Table 1. Baseline characteristics of the CSA Leiden cohort and CSA Rotterdam cohort.

	CSA Leiden (n = 433)	CSA Rotterdam (n = 101)
Female sex, n (%)	340 (79)	78 (77)
Age, mean (s.d.), years	44 (13)	45 (12)
Symptom duration, median (IQR), weeks	19 (10–48)	19 (12–32)
Positive squeeze test hand, n (%)	177 (42)	34 (34)
Morning stiffness ≥60 min, n (%)	65 (18)	19 (22)
Start of symptoms in small joints, n (%)	391 (93)	85 (93)
TJC68, median (IQR)	4 (2–9)	3 (0–7)
CRP, median (IQR)	3.0 (1.9–4.1)	3.0 (1.0–4.0)
RF positive, n (%)	81 (19)	25 (26)
ACPA positive, n (%)	58 (14)	25 (25)

CSA: clinically suspect arthralgia; IQR: interquartile range; TJC68: tender joint count of 68 joints.