Table 3

Odds ratios for developing RF and anti-CCP antibodies in the presence of tobacco exposure and/or shared epitope alleles in patients with undifferentiated arthritis

(A) All UA patients at two weeks:
TE	SE	IgM RF+	IgM RF−	OR	95% CI	p Value
−	−	12	55	1.00	−	−
+	−	13	48	1.24	0.47 to 3.29	0.63
−	+	19	60	1.45	4.60 to 3.59	0.34‡
+	+	18	54	1.53	0.62 to 3.82	0.31‡
						0.75π

TE	SE	Anti-CCP+	Anti-CCP−	OR	95% CI	p Value
−	−	6	54	1.00	–	to
+	−	9	48	1.69	0.49 to 6.19	0.35
−	+	20	47	3.83	1.33 to 12.53	0.01‡
+	+	21	47	4.02	1.40 to 13.09	0.01‡
						<0.01π


(B) Subgroup of UA patients who develop RA within one year:
TE	SE	IgM RF+	IgM RF−	OR	95% CI	p Value
−	−	6	12	1.00
+	−	8	14	1.14	0.26 to 5.24	0.84
−	+	15	22	1.36	0.37 to 5.44	0.61‡
+	+	19	13	2.92	0.76 to 11.90	0.08‡
						0.87π

TE	SE	Anti-CCP+	Anti-CCP−	OR	95% CI	p Value
−	−	8	10	1.00
+	−	8	13	0.77	0.18 to 3.33	0.69
−	+	19	16	1.48	0.41 to 5.46	0.50‡
+	+	21	9	2.92	0.74 to 11.66	0.08‡
						0.12π

(C) Subgroup of persistent UA patients at one year:
TE	SE	IgM RF+	IgM RF−	OR	95% CI	p Value
−	−	6	37	1.00
+	−	5	32	0.96	0.21 to 4.20	0.95
−	+	9	34	1.63	0.46 to 6.17	0.39‡
+	+	4	33	0.75	0.14 to 3.48	0.67‡
						0.62π

TE	SE	Anti-CCP+	Anti-CCP−	OR	95% CI	p Value
‡Comparison 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; UA, undifferentiated arthritis.
−	−	1	36	1.00
+	−	2	34	2.12	0.10 to 128	0.54
−	+	8	27	10.67	1.26 to 486	0.01‡
+	+	4	32	4.50	0.41 to 227	0.16‡
						0.03π