Management of Ankylosing Spondylitis: Immunopathogenesis and Treatment Approach
Optimal Management Strategy
Optimal management of ankylosing spondylitis requires a combination of non-pharmacological and pharmacological treatments that are complementary and both essential throughout the disease course. 1
Disease Monitoring Framework
Monitor disease activity using the ASAS core set every 2-6 months based on symptoms and treatment intensity. 1, 2
Key Monitoring Parameters:
- Physical function: BASFI or Dougados Functional Index 1
- Pain assessment: VAS for spine pain at night and during day 1
- Spinal mobility: Chest expansion, modified Schober test, occiput-to-wall distance, BASMI 1
- Morning stiffness duration 1
- Peripheral joints and entheses: Swollen joint count and painful entheses assessment 1
- Acute phase reactants: ESR 1
- Imaging: AP and lateral lumbar spine x-ray, lateral cervical spine, AP pelvis (SI joints and hips) 1
Radiographic monitoring is not needed more frequently than every 2 years, though syndesmophytes can develop within 6 months in rapidly progressing cases. 1
Non-Pharmacological Treatment (Foundation Throughout Disease Course)
Patient education and regular exercise are mandatory cornerstone treatments with Level Ib evidence supporting their use. 1, 3, 2
Exercise and Physical Therapy:
- Home exercise programs improve function in the short term compared to no intervention 1
- Group physical therapy shows superior patient global assessment outcomes compared to home exercise alone 1, 2
- Focus on gentle isometric muscle strengthening that minimizes joint movement 3
- Spa therapy provides cost-effective benefits for physical functioning over 3 months 1
Patient Education:
- Education and behavioral therapy improve motivation, reduce anxiety, and are cost-effective over 12 months 1
- Patient associations and self-help groups should be considered 1
Pharmacological Treatment Algorithm
First-Line: NSAIDs
NSAIDs are the first-line drug treatment for all patients with pain and stiffness, with Level Ib evidence showing improvement in spinal pain, peripheral joint pain, and function over 6 weeks. 1, 3, 2
Continuous NSAID treatment is preferred for patients with persistent active symptomatic disease. 2
NSAID Selection Based on GI Risk:
- Standard GI risk: Any NSAID (coxibs are equally effective) 1
- Increased GI risk: Either non-selective NSAID plus gastroprotective agent OR selective COX-2 inhibitor 1, 3, 2
Common pitfall: Switching NSAIDs prematurely—ensure adequate dosage and duration before declaring treatment failure. 4
Second-Line: TNF Inhibitors
Anti-TNF treatment should be initiated in patients with persistently high disease activity despite adequate NSAID therapy, with Level Ib evidence supporting large treatment effects. 1, 3, 5, 6
TNF Inhibitor Indications:
- Persistent high disease activity after adequate NSAID trial 3, 7
- Axial disease with symptom duration exceeding 3 months 6
- Younger patients with shorter disease duration and less functional disability respond better 1
Specific TNF Inhibitor Dosing (Infliximab):
For ankylosing spondylitis: 5 mg/kg IV at weeks 0,2, and 6, then every 6 weeks for maintenance. 8
TNF inhibitors improve spinal pain, function, inflammatory biomarkers, and spinal inflammation on MRI over at least 6 months. 1, 5, 6
Role of Conventional DMARDs
Sulfasalazine has proven effectiveness primarily in patients with peripheral joint involvement, high disease activity, or short disease duration. 4, 9
There is insufficient evidence to support routine use of methotrexate or other conventional DMARDs for axial disease. 1, 6, 10
Adjuvant Therapies
Analgesics (paracetamol, opioids) may be used for pain control when NSAIDs are insufficient, contraindicated, or poorly tolerated. 3, 4
Local corticosteroid injections directed to sites of musculoskeletal inflammation (enthesopathy, peripheral joints) should be considered. 3, 4, 9
Sacroiliac joint pain may be managed with corticosteroid injection under fluoroscopic or CT guidance. 4
Surgical Management
Hip Arthroplasty:
Total hip arthroplasty should be considered in patients with refractory pain or disability and radiographic evidence of structural hip damage, independent of age. 3, 2
Spinal Surgery:
Corrective osteotomy and stabilization procedures are valuable in selected patients with:
- Fixed kyphotic deformity requiring restoration of balance and horizontal vision 3, 2
- Segmental instability from spinal pseudarthrosis or Andersson lesion 3
Spinal surgery has Level IV evidence supporting excellent functional restoration in appropriately selected patients. 1
Management of Extra-Articular Manifestations
Extra-articular manifestations (acute uveitis, conjunctivitis, carditis, inflammatory bowel disease, vascularitis) require collaborative management with respective specialists. 1, 7
For patients with concurrent inflammatory bowel disease, monoclonal antibody anti-TNF agents are strongly preferred over etanercept. 7
TNF inhibitors can simultaneously treat both AS and vasculitic manifestations when present. 7
Critical Clinical Pitfalls to Avoid
Do not delay TNF inhibitor initiation in patients with persistently high disease activity—younger patients with shorter disease duration have better responses. 1
Do not use conventional DMARDs for isolated axial disease—they lack evidence for efficacy in this setting. 1, 6, 10
Do not perform radiographic monitoring more frequently than every 2 years unless rapid progression is suspected. 1, 2
Do not discontinue non-pharmacological treatments when starting medications—they remain essential throughout the disease course. 1, 2
Recognize that hip involvement is the most important predictor of severe disease and warrants aggressive management. 1