Table 1 Formulas used to calculate disease activity measures.

Status* disease activity measure	Formula
DAS44/ESR‐4 item10
DAS44/ESR‐3 item3
DAS44/CRP‐4 item3
DAS44/CRP‐3 item3
DAS28/ESR‐4 item11
DAS28/ESR‐3 item3
DAS28/CRP‐4 item3
DAS28/CRP‐3 item3
SDAI8	TJC28 + SJC28 + patient global (10 cm) + MD global (10 cm) + CRP
CDAI13	TJC28 + SJC28 + patient global (10 cm) + MD global (10 cm)

Response† disease activity measure	Criteria
EULAR improvement criteria	Please see table 4
ACR X% (20/50/70) (response measure)9	TJC 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.