Genetic polymorphisms in PTPN22, PADI-4, and CTLA-4 and risk for rheumatoid arthritis in two longitudinal cohort studies: evidence of gene-environment interactions with heavy cigarette smoking

Table 5 Stratified analyses of genotype and RA risk in the pooled NHS/NHSII samples

Gene/genotype	RF status of RA cases (versus controls)
	RF-positive cases	RF-negative cases
PTPN22
CC	1.00 (ref.)	1.00 (ref.)
CT/TT	1.75 (1.18–2.59)	1.32 (0.85–2.06)
CTLA-4
AA	1.00 (ref.)	1.00 (ref.)
AG/GG	1.18 (0.78–1.80)	1.11 (0.71–1.72)
PADI-4
GG	1.00 (ref.)	1.00 (ref.)
GA/AA	1.10 (0.79–1.54)	0.96 (0.66–1.38)

The analysis was unconditional logistic regression adjusting for year of birth, pack-year smoking, parity, breast-feeding, menstrual irregularity, age at menarche, menopausal status and postmenopausal hormone use. Values are expressed as odds ratio (95% confidence interval). CI, confidence interval; NHS, Nurses' Health Study; OR, odds ratio; RA, rheumatoid arthritis; RF, rheumatoid factor.

ISSN: 1478-6362