... whether they currently smoked and the number of cigarettes smoked per day From these reports, we calculated pack years of smoking (product of years of smoking and packs of cigarettes per day) Other ... in controls and 14% in cases) In analyses involving CTLA-4 and PADI-4, we assessed the risk for RA in dominant, additive, and recessive models Gene-environment and gene-gene interactions We conducted ... dRF-negative RA cases and all controls eP for AP, one of the indices of additive interactions between binary PTPN22 genotype and binary HLA-SE genotype f95% confidence interval and P value for AP not applicable...