What is the recommended diagnosis and treatment approach for a patient presenting with symptoms of spondylitis, including chronic back pain and stiffness?

Diagnosis and Management of Spondylitis

Initial Recognition and Screening

For patients presenting with chronic back pain and stiffness, suspect axial spondyloarthritis (including ankylosing spondylitis) if the pain is inflammatory in nature—characterized by insidious onset before age 45, morning stiffness lasting >30 minutes, improvement with exercise but not rest, alternating buttock pain, and pain worsening at night. 1, 2, 3

Key Clinical Features to Identify

• Inflammatory back pain (IBP) is present in 70-80% of patients and increases the probability of axial spondyloarthritis from 5% to 14% 1, 4
• Look for alternating buttock pain, which is highly characteristic 2, 3
• Assess for good response to NSAIDs within 48 hours—approximately 75% of patients with axial spondyloarthritis show good or very good response to full-dose NSAID therapy 1, 5
• Examine for peripheral manifestations: enthesitis (heel pain, Achilles tendinitis), peripheral arthritis, or dactylitis 1, 4
• Screen for extra-articular manifestations: acute anterior uveitis (most common, occurring in up to 40% of patients), psoriasis, or inflammatory bowel disease 6, 4
• Obtain family history of spondyloarthritis, psoriasis, or inflammatory bowel disease 1, 4

Physical Examination Findings

• Reduced lumbar spine mobility in sagittal and frontal planes (positive Schober test) 1, 6
• Reduced chest expansion relative to age and sex-matched normal values 1
• Limitation of spinal motion 1

Diagnostic Workup

Laboratory Testing

• HLA-B27 testing: Positive in 74-89% of patients; when positive in a patient with chronic back pain, post-test probability increases to 32% 1, 2, 6
• Inflammatory markers (ESR and CRP): Useful but normal in 50% of cases—do not rule out disease based solely on normal inflammatory markers 1, 5, 6
• Complete blood count 5

Critical Pitfall: Do not rule out axial spondyloarthritis based solely on negative HLA-B27 or normal inflammatory markers, as 10% of patients are HLA-B27 negative and 50% have normal inflammatory markers 5

Imaging Strategy

First-line imaging: Plain radiographs of sacroiliac joints (sensitivity 66%, specificity 68% for sacroiliitis) 1, 2, 6

If radiographs are negative or equivocal and clinical suspicion remains high:

• MRI of sacroiliac joints without IV contrast (rating 8/9 "usually appropriate") is the preferred next step 1, 6
• MRI can detect early inflammatory changes before structural damage appears on radiographs 1, 6
• CT of sacroiliac joints without IV contrast (rating 7/9) is an alternative for patients unable to undergo MRI 1

If sacroiliac imaging is negative but inflammatory back pain persists:

• X-ray of the spine (rating 9/9) 1
• MRI spine without IV contrast (rating 8/9) 1

Avoid: Bone scintigraphy, FDG-PET/CT, and ultrasound of sacroiliac joints are not appropriate for diagnosis 1

Referral to Rheumatology

Refer to rheumatology when patients have chronic low back pain (>3 months) starting before age 45 PLUS at least 4 of the following:

• Back pain occurring before age 35 1, 5, 2
• Waking at night to alleviate back pain symptoms 1, 5
• Buttock pain 1, 5
• Improvement in pain with movement or within 2 days of taking an NSAID 1, 5
• First-degree relative with spondyloarthritis 1, 5
• Current or previous arthritis, enthesitis, or psoriasis 1, 5

Also refer if only 3 criteria are met AND HLA-B27 is positive 1

Additional referral triggers:

• Evidence of sacroiliitis on radiographs or MRI 5, 6
• Persistently high disease activity despite 2-4 weeks of optimal NSAID therapy 5
• Difficulties performing activities of daily living despite NSAID treatment 5
• Suspected acute anterior uveitis—requires immediate ophthalmology referral 1, 6

Initial Treatment Approach

First-Line Pharmacologic Management

Start NSAIDs at the lowest effective dose, then titrate to maximum tolerated doses while weighing cardiovascular, gastrointestinal, and renal risks 1, 5, 2

• Continuous NSAID use is preferred over on-demand dosing for patients who respond well and remain symptomatic 5
• If the first NSAID is ineffective after 2-4 weeks, trial a different NSAID before escalating therapy 1, 5
• For patients with gastrointestinal risk factors, consider COX-2 selective NSAIDs or add gastroprotective agents 5
• Approximately 75% of patients show good or very good response within 48 hours of full-dose NSAID therapy 5, 2

Non-Pharmacologic Interventions

All patients must be referred to a specialist for structured exercise programs—these are more beneficial than home exercises alone 1, 5

• Physical therapy should be considered for all patients 5
• Hydrotherapy can be considered for pain management 1, 5
• Smoking cessation is essential, as smoking worsens disease progression 5

Adjunctive Therapies

• Local corticosteroid injections for symptomatic enthesitis or nonprogressive monoarthritis 1
• Sacroiliac joint corticosteroid injection (guided by fluoroscopy or CT) for persistent sacroiliac pain 1, 7
• Short-term oral corticosteroids can be added if NSAIDs are ineffective for peripheral manifestations 1

Critical Pitfall: Do not use conventional DMARDs (methotrexate, sulfasalazine, leflunomide) for purely axial disease—they are ineffective 5. Sulfasalazine may only be considered if peripheral arthritis is present 1, 5

Disease Activity Monitoring

Use the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) to monitor disease activity 1, 2:

• BASDAI >4 (on 0-10 scale) indicates active disease requiring treatment escalation 1
• Assess: fatigue, spinal pain, peripheral joint pain, tenderness, and morning stiffness duration/intensity 1

Additional monitoring parameters (ASAS core set) 1:

• Physical function (BASFI or Dougados functional index)
• Pain (VAS for spine at night and overall spine pain)
• Spinal mobility (chest expansion, modified Schober, occiput-to-wall distance, lateral lumbar flexion)
• Patient global assessment
• Peripheral joints and entheses (swollen joint count, enthesitis score)
• Acute phase reactants (ESR or CRP)

Treatment Escalation (Rheumatology-Directed)

For patients with persistently high disease activity (BASDAI >4) despite adequate NSAID trials and physical therapy, biologic DMARDs become the next treatment step 1, 5

Criteria for Anti-TNF Therapy

Patients must meet ALL of the following 1:

• Active disease for >4 weeks 1
• BASDAI >4 (0-10 scale) AND expert opinion supporting treatment 1
• Adequate therapeutic trials of at least 2 NSAIDs (3 months at maximal recommended dose unless contraindicated) 1
• For patients with peripheral arthritis: insufficient response to at least one local corticosteroid injection if appropriate 1
• For persistent peripheral arthritis: therapeutic trial of sulfasalazine (4 months at standard target dose) 1

Response criteria: BASDAI 50% relative change or absolute change of 20 mm (0-100 scale) at 6-12 weeks 1

Available biologics include TNF inhibitors (etanercept 8, others) and IL-17 inhibitors (secukinumab 9)

Common Diagnostic Pitfalls

• The typical delay between symptom onset and diagnosis is 5-7 years—maintain high clinical suspicion for inflammatory back pain patterns 1, 6
• Plain radiographs may be normal early in disease; MRI is more sensitive for detecting sacroiliitis 5, 6
• Axial spondyloarthritis occurs equally in men and women 1
• Disease can be present even in persons without sacroiliitis on radiography 1
• Do not rule out disease based on a single symptom or test result 1