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Table 3 Calculating measures of biological interaction between genotypes and environmental exposures

From: The 341C/T polymorphism in the GSTP1 gene is associated with increased risk of oesophageal cancer

Dichotomous risk factors   RR 95% CI RERI AP S
Risk 1 a (Genotypes) Risk 2   lower upper    
GSTT1*0/*0 alcohol 2.158 1.175 3.965 -0.322 -0.149 0.783
GSTT1*0/*0 smoking 1.771 0.958 3.274 -1.559 -0.880 0.331
GSTT1*0/*0 wood/charcoal 2.738 1.443 5.198 0.213 0.078 1.140
GSTM1*0/*0 alcohol 0.399 0.165 0.760 0.058 0.145 0.912
GSTM1*0/*0 wood/charcoal 1.075 0.508 2.276 -1.641 -1.527 0.044
GSTM1*0/*0 smoking 0.364 0.190 0.699 -0.148 -0.407 1.304
GSTP1 313 A/G +G/G alcohol 0.922 0.488 1.743 0.597 0.647 0.115
GSTP1 313A/G +G/G smoking 0.779 0.390 1.553 0.113 0.145 0.663
GSTP1 313A/G +G/G wood/charcoal 1.738 0.978 3.087 0.185 0.107 1.335
GSTP1 341C/T+T/T alcohol 6.321 3.054 13.09 -0.514 -0.081 0.912
GSTP1 341C/T+T/T smoking 4.284 2.158 8.507 1.032 0.241 1.458
GSTP1 341C/T+T/T wood/charcoal 29.87 8.968 99.49 27.38 0.917 19.40
  1. aThe references for the interaction exposures were; GSTM1*1 + non-exposure, GSTT1*1 + non-exposure, GSTP1 313 A/A + non-exposure, GSTP1 341 C/C + non-exposure. Where non exposure refers to any of the following; non-smoker, non-alcohol consumer, and not exposed to use of wood/charcoal. The interaction model used could only factor in two dichotomous risk factors. Thus the following genotype combinations were used; GSTM1 (GSTM1*1/*1 vs. GSTM1*0/*0); GSTT1 (GSTT1*1/*1 vs. GSTT1*0/*0); GSTP105 (A/A vs. A/G+GG); GSTTP114 (C/C vs. C/T+T/T). For each interaction, four disjoint categories were created. For example, in the case of smoking and GSTP114 (non-smoker and C/C, non-smoker and C/T+TT, smoker and C/C, smoker and C/T+T/T). RR= relative risk; RERI = the relative excess risk due to interaction; AP = the attributable risk due to interaction; S = the synergy index.