Rheumatoid Arthritis

Introduction

Rheumatoid arthritis (RA) is a chronic autoimmune disorder primarily affecting the joints. It causes inflammation, pain, and swelling, leading to joint deformity and functional impairment. This guide provides an overview of the key concepts related to RA for usmle step 1 preparation.

Epidemiology

RA is estimated to affect approximately 1% of the global population, with women being more commonly affected than men. The disease typically presents between the ages of 30 and 50, but can occur at any age.

Etiology and Pathogenesis

RA is believed to result from a combination of genetic and environmental factors. The exact cause remains unknown, but several risk factors have been identified, including genetic predisposition (HLA-DRB1 alleles), smoking, and certain infections.

The pathogenesis of RA involves activation of the immune system, leading to chronic synovial inflammation. Autoantibodies, such as rheumatoid factor (RF) and anti-cyclic citrullinated peptide (anti-CCP) antibodies, are commonly found in RA patients.

Clinical Presentation

RA typically presents with symmetric polyarthritis, affecting small and large joints. Common symptoms include joint pain, morning stiffness, swelling, and fatigue. Extra-articular manifestations, such as rheumatoid nodules, vasculitis, and lung involvement, may also be observed.

Diagnosis

The diagnosis of RA is primarily clinical, based on the characteristic presentation and exclusion of other possible causes. Diagnostic criteria, such as the 2010 American College of Rheumatology (ACR)/European League Against Rheumatism (EULAR) criteria, are often used to aid in diagnosis.

Laboratory tests, including RF and anti-CCP antibodies, can support the diagnosis. Imaging studies, such as X-rays and ultrasound, may reveal characteristic joint erosions and synovitis.

Management

The management of RA involves a multidisciplinary approach, including pharmacologic and non-pharmacologic interventions.

Pharmacologic treatment options include nonsteroidal anti-inflammatory drugs (NSAIDs), disease-modifying antirheumatic drugs (DMARDs), such as methotrexate, and biologic agents, such as tumor necrosis factor (TNF) inhibitors. Corticosteroids may be used for short-term symptom relief.

Non-pharmacologic interventions include physical therapy, occupational therapy, and patient education. Regular exercise, joint protection techniques, and assistive devices can help improve function and quality of life.

Prognosis

RA is a chronic condition with a variable prognosis. Early diagnosis and aggressive management have been shown to improve outcomes. However, RA can lead to joint destruction, disability, and systemic complications if left untreated or poorly controlled.

Conclusion

Rheumatoid arthritis is a chronic autoimmune disorder characterized by joint inflammation and deformity. It has a significant impact on patients' quality of life. Understanding the epidemiology, etiology, pathogenesis, clinical presentation, diagnosis, and management of RA is crucial for medical professionals preparing for the USMLE Step 1 exam.