Elements of the Simplified Disease Activity Index (SDAI), the Clinical Disease Activity Index (CDAI), the Disease Activity Score (DAS), and the 28-joint DAS (DAS28)*24.
| Elements | SDAI | CDAI | DAS | DAS28 |
|---|---|---|---|---|
| No. of swollen joints | Simple count (0–28) | Simple count (0–28) | More extensive joint counts (0–2.86) | Simple count, square root transformed (0–1.48) |
| No. of tender joints | Simple count (0–28) | Simple count (0–28) | Ritchie Index: graded joint counts; square root transformed (0–4.77) | Simple count, square root transformed (0–2.96) |
| Acute-phase reactants | CRP, mg/dl (0.1–10.0) | — | ESR, log transformed (0.23–1.51)** | ESR, log transformed (0.49–3.22)** |
| Patient global health | — | — | VAS, mm (0–0.72)** | VAS, mm (0–1.40)** |
| Patient global disease activity | VAS, cm (0–10.0) | VAS, cm (0–10.0) | — | — |
| Evaluator global disease activity | VAS, cm (0–10.0) | VAS, cm (0–10.0) | — | — |
| Total index | No immediate scoring due to CRP; simple calculation possible (0.1–86.0) | Immediate scoring due to CRP; simple calculation possible (0.1–76.0) | No immediate scoring due to ESR; simple calculator required (0.23–9.87) | No immediate scoring due to ESR; simple calculator required (0.49–9.07) |
↵* Based on transformation and weighting of individual elements according to the formula of the respective index; assumed ranges are 2–100 mm/h for ESR, and 0.1–10 mg/dl for CRP. Table reproduced with permission (Clin Exp Rheumatol 2005;23 Suppl 39:S100–8).
↵** The DAS and DAS28 formulae have also been modified to include CRP instead of ESR, and to substitute the patient global health by a constant. These versions are less commonly used and not well validated. CRP: C-reactive protein; ESR: erythrocyte sedimentation rate; VAS: visual analog scale.