treatment was less crucial in the past, when therapeutic options were quite limited. This has changed with the development of TNF-α inhibitors that are used effectively to treat AS and arrest progression of peripheral arthritis in other SpA.[7] A major challenge over recent decades has been the lack of diagnostic or classification criteria, which could help with early establishment of diagnosis to allow for timely and proper treatment, and facilitate clinical trial design, respectively. The development of the Assessment of SpondyloArthritis International Society (ASAS) classification criteria for both axial and peripheral SpA has been a welcome advance in this regard. This article discusses the new criteria and their potential promises and pitfalls.

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