Chapter 163: The Spondyloarthritides

DEFINITION

The spondyloarthritides (SpA) are a family of diseases that include ankylosing spondylitis (AS), reactive arthritis (ReA), psoriatic arthritis (PsA), enteropathic arthritis, juvenile-onset SpA, and undifferentiated SpA. More recently, these disorders have been broadly classified as predominantly axial SpA, affecting the spine, pelvis, and thoracic cage, or predominantly peripheral SpA, affecting the extremities. Classification criteria based on these main clinical features have been developed that aide in early identification (Tables 163-1 and 163-2).

TABLE 163-1: ASAS Criteria for Classification of Axial Spondyloarthritis (To Be Applied for Pts with Back Pain ≥3 Months and Age of Onset <45 Years)^a
SACROILIITIS ON IMAGING PLUS ≥1 SPA FEATURE	OR	HLA-B27 PLUS ≥2 OTHER SPA FEATURES
Sacroiliitis on imaging Active (acute) inflammation on MRI highly suggestive of SpA-associated sacroiliitis^b and/or Definite radiographic sacroiliitis according to modified New York criteria^c		SpA features Inflammatory back pain^d Arthritis^e Enthesitis (heel)^f Anterior uveitis^g Dactylitis^e Psoriasis^e Crohn’s disease or ulcerative colitis^e Good response to NSAIDs^h Family history of SpAⁱ HLA-B27 Elevated CRP^j

_aSensitivity 83%, specificity 84%. The imaging arm (sacroiliitis) alone has a sensitivity of 66% and a specificity of 97%.

_bBone marrow edema and/or osteitis on short tau inversion recovery (STIR) or gadolinium-enhanced T1 image.

_cBilateral grade ≥2 or unilateral grade 3 or 4.

_dSee text for criteria.

_ePast or present, diagnosed by a physician.

_fPast or present pain or tenderness on examination at calcaneus insertion of Achilles tendon or plantar fascia.

_gPast or present, confirmed by an ophthalmologist.

_hSubstantial relief of back pain at 24–48 h after a full dose of NSAID.

_iFirst- or second-degree relatives with ankylosing spondylitis (AS), psoriasis, uveitis, reactive arthritis (ReA), or inflammatory bowel disease (IBD).

_jAfter exclusion of other causes of elevated CRP.

Abbreviations: ASAS, Assessment of Spondyloarthritis International Society; CRP, C-reactive protein; MRI, magnetic resonance imaging; NSAIDs, nonsteroidal anti-inflammatory drugs; SpA, spondyloarthritis.

Source: Rudwaleit M et al: The development of assessment of spondyloarthritis international society classification criteria for axial spondyloarthritis (part II). Ann Rheum Dis 68:777, 2009. Adapted by permission from BMJ Publishing Group Limited.

TABLE 163-2: ASAS Criteria for Peripheral Spondyloarthritis^a
Arthritis^bOr Enthesitis Or Dactylitis
PLUS EITHER One or more of the following SpA features: Psoriasis Crohn’s disease or ulcerative colitis Preceding infection Uveitis HLA-B27 Sacroiliitis on imaging (radiographs or MRI) OR two or more of the following SpA features: Arthritis Enthesitis Dactylitis Inflammatory back pain ever Family history for SpA

_aSensitivity 78%, specificity 82%.

_bPeripheral arthritis, usually predominantly lower limb and/or asymmetric. The various SpA features are as defined in Table 163-1. Preceding infection refers to preceding gastrointestinal or urogenital infection.

Source: Rudawaleit M et al: The assessment of spondyloarthritis international society classification criteria for peripheral spondyloarthritis and for spondyloarthritis in general. Ann Rheum Dis 70:25, 2011. Adapted by permission from BMJ Publishing Group Limited.

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