Tests Needed to Follow Rheumatoid Arthritis Patients
Follow rheumatoid arthritis patients with composite disease activity measures that include joint counts every 1-3 months during active disease, using validated tools such as DAS28, CDAI, or SDAI, along with regular monitoring of inflammatory markers (ESR or CRP) and routine safety laboratory tests (complete blood count, liver enzymes, and creatinine) at least monthly for the first 3 months, then every 4-12 weeks thereafter. 1, 2
Disease Activity Monitoring
The cornerstone of RA follow-up is regular assessment using composite disease activity measures rather than relying on individual laboratory tests alone. The 2016 treat-to-target recommendations emphasize that follow-up examinations must employ composite measures that include joint counts 1.
Recommended Composite Measures
The American College of Rheumatology identifies six validated tools for point-of-care disease activity measurement 2:
Provider-based measures:
- DAS28 (using ESR or CRP) - includes 28 joint count, inflammatory marker, and patient global assessment
- CDAI (Clinical Disease Activity Index) - includes joint counts and patient/physician assessments, no laboratory required
- SDAI (Simplified Disease Activity Index) - adds CRP to CDAI components
Patient-reported measures:
- RAPID-3, PAS, or PAS-II - can be completed in waiting room without formal joint examination
Frequency of Assessment
- Every 1-3 months during active disease until treatment target is achieved 1
- More frequent monitoring allows for timely treatment adjustments to reach remission or low disease activity
Laboratory Monitoring
Inflammatory Markers
While composite measures are essential, ESR and CRP provide objective inflammatory data and are incorporated into DAS28 and SDAI 2. However, recognize that approximately 40% of RA patients have normal inflammatory markers even at presentation, so these cannot be used in isolation 3, 4.
Safety Monitoring for DMARD Therapy
Mandatory tests for patients on methotrexate or other DMARDs 5:
- Complete blood count - monitor for cytopenias
- Serum transaminases (liver enzymes) - detect hepatotoxicity
- Serum creatinine with creatinine clearance calculation - assess renal function
Monitoring schedule:
- At least monthly for the first 3 months of therapy
- Then every 4-12 weeks thereafter 5
Baseline Testing Before Starting DMARDs
Before initiating methotrexate or other DMARDs 5:
- Complete blood count
- Liver enzymes
- Creatinine with creatinine clearance
- Chest radiograph
- Hepatitis B and C serologies
- Serum albumin
- If respiratory history/symptoms: pulmonary function tests with DLCO
Critical Pitfalls to Avoid
Do not rely solely on laboratory tests for disease activity assessment. Patient-reported functional status (measured by questionnaires) is actually more predictive of severe long-term outcomes like work disability and mortality than ESR or CRP 3. A patient questionnaire is abnormal in 89% of RA patients at presentation, making it more sensitive than inflammatory markers 3.
Do not use rheumatoid factor or anti-CCP antibodies for disease monitoring. These are diagnostic tests, not monitoring tools. More than 30% of RA patients are seronegative 4, and antibody levels do not reliably track with disease activity.
Do not skip composite measures in favor of just checking labs. The evidence strongly supports that composite disease activity scores that include joint examination are superior to laboratory tests alone for guiding treatment decisions 1, 2.
Practical Implementation
For busy clinical practices, CDAI offers an excellent balance - it includes formal joint assessment but requires no laboratory testing, making it efficient while maintaining validity 2. For practices with limited time for joint counts, RAPID-3 can be completed by patients independently and correlates well with more complex measures 2.
The treat-to-target approach requires documented disease activity scores at each visit to determine if treatment intensification is needed, with the goal of achieving remission or at minimum low disease activity 1, 6.