Table 1 Formulas used to calculate disease activity measures
Status* disease activity measureFormula
DAS44/ESR-4 item10Formula
DAS44/ESR-3 item3Formula
DAS44/CRP-4 item3Formula
DAS44/CRP-3 item3Formula
DAS28/ESR-4 item11Formula
DAS28/ESR-3 item3Formula
DAS28/CRP-4 item3Formula
DAS28/CRP-3 item3Formula
SDAI8TJC28 + SJC28 + patient global (10 cm) + MD global (10 cm) + CRP
CDAI13TJC28 + SJC28 + patient global (10 cm) + MD global (10 cm)
Response† disease activity measureCriteria
EULAR improvement criteriaPlease see table 4
ACR X% (20/50/70) (response measure)9TJC and SJC must exhibit X% improvement plus X% improvement of any 3 of: acute phase reactant (ESR/CRP), MD global, patient global, pain, and physical function
  • RAI, Ritchie Articular Index (0–78); SJC44, swollen joint count for 44 joints; SJC28, swollen joint count for 28 joints; TJC28, tender joint count for 28 joints; patient global or GH, patient global assessment; MD global, physician global assessment; ESR, Westergren erythrocyte sedimentation rate (mm/h); CRP, C-reactive protein (mg/dl); SDAI, Simplified Disease Activity Index; CDAI, Clinical Disease Activity Index; DAS, Disease Activity Score (http://www.das-score.nl/www.das-score.nl).

  • *Status measure assesses disease activity at a specific point in time.

  • †Response measure assesses how disease activity changes over time, eg, response to medication.