Table 2

The relation between IgM-RF status and levels and outcome variables

Correlation of IgM-RF levels at baseline^#

P¹

IgM-RF positive at baseline (n = 255)^$

IgM-RF negative at baseline (n = 280)^$

P²

IgM-RF level at baseline (IU/ml), median (IQR)

x

100 (60-200)

10 (6-14)

IgM-RF level at 1 year (IU/ml), median (IQR)

x

51 (23-97)

9 (5-10)

DAS28 at baseline

0.11

0.01

4.88 (1.19)

1.66 (1.29)

0.01

HAQ at baseline

0.01

0.79

1 (0.5-1)

0.94 (0.5-1.5)

0.49

SHS at baseline

0.11

0.02

0 (0-1)

0 (0-0)

0.00

DAS28 at 2-year follow-up

0.17

0.69

2.92 (1.30)^&

2.84 (1.23)^&

0.58

HAQ at 2-year follow-up

0.04

0.41

0.5 (0-0.88)

0.38 (0-0.88)

0.43

SHS at 2-year follow-up

0.22

0.00

2 (0-9)

0 (0-4)

0.00

^#Spearman correlation ^$Median with IQR unless stated otherwise^&Mean with SD P-value of correlation² P-value IgM-RF positive versus IgM-RF negative.

DAS = disease activity score; HAQ = Health Assessment Questionnaire; Ig = immunoglobulin; IQR = interquartile range; RF = rheumatoid factor; SD = standard deviation; SHS = Sharp-van der Heijde score.

Ursum et al. Arthritis Research & Therapy 2010 12:R8   doi:10.1186/ar2907