Treatment for Psoriatic Arthritis
Start with NSAIDs for mild disease, rapidly initiate DMARDs (methotrexate, sulfasalazine, or leflunomide) for moderate-to-severe disease, and escalate to TNF inhibitors after failing at least one DMARD trial of >3 months with >2 months at target dose. 1
Initial Treatment Based on Disease Severity
Mild Peripheral Arthritis
- Use NSAIDs as first-line therapy for symptom control 1
- Add intra-articular glucocorticoid injections for persistently inflamed joints, but never inject through psoriatic plaques due to infection risk 1, 2
- Avoid systemic corticosteroids for chronic use due to risk of post-steroid psoriasis flare 2
Moderate-to-Severe Peripheral Arthritis
- Initiate DMARDs rapidly rather than waiting for NSAID failure 1, 2
- Methotrexate 15-25 mg weekly with folic acid is the preferred first-line DMARD when significant skin involvement coexists (Level B evidence) 1, 2
- Sulfasalazine or leflunomide are alternative first-line DMARDs with Level A evidence for peripheral arthritis 1, 2
- In patients with concomitant diabetes, use sulfasalazine or leflunomide instead of methotrexate due to higher risk of fatty liver disease and hepatotoxicity 1
Escalation to Biologic Therapy
When to Escalate
- Progress to TNF inhibitors after failing at least one DMARD trial (defined as >3 months treatment with >2 months at standard target dose) 1, 2
- Consider TNF inhibitors earlier in patients with poor prognostic factors: polyarticular disease, elevated ESR, existing joint damage, dactylitis, nail involvement, or diminished quality of life 1, 2
TNF Inhibitor Selection
- All three TNF inhibitors (etanercept, infliximab, adalimumab) are equally effective for peripheral arthritis and inhibiting radiographic progression (Level A evidence) 1, 2
- Etanercept dosing: 50 mg weekly for rheumatoid arthritis, ankylosing spondylitis, and psoriatic arthritis 3
- TNF inhibitors can be used as monotherapy or combined with methotrexate at reduced doses (10-15 mg weekly) 1
Special Clinical Scenarios
Axial Disease
- Start with NSAIDs and physiotherapy 1
- Progress to TNF inhibitors if inadequate response 1
- Consider IL-17 inhibitors if significant skin involvement 1
Enthesitis and Dactylitis
- Start with NSAIDs and local measures 1
- Progress to DMARDs for resistant cases 1
- Consider TNF inhibitors for severe or refractory cases, as dactylitis indicates disease severity warranting aggressive treatment 1, 2
Latent Tuberculosis
- Screen all patients for tuberculosis before starting biologics or immunosuppressive therapy using tuberculin skin test (induration ≥5 mm is positive) 4
- Start isoniazid 300 mg daily for 9 months at least 1 month before biologic therapy when possible 4
- Use conventional DMARDs (methotrexate, sulfasalazine, or leflunomide) while awaiting TB clearance 4
- Perform annual tuberculosis screening for patients on biologics 4
Treatment Goals and Monitoring
Target
- Aim for remission or low disease activity through regular disease activity assessment 1, 2
- Primary goal is maximizing quality of life through symptom control, prevention of structural damage, normalization of function, and social participation 2
Defining Treatment Failure
- DMARD failure: inadequate response after >3 months treatment with >2 months at standard target dose 2
- Evidence of progression of joint damage on radiographs indicates inadequate response 2
Critical Safety Warnings
TNF Inhibitors
- Increased risk of serious infections including tuberculosis reactivation, invasive fungal infections, and opportunistic infections 3
- Lymphoma and other malignancies reported in children and adolescents treated with TNF-blockers 3
- Discontinue if patient develops serious infection or sepsis 3