Table 1. Patient characteristics.

Data are n (%), mean ± SD or median (IQR). Please see the flowchart (Fig. 1); 11 patients with CSA developed clinical arthritis but not RA and were neither included in the group that developed RA, nor in the group that did not progress to RA.

	All CSA-patients, at CSA-onset (n=600)	CSA-patients developing RA, at CSA-onset (n=88)	CSA-patients not developing RA, at CSA-onset (n=501)	RA-patients, at diagnosis (n=710)
Female	469 (78)	65 (74)	398 (79)	448 (63)
Age in years	44 ± 13	48 ± 13	43 ± 12	59 ± 15
Symptom duration in days	137 (68-310)	153 (61-364)	134 (68-296)	93 (49-219)
Fatigue	51 ± 29	45 ± 29	52 ± 28	50 ± 30
Pain	47 ± 23	48 ± 27	47 ± 22	58 ± 25
TJC-53	5 (2-10)	5 (2-7)	5 (2-10)	8 (4-14)
CRP increased (≥5 mg/L)	130 (22)	32 (36)	96 (19)	468 (66)
DAS44-CRP	2.2 ± 0.7	2.1 ± 0.6	2.2 ± 0.7	3.5 ± 1.0
ACPA-positive	79 (13)	45 (51)	33 (7)	311 (44)
RF-positive	115 (19)	51 (58)	63 (13)	343 (48)
Number of small joints with imaging detected inflammation (0-10)	0 (0-1)	2 (1-3)	0 (0-1)	3 (1-5)

CSA: clinically suspect arthralgia; RA: rheumatoid arthritis; TJC: tender joint count; CRP: c-reactive protein; DAS: Disease Activity Score; ACPA: anti-citrullinated protein antibody; RF: rheumatoid factor; MRI: magnetic resonance imaging.