How is CDAI calculated?

CDAI = TJC28 + SJC28 + PGA (0-10 cm VAS) + EGA (0-10 cm evaluator global); range 0-76; remission ≤2.8; LDA >2.8-≤10; moderate >10-≤22; high >22; no lab required - suitable for point-of-care and resource-limited settings.

What is the advantage of CDAI over DAS28?

CDAI requires no laboratory values (no CRP or ESR), making it immediately available at each visit; highly correlated with DAS28 and SDAI; simplicity encourages consistent use; particularly useful for monitoring between lab draws.

How does SDAI differ from CDAI?

SDAI (Simplified Disease Activity Index) = TJC28 + SJC28 + PGA + EGA + CRP (mg/dL); SDAI ≤3.3 = remission; SDAI is similar to CDAI but adds a CRP component; both have equivalent clinical validity in most settings.

What CDAI remission rate is achievable with modern biologic DMARDs?

Approximately 25-35% of RA patients on biologic therapy achieve CDAI remission (≤2.8) at 12 months; treat-to-target studies with tight monitoring show 30-50% remission rates at 2 years; longer disease duration reduces remission likelihood.

Is CDAI appropriate for assessing biologic and JAK inhibitor response?

Yes, CDAI is used in T2T protocols for all DMARD therapies; JAK inhibitors (upadacitinib, baricitinib) show particularly rapid CDAI response (CDAI remission at 12 weeks in 30-40% vs 15% for methotrexate alone).

Clinical Disease Activity Index (CDAI) for Rheumatoid Arthritis

Calculates CDAI for rapid bedside RA assessment without laboratory values, integrating tender joint count, swollen joint count, patient global assessment, and evaluator global assessment.

Weight

Height

Clinical Guidance

BMI is a screening measure of body size, not a direct measure of body fat. The standard WHO categories are underweight (<18.5), normal (18.5–24.9), overweight (25–29.9), and obese (≥30).

BMI can overestimate body fat in athletes with high muscle mass and underestimate it in older adults with low muscle mass. Interpret it alongside waist circumference and clinical context rather than as a standalone diagnosis.

⚕ Clinical Disclaimer: These calculators are for educational and reference purposes only. Always verify results with qualified clinical judgment and current clinical guidelines. Do not use as a sole basis for medical decisions.

How to Use

Enter the values for the patient or scenario you are assessing. Calculates CDAI for rapid bedside RA assessment without laboratory values, integrating tender joint count, swollen joint count, patient global assessment, and evaluator global assessment. Use the cdai ra score result to inform your clinical assessment.

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