What are the typical presentation and treatment options for psoriatic arthritis?

Psoriatic Arthritis: Presentation and Treatment Options

Psoriatic arthritis (PsA) is a chronic inflammatory musculoskeletal disease associated with psoriasis, manifesting most commonly with peripheral arthritis, dactylitis, enthesitis, and spondylitis, requiring early identification and treatment to prevent permanent joint damage and disability. 1

Clinical Presentation

Joint Manifestations

• Peripheral arthritis patterns:

  • Asymmetric oligoarthritis (≤4 joints)
  • Symmetric polyarthritis (≥5 joints)
  • Distal interphalangeal joint involvement (characteristic)
  • Arthritis mutilans (severe, destructive form)

• Axial involvement:

  • Occurs in 25-70% of PsA patients 2
  • Usually presents with inflammatory back pain
  • Often occurs together with peripheral arthritis
  • May show radiographic evidence of asymmetric sacroiliitis

• Distinctive features:

  • Dactylitis ("sausage digit"): Combination of enthesitis and synovitis affecting an entire digit 1
  • Enthesitis: Inflammation at insertion sites of tendons, ligaments, or joint capsules into bone
    • Common sites: Achilles tendon insertion, plantar fascia, pelvic and spinal ligaments 1

Skin and Nail Manifestations

• Psoriasis precedes arthritis in 80% of cases 3
• Skin and joint symptoms present simultaneously in some patients
• Arthritis precedes skin symptoms in 10-15% of cases 1
• Nail involvement in 80-90% of PsA patients 1
  • Pitting, onycholysis, dystrophy

Systemic Features

• Morning stiffness lasting >30 minutes (key diagnostic clue) 1
• Fatigue
• Reduced quality of life and functional capacity

Epidemiology and Natural History

• Affects men and women equally 1
• Prevalence: 1-2 per 1,000 in general population 1
• Annual incidence of PsA in psoriasis patients: 2.7% 1
• Initially presents as oligoarticular and mild disease
• Becomes polyarticular over time
• Severe disease develops in at least 20% of patients 4
• Associated with increased mortality from cardiovascular disease 5

Treatment Approach

Initial Assessment and Treatment Goals

• Primary treatment objectives:
  • Maximize health-related quality of life
  • Control symptoms
  • Prevent structural damage
  • Normalize function and social participation 6

Pharmacologic Treatment Algorithm

1. First-line therapy:

   • NSAIDs for mild peripheral joint involvement
     • Should provide relief within weeks
     • Not effective for skin manifestations
     • Should not be the only therapy beyond 3 months if active disease persists 6
   • Intra-articular glucocorticoid injections for localized disease

2. Second-line therapy (if NSAIDs inadequate):

   • Conventional synthetic DMARDs (csDMARDs):
     • Methotrexate (15-25 mg/week): Preferred for patients with both skin and joint involvement 6
     • Alternatives: Leflunomide, sulfasalazine, cyclosporine
     • Note: csDMARDs are not effective for axial manifestations 6

3. Third-line therapy (if csDMARDs inadequate):

   • Biologic DMARDs:
     • TNF inhibitors (etanercept, adalimumab, infliximab, golimumab, certolizumab): Effective for both skin and joint manifestations 6, 7
     • IL-17 inhibitors (secukinumab, ixekizumab): Particularly effective for significant skin involvement 6
     • IL-12/23 inhibitors (ustekinumab): Consider for concomitant inflammatory bowel disease 6

4. Fourth-line therapy:

   • JAK inhibitors (tofacitinib): For inadequate response to at least one csDMARD and one biologic 6
   • PDE4 inhibitors (apremilast): For mild disease with inadequate response to csDMARDs 6

Treatment Based on Disease Pattern

• Polyarticular disease:

  • Rapidly initiate csDMARD, preferably methotrexate 6

• Oligoarticular disease:

  • Consider csDMARD if poor prognostic factors present 6

• Axial involvement:

  • NSAIDs and physiotherapy as first-line for mild to moderate disease
  • TNF inhibitors for moderate to severe axial disease 6

• Predominant enthesitis:

  • NSAIDs as first-line therapy
  • For severe enthesitis unresponsive to NSAIDs, TNF inhibitors should be considered 1

• Dactylitis:

  • Local steroid injections
  • If unresponsive, systemic therapy as for peripheral arthritis

Monitoring and Treatment Failure

• Regular monitoring using validated measures:

  • 28-joint Disease Activity Score (DAS28)
  • American College of Rheumatology (ACR) response criteria 6

• DMARD failure defined as:

  • Treatment for >3 months with >2 months at standard target dose without adequate response
  • Intolerance/toxicity leading to withdrawal 6

• Consider treatment failure if:

  • No acceptable clinical improvement after appropriate duration of therapy
  • Evidence of progression of joint damage on radiographs 6

Special Considerations

• Screening for latent tuberculosis before initiating anti-TNF treatment 6
• TNF inhibitors carry risks of serious infections and malignancies 6
• Cyclosporine should be limited to less than 12 consecutive months due to cumulative toxicity 6

Prognosis

• Without treatment, PsA can lead to persistent inflammation, progressive joint damage, severe physical limitations, and disability 1
• Early identification and treatment are crucial for improving long-term outcomes 1
• Up to 20% of patients develop extremely destructive and disfiguring forms of the disease 8

Remember that early diagnosis and treatment are essential to prevent joint damage and disability in patients with PsA. The heterogeneous presentation requires careful assessment of all musculoskeletal and skin manifestations to guide appropriate therapy.