What is the initial treatment approach for patients with psoriatic arthritis?

Initial Treatment Approach for Psoriatic Arthritis

For treatment-naive patients with active psoriatic arthritis, initiate a TNF inhibitor biologic over conventional synthetic DMARDs (methotrexate, sulfasalazine, or leflunomide) as first-line therapy, based on the 2018 ACR/NPF guideline recommendations. 1

Treatment Algorithm Based on Disease Presentation

For Polyarthritis (≥5 joints involved):

• Start with a conventional synthetic DMARD (csDMARD) rapidly, with methotrexate preferred when significant skin involvement is present 1
• Methotrexate should be initiated early in patients with active disease, particularly those with many swollen joints, structural damage with inflammation, elevated ESR/CRP, or clinically relevant extra-articular manifestations 1
• If inadequate response after at least 3 months (with >2 months at standard target dose), escalate to a biologic DMARD (bDMARD), specifically a TNF inhibitor 1

For Oligoarthritis (≤4 joints involved):

• NSAIDs may be used initially to relieve musculoskeletal symptoms, though cardiovascular and gastrointestinal risks must be considered 1, 2
• Consider csDMARD therapy even in oligoarthritis if poor prognostic factors are present: structural damage, high ESR/CRP, dactylitis, or nail involvement 1
• Local corticosteroid injections should be used as adjunctive therapy for inflamed joints 1, 2

Hierarchy of Biologic Selection (when csDMARD fails):

The 2018 ACR/NPF guideline establishes this preference order for treatment-naive patients 1:

1. TNF inhibitor (first choice)
2. IL-17 inhibitor (second choice)
3. IL-12/23 inhibitor (third choice)

When significant skin involvement is present alongside arthritis, IL-17 inhibitors or IL-12/23 inhibitors may be preferred over TNF inhibitors to address both manifestations simultaneously 1

Disease-Specific Manifestations

Enthesitis:

• Mild: NSAIDs and local corticosteroid injections 1, 2
• Resistant: DMARDs in context of co-existing active disease 1
• Severe: TNF inhibitors (infliximab has Level A evidence) 1, 2

Dactylitis:

• Initial: NSAIDs 1
• Many clinicians rapidly progress to injected corticosteroids 1
• Resistant: DMARDs, nearly always with co-existing active disease 1

Axial Disease:

• TNF inhibitors should be considered for predominantly axial disease with active symptoms and insufficient response to NSAIDs 1
• When relevant skin involvement exists, IL-17 inhibitors may be preferred 1
• Traditional oral DMARDs (methotrexate, leflunomide, sulfasalazine) have not shown efficacy for axial manifestations and should not be used for this indication 1

Critical Treatment Principles

Treatment must aim for remission or, alternatively, low disease activity through regular assessment and appropriate therapy adjustment 1

Common Pitfalls to Avoid:

• Do not use gold salts, chloroquine, or hydroxychloroquine in PsA due to potential to worsen psoriasis 1
• Systemic corticosteroids are not recommended for chronic use due to risk of post-steroid psoriasis flare, though they may be used cautiously at the lowest effective dose for short-term management 1
• Do not delay DMARD initiation in patients with polyarthritis or poor prognostic factors—early treatment improves long-term outcomes 1

Definition of DMARD Failure:

A patient has failed a DMARD when 1:

• Treatment for >3 months, with >2 months at standard target dose, without adequate response
• OR treatment withdrawn before 2 months due to intolerance/toxicity
• Patients who do not respond by Week 14 are unlikely to respond with continued dosing 3

Specific Drug Dosing for Initial Therapy

TNF Inhibitors (when indicated):

Infliximab: 5 mg/kg IV at weeks 0,2, and 6, then every 8 weeks for maintenance 3

• Can be used with or without methotrexate for psoriatic arthritis 3
• For patients who respond then lose response, consider increasing to 10 mg/kg 3

The 2020 EULAR recommendations emphasize that rheumatologists should primarily manage musculoskeletal manifestations, with dermatologist collaboration when clinically significant skin involvement is present 1. This multidisciplinary approach ensures comprehensive disease management while maintaining clear treatment responsibility.