Axial Spondyloarthritis Flashcards
Definition and epidemiology of AxSpA
-A chronic inflammatory disease mainly affecting the spine, and sacroiliac joints
-Prevalence of AxSpA approximately 0.6% in UK population
-May be a history of PsA or inflammatory bowel disease and iritis
=Overlapping immunogenetic basis
-Peak incidence late teens to early 20’s, 45 yrs or younger
-Men affected more commonly than women (3.5:1)
Pathophysiology of AxSpA
-Genetic predisposition
=HLA-B27 – positive in 90% of patients
=Other loci include ERAP, IL-23R, IL-12, IL-12R
-Environmental trigger
=Infectious trigger, alteration in microbiome?
-Increased production of IL-23
-Activation of Th17 cells
-Increased IL-17 and TNF production
-Inflammatory infiltrate of joints and tendons at enthesis
Clinical features of AxSpA
-Inflammatory low back pain with insidious onset
=Night pain and morning stiffness (sacroiliac region sometimes radiating to buttocks, 30 mins+)
=Pain and stiffness improved by exercise
=Good response to NSAID
=3 months, insidious onset
-Large joint arthritis
-Uveitis
-Psoriasis
-Osteoporosis and vertebral fractures
-Aortic regurgitation
-Upper lobe fibrosis
-Enthesitis
-Dactylitis
-RF
=recent genitourinary infection and a family history of spondyloarthritis or psoriasis
Physical examination in AxSpA
-Limited range of spine movements in all directions (lateral flexion)
=Abnormal Schrober’s test (reduced forward flexion): a line is drawn 10 cm above and 5 cm below the back dimples (dimples of Venus). The distance between the two lines should increase by more than 5 cm when the patient bends as far forward as possible
=May be normal in early disease
-Reduced chest expansion
=Normal in early disease
-Anterior Uveitis (acutefully painful red eye with photophobia or blurred vision)
-Aortic regurgitation (very rare)
-Apical fibrosis
-Achilles tendonitis
-AV node block
-Amyloidosis
-Arthritis (peripheral, asymmetric, 25%, more common if female)
-Cauda equina syndrome?
-Fixed flexion deformity in advanced disease
Investigations in AxSpA
-Imaging
=plain X-ray lumbar spine and pelvis: Sacroileitis (subchondral erosions, sclerosis), syndesmophytes, vertebral fractures, may be normal in early disease, squaring of lumbar vertebrae, bamboo spine (late and uncommon)
=MRI: Marrow oedema - more sensitive for early disease, if x-ray negative for sacroiliac involvement but suspicions high
=DEXA: Osteoporosis
-CXR: apical fibrosis
-Routine bloods
=ESR and CRP may be raised but may be normal
-Immunology
=Autoantibodies negative
=HLA B27 positive but not diagnostic (90% patients with AS, 10% normal)
-Spirometry may show restrictive defect (pulmonary fibrosis, kyphosis and ankylosis of the costovertebral joints)
Management of AxSpA
-NSAID
=Trial of at least two NSAID for 2-4 weeks, full dose
-Progress to biologic therapy if inadequate response
-Immunosuppressive therapy
=MTX, Sulfasalazine, Leflunomide for peripheral synovitis
=Not effective for axial disease
=Anti-TNF therapy is persistently high disease activity despite conventional treatments
-Corticosteroids
=Ineffective for axial disease (may worsen osteoporosis)
=Intra-articular steroids for peripheral synovitis
Role of biologics in AxSpA
-Indicated for active disease which has responded inadequately to DMARD
=BASDAI score >4.0
-Licensed treatment options are:
=Anti-TNF therapy
=Secukinumab (IL-17)
-Investigational (unlicensed) drugs
=IL-23 blockers, JAKi)
Non-pharmacological treatment for AxSpA
-Physiotherapy
=Very important in AxSpA (regular exercise like swimming)
=Back exercises to prevent flexion deformity
=Maintain good posture
-Occupational therapy
=May play role in those with peripheral arthritis
-Orthopaedic surgery
=Arthroplasty (especially THR)
=Spinal surgery seldom used (osteotomy, spinal decompression)
Main differential of AxSpA
-Prolapse intervertebral disc = Pain follows nerve root distribution.
-Mechanical back pain = Worse on movement, relieved by rest
Referral criteria for suspected axial spondyloarthritis
If a person has low back pain that started before the age of 45 years and has lasted for longer than 3 months, refer the person to a rheumatologist for a spondyloarthritis assessment if 4 or more of the following additional criteria are also present:
low back pain that started before the age of 35 years (this further increases the likelihood that back pain is due to spondyloarthritis compared with low back pain that started between 35 and 44 years)
waking during the second half of the night because of symptoms
buttock pain
improvement with movement
improvement within 48 hours of taking non-steroidal anti-inflammatory drugs (NSAIDs)
a first-degree relative with spondyloarthritis
current or past arthritis
current or past enthesitis
current or past psoriasis.
If exactly 3 of the additional criteria are present, perform an HLA‑B27 test. If the test is positive, refer the person to a rheumatologist for a spondyloarthritis assessment.
