Ankylosing Spondylitis

Ankylosing Spondylitis is a topic covered in the Harrison's Manual of Medicine.

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DEFINITION

Ankylosing spondylitis (AS) belongs to the family of spondyloarthritides that also includes reactive arthritis (Chap. 162), psoriatic arthritis (Chap. 161), enteropathic arthritis (Chap. 165) juvenile-onset spondyloarthritis, and undifferentiated spondyloarthritis. Classification criteria based on their main clinical features of axial spondyloarthritis (Table 160-1) and peripheral spondyloarthritis (Table 160-2) have been developed that aide in early identification. AS is a chronic and progressive inflammatory disease of the axial skeleton with sacroiliitis (usually bilateral) as its hallmark. Peripheral joints and extra-articular structures may also be affected. Most frequently presents in second or third decade more commonly in men; strong association with histocompatibility antigen HLA-B27.

TABLE 160-1: ASAS CRITERIA FOR CLASSIFICATION OF AXIAL SPONDYLOARTHRITIS (TO BE APPLIED FOR PATIENTS WITH BACK PAIN ≥3 MONTHS AND AGE OF ONSET <45 YEARS)a
Sacroiliitis on Imaging Plus or ≥1 SpA FeatureHLA-B27 Plus ≥ 2 Other SpA Features
Sacroiliitis on imagingSpA features

• Active (acute) inflammation on MRI highly suggestive of SpA-associated sacroiliitisb

and/or

• Definite radiographic sacroiliitis according to modified New York criteriac

• Inflammatory back paind

• Arthritise

• Enthesitis (heel)f

• Anterior uveitisg

• Dactylitise

• Psoriasise

• Crohn’s disease or ulcerative colitise

• Good response to NSAIDsh

• Family history of SpAi

• HLA-B27

• Elevated CRPj

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; SpA, spondyloarthritis.
Source: From M Rudwaleit et al: Ann Rheum Dis 68:777, 2009. Copyright 2009, with permission from BMJ Publishing Group Ltd.
TABLE 160-2: ASAS CRITERIA FOR PERIPHERAL SPONDYLOARTHRITISa
Arthritisb

or

plus

Enthesitis
One or more of the following:
  • Uveitis
  • Psoriasis
  • Crohn’s disease or ulcerative colitis
OR two or more of the following:
  • Arthritis
  • Enthesitis
  • Dactylitis
  • Inflammatory back pain ever
  • Family history for SpA
aSensitivity 79.5%, specificity 83.3%.
bPeripheral arthritis, usually predominantly lower limb and/or asymmetric.
Abbreviations: ASAS, Assessment of Spondyloarthritis International Society; SpA, spondyloarthritis.
Source: M Rudawaleit et al: Ann Rheum Dis 70:25, 2011.

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Citation

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TY - ELEC T1 - Ankylosing Spondylitis ID - 623081 Y1 - 2017 PB - Harrison's Manual of Medicine UR - https://harrisons.unboundmedicine.com/harrisons/view/Harrisons-Manual-of-Medicine/623081/all/Ankylosing_Spondylitis ER -