Psoriatic arthritis (PsA)

• Asymmetric, DIP or spinal arthritis, arthritis mutilans; dactylitis ('sausage' digits); enthesitis; psoriasis, nail pitting and onycholysis.

• Investigations: ESR/CRP, RF and anti-CCP (usually negative), HLA-B27 if axial; X-ray (pencil-in-cup, erosions), ultrasound, MRI for sacroiliitis. CASPAR criteria.

Non-pharmacological management

• Weight reduction, skin care, physiotherapy, stress reduction, stop smoking, limit alcohol.

Pharmacological management

1. NSAIDs – mild arthritis, enthesitis or axial symptoms; not monotherapy for moderate–severe disease.

• A: Ibuprofen (PO) 400–800 mg every 8 hours,

• OR C: diclofenac (PO) 50 mg every 8–12 hours (or diclofenac gel 1% every 6 hours),

• OR A: piroxicam (PO) 20 mg once daily, OR D: meloxicam (PO) 7.5–15 mg once daily,

• OR S: ketoprofen (PO) 75 mg every 8 hours (or ketoprofen gel 2.5% every 6 hours).

• Add a PPI when the risk of NSAID gastrointestinal complications is high.

2. csDMARDs

• S: Methotrexate (PO) 15–25 mg once weekly AND A: folic acid (PO) 5 mg weekly (not on the methotrexate day) (best with skin and nail disease),

• OR D: sulfasalazine (PO) 500 mg every 12 hours, increased by 500 mg weekly to 2–3 g/day in divided doses,

• OR S: leflunomide (PO) 10 mg once daily, increased to 20 mg.

3. Biologic / 4. targeted: S: adalimumab (SC) 40 mg every 2 weeks; S: tofacitinib (PO) 5 mg every 12 hours after biologic failure.

• Avoid oral steroids in active psoriasis (flares).

• Start DMARDs early in erosive disease; monitor with DAPSA, PASI, HAQ-DI.

• Surgery for severe damage: synovectomy, joint replacement, tendon repair, arthrodesis.