Among various methods of measuring disease activity in rheumatoid arthritis, we will be discussing Clinical Disease Activity Index (CDAI).
CDAI = TJC(28) + SJC(28) + PGA(10) + EGA(10)
- TJC = Tender Joint Count
- SJC = Swollen Joint Count
- PGA = Patient’s Global Assessment
- EGA = Evaluator’s Global Assessment
Interpretation of CDAI:
| CDAI Score Range | Disease Severity |
|---|---|
| ≤ 2.8 | Remission |
| > 2.8 – 10.0 | Low |
| > 10.0 – 22.0 | Moderate |
| > 22.0 | High |
DMARD naive patients
Low disease activity: Hydroxychloroquine (better tolerated) > Sulfasalazine (less immunosuppressive) > Methotrexate (better dosing flexibility & lower cost) > Leflunomide
Moderate to High disease activity:
- Oral methotrexate ≥ 15 mg/week within 4-6 weeks over oral methotrexate <15 mg/week
- Intolerance: Oral methotrexate > Split dose of oral methotrexate over 24 hours or Switching to weekly subcutaneous methotrexate or increasing folic/folinic acid dose > Switching DMARDs
- Not at target: Oral methotrexate > Subcutaneous methotrexate > Switching or adding DMARDs > Intra-articular steroid alone.
- Target = Low disease activity > Remission
- Corticosteroid: No corticosteroid > Short term corticosteroid (<3 months) > Longer term corticosteroid (≥3 months)
Modification of DMARDs
Not at target: Methotrexate + b/tsDMARD (switching to different class if required) > Methotrexate + Sulfasalazine + Hydroxychloroquine
At target with corticosteroids: DMARDs (addition/switching) > DMARDs + steroid continuation
Remission for ≥6 months: Continuation of all DMARDs at current dose > Dose reduction (maintain therapeutic dose of atleast 1 DMARD) > Gradual discontinuation of Sulfasalazine > Gradual discontinuation of Hydroxychloroquine > Gradual discontinuation of Methotrexate > Gradual discontinuation of b/tsDMARD
Progressive subcutaneous nodules on methotrexate: Switching DMARD > Continuing methotrexate
Reference and further reading: Fraenkel L, Bathon JM, England BR, St Clair EW, Arayssi T, Carandang K, Deane KD, Genovese M, Huston KK, Kerr G, Kremer J, Nakamura MC, Russell LA, Singh JA, Smith BJ, Sparks JA, Venkatachalam S, Weinblatt ME, Al-Gibbawi M, Baker JF, Barbour KE, Barton JL, Cappelli L, Chamseddine F, George M, Johnson SR, Kahale L, Karam BS, Khamis AM, Navarro-Millán I, Mirza R, Schwab P, Singh N, Turgunbaev M, Turner AS, Yaacoub S, Akl EA. 2021 American College of Rheumatology Guideline for the Treatment of Rheumatoid Arthritis. Arthritis Rheumatol. 2021 Jul;73(7):1108-1123. doi: 10.1002/art.41752. Epub 2021 Jun 8. PMID: 34101376.