Table 2 Comparison of IgM‐RF+ and IgM‐RF– patients.

Variables	IgM‐RF+	IgM‐RF−	p Value
	(n = 54)	(n = 26)
CRP (mg/ml)	1.5 (2.1)	2.0 (3.3)	0.96*
MMP‐3 (%)	51.9	34.6	0.23**
Number of joints with synovitis	12.1 (5.6)	10.6 (7.8)	0.22*
Mean E‐rate of 30 joints	7.6 (3.2)	7.6 (2.3)	0.58*
Bone marrow oedema
%	63.0	42.3	0.08**
No	2.7 (3.5)	1.4 (2.7)	0.07*

Data are mean (SD) unless stated otherwise. Division of patients by IgM‐RF seropositivity showed a higher proportion of patients with bone marrow oedema compared with those negative for the antibody, but the difference was not significant: *by Mann‐Whitney U test; †by χ² test.