Rheumatoid Arthritis Diagnosis and Treatment
Diagnose rheumatoid arthritis using the 2010 ACR/EULAR classification criteria requiring a score ≥6/10 points based on joint involvement, serology, acute phase reactants, and symptom duration, then immediately initiate methotrexate as first-line disease-modifying therapy to prevent irreversible joint damage and disability. 1
Diagnostic Criteria
Apply the 2010 ACR/EULAR scoring system to any patient with at least one joint showing definite clinical synovitis not better explained by another disease. 1
Scoring Algorithm (≥6/10 points = definite RA):
Joint Involvement (0-5 points): 1
- 1 large joint = 0 points
- 2-10 large joints = 1 point
- 1-3 small joints (with or without large joints) = 2 points
- 4-10 small joints (with or without large joints) = 3 points
10 joints including ≥1 small joint = 5 points
Serology (0-3 points): 1
- Negative RF and negative ACPA = 0 points
- Low positive RF or low positive ACPA = 2 points
- High positive RF or high positive ACPA = 3 points
Acute Phase Reactants (0-1 point): 1
- Normal CRP and normal ESR = 0 points
- Abnormal CRP or abnormal ESR = 1 point
Symptom Duration (0-1 point): 1
- <6 weeks = 0 points
- ≥6 weeks = 1 point
Clinical Features to Identify
Look for symmetric polyarthritis affecting small joints, particularly metacarpophalangeal joints, proximal interphalangeal joints, wrists, and metatarsophalangeal joints. 1, 2 Morning stiffness lasting ≥1 hour is characteristic. 1 The distal interphalangeal joints are typically spared. 3
For example, a patient with early-morning stiffness, a swollen wrist joint, and strongly positive ACPA results for 6 weeks (or less with abnormal CRP) fulfills criteria for RA and requires immediate disease-modifying therapy. 1
Laboratory Assessment
Order ACPA testing (90% specificity, 60% sensitivity) and rheumatoid factor (70% specificity, similar sensitivity to ACPA). 1 ACPA is more specific than RF and should be prioritized. 1
Measure CRP rather than ESR because CRP is more reliable, simpler, and not age-dependent. 1 Measuring both acute-phase reactants offers no additional clinical value. 1
Critical Diagnostic Pitfalls
Do not delay treatment waiting for positive serology—seronegative RA accounts for 20-30% of cases and has similar prognosis. 3 Negative RF does not exclude RA. 3
Do not dismiss the diagnosis based on normal ESR/CRP—acute phase reactants can be normal even in active disease. 3 They are poor predictors of RA. 3
Consider advanced imaging (ultrasound or MRI) when clinical suspicion is high but ACR/EULAR score is <6/10. 3 Ultrasound is superior to clinical examination for detecting synovitis that predicts disease progression. 3 MRI is more sensitive than ultrasound in early stages and can detect bone marrow edema, the best single predictor of future disease progression. 3
Treatment Strategy
First-Line Therapy
Initiate methotrexate immediately upon diagnosis as the first-line disease-modifying antirheumatic drug (DMARD). 4, 5, 6, 7 Prescribe methotrexate at an optimal dose of 25 mg weekly in combination with glucocorticoids. 6 This regimen achieves remission or low disease activity in 40-50% of patients. 6
For patients with contraindications to methotrexate, use leflunomide or sulfasalazine as first-line alternatives. 4
Add short-term glucocorticoids when initiating or changing conventional synthetic DMARDs, but taper as rapidly as clinically feasible. 4
Treatment Target and Monitoring
The treatment target is sustained remission or low disease activity, which must be achieved within 6 months. 4, 6 Early treatment with methotrexate plus glucocorticoids prevents irreversible joint damage in up to 90% of patients. 6
Monitor disease activity every 1-3 months using composite measures: DAS28, SDAI, or CDAI. 1, 4 The SDAI and CDAI are preferred because they don't require complicated calculations, and CDAI doesn't require acute-phase reactant measurement. 1
If no improvement by 3 months or target not reached by 6 months, adjust therapy immediately. 4, 6
Escalation Strategy
If inadequate response after 3 months of methotrexate, add a biologic DMARD (TNF inhibitor such as adalimumab, etanercept, or infliximab) or Janus kinase inhibitor in combination with methotrexate. 8, 6, 9 Sequential application of these targeted therapies allows up to 75% of patients to reach the treatment target over time. 6
For difficult-to-treat RA (failure of ≥2 biologic/targeted synthetic DMARDs with different mechanisms after failing conventional synthetic DMARD), consider alternative biologic agents including IL-6 inhibitors, costimulation blockers (abatacept), or anti-CD20 antibodies (rituximab). 4, 9
Pre-Treatment Screening
Screen all patients for hepatitis B, hepatitis C, and tuberculosis before starting biologic agents. 3, 7 Use methotrexate with caution in patients with hematologic abnormalities or active infections. 3
Long-Term Management
Obtain baseline bilateral hand, wrist, and foot X-rays to monitor structural damage progression. 3 Erosions predict disease persistence and progression. 3
Continue NSAIDs and low-dose steroids as needed for symptom control, but recognize these do not prevent joint damage. 5, 9 The primary goal is disease remission through DMARDs, not just symptom management. 3, 6
Refer patients to rheumatology within 1-2 weeks of suspected diagnosis to enable early aggressive therapy. 1 Early diagnosis and treatment can avert or substantially slow joint damage progression in up to 90% of patients. 6