Anticitrullinated protein antibody (ACPA) in rheumatoid arthritis: influence of an interaction between HLA-DRB1 shared epitope and a deletion polymorphism in glutathione s-transferasein a cross-sectional study

Table 2 Association of GSTM1-null, HLA-DRB1 shared epitope (SE) and smoking with ACPA positivity in rheumatoid arthritis^a

	VARA (n= 703)			SONORA (n= 610)
	ACPA+ (%)	OR (95% CI)	Pvalue	ACPA+ (%)	OR (95% CI)	Pvalue
GSTM1-present	73	Ref.	-	69	Ref.	-
GSTM1-null	79	1.45 (1.02 to 2.05)	0.039	69	1.00 (0.71 to 1.42)	0.981
Never smoking	69	Ref.	-	69	Ref.	-
Ever smoking	78	1.48 (0.97 to 2.26)	0.067	68	0.90 (0.62 to 1.30)	0.574
Former smoking	77	1.41 (0.91 to 2.19)	0.129	65	0.77 (0.52 to 1.14)	0.193
Current smoking	81	1.68 (0.98 to 2.88)	0.059	74	1.23 (0.76 to 1.99)	0.407
SE-negative	53	Ref.	-	54	Ref.	-
SE-positive (one or two alleles)	84	4.36 (2.98 to 6.37)	< 0.001	75	2.56 (1.77 to 3.70)	< 0.001
SE-positive (one allele)	79	3.23 (2.17 to 4.81)	< 0.001	68	1.77 (1.21 to 2.60)	0.003
SE-positive (two alleles)	93	10.65 (5.61 to 20.20)	< 0.001	92	10.27 (5.05 to 20.89)	< 0.001

^aACPA, anticitrullinated protein antibody; CI, confidence interval; GSTM1, glutathione S-transferase Mu-1; OR, odds ratio; SE, shared epitope; SONORA, Study of New-Onset Rheumatoid Arthritis; VARA, Veterans Affairs Rheumatoid Arthritis Registry. All analyses are age- and gender-adjusted. "Ref." = referent group in each analysis.

ISSN: 1478-6362