Seropositivity is associated with insulin resistance in patients with early inflammatory polyarthritis: results from the Norfolk Arthritis Register (NOAR): an observational study

Table 3 Associations between rheumatoid factor and anti-CCP antibodies with insulin resistance alone and in combination with one another after serial adjustment

Variable	Numbers of patients	Association with HOMA-IR TRF & IP risk factor adjusted IR β-Coefficient OR (95% CI) ^#
RF +ve *	90 (47%)	0.867 (0.204, 1.530)
ACPA +ve *	66 (35%)	1.423 (0.701, 2.146)
RF-ve/ACPA -ve	96 (49%)	0
RF +ve/ ACPA -ve ^†	29 (15%)	-0.015 (-0.973, 0.944)
ACPA+ve/ RF -ve^†	6 (3%)	0.932 (-0.898, 2.763)
Both RF+ve/ACPA+ve ^†	60 (31%)	1.472 (0.695, 2.250) ^√

* = Seropositive vs. seronegative for RF and ACPA (n = 193 and 191, respectively)
† = Patients stratified into four groups depending on autoantibody status and compared with other groups (n = 191)
√ = Model significantly different in patients positive for both RF and ACPA relative to those RF positive only (P = 0.0061) with age and gender and other parameters adjusted.)
^▲Linear regression producing β-coefficients were used for continuous outcome. β-coefficients are considered statistically significant if their 95% CI values do not include zero.
^#Logistic regression producing odds ratios used for binary outcomes. Odds ratios are considered significant if the 95% CI values do not include 1.
ACPA, anti-CCP antibody; IP, inflammatory polyarthritis; RF, rheumatoid factor.

ISSN: 1478-6362