Rheumatoid Arhritis for the Physician Assistant Licensing Exam
Overview of Rheumatoid Arthritis (RA)
- Definition: RA is a chronic, systemic autoimmune disease characterized by inflammation of the synovial joints, leading to joint destruction, deformity, and disability.
Pathophysiology
- Autoimmune Mechanisms: Immune system attacks the synovium, causing chronic inflammation and pannus formation (abnormal layer of fibrovascular tissue).
- Cytokines and Inflammatory Mediators: TNF-alpha, IL-1, and IL-6 play key roles in joint inflammation and destruction.
- Joint Damage: Persistent inflammation leads to cartilage and bone erosion, as well as joint deformity.
Risk Factors
- Genetic Predisposition: HLA-DR4 gene association and family history increase risk.
- Gender: More common in women, with a peak incidence in middle age.
- Smoking: Strongly associated with increased risk and severity of RA.
- Environmental Factors: Potential triggers include infections and hormonal changes.
Symptoms and Signs
- Symmetric Joint Involvement: Small joints of the hands (MCP, PIP), wrists, and feet are commonly affected; large joints may also be involved.
- Morning Stiffness: Lasts >1 hour and improves with activity (unlike osteoarthritis).
- Joint Swelling and Pain: Tenderness, warmth, and swelling are typical, with decreased range of motion.
- Systemic Symptoms: Fatigue, low-grade fever, and weight loss may be present.
- Rheumatoid Nodules: Firm, subcutaneous nodules, often found over extensor surfaces.
Extra-Articular Manifestations
- Pulmonary: Interstitial lung disease, pleuritis, and rheumatoid nodules.
- Cardiovascular: Pericarditis, increased risk of coronary artery disease.
- Ocular: Episcleritis, scleritis, and Sjögren's syndrome (secondary dry eyes and mouth).
- Hematologic: Anemia of chronic disease, thrombocytosis, and Felty's syndrome (RA, splenomegaly, and neutropenia).
Diagnosis
- Clinical Presentation: Symmetric joint involvement, morning stiffness, and extra-articular symptoms.
- Laboratory Studies:
- Rheumatoid Factor (RF): Positive in ~70-80% of cases but not specific to RA.
- Anti-Cyclic Citrullinated Peptide (Anti-CCP): Highly specific for RA and may predict disease severity.
- ESR and CRP: Elevated in active disease.
- Imaging:
- X-rays: Early findings include soft tissue swelling and periarticular osteopenia; later, joint space narrowing and erosions develop.
- Ultrasound/MRI: Useful for detecting early joint inflammation and damage.
Management
- Non-Pharmacologic:
- Exercise and Physical Therapy: Joint protection, range-of-motion exercises, and strengthening.
- Occupational Therapy: Use of assistive devices and adaptive strategies.
- Pharmacologic Treatment:
- NSAIDs: For symptom relief but do not alter disease progression.
- Corticosteroids: Low-dose oral or intra-articular injections for acute symptom control.
- Disease-Modifying Antirheumatic Drugs (DMARDs): Methotrexate is the first-line DMARD; others include leflunomide, sulfasalazine, and hydroxychloroquine.
- Biologic Agents: TNF inhibitors (e.g., etanercept, infliximab), IL-6 inhibitors (e.g., tocilizumab), and others for patients who do not respond to conventional DMARDs.
- Surgical Options: Joint replacement or synovectomy in severe, refractory cases.
Essential Points
- Early Diagnosis and Treatment: Aggressive treatment with DMARDs can slow disease progression and prevent joint damage.
- Multisystem Disease: RA is not just a joint disease; look for extra-articular manifestations in the pulmonary, cardiovascular, and ocular systems.
- Treatment Goal: Achieve and maintain remission or low disease activity to preserve joint function and improve quality of life.