Table 2. Demographic and clinical characteristics of patients with ACPA-negative undifferentiated arthritis according to the pattern of joint involvement.

	Group 1 hand N=302	Group 2 hand+large N=77	Group 3 large N=23
Age	54.7 (15.2)*	50.2 (15)*†	42.2 (15.3)*†
Female gender	225 (74.5)	59 (76.6)	15 (65.2)
Psoriasis (family history)	21 (7)	7 (9.1)	3 (13)
Symptoms duration, weeks	24.4 (12.3–36.6)	22.4 (11–33.1)	21.3 (9.2–28.4)
Symptoms duration (weeks)
<6	10 (3.3)*	12 (15.6)*	3 (13.0)
<12	60 (19.9)*	24 (31.2)*	7 (30.4)
Morning stiffness (min)
<30	71 (23.5)	14 (18.2)	6 (26.1)
30–60	130 (43)	38 (49.4)	12 (52.2)
>60	101 (33.4)	25 (32.5)	5 (21.7)
SJC28	2.4 (1.1)*	2.7 (2.2)†	1.1 (0.7)*†
SJC44	2.4 (1.6)*	3.4 (2.3)*†	1.5 (0.9)*†
Monarthritis	104 (34.4)*	0 (0)*†	18 (78.3)*†
Oligoarthritis	180 (59.6)*	69 (89.6)*†	5 (21.7)*†
Polyarthritis	18 (6)	8 (10.4)	0 (0)
Symmetric arthritis	124 (41.1)*	33 (42.9)	5 (21.7)*
TJC28	3.9 (5.5)	3.7 (4.3)	1.9 (2.5)
TJC46	5.7 (8.2)	6.2 (6.9)†	3.2 (3.8)†
DAS28	3.6 (1.1)	3.6 (1)	3.3 (0.8)
VAS pain	53.8 (25.2)	55.1 (26.3)	55.6 (22.1)
PGA	52.3 (25.6)	52.8 (26.8)	57.3 (19.6)
HAQ	0.56 (0.47)*	0.71 (0.57)*	0.69 (0.41)*
ESR	14.2 (15.4)	16.5 (18.5)	13.8 (14.5)
CRP	0.6 (1)*	0.7 (1.1)	1 (1.5)*
RF	14 (4.6)	3 (3.9)	1 (4.3)
ANA	134 (44.4)	39 (50.6)	13 (56.5)
SHS erosion score ≥1	23 (7.6)	6 (7.8)	1 (4.3)

^*P<0.05 group 1 vs others.

^†P<0.05 group 2 vs group 3.

ACPA, anticitrullinated protein autoantibodies; ANA, antinuclear antibodies; CRP, C reactive protein; DAS28, 28-joints Disease Activity Score; ESR, erythrocyte sedimentation rate; HAQ, Health Assessment Questionnaire; PGA, Patient Global Assessment; RF, rheumatoid factor; SHS, Sharp van der Heijde Score; SJC, swollen joint count; TJC, tender joint count; VAS, visual analogue scale.