Table 7.

Predisposing effect of shared epitope genotypes on anticyclic citrullinated peptide antibody and rheumatoid factor seropositivity

	aCCP		RF
SE groups	OR (95% CI)	P value	OR (95% CI)	P value
S1 (n = 24)	2.4 (1.1 to 5.4)	0.0113*	1.6 (0.9 to 2.9)	0.1245
S3D (n = 17)	2.3 (1.0 to 5.4)	0.0287*	1.7 (0.9 to 3.0)	0.1059
S1/S3D (n = 50)	2.3 (1.0 to 5.3)	0.0049**	1.6 (0.9 to 2.9)	0.0611
S2 (n = 11)	2.2 (0.9 to 5.2)	0.0995	1.6 (0.9 to 3.1)	0.1930
S3P (n = 28)	2.5 (1.1 to 5.6)	0.0075**	1.6 (0.9 to 3.0)	0.0563
S2/S3P (n = 47)	2.4 (1.1 to 5.5)	0.0025**	1.6 (0.9 to 2.8)	0.0687

aCCP = anticyclic citrullinated peptide antibodies; RF = rheumatoid factor; SE = shared epitope. OR (95% CI) and P values were calculated using Fisher's exact test to compare rheumatoid arthritis patients with RA patients with the X/X genotype (n = 12). *P < 0.05. **P ≤ 0.008 values are highly significant. Groups S1, S3D, S2 and S3P consisted of the pooled homozygotes (SS) and heterozygotes (SX) for each group. Group S1/S3D consisted of S1/S1, S1/X, S3D/S3D, S3D/X and S1/S3D. Group S2/S3P consisted of S2/S2, S2/X, S3P/S3P, S3P/X and S2/S3P.