Independent associations of anti-cyclic citrullinated peptide antibodies and rheumatoid factor with radiographic severity of rheumatoid arthritis

Table 3 Association between SE alleles and anti-CCP status

RF status	Number of SE alleles	Proportion anti-CCP positive	OR (95% CI)	P
All	2	214/241	4.94 (2.94–8.22)	<0.001
	1	307/373	2.90 (1.89–4.43)
	0	98/159	1
RF positive	2	162/170	4.15 (1.79–9.58)	<0.01
	1	236/253	2.85 (1.41–5.77)
	0	78/94	1
RF negative	2	52/71	6.16 (3.00–12.6)	<0.001
	1	71/120	3.26 (1.74–6.11)
	0	20/65	1

Absolute numbers of anti-CCP-positive patients in each subgroup are given. OR with 95% CI are shown for anti-CCP positivity associated with carriage of two or one SE allele versus no SE alleles for RF positive, RF negative and combined subgroups. P values are for χ² tests with two degrees of freedom comparing the proportion of anti-CCP positive patients in subgroups carrying two, one, or no SE alleles. anti-CCP, anti-cyclic citrullinated peptide antibody; CI, confidence interval; NS, not significant; OR, odds ratio; RF, rheumatoid factor; SEM, standard error of the mean.

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