Table 2

Odds ratios for developing rheumatoid factor and anti-cyclic-citrullinated peptide antibodies in the presence of tobacco exposure and/or shared epitope alleles in all patients with rheumatoid arthritis at one year

	TE	SE	RF+	RF−	OR	95% CI	p Value
	−	−	23	31	1.00	–	–
	+	−	25	23	1.47	0.62 to 3.45	0.33
	−	+	54	54	1.35	0.66 to 2.75	0.37*
	+	+	72	30	3.23	1.54 to 6.81	<0.001*
							0.002 π

	TE	SE	Anti-CCP+	Anti-CCP−	OR		p Value
	−	−	18	34	1.00	−	–
	+	−	17	30	1.07	0.43 to 2.65	0.87
	−	+	58	44	2.49	1.18 to 5.31	0.01†
	+	+	67	24	5.27	2.37 to 11.80	<0.001†
							<0.001 π

Anti-CCP	TE	SE	RF+	RF−	OR	95% CI	p Value
+	−	−	14	4	1.00	–	–
+	+	−	17	0	∞	∞	0.10
+	−	+	46	12	1.10	0.22 to 4.42	0.88‡
+	+	+	54	13	1.19	0.24 to 4.68	0.79‡
							0.23
−	−	−	7	27	1.00	–	–
−	+	−	8	22	1.40	0.38 to 5.32	0.57
−	−	+	6	38	0.61	0.12 to 2.40	0.41‡
−	+	+	7	17	1.59	0.39 to 6.34	0.45‡
							0.39π

RF	TE	SE	Anti-CCP+	Anti-CCP−	OR	95% CI	p Value
*TE−/SE+ v TE+/SE+: OR = 2.4 (95% CI, 1.3 to 4.4), p = 0.002.
†TE−/SE+ v TE+/SE+: OR = 2.1 (95% CI, 1.1 to 4.1), p = 0.02).
‡Comparison of TE−/SE+ v TE+/SE+ not significant.
π, p value of χ² analysis of 2×4 table.
CI, confidence interval; anti-CCP, anti-cyclic-citrullinated peptide; OR, odds ratio; RF, rheumatoid factor; SE, presence of one or two shared epitope alleles; TE, current and past smokers as indicated in the medical history.
+	−	−	14	7	1.00	–	–
+	+	−	17	8	1.06	0.26 to 4.34	0.92
+	−	+	46	6	3.83	0.91 to 16.07	0.03‡
+	+	+	54	7	3.86	0.96 to 15.11	0.02‡
							0.02π
−	−	−	4	27	1.00	–	–
−	+	−	1	22	0.31	0.01 to 3.47	0.28
−	−	+	12	38	2.13	0.56 to 9.97	0.22†
−	+	+	13	17	5.16	1.28 to 24.71	0.01‡
							0.04π