Rheumatoid Arthritis vs Psoriatic Arthritis
Rheumatoid Arthritis and Psoriatic Arthritis are easy to mix up on the boards. Here's a side-by-side comparison — presentation, workup, imaging, and first-line treatment — drawn from our full outlines.
Rheumatoid Arthritis vs Psoriatic Arthritis at a glance
- Rheumatoid Arthritis: Chronic symmetric inflammatory polyarthritis with autoantibodies and erosive joint damage.
- Psoriatic Arthritis: Seronegative inflammatory arthritis associated with psoriasis; classic features include dactylitis, enthesitis, and DIP involvement.
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Side-by-side comparison
| Feature | Rheumatoid Arthritis | Psoriatic Arthritis |
|---|---|---|
| At a glance | Chronic symmetric inflammatory polyarthritis with autoantibodies and erosive joint damage. | Seronegative inflammatory arthritis associated with psoriasis; classic features include dactylitis, enthesitis, and DIP involvement. |
| Classic presentation | Symmetric MCP/PIP/wrist swelling with positive MCP/MTP squeeze test, plus rheumatoid nodules in seropositive disease.; Insidious symmetric polyarthritis of small joints (MCP, PIP, wrists, MTPs); Morning stiffness lasting >1 hour, improving with activity; Fatigue, low-grade fever, weight loss; Hand weakness and difficulty with grip;… | Joint pain with morning stiffness >30 minutes, improving with activity; Asymmetric oligoarthritis (most common pattern), DIP-predominant, polyarticular RA-like pattern, arthritis mutilans, or axial pattern; Dactylitis — sausage digit from combined tenosynovitis and arthritis; Enthesitis — Achilles, plantar fascia, lateral epicondyle;… |
| Workup / key labs | 2010 ACR/EULAR classification: score ≥6 of 10 across (a) joint involvement, (b) serology (RF/anti-CCP), (c) acute-phase reactants, and (d) symptom duration ≥6 weeks classifies as RA.; RF and anti-CCP (anti-CCP higher specificity; both predict erosive disease); ESR and CRP (elevated, used to track activity); CBC (normocytic anemia of… | CASPAR classification criteria: inflammatory articular disease (joint, spine, or entheseal) plus ≥3 points from psoriasis, nail changes, RF-negative, dactylitis history, and juxta-articular new bone formation.; RF and anti-CCP — typically NEGATIVE (some patients have low-titer positivity); ESR, CRP — variably elevated; can be normal in… |
| Imaging | Plain radiographs of hands and feet — periarticular osteopenia, symmetric joint-space narrowing, marginal erosions (MTPs often earliest); Ultrasound or MRI — more sensitive for early synovitis and erosions before plain-film changes; Cervical spine flexion/extension films in established disease to assess atlantoaxial subluxation prior to… | Plain radiographs — 'pencil-in-cup' deformity at DIPs, periostitis, fluffy new bone formation, marginal erosions, ankylosis, asymmetric sacroiliitis, non-marginal syndesmophytes (large, asymmetric, parasyndesmophytes); Ultrasound or MRI — detects enthesitis, synovitis, dactylitis, and bone marrow edema before radiographic change |
| First-line treatment | Early DMARD therapy within 3 months of diagnosis — methotrexate is anchor drug; start 10-15 mg PO/SC weekly with folic acid 1 mg daily; Conventional DMARDs — methotrexate, hydroxychloroquine, sulfasalazine, leflunomide (often combined as 'triple therapy'); Bridging low-dose prednisone (≤10 mg/day) until DMARD takes effect; taper as… | Mild peripheral disease: NSAIDs — naproxen, ibuprofen, meloxicam — plus intra-articular steroid injections; Conventional DMARDs for peripheral arthritis: methotrexate, sulfasalazine, leflunomide (also helps skin disease, especially MTX); Treat skin disease in parallel with topical agents and phototherapy as needed |
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